Environmental Imperatives ReconsideredLISTO

8122019 Environmental Imperatives ReconsideredLISTO

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Current Anthropology Volume 40 Number 2 April 1999983209 1999 by The Wenner-Gren Foundation for Anthropological Research All rights reserved 0011-3204994002-0001$300

EnvironmentalImperatives

ReconsideredDemographic Crises in WesternNorth America during theMedieval Climatic Anomaly

by Terry L Jones Gary MBrown L Mark Raab Janet L

McVickar W GeoffreySpaulding Douglas J KennettAndrew York and Phillip LWalker

Review of late Holocene paleoenvironmental and cultural se-quences from four regions of western North America shows strik-ing correlations between drought and changes in subsistence pop-

ulation exchange health and interpersonal violence during theMedieval Climatic Anomaly (ad 800ndash1350) While ultimate cau-sality is difficult to identify in the archaeological record syn-chrony of the environmental and cultural changes and the nega-tive character of many human responsesmdashincreasedinterpersonal violence deterioration of long-distance exchange re-lationships and regional abandonmentsmdashsuggest widespread de-mographic crises caused by decreased environmental productiv-ity The medieval droughts occurred at a unique juncture in thedemographic history of western North America when unusuallylarge populations of both hunter-gatherers and agriculturalistshad evolved highly intensified economies that put them in un-precedented ecological jeopardy Long-term patterns in the archae-ological record are inconsistent with the predicted outcomes ofsimple adaptation or continuous economic intensification sug-gesting that in this instance environmental dynamics played amajor role in cultural transformations across a wide expanse of

western North America among groups with diverse subsistencestrategies These events suggest that environment should not beoverlooked as a potential cause of prehistoric culture change

terry l jones is Assistant Professor of Anthropology at Califor-nia Polytechnic State University San Luis Obispo Calif 93407USA

gary m brown is Project Manager with Western Cultural Re-source Management Inc 52 Camino del Oso Placitas NM87043 USA

l mark raab is Professor of Anthropology at California StateUniversity Northridge Calif 91330-8244 USA

137

janet l mc vickar is Project Director in the Anthropology Pro-gram of the the National Park Service PO Box 728 Santa FeNM 87504 USA

douglas j kennett is Assistant Professor of Anthropology atthe California State University Long Beach Calif 90840 USA

andrew york is Senior Archaeologist with KEA Environmen-tal 1420 Kettner Blvd Suite 620 San Diego Calif 92101USA

w geoffrey spaulding is Manager of Environmental Ser-vices Dames and Moore 7115 Amigo St Suite 110 Las VegasNev 89119 USA

phillip l walker is Professor of Anthropology at the Univer-sity of California Santa Barbara Calif 93106-3210 USA

The present paper was submitted 16 ii 98 and accepted 5 vi 98the final version reached the Editorrsquos office 6 vii 98

Once there was a famine there was no rainand no food They ate bleached bones pounded inthe mortar and acorn mush made of manzanitasThere were no deer and no meat it was a great fam-

ine The poor people ate alfilerillo seeds One oldwoman killed and roasted and ate her son wasvery hungry Then her brother came and killed herwith three arrows because she had eaten her childThey did not bury her but left her to be eaten by the coyotes It was a great famine But the peoplewho lived on the shore did not die because they ateabalones But even they were thin because they

had nothing but seaweed to eatmaria ocarpia Salinan-speaker 1918

While the need to recognize paleoenvironmental vari-ability in archaeological models is well established inthe study of North American prehistory the role of en-

vironment as an influence on cultural change has in re-cent years been increasingly overlooked Misgivingsabout environmental determinismmdashthe flawed theoryrooted in Greek and Roman philosophy that attemptsto equate climatic regimes with personality types andposits mechanistic responses to climatic changemdashhaveencouraged the development of population-based expla-nations first as part of cultural evolutionary construc-tions and most recently in the form of neo-Darwinismand models of economic intensification Some have re-jected ecological approaches altogether in favor of post-modernist foci on power social conflict elite conspira-cies and gender inequities minimally influenced byenvironmental context (eg Bender 1985 Brumfiel

1992) Both postmodernists and neo-Darwinists furtherpoint to an overemphasis on adaptationism in manyecological studies that ignores the full spectrum of bio-logical and behavioral variability involved in humanevolution Despite the recent disregard for environmentas a cause of cultural change and the success of someneo-Darwinian models in which environmental causal-ity is shunned we suggest that the categorical rejectionof environment as a potential cause of cultural changewill lead to unsuccessful if not naıve characterizationsof prehistoric human behavior This is not to say that



138 c u r r e n t a n t h r o p o l o g y Volume 40 Number 2 April 1999

other factors do not play pivotal roles but we suggestthat the linkages between the physicalbiotic environ-ment and human subsistence and settlement are suffi-ciently tight to warrant serious consideration of envi-ronmental change as a potentially important factor inexplanations of cultural change Environment can anddid cause cultural changes in the prehistoric past and

attribution of cause to environment in archaeologicalmodels need not be deterministic A downturn in envi-ronmental productivity in particular can affect culturechange by creating demographic imbalances that re-quire some kind of response but they do not dictate thecharacter of the response in a given area Demographicstress can be felt in various ways but more often thannot its effects are negative (eg increased mortalitypoor health and decreased fecundity) Downturns re-lated to climate can simultaneously affect large por-tions of a continent or similar latitudinal zones acrosscontinents so that synchronous cultural changes maycrosscut vastly different subsistence regimes As simpleas these points may be current theories of prehistoric

humanenvironmental relationships increasingly fail toacknowledge circumstances of environmentally in-duced culture change particularly those engenderingnegative human behaviors and outright cultural fail-ures

In western North America a theoretical amalgam hasemerged from a long complex history of thought inwhich hunter-gatherers and agriculturalists have beenperceived very differently in their relationships withthe physical environment Cultural ecological theoriesfrom the early part of this century based largely on eth-nographic observations acknowledged subsistencedifficulties for both foragers and agriculturalists in aridenvironments (eg Antevs 1948 Douglass 1929 Wor-

mington 1947 Steward 1938) but envisioned a benignenvironmental past for hunter-gatherers in California(Kroeber 1925) In the 1950s and rsquo60s these perspectivesgave way to models of adaptation in which environmen-tal flux was routinely accommodated by simple culturaladjustments and or migration (Kroeber 1955) that withfew exceptions (eg Moratto King and Woolfenden1978) involved no crises stress violence or demo-graphic or environmental problems Much of westernNorth American prehistory was linked to incrementalpopulation growth and unilinear cultural evolution(Fredrickson 1974 Chartkoff and Chartkoff 1984)These perspectives have recently been supplanted byneo-Darwinian constructs and models of economic in-

tensification applied to both foragers (Baumhoff andBettinger 1982 Basgall 1987 Bouey 1987 Hildebrandt1997) and agriculturalists (Ezzo 1992) that ignore envi-ronmental flux as a cause of change and posit linear pro-gessions in human subsistence and social complexity(Fredrickson 1994)

Some types of environmental events however pro-voke changes that simply cannot be ignored Especiallycritical are those that impact the quality and abundanceof basic subsistence resources most obvious of whichare high-intensity rapidly transpiring environmental

oscillations associated with natural disasters (egfloods fires hurricanes) and short-term ecological ca-tastrophes (see Torrey 1978 1979 Oliver-Smith 1996)Such events are commonly overlooked in adaptationistmodels They may be hard to recognize in the archaeo-logical record particularly in the distant past but inter-vals of sustained andor repeated ecological and demo-

graphic instability should be detectable The thesis wedevelop here is that the interval between ad 800 and1350 known to climatologists alternatively as the Me-dieval Warm Period the Secondary Climatic Optimumthe Little Optimum (Ingram Farmer and Wigley 1981Sulman 1982) or the Medieval Climatic Anomaly(Stine 1994) was a time of increased aridity that co-incided with a unique pattern of demographic stressand frequent economic crises across much of westernNorth America Large populations of agriculturalistsand hunter-gatherers were confronted with serious andabrupt declines in productivity caused by repeated andprolonged droughts This interval is increasingly recog-nized as a time of droughts and warm temperatures in

many parts of the world (Lamb 1977 1982 Hughes andDiaz 1994) It also witnessed a profusion of widespreadcultural changes in the archaeological record many ofthem quite extreme (eg increases in interpersonal vio-lence declines in health deterioration of long-distancetrade networks population reductions andor reloca-tions site and regional abandonments and occupa-tional hiatuses) We believe that the plethora of culturalchanges and the negative character of many of them re-flect widespread crises related to populationresourceimbalances drought-related environmental deteriora-tion and shortages of food and water Many current in-terpretations of regional prehistories with some recentexceptions (eg Arnold 1992a b) largely fail to con-

sider the possibility of environmentally induced demo-graphic stress in nondeterministic ways This is partic-ularly true in California where the biotic environmenthas been portrayed as rich and reliable with no sus-tained intervals of resource shortage Recent archaeo-logical models (eg Basgall 1987 Bouey 1987 Hilde-brandt 1997) associate persistent population growthwith this perceived environmental richness but fail toconsider that economic intensification could placehunter-gatherers in positions of demographic risk simi-lar to those of sedentary agriculturalists

Our thesis begins with paleoclimatic and paleohydro-logic data demonstrating that the period between ad800 and 1350 was punctuated by lsquolsquoepic droughtsrsquorsquo (Stine

1994) These droughts and the more broadly timed epi-sodes of increased temperatures attendant upon the Me-dieval Climatic Anomaly had direct effects on terres-trial ecosystems by impacting water sources andreducing primary production and therefore harvestablebiomass The relationship between effective moistureand primary production is well documented (eg Bar-bour Bourke and Pitts 1987 Lieth 1975 Shmida Even-ari and Noy-Meir 1986) Equally important from thepoint of view of understanding the constraints on peo-ples in arid-to-semiarid regions is the steep relationship



j o n e s e t a l Environmental Imperatives Reconsidered 139

between incremental increases (or decreases) in precipi-tation and ecosystem productivity The availability ofharvestable plant resources in either agricultural or nat-ural ecosystems is a direct function of productivity Themore severe and prolonged the drought the greater itsdeleterious effect on ecosystem productivity and conse-quent terrestrial resource availability These relation-

ships are not hypothetical they represent realities facedby traditional peoples in a variety of socioeconomic andpolitical systems At the same time we acknowledgethat various responses might be possible as no environ-mental challenge forces a human population to changein a particular way

Given the biological realities we should expect thatthe prolonged droughts of the Medieval ClimaticAnomaly impacted the availability of food and water tothe point that human societies experienced significantdemographic stress With this expectation we turn tothe archaeological records of four regions in westernNorth America to determine whether important cul-tural changes can be explained as direct or indirect ef-

fects of stress Because this study is concerned with therelatively recent past the archaeological record oughtto be sufficiently detailed to provide the information re-quired to demonstrate synchrony and to determinewhether changes are consistent with predicted re-sponses to environmental stress and resource shortagesGiven the differences in subsistence strategies popula-tion density social organization and bioclimatic con-text between the regions we examine we should expectto see a spectrum of human responses Nevertheless wecan also anticipate evidence for population reductionsresulting from reduced ecosystem carrying capacity andpopulation shifts to areas with more predictablepro-ductive resources Sociopolitically reduced resource

availability should be reflected in increased competi-tion between groups and social stress within groupsThe alternative hypothesis based on adaptationist per-spectives would posit little or no demographic stressand a less tumultuous past as incremental populationgrowth continued simple adaptive adjustments wouldbe made (eg more low-ranked foods would be added todiets new extractive technologies would be developedand intergroup trade would increase)

Our paper has four parts The first discusses past andcurrent perceptions of prehistoric human ecology inwestern North America This is followed by a review oflate Holocene paleoenvironmental records showing theevidence for widespread and prolonged aridity during

the Medieval Climatic Anomaly This in turn is fol-lowed by archaeological case studies from the ColoradoPlateau the central California coast the southern Cali-fornia coast and the Mojave Desert (fig 1) all of whichshow signs of significant cultural flux synchronouswith periods of drought These droughts cannot be con-sidered the sole cause of major cultural changes formore often than not human behavior is a response tomultiple social and environmental variables (MorattoKing and Woolfenden 1978151) Attributing certainsignificant cultural changes to demographic stress re-

sulting from severe downturns in environmental pro-ductivity is nonetheless warranted since trends in thearchaeological record are inconsistent with predictionsof economic intensification or simple adaptation

Ecological Themes in Western NorthAmerican Prehistory

The influence of environment has long been a theme inwestern North American prehistory and ethnology In1938 Julian Steward suggested that hunter-gathererlifeways in the Great Basin were heavily influencedthough not determined by difficulties of local ecologylsquolsquoThis however must not be construed as lsquoenvironmen-tal determinismrsquo which is generally understood to pos-tulate some kind of automatic and inevitable effect ofenvironment upon culturersquorsquo (Steward 19382) Jesse Jen-ningsrsquos (1957) Desert Culture model was more deter-ministic It envisioned a mobile opportunistic hunter-

gatherer lifeway that persisted largely unchanged in theGreat Basin for more than 9000 years as an effective ifnot necessary adaptation to extreme environmentalconditions A counterproposal was developed by RobertHeizer and his students who argued that most of theGreat Basin was abandoned because of hot dry condi-tions during the Altithermal a warm interval originallydefined by Antevs (1948 1953) and variously dated be-tween ca 8000 and 4000 years bp People werethought to have returned to the Basin only when cli-mate ameliorated A measure of determinism is impliedin the putative inability of hunter-gatherers to copewith these conditions for thousands of years On theCalifornia coast Glassow Wilcoxon and Erlandson

(1988) suggested that populations of maritime hunter-gatherers in the Santa Barbara Channel were suppressedduring the Altithermal but increased dramaticallywhen marine productivity improved afterward Thismodel perpetuates deterministic thinking about the Al-tithermal as it draws parallels between natural produc-tivity and human population with an inevitable humanadaptation to increased environmental productivityMoratto (1984) likewise suggested that human numbersdecreased in California during the peak of the Altither-mal and that much of the regionrsquos settlement and lan-guage history can be related to climatic fluctuationswith warm intervals producing retreat from the aridsectors Moratto King and Woolfenden (1978) were the

first to suggest that the period between ad 600 and1400 may have been marked by social disruption andviolence related to stresses wrought by an intensewarmdry episode However the distinctiveness of theMedieval Climatic Anomaly as an interval of crisis un-matched during the late Holocene is lost in Morattorsquosoverarching model of continuous climate change andpopulation migration

Other recent conceptualizations of humanenviron-ment relationships among western North Americanhunter-gatherers attribute limited measures of cause to




Fig 1 The Southwestern United States showing major geographic regions mentioned in text

environmental change Larson Johnson and Michael-son (1994) have suggested that the final native retreatfrom San Miguel Island in the Santa Barbara Channel tomainland Spanish missions coincided with a severe ElNin ˜ o that rendered the islandrsquos marine resource base in-adequate This study is unprecedented in California forits consideration of global climatic influences on localculture change although it attributes ultimate causal-ity to the historical phenomenon of Spanish missioniza-tion Of more relevance to the current discussion is thedebate in southern California over the relationships ofenvironmental variability subsistence and exchangeduring the transition between Middle and Late periods

of regional prehistory (ca ad 1200ndash1300) In two pro-vocative papers Arnold (1992a b) has linked a dramaticincrease in production of exchange commodities (shellbeads) on Santa Cruz Island to an interval of warm seatemperatures and depressed marine productivity Bor-rowing Gouldrsquos (1984) concept of punctuated equilib-rium from paleontology Arnold explains this purportedemergence of elite-managed craft specialization as a re-sponse to catastrophic environmental change (More re-cently however Arnold Colten and Pletka [1997] havedeemphasized the role of environment as a primary

causal variable [Raab and Bradford 1997]) Arnoldrsquos the-sis helped to precipitate our own interest in the earlycenturies of the current millennium and the possibilitythat environmental deterioration was a cause of changeover a much wider area than Santa Cruz Island or theSanta Barbara Channel

Conceptualizations of humanenvironmental rela-tionships in the American Southwest have taken acourse more similar to that in the Great Basin whereexplanations of culture change related to the arid andunpredictable physical environment have a long his-tory Beginning with Douglassrsquos (1929) discovery of thelsquolsquoGreat Droughtrsquorsquo in the tree-ring record of the late 13th

century periods of sustained drought and correspondinglocal and regional abandonments have been observed inmany cases on the Colorado Plateau Early efforts (egFritts Smith and Stokes 1965 Wormington 1947) pos-iting somewhat mechanistic responses have been re-placed by more sophisticated models (eg Euler et al1979 Dean et al 1985 Dean 1988a Gumerman 1988Lipe 1995) that recognize climate change as a signifi-cant causal variable within a systemic perspectiveAlthough these models emphasize the potential for ad-justment to environmental flux some hint at the




possibility of crisis emerging when populations exceedcarrying capacity Lipe (1995) has summarized abun-dant evidence for social turbulence including warfaredecreased interregional trade and sociopolitical disinte-gration preceding the abandonment of large portions ofthe Colorado Plateau Haas and Creamer (1992) havelikewise suggested that interpersonal violence was

among the behaviors exceeding simple cultural adjust-ment to environmental stress A growing body of corre-lations between drought-related environmental stressand population dynamics indicates that simple adaptiveadjustment cannot account for many diachronic pat-terns in Southwestern prehistory (eg Larson and Mi-chaelson 1990 Larsen et al 1996) Arguments againstdrought-related causality have also been advanced (egAllison 1996 Lightfoot and Upham 1989 Plog 1990)but as Larsen et al (1996218) point out it is prematureto dismiss the influence of drought on prehistoricSouthwestern population trajectories especially whenthe ecological effects of large sedentary populations aretaken into account At the extreme paleoecological

data have been argued to indicate that deforestation ofChaco Canyon was due to fuelwood and constructiondemands (Betancourt and Van Devender 1981 Samuelsand Betancourt 1983 Betancourt 1990) If such ecosys-tems were already stressed by the intensive land usepractices of a sedentary population a rapid shift to in-creased aridity could have had a dramatic impact onboth environment and human populations

While assertions that drought-related environmentalproblems influenced Puebloan agriculturalists havebeen made for nearly a century the possibility that sim-ilar problems were experienced by hunter-gatherers inadjoining areas of the Great Basin and California hasonly recently been considered In addition to the Sali-

nan myth recounted above (quoted by Mason 1918120)reference to drought-related famines can be found inethnographic accounts of the Chumash (Walker De-Niro and Lambert 1989351) Pomo (Kniffen 1939366)and Shoshone (Steward 193820) Nonetheless with fewexceptions (eg Arnold 1992a b Walker DeNiro andLambert 1989) there has been little attempt to considerthe archaeological implications of such events Foodshortages are thought to have been relatively brief andpredictable seasonal phenomena (see de Garine andHarrison 1988vi) that would have left no lasting large-scale archaeological signatures

There appears to have been little attempt to recognizecrisis events outside the Southwest but there has been

ample consideration of the effectiveness of hunter-gath-erer subsistence practices relative to those of agricultur-alists in fending off catastrophic famine Most of thesetheories have been developed as explanations for theadventacceptance of agriculture by some hunter-gath-erers and the persistence of foraging lifeways amongothers (Shnirelman 1992 Testart 1988) Hunter-gather-ers of western North America inhabited a full spectrumof environments from the diverse terrestrialmarineecotone of the Santa Barbara Channel to the depauper-ate arid regions of the Mojave Desert and the Great Ba-

sin An early opinion on resource diversity and faminewas offered by Kroeber (1925524) who suggested thatCaliforniarsquos varied environment rendered its inhabi-tants immune to catastrophe

The food resources of California were bountiful intheir variety rather than in their overwhelmingabundance If one supply failed there were hun-dreds of others to fall back upon If a drought with-ered the corn shoots if the buffalo unaccountablyshifted or if the salmon failed to run the very exis-tence of people in other regions was shaken to itsfoundations But the manifold distribution of avail-able foods in California and the working out of cor-responding means of reclaiming them prevented afailure of the acorn crop from producing similar ef-fects It might produce short rations and rackinghunger but scarcely starvation

For Indians in the resource-poor Great Basin howeverSteward (1938) felt that famine was an intrinsic part oftheir existence and that it contributed to low popula-

tion densityKroeberrsquos perspective has been replaced in recent

years by recognition that groups throughout westernNorth America were dependent upon storage (Testart1982) including acorns in California and pine nuts inthe Great Basin Acorn economies in particular arenow seen as highly inefficient and labor-intensive (egBasgall 1987) The dense sedentary populations associ-ated with them have repeatedly been likened to thosesupported by agriculture in the Southwest (Baumhoff1978 Bean and Lawton 1976 Meighan 1959) Nearly allarchaeologists assume that these storage-dependenteconomies arose from nonstoring New World predeces-sors (see Basgall 1987 Glassow 1991 Wills 1988) Tes-

tart (1988) makes a strong case that storage-dependenthunter-gatherers were more at risk from long-termshortfalls than were nonstoring foragers While storageis a mechanism for countering seasonal shortfalls stor-age-reliant hunter-gatherers were inevitably dependenton a few staples suited for long-term storage the failureof which could cause significant subsistence problems(Testart 1988173) In these intensive economies stor-age did not provide insurance against shortfalls that per-sisted longer than a few seasons As a consequenceTestart suggested that the level of susceptibility of stor-age-reliant hunter-gatherers to food shortages and catas-trophic famine was probably comparable to that of agri-culturalists It is worth mentioning Cohenrsquos (1977)

likening of the demographic stresses that precipitatedthe adventacceptance of agriculture by hunter-gather-ers to a crisis-like situation caused strictly by humanpopulation growth If agricultural and intensive hunt-ing-gathering economies incorporated or caused stressesunder favorable environmental circumstances episodesof rapid environmental deterioration would have hadthe potential to cause serious subsistence stress

Historical accounts reveal any number of environ-mentally induced crises among hunter-gatherers in dif-ferent parts of the world (Shnirelman 199228) Among




foragers living adjacent to agriculturalists or pasto-ralists such crises often produced shifts in subsistenceSome Kung San for example engaged in farming dur-ing periods of abundant precipitation but mostly for-aged during normally dry and drought years (Shnirel-man 199234) Upham (1982 1984a) argued that asimilar dynamic existed among Puebloan societies of

the American Southwest with drought-related cropfailures precipitating increased hunting and gatheringIn aboriginal economies not exposed to agriculture eco-nomic orientation did not change in the face of periodicresource shortfalls and death rates sharply increased(Shnirelman 199234) Hunter-gatherers can shift tofood production in the face of demographic pressureonly where conditions allow farming and when the eco-logical transition is gradual enough to provide peoplewith time to transform their subsistence practices andvalue systems (Shnirelman 199234) Without these fac-tors a demographic crisis may result in disintegrationof economies interregional aggression violence andextinction of some groups We believe that the archaeo-

logical record of the Medieval Climatic Anomaly inwestern North America reflects a time during which de-mographic crises of this type were widespread becauseof a convergence of growing populations and abrupt de-clines in biotic productivity caused by prolonged and se-vere droughts

Synchrony of InterregionalPaleoenvironmental Change

Evidence for significant environmental variability dur-ing the Medieval Climatic Anomaly is now available

from various locations beyond the limits of the Pueb-loan area including the California coast and arid inte-rior deserts in southern California and the Great BasinDuring this interval there were widespread and pro-longed periods of decreased precipitation and frequentdrought (Stine 1990 1994) warm summer temperatures(Graumlich 1993) and high incidence of fires (Swetnam1993) Some (eg Arnold 1992a b Colten 1993) arguethat low marine productivity during an extended inter-val of warm sea temperatures (ie a 100-year El Nin ˜ o[Arnold 1992b133]) contributed to problems along theCalifornia coast However more recent studies suggestthat the Medieval Climatic Anomaly was characterizedby low frequency and intensity of El Nin ˜ os (Anderson

1994) and that drought-related decreases in terrestrialproductivity were much more significant than changesin the marine environment (Colten 1995) Evidencefrom a variety of interior settings suggests that the pe-riod between ca ad 800 and 1350 was a time of gener-ally warm climate (eg Hughes and Diaz 1994) but theentire 600-year period was not consistently warm anddry throughout western North America Rather it waspunctuated by two intervals of extreme drought(Graumlich 1993 Stine 1994) with a shorter interveningperiod of high rainfall in some localities (Leavitt 1994)

Although some emphasize unusual climatic variabilityduring the period (eg Dean 1994) a cursory examina-tion of high-resolution Holocene paleoenvironmentalrecords (eg Graumlich 1993 Kreutz et al 1997) re-veals that variability is more the rule than the excep-tion during the late Holocene and that the medieval pe-riod stands out as a time of prolonged and severe

droughts What we focus on here are the effects of thesedroughts in the Great Basin and Sierra Nevada thesouthern California coast the Mojave Desert and theColorado Plateau

the great basin and sierra nevada

Significant dry intervals are indicated by fine-grainedrecords from the western Great Basin where Stine(1994549) has produced compelling evidence for lsquolsquoepicrsquorsquodroughts ca ad 892ndash1112 and 1209ndash1350 based ondating of drowned tree stumps at Mono Lake and sev-eral other locations The stumps are derived from treesthat grew when lake levels dropped Stine contends that

these droughts were anomalous in their severity rela-tive to the rest of the Holocene and much more severeand prolonged than anything known historically Datafrom the bristlecone pine (Pinus longaeva) tree-ring se-quence in the White Mountains (LaMarche 19741047)match the patterns identified by Stine The early centu-ries (ca 800ndash1050) of the medieval period were markedby cool dry conditions (overlapping Stinersquos first epicdrought) and were followed by a warm wet interval ca1050ndash1150 (also reported by Leavitt 1994) and thenwarm dry conditions between 1150 and 1330 (approxi-mating Stinersquos second drought) Relatively coarse-grained paleoenvironmental records from elsewhere inthe western Great Basin (eg Lead Lake in western Ne-

vada and Diamond Pond in eastern Oregon [WigandDavis and Pippin 1990]) indicate aridity between caad 1 and 1400 with some equivocal suggestions of wetconditions between ad 500 and 1000 (Currey andJames 1982 Davis 1982)

Clear evidence of warm and dry conditions during theMedieval Climatic Anomaly in the Sierra Nevada is re-ported by Graumlich (1993) on the basis of a tree-ringsequence covering the past millennium She argues thatthe period between ad 1100 and 1375 is highly un-usual because of increased summer temperatures whichpeaked ca 1150 Severe droughts are evident at ca1020ndash70 1197ndash1217 and 1249ndash1365 but Graumlichconsiders them less anomalous relative to the precipita-

tion cycle of the past millennium than the high sum-mer temperatures She further argues that anomaloustemperatures were a product of the convergence of ex-ternal climatic factors (eg volcanic ash solar events)with internal oscillations (ocean circulation patterns)(Graumlich 1993254) Corroborating this portrait of Si-erran conditions is a 2000-year record of fire scars ingiant sequoias (Sequoia gigantea) Citing earlier studiesthat demonstrated a correlation between areas burnedin the United States and the El Nin ˜ o Southern Oscilla-tion (Swetnam and Betancourt 1992) Swetnam (1993




887) reports that fire frequencies were higher in thesouthern Sierra between 1000 and 1300 than during anyother interval in the past two millennia

the southern california coast

Larson and Michaelsen (1989) and Larson Johnson and

Michaelsen (1994) summarize a 1600-year tree-ringrecord that elucidates the paleoclimate of coastal south-ern California This sequence includes evidence fordroughts between ad 750 and 770 high rainfall be-tween 800 and 980 and rapidly developing drought be-tween 980 and 1030 Conditions were wetter between1030 and 1100 but the interval between 1100 and 1250was one of sustained drought with the period between1120 and 1150 being particularly harsh (Larson and Mi-chaelsen 198923) This last drought partially overlapswith the warm dry conditions in the Sierra Nevada andat Mono Lake detected by Stine (1994) and Graumlich(1993)

A reconstruction of southern California coastal vege-

tation from a 7000-year pollen core from San JoaquinMarsh (fig 2) located 7 km from the Pacific Ocean atthe head of Newport Bay (Davis 1992) also provides evi-dence for dry conditions during the Medieval ClimaticAnomaly The marsh is a paleoestuary that has alter-nated between fresh- and saltwater conditions De-creased stream flow and lower discharge of springs feed-ing the marsh caused saltwater incursions marked bylower pollen deposition and sedimentation rates thepresence of marine-estuarine organisms such as dino-flagellates and foraminifera and the pollen of saltmarsh plants (Davis 199293) Conversely periods ofhigh stream flow are marked by comparatively rapidsedimentation rates abundant palynomorphs and high

percentages of Compositae pollen from terrestrial com-munities (Davis 199292ndash98) Prior to ca 1000 bcCompositae pollen dominates the pollen record but caad 200 it is supplanted by Chenopodiaceae- Ama-

ranthus indicating saltwater incursion and reducedfreshwater runoff These conditions persisted until ca1500 Although this record is one of low temporal reso-lution suggesting a longer-lived phenomenon than isindicated by tree rings it is chronologically consistentwith other paleoenvironmental indicators from the cen-tral and southern California coast

the mojave desert

Although the Mojave Desert is part of the Great Basinculture area the bioclimatic regimes of the two desertsare distinct The Great Basin Desert is a largely semi-arid steppe environment with generally more produc-tive valley-bottom and montane communities whilethe Mojave Desert is largely arid and supports vast ex-panses of low-productivity desert scrub Late Holocenepaleoenvironmental records from the Mojave Desertand the trough of the Lower Colorado River have previ-ously been assessed for evidence of drought during themedieval period The clearest data come from packrat

midden and paleohydrologic records that indicate en-hanced aridity beginning by ad 600 and lasting untilat least 1200 (fig 3 table 1) During this period packratmidden records of xeric vegetation are common andthere are few records of mesic vegetation Furthermorethere are essentially no published records of increasedspring activity or desert lake high stands between 900

and 1350 One record (fig 3 12) from that period is froma spring in the Las Vegas Valley that remained activeeven after the local aquifer was significantly drawndown by heavy urban pumping in modern times (deNar-vaez 1995) The absence of evidence for such paleohy-drologic features during the medieval period is signifi-cant particularly in contrast with the followingcenturies of cold and wetter climate referred to bysome as the Little Ice Age (see Gribbin and Lamb 1978Grove 1988) The autecology of plant species that wererestricted to higher elevations during this period sug-gests that the Medieval Climatic Anomaly was charac-terized by warmer winter temperatures The paleohy-drologic data speak more directly to changes in

precipitation and consequent recharge and runoff Gen-eral lack of evidence for spring activity and lacustrineevents in the desert interior indicates less winter pre-cipitation during the Medieval Climatic Anomaly thanduring succeeding centuries

Blackbrush (Coleogyne ramosissima) desert scrub isa relatively high-productivity vegetation type currentlyrestricted to elevations above 1200 m by moisturedeficits near its lower limit (Beatley 1975) Packrat mid-den studies clearly show descent of this vegetation intowarmer habitats near the end of the medieval period inthe Mojave Desert The downward migration of thismesic vegetation type suggests that conditions had pre-viously been warmer and drier Stratigraphic and arch-

aeofaunal evidence for perennial lake stands in the cur-rently hyperarid Mojave Sink (fig 3 table 1) provide astrong contrast with the preceding Medieval ClimaticAnomaly

Immediately southwest of the Mojave Desert in theSalton Sink the timing of the episodic filling and desic-cation of Lake Cahuilla stands out as sharply distinctfrom the chronologies of drought related above Geo-morphic analysis and the historical record demonstratethat these lake high stands were forced not by climatechange but by the shifting of the Lower Colorado Riverchannel (Fenneman 1931 Waters 1983) Although ex-pansive the deltaic cone of the Colorado River providesan alluvial barrier only about 15 m high between the

river and the Salton Sink and because the latter is be-low sea level the river periodically breaches this barrierand fills the basin This episodically created freshwaterlake covered an area of approximately 5700 km 2 witha maximum depth of about 96 m in response to eventsthat have no known relation to climatic change Theearlier chronology of Lake Cahuilla is not well knownbut there are sufficient stratigraphic exposures to estab-lish the timing of younger late Holocene lake episodesThe oldest lacustrine interval dates to about 350 bcAfter this time there were four closely spaced lacustrine




Fig 2 California the western Great Basin and sites mentioned in text

intervals between ca ad 550 and 1550 each punctu-ated by abrupt desiccation and refilling (Waters 1983)It appears that Lake Cahuilla was often full during themedieval period although not necessarily as a result ofclimatic factors

the colorado plateau

Paleoclimatic reconstructions for the late Holocene onthe Colorado Plateau are based on tree rings pollenplant macrofossils faunal remains and geomorphologyHigh-resolution dendrochronological data (Dean andRobinson 1977 Euler et al 1979 Dean 1988a b) reveala series of droughts during the 1st millennium adwith a major drought at least once every century untilca ad 750 when they decreased in magnitude untilthe late 900s The latter period was dry but accompa-nied by pronounced temporal variability in effective

moisture After 1000 temporal variability declined butspatial variability in moisture increased until ca 1140A long-term drought (ca 1065ndash1100) occurred duringthis period the effects of which were probably offset insome areas by spatial variability in effective moistureA few decades later another long-term drought (ca1130ndash1150) was followed by a series of shorter less in-tense droughts which culminated in the Great Drought

dating from 1276 to 1299 These arid conditions werefollowed by a period of consistently above-averagemoisture from 1300 to 1350 after which dry conditionsreturned

Changes in temperature evaluated independentlyfrom effective moisture reconstructions are indicatedby timberline fluctuations and pollen from montanesediments (Peterson 1987 1988) Much of the past twomillennia was cool with warmer conditions prevailingfrom ad 800 to 900 and from 1100 to 1200 Most of the




Fig 3 Paleoenvironmental records from the MojaveDesert and lower Colorado River Trough Packratmidden records of xeric vegetation conditions (opentriangles) and mesic vegetation conditions (closedtriangles) compared with paleohydrologic records

from springs and lake high stands (Numbers refer totable 1)

prolonged droughts indicated by the tree rings coincidedwith cool temperatures but one occurred during a 12th-century warm interval The Great Drought occurred

after the onset in the 13th century of cooler conditionswhich persisted into the Little Ice Age

Geomorphic studies indicate significant hydrologicalvariability during the Medieval Climatic Anomaly Astudy of several major rivers documented a prolongedperiod of regular flooding between 400 bc and ad1200 with a peak in flood frequency and magnitudeduring the last 200 years of this period (Ely et al 1993)A decline in flood frequency between 1200 and 1400was followed by a second prolonged period of floodingwhich persisted to the present In a study of hydrologicvariability in intermittent drainages a stable hydrologicregime was identified throughout the 1st millenniumad shifting to unstable conditions between 1100 and

1300 (Agenbroad et al 1989) A return to stable hydro-logic conditions followed with brief intervals of insta-bility occurring in the last 300 years The first shift tounstable hydrologic conditions occurred during peakflooding in the perennial drainages For the most parthowever instability in intermittent drainages coin-cided with a decline in flood intensity on major riversThe lowering of water tables along intermittent drain-ages during peak flooding of rivers may indicate a de-cline in summer precipitation and a possible increase in

temperatures coinciding with increased winter mois-ture However summer and winter moisture both ap-pear to have declined dramatically between 1200 and1300 and increased after that time

Although the Colorado Plateau is generally semiaridthese studies show that from ca ad 1050 to 1300 a se-ries of significant changes occurred in the region (1)

major droughts became common occasionally oc-curring as sustained intervals of substandard moistureon the order of a decade or more (2) temperature in-creased notably toward the middle of this arid periodand (3) unprecedented hydrologic instability occurred inboth primary and secondary drainages as water tablesdropped and erosion increased

Correlations with the Archaeological RecordCase Studies

Detailed consideration of late Holocene archaeological

sequences from four regions of western North Americashows striking correlations between changes in sub-sistence interregional exchange frequency of warfareand interpersonal violence regional abandonments andmajor population movements on the one hand andevents in the paleoenvironmental record on the otherSpecific cultural responses vary between regions buteach shows diachronic changes that are difficult to at-tribute to simple adaptive adjustment or economic in-tensification Rather events in each of these regions arebest explained as responses to environmental deteriora-tion and demographic stress The most striking recordcomes from the Colorado Plateau where fine-grainedarchaeological and paleoenvironmental sequences illu-

minate a convergence of growing populations withrapid drought-related environmental deterioration Theecological effects of large sedentary populations on sur-rounding communities are likely to have exacerbatedthis situation Other areas experienced contemporane-ous deleterious effects Diachronic patterns in threehunter-gatherer regionsmdashthe central California coastthe southern California coast and the Mojave Desertmdashalso show correlations that are not easily explained byincremental population growth adaptive adjustmentor economic intensification

drought-related demographic stress among

agriculturalists the colorado plateauThe correlation between the Great Drought (ad 1276ndash1299) and abandonment of the Four Corners area (fig 4)is so perfect that many Southwesternists have seen thetwo events as unquestionably linked Major abandon-ments of portions of the Colorado Plateau show remark-able temporal and ecological correlation with paleocli-matic changes for the period examined in this paperThe magnitude of these changes appears to have beenconsiderable especially between 1050 and 1300 when




t a b l e 1Sources of Data on Environmental Change in the Mojave Desert and the Lower Colorado River Trough

No Locality Indicator Reference

1 Vicinity of Searchlight extreme southern Coleogyne ramosissima presenceabsence Hunter and McAuliffe (1994)

Nevada2 Mojave Sink central Mojave Desert Lacustrine sediments indicating perennial Enzel et al (1992)lake stand

3 Picacho Peak vicinity of Yuma extreme Hilaria rigida presence Cole (1986)southeastern California

4 Hornaday Mountains Sonora immediately Cercidium floridum Prosopis juliflora Van Devender et al (1990)northeast of the head of the Gulf of Ca- presenceabsencelifornia

5 Greenwater Valley Funeral Range immedi- C ramosissima and Eriogonum fascicula- Cole and Webb (1985)ately east of Death Valley eastern Ca- tum presenceabsencelifornia

6 Fortymile Wash eastern Amargosa Desert Purshia glandulosa and Larrea tridentata Spaulding (1990)southern central Nevada covariance

7 Granite Mountains central Mojave Desert C ramosissima Salvia mohavensis and Spaulding (1995)Ephedra viridis abundance

8 Sheep Range southern Nevada Pinus monophylla and Juniperus os- Spaulding (1981)teosperma abundance

9 Amargosa Desert southern Nevada Peat growth indicating spring discharge Mehringer and Warren (1976)10 Northern Las Vegas Valley southern Organic-rich spring-margin sediments Haynes (1967)Nevada

11 Northern Las Vegas Valley southern Organic-rich spring-margin sediments deNarvaez (1995)Nevada

12 Mojave Sink central Mojave Desert Freshwater clam ( Anodonta californiana) Drover (1979)middens

13 M ojave Sink central Mojave Desert Tufa indicating lake high stand Berger and Meek (1992)

they were accompanied by alluvial instability and thebeginning of a shift toward increased erosion and de-pressed water tables This generally unstable period ap-pears to have been significant enough to have impactedall traditional subsistence options not just farming

Shifts from farming to hunting and gathering as hy-pothesized by Upham (1984a) may have been theoreti-cally feasible in favorable environments during times ofrelatively low population density but not when popula-tion reached the inflated levels common during the me-dieval period (see Minnis 1985146ndash50)

Agriculture was adopted about three millennia ago inmuch of the Southwest but it took on real economicimportance within the past two millennia as it spreadthroughout the Colorado Plateau (Ambler 1966 Berry1982 Lindsay 1986 Wills 1988 Larson and Michaelsen1990 Brown 1992 Hogan 1994) Its spread during the1st millennium ad occurred under conditions gener-ally favorable to lowland farming (ie regular flooding

in major river systems and stable alluvial systems intributaries) Droughts may have periodically curtailedupland farming but small populations could have con-centrated their agricultural efforts in lowlands After1050 paleoclimatic data show more severe deteriora-tion including a variety of climatic vegetational andhydrologic processes The compounded impact on bothfarmers and hunter-gatherers must have been signi-ficant However another major reason that thesepaleoenvironmental changes had deleterious conse-quences was the great density of population across the

Colorado Plateau by this time (Dean et al 1985 Dean1988b Plog et al 1988 Larson and Michaelsen 1990Van West and Lipe 1992)

It is widely recognized that during the Pueblo II pe-riod from ad 900 to 1150 a population boom coin-

cided with expansion into many new areas and a widevariety of habitats Population density in most areasand the regional population level throughout the Colo-rado Plateau reached unprecedented highs during thelate Pueblo II period (Euler 1988 Cordell and Gumer-man 1989) This peak coincides with paleoenvironmen-tal conditions conducive to hunting gathering andagriculture in both upland and lowland areas as indi-cated by high groundwater and geomorphic reconstruc-tions (Brown 1996) followed by successive droughts to-ward the end of the 11th century and earlyndashmid-12thcentury preceding the Pueblo IIndashIII transition The pe-riod 1130ndash1150 marks a major decrease in effectivemoisture accompanied by heavy flooding and generally

unstable alluvial systems possibly marking a shift fromsummer-dominant toward winter-dominant precipita-tion Puebloan occupation ended in major portions ofthe Colorado Plateau during the mid-1100s especiallyin areas to the west and north Termination of VirginAnasazi settlement on the west is frequently attributedto long-term drought between 1120 and 1150 in the con-text of population growth (Schwartz Chapman andKepp 1980 Schwartz Kepp and Chapman 1981 Larson1987 Larson and Michaelsen 1990) while the end of oc-cupation by many Fremont populations across the




Fig 4 Major archaeological regions of the American Southwest

northern half of the Colorado Plateau may also be re-lated to paleoclimatic change (Lindsay 1986) Althoughpaleoenvironmental data suggest a temporary increasein effective moisture after 1150 this may have been toolate to help many agricultural groups particularly thoseinhabiting areas on the west and north characterized bywinter-dominant precipitation patterns that were lessbeneficial to farmers

Dean (1988b) cautions against relating phase transi-tions to paleoenvironmental changes but the chrono-logical correlations are compelling Widespread aban-donments toward the end of the Pueblo II periodprecede the marked population aggregation characteris-

tic of the Pueblo III period (ca ad 1150ndash1300) in thelimited areas where Pueblo III sites are representedAbandonment and concurrent aggregation might belinked as a single trend toward fundamental reorganiza-tion In our view this transition is not just the kind ofrecognizable change in diagnostic material traits thatDean assumes to be typical of most phase transitionsit is a cultural transformation The Pueblo IIIndashIV transi-tion is an even more remarkable instance of organiza-tional change that is at least partially attributable to en-vironmental change The Great Drought and the shift

to cooler temperatures at the beginning of the Little IceAge both put considerable stress on agricultural sys-tems Pueblo III population levels appear to have ex-ceeded the carrying capacity of some areas and thedenser occupation of neighboring areas limited opportu-nities for relocating the large villages characteristic ofthis time (Van West and Lipe 1992) In addition manyareas that were abandoned appear to have been undergo-ing a change toward relatively autonomous lsquolsquotribalrsquorsquo pol-ities characterized by intergroup warfare (Haas andCreamer 1992 Wilcox and Haas 1994 Lipe 1995) vari-ous kinds of sociopathic violence (Nickens 1975Turner and Turner 1990 1992 White 1992) and re-

duced interregional interaction (Neily 1983 Green1992)

Why cultural systems across so much of the South-west collapsed rather than splitting or implementingtechnological options such as agricultural intensifica-tion remains an important issue By ad 1300 all theagricultural settlements in the northern Colorado Pla-teau and most of those in the central portion had beenabandoned The early Pueblo IV period (ca 1300ndash1450)is represented in only a few areas on the southern edgeof the Colorado Plateau including the Hopi Zuni and




Acoma areas where Puebloan traditions persist to thepresent and the Little Colorado drainage where largetowns were established during this period but aban-doned during the 15th century Although these areascould have absorbed some population from the FourCorners region evidence of migrations is limited TheRio Grande Valley east of the Colorado Plateau and the

transitional zone to the south are the most widely ac-cepted candidates for recipients of major populationsfrom the Four Corners region The areas where signifi-cant Pueblo IV populations were located thus occur al-most exclusively to the south and east in the directionsof greater summer precipitation

In addition to both agricultural intensification and di-versification Pueblo IV is characterized by some of themost abundant evidence for exchange and specializedproduction of nonsubsistence commodities in theSouthwest Chavez Pass on the southwestern marginof the Colorado Plateau appears to have functioned as agateway community that facilitated exchanges betweenthe Colorado Plateau and groups inhabiting different

environmental zones to the south (Upham 1982Upham and Plog 1986) Communities such as ChavezPass may have specialized in nonsubsistence economicactivities such as production and exchange of potteryobsidian marine shell jewelry and other exotic items(Cordell and Plog 1979 Upham 1982 Brown 19821990) Such activities would have been crucial to thesurvival of groups in the area since they also appear tohave exceeded the local carrying capacity (Upham1984b) The systems of economic interdependence typi-cal of this period may have provided alternative formsof organization to the autonomous tribal societies char-acteristic of many areas that had been abandoned by theend of the Pueblo III period (compare Upham 1982 with

Haas and Creamer 1992) Where the issue has been ex-amined such alternative interregional economies ap-pear to have developed initially about the same time asprovincial tribal organizations elsewhere on the Colo-rado Plateau that is during the Pueblo III period (Brown1982 1990) Thus these two types of organizationmight represent differing means of coping with environ-mental stress one of which suffered widespread failure(abandonment) while the other developed into classicalPueblo IV regional systems

settlement disruption and exchangedeterioration among hunter-gatherers the

central california coastThe suggestion that drought-related problems occurredin central California during the late Holocene was firstadvanced by Moratto King and Woolfenden (1978)who associated signs of social disruption in the south-ern Sierra Nevada foothills between ad 600 and 1500with warm dry climatic conditions The central Cali-fornia coast also shows changes in technology settle-ment and exchange during the Medieval ClimaticAnomaly inconsistent with progressive social evolutionor economic intensification Rather diachronic pat-

terns show some similarities with parts of the ColoradoPlateau as the regional economy apparently reachedpeak intensity and sophistication during the early medi-eval period and declined thereafter The punctuated na-ture of technological change in this region is strikingas is the chronological correlation with the interval ofmedieval droughts Artifact assemblages show little

typological or stylistic change between 3500 bc andapproximately ad 500 after which smaller projectilepoints associated with the bow and arrow begin to ap-pear in small numbers alongside large dart andor spearpoints Between 1200 and 1400 however bow technol-ogy overwhelms the earlier weaponry arrow pointsdominate assemblages thereafter (Jones 1995) Thistechnological transition is coeval with a major disrup-tion in settlement indicated by radiocarbon-based occu-pation sequences showing that few if any sites werecontinuously occupied through the Medieval ClimaticAnomaly (figs 5 and 6) Sites occupied earlier than 1200show signs of abandonment while settlements first in-habited ca 1200ndash1400 are single components with no

signs of earlier useObsidian frequency profiles show that sites postdat-

ing ad 1000 yield far less of this trade commodity thanearlier deposits From 3500 bc until ad 1000 obsid-ian bifaces were regularly imported to the central coastfrom nine distant locations (fig 7) Appearing in smallquantities during the Early period (3500ndash600 bc) thiscommodity was increasingly abundant until ad 1000after which it disappeared from the record and never re-appeared in significant quantities An obsidian-hydra-tion profile depicting results from over 50 excavatedsites shows the pattern clearly as high frequencies ofhydration readings fall into the Early and Middle periodmicron spans but almost none represent the Late period

(fig 8) Interregional exchange networks apparently de-teriorated between ca 1000 and 1300 A study of one ofthe obsidian quarries (Coso in the Mojave Desert) showsthat production declined markedly after ca 1275 (Gil-reath and Hildebrandt 1995)

Chronological correlations between these archaeolog-ical transitions and droughts during the medieval perioddo not prove environmental causality Nonethelessthey are difficult to overlook inasmuch as the abruptchanges in settlement and exchange are inconsistentwith the predictions of incremental population growthand subsistence intensification Intensification modelspredict decreases in efficiency as labor-intensive com-modities such as acorns and fish increase in dietary

significance (Basgall 1987) more diminutive quarryare pursued (Broughton 1994a Hildebrandt and Jones1992) exchange networks expand and complex socialstructures evolve to complement increasingly sophisti-cated intergroup relationships (Jackson 1986) On thecentral coast many diachronic patterns leading up tothe Medieval Climatic Anomaly are consistent withthese predictions but changes occurring between ad1000 and 1400 are different in that diets did not con-tinue to broaden and trade horizons contracted It seemslikely that these changes reflect demographic problems




Fig 5 Settlement disruption during the Medieval Climatic Anomaly on the Big Sur coast of centralCalifornia

that could not be solved by simple adaptive adjustmentor further intensification and that settlement shifts anddeterioration of exchange reflect large-scale population

movements akin to those on the Colorado Plateau Thecomplex distribution of language stocks in California atthe time of historic contact has long been recognized asa reflection of multiple prehistoric population move-ments (Kroeber 1955 Moratto 1984) While the historyof these movements is debated there is growing evi-dence for massive shifts in central California during themedieval period (Moratto 1984560) This again reflectsa correlation between environment and cultural changethat suggests a causal relationship between the two

violence and settlement disruption thesouthern california coast

Evidence for abrupt cultural changes during theMiddleLate transition (ca ad 1200ndash1300) not readilyaccommodated by economic intensification or gradu-alist adaptive models is also apparent along the south-ern California Bight Ethnohistorical accounts ofdrought conditions have been recorded for the Chu-mash (Walker DeNiro and Lambert 1989351) In thearchaeological record trends in settlement patternshealth conditions violence and regional trade are cor-related with demographic stress during the MiddleLatetransition Lambert and Walker (1991) and Arnold

(1987 1992a b) were among the first to call attentionto these patterns and Arnold (1992a b) specifically at-tributed changes during the MiddleLate transition to

major climatic shifts She (1992b134) reported distinc-tive signs of settlement disruption on Santa Cruz Islandca 1200ndash1300 with many sites exhibiting either an oc-cupational hiatus or abandonment Detailed strati-graphic studies at sites CA-SCRI-191 (Cristy Ranch) andCA-SCRI-240 (Prisonerrsquos Harbor) date occupational hia-tuses ca 1250ndash1300 (Arnold 1992a76) Islands such asSanta Cruz contain small rain catchments relative tothe mainland persistent drought conditions are likelyto have had devastating impacts

On the mainland a major settlement shift ca ad1000 in the San Diego area (Christenson 1992) is gener-ally attributed to migration of Yuman- and Shoshonean-speakers from the interior (Warren 1968) although Mor-

atto (1984560) argues that this intrusion took placeearlier Marine foods seem to have increased in signifi-cance relative to terrestrial resources during theMiddleLate transition in contrast to Arnoldrsquos findingsfrom Santa Cruz Island but this trend is consistentwith that on the mainland of the central coast Faunalremains from CA-SBA-1731 suggest that marine re-sources provided an average of at least 76 of the ani-mal protein consumed (Erlandson 1993191) At thesame time that many sites on Santa Cruz Island werebeing abandoned the inhabitants of this mainland site




Fig 6 Settlement disruption during the Medieval Climatic Anomaly in the Monterey Bay area of central

California

apparently turned to the sea for most of their proteinneeds consistent with depressed terrestrial productiv-ity during an interval of persistent drought

Competition for scarce food resources both marineand terrestrial was another apparent outgrowth of theMedieval Climatic Anomaly as the need to controlfood sources and remain in proximity to reliable sourcesof fresh water seems to have solidified boundaries andfostered a territorial settlement pattern (True 1990)High population density around water sources is alsolikely to have promoted disease (Walker 1986) Violent

encounters between groups competing for vital re-sources would be another anticipated outgrowth of re-source scarcity Osteological signs of poor health and vi-olence reached an all-time peak in the Santa BarbaraChannel between ad 300 and 1150 (Lambert 1993Lambert and Walker 1991 Walker 1986 1989 Walkerand Lambert 1989 Walker DeNiro and Lambert 1989)High levels of interpersonal violence are evident at CA-VEN-110 (Calleguas Creek) on the mainland coast nearPoint Mugu where a large cemetery was established inthe 13th century (Raab 1994) Whereas Walker (1989)

interprets compression fractures of the skull as prod-ucts of ritualized sublethal combat arrow wounds inthe individuals interred in the Calleguas Creek ceme-tery attest to warfare intended to inflict death Docu-mented projectile wounds are rare in most prehistoricburial populations on the south coastmdashwith the excep-tion of burial populations from the MiddleLate transi-tion In a study of four prehistoric cemeteries in theSanta Monica Mountains dating as early as 400 bcMartz (1984) did not describe a single definite projectilewound At Medea Creek a historic-period cemetery

King (1982151ndash85) found that only 13 of more than300 burials showed evidence of violence including pos-sible arrow wounds skull fractures dismembermentand cannibalism In sharp contrast up to 10 percentof the burials at Calleguas Creek (1200ndash1300) showedarrow wounds (Walker and Lambert 1989210) More-over both males and females were victims suggesting astyle of warfare or raiding in which entire communitieswere exposed

Arnold (1992a b) has linked emergent social com-plexity with environmental stress during the Middle




Fig 7 Obsidian sources represented at archaeological sites on the central California coast (from Jones 1995)

Late transition in the Santa Barbara Channel She con-tends that during this critical transition shell-beadmanufacture by specialists was brought under the con-trol of chiefs in a system designed to buffer subsistencefailures by providing a commodity that could be tradedto groups on the mainland for food Study of local mor-tuary patterns confirms that important shifts in socialcomplexity took place ca ad 1100 among the Chu-mash (Martz 1984489ndash90) as a decline in the impor-tance of the religious leaders coincided with an increasein the importance of the hereditary political group Thisshift in status and a corresponding increase in the pro-portion of subadults in burials with status objects sug-gests the development of a nobility with an emphasis

on lineage and ascriptionTrade relationships show significant evidence for

change during the MiddleLate transition as well Al-though Olivella and abalone shells were imported fromthe California coast to the Puebloan area at least asearly as ad 500 the volume of trade increased signifi-cantly after 1000 Between 500 and 1150 Anasazi set-tlements on the lower Virgin River were importinglarge quantities of Pacific coast shells which are foundas burial offerings but this trade relationship endedwhen the Virgin River sites were abandoned ca 1150

Between 900 and 1150 shells steatite and asphaltumfrom the Pacific coast were being imported by peopleliving at the Willow Beach site near Hoover Dam onthe Colorado River (Schroeder 1961) This expandedtrade with Yuman peoples probably accounts for thepresence of pottery of Anasazi and Hohokam manufac-ture in late Middle-period sites around the Santa Bar-bara Channel including Sacaton Red-on-Buff sherdsfrom the Gila River found at CA-LAN-267 (dating ca900ndash1100) (Walker 1951 Ruby and Blackburn 1964)and Cibola White ware found at the Century Ranch Site(CA-LAN-227) that probably was manufactured ca1000 (King Blackburn and Chandonet 196873) South-western pottery disappeared from the southern Califor-

nia coast after 1150Arnold (1987 1992a b) documents a major increase

in shell-bead manufacture on Santa Cruz Island as anapparent strategy for buffering food shortages in thisvulnerable insular setting Manufacture and exporta-tion of steatite artifacts also increased markedly ca ad1200 on Santa Catalina Island (Wlodarski et al 1984342) This increase in trade activities contrasts with thesituation on the central California coast and seems toreflect geographically limited exchange tied directly tosubsistence the goods produced on the islands are not




Fig 8 Obsidian-hydration profiles from the central California coast (from Jones and Waugh 1995)

found in large numbers away from the south coast

mainland

population decline and aggregation in aridenvironments the mojave desert

The effects of climatic shifts on aboriginal populationsin the Mojave Desert have been debated for decades Ithas frequently been argued that since the biotic regimewas with minor variation constant during the Holo-cene human use of the region was little influenced byclimate change (Basgall and Hall 1992) Water not foodmay have been the critical factor in foraging decisionsunder extremely arid conditions (Kelly 1995126) InAustraliarsquos desert interior for example potential water

shortfalls are a major risk factor and decisions regard-ing group movement are often based on close monitor-ing of weather patterns (Gould 198060 69ndash70 Yellen1976 cf Kelly 1995) In response to uncertaintyhunter-gatherers may tether themselves to reliable wa-ter sources sometimes sacrificing foraging efficiency(Cane 1987 Kelly 1995) Extended droughts in the Mo-jave Desert during the Medieval Climatic Anomaly arelikely to have substantially reduced the number of wa-ter sources Spring discharge and seasonal flooding ofthe Mojave River would have declined and high stands

in desert playa lakes would have been infrequent As a

result sources of water would have been widely dis-persed and less predictable and the risk associated withforays into the desert interior would have been greater

Occupations in the Mojave Desert during the 500-year period preceding the Medieval Climatic Anomaly(ca ad 300ndash800) the Medieval Climatic Anomaly it-self (ad 800ndash1300) and the following 500-year period(ad 1300ndash1800) show signs of significantly reduceduse of the desert probably due to decreased availabilityof water Of 84 radiocarbon-dated archaeological com-ponents spanning 300ndash1800 25 date to 300ndash800 12 tothe Medieval Climatic Anomaly and 47 to 1300ndash1800(fig 9) The spatial distribution of components alsoshows that medieval components are closely associated

with a few perennial water sourcesmdashmajor springs andperennial oases along the Mojave River (such as OroGrande [CA-SBR-72] Afton Canyon [CA-SBR-85] andBitter Spring) (fig 10) Oro Grande and Afton Canyonlie along the Mojave River drainage with its vast catch-ment area (Enzel et al 1992) Shallow groundwater flowin this drainage would have been among the most per-sistent during dry periods Similarly Bitter Spring is thelargest and most reliable spring in the Tiefort Basinarea These patterns suggest that hunter-gatherers ofthe central Mojave Desert who were free from the type




Fig 9 Radiocarbon-dated archaeologicalcomponents from the Mojave Desert California

of climatic dependence that agriculturalists experi-enced were nevertheless affected by the unusual aridityof the Medieval Climatic Anomaly That fewer dated

components from this period exist suggests a reductionin population size as well as a narrower focus on reliablewater sources In the Mojave Desert a decline in annualrainfall would lead to a reduction in the number and re-liability of water sources a critical factor in a regioncharacterized by vast waterless expanses Moreoverdroughts such as those demonstrated by Stine (1994)would have led to a reduction of ecosystem productivityin all habitats (Spaulding 1995) Although these data donot demonstrate that there was a decline in human car-rying capacity during the Medieval Climatic Anomalythe regional decrease in dated components suggests thatthis may indeed have been the case

The area in the immediate vicinity of the Salton Sink

however witnessed a very different sequence of envi-ronmental events with the intermittent formation ofLake Cahuilla As noted above episodic filling of thelake does not appear to be directly related to climaticchanges The lakersquos late Holocene chronology clearlyshows that it was full during much of the Medieval Cli-matic Anomaly (Waters 1983) The sudden appearanceof a 5700-km2 body of fresh water in this hyperarid ba-sin must have been a significant draw for hunter-gather-ers throughout the region particularly during a time ofpersistent drought The archaeological record of the Sal-

ton Sink provides strong evidence for human presencearound the lake during the medieval period Some re-searchers (Aschmann 1959 Wilke 1978) posit a rela-tively dense sedentary occupation Others (Weide 1976Schaefer 1986 1988) believe that most lakeshore sitesrepresent short-term temporary camps

Several factors may have rendered the Lake Cahuilla

shoreline more suitable for short-term use and perhapslimited its value as a refuge from medieval droughtFirst throughout much of each lacustrine episode itsshorelines would have been either rapidly advancing orrapidly receding which would probably not have al-lowed the formation of stable or highly productiveshore-margin biotic communities Second the lakersquos sa-linity may have been too high for much of this time toprovide a suitable source of drinking water even forpopulations with few options Laylanderrsquos (1994) recentestimates of Lake Cahuilla salinity suggest that dis-solved solids in the water would have exceeded the cur-rent municipal limit of 330 ppm within a few monthsand reached 1000 ppm within 25 years Thus while the

lake may have provided a productive environment forcertain resources such as fish or waterfowl its effect asa magnet for regional populations during the MedievalClimatic Anomaly was probably limited

Summary

A growing body of paleoenvironmental informationshows evidence for significant periods of drought duringthe Medieval Climatic Anomaly While the chronologyof drought-related environmental deterioration is notfully synchronous throughout all of western NorthAmerica most areas show evidence for two intervals of

decreased precipitation (early medieval ad 900ndash1100and late medieval ad 1150ndash1350) separated by a pe-riod of amelioration Chronological disparity is greatestfor the earlier period although some interregional syn-chrony is also evident (fig 11) There are also some in-triguing complementary comparisons such as the oc-currence of two successive epic droughts on theColorado Plateau during a period of increased effectivemoisture in the White Mountains The late medievalcorresponds with the latter of Stine and Graumlichrsquostwo epic droughts in the Sierra Nevada and westernGreat Basin and includes the Great Drought (1276ndash99)on the Colorado Plateau Depressed environmental pro-ductivity seems to have been a much broader problem

during this period in western North America than hasever been previously recognized Scale and severity con-form with Stinersquos (1994) characterization of climateduring the medieval period as anomalous in comparisonwith much of the late Holocene

Chronological resolution for the archaeological rec-ord of human responses to these dry intervals varies sig-nificantly across western North America but the latemedieval droughts seem to have caused more dramaticresponses than the first Temporal control is best on theColorado Plateau where most populations survived an




Fig 10 Site component locations before during and after the Medieval Climatic Anomaly in the MojaveDesert California




Fig 11 Comparison of regional paleoenvironmental sequences in western North America ad 800ndash1500

epic drought between 1065 and 1100 through agricul-tural intensification that continued into the mid-1100s Agricultural settlements across much of thenorthern Colorado Plateau were abandoned during asubsequent epic drought between 1130 and 1150 whilepopulations aggregated to the south and east Nucle-ation was ultimately curtailed during the GreatDrought with the final collapse of settlements acrossmost of the central Colorado Plateau Centuries of pop-ulation growth limited the subsistence options thatwere formerly available to dispersed farming groupsand during the later droughts many Puebloan popula-tions were beyond a carrying capacity that had declinedas a result of extended drought Throughout the late

medieval period there is mounting evidence for in-tergroup warfare and interpersonal violence in this con-text of food stress Interregional commerce and interac-tion declined in many places but intensified in a fewareas

Forager populations in three regions of California alsoweathered the early droughts of the Medieval ClimaticAnomaly although chronological resolution is muchpoorer in those areas Human exploitation of the Mo-jave Desert seems to have been suppressed throughoutmost of the Medieval Climatic Anomaly Depletion of

water sources (particularly springs) rendered much ofthe desert uninhabitable and forced people to congre-gate at locations with reliable water Depletion of watersources would have serious implications for food avail-ability and social relationships Shrinking foraging radiiwould combine with depressed biotic productivity toexacerbate competition for food near the few sources ofreliable water On the coast there is significant evi-dence for settlement instability population movementexchange breakdown and interpersonal violence duringthe terminal centuries of the Medieval Climatic Anom-aly Research of the past several decades has empha-sized the high population density of California hunter-gatherers their intensified economies and their rela-

tively complex sociopolitical systems Still the depen-dence by these people on a few ubiquitous labor-inten-sive storable resources put them in ecological jeopardyWhile much of the Holocene archaeological record mayreflect a process of intensification and populationgrowth among California foragers these economieswere at risk from the type of high-intensity environ-mental change that impacted Puebloan cultures Wide-spread andor repeated failures of the acorn crop thefundamental subsistence staple of native Californiawould have readily precipitated major subsistence prob-




lems Settlement disruption and interpersonal violencerepresented in the archaeological record are consistentwith demographic stress These trends are not compati-ble with the predicted outcomes of ongoing intensifica-tion or simple adaptive adjustment Synchrony with thelate medieval drought suggests that decreased availabil-ity of food and water due to significantly lowered envi-

ronmental productivity was a major cause of these shiftsCentral and southern California and portions of the

Colorado Plateau show complex changes in exchangepractices during the Medieval Climatic AnomalyThese changes seem to signal deterioration of broad-scale interregional socialtrade networks and their re-placement in some instances by localized cells ofintensive short-distance trading Intergroup social rela-tionships that facilitated the movement of Puebloanpottery from the Southwest to the shores of southernCalifornia and obsidian from distant sources in thewestern Great Basin to the central California coast ap-parently broke down during the late medieval periodOn the islands off southern California and at certain nu-

cleated settlements on the southern margin of the Colo-rado Plateau however production of trade goods in-creased dramatically during this period Arnold (1992ab) provides strong evidence for increased production ofshell beads and bead drills on Santa Cruz Island ca ad1250 On the Colorado Plateau there is ample evidencefor a specialized network of lithic production and ex-change that also intensified after 1250 (Brown 19821991) Many exchange models based on the premises ofunilinear cultural evolution andor adaptationism (egFredrickson 1974 Chartkoff and Chartkoff 1984 Chart-koff 1989) posit simple increases through time in ex-change concurrent with incremental populationgrowth Jackson and Ericson (1994) have proposed a re-

vised lsquolsquoincrementalrsquorsquo model for prehistoric California inwhich through time greater numbers of goods were ex-changed over shorter distances but even such a revision(see Hughes 1994) does not accommodate the punctu-ated nature of changes in trade during the Medieval Cli-matic Anomaly Rather demographic stress caused bydrought-related declines in environmental productivityseems to have fostered deterioration of formerly wide-reaching and amiable social relations that facilitatedmovement of goods across great distances However lo-calized intensification of exchange during a period gen-erally characterized by breakdowns in social relation-ships may have been dependent on individualizedsociopolitical situations and opportunities Environ-

mentally induced stress can be useful for explaining thetiming of changes but not the character of all humanresponses

Conclusions

In our opinion many patterns in settlement exchangehuman health and intergroup relations during the Me-dieval Climatic Anomaly (ad 800ndash1350) in the four re-

gions examinedmdashthe Colorado Plateau the central Cal-ifornia coast the southern California coast and theMojave Desertmdashcan be explained with a model of de-creased environmental productivity caused by severeprolonged and widespread drought The archaeologicalrecords in these four cases fail to match the predictedoutcomes of unilinear cultural evolution incremental

population growth adaptive adjustment or economicintensification There are too many abrupt changes andtoo many signs of desperation for these to representsimple and gradual population-based progressions Hu-man health and social relations were better and settle-ments were more stable at the onset of the MedievalClimatic Anomaly than they were at its conclusion Incontrast with evolutionary theories that posit differentenvironmental relationships for agriculturalists thanfor foragers the late-medieval droughts seem to havecaused severe ecological imbalances among bothgroups While drought-related problems have been ac-knowledged for agriculturalists of the Colorado Plateaumost models of western North American hunter-gath-

erer prehistory based on theories of cultural ecologyadaptation and economic intensification fail to recog-nize signs of widespread demographic crises during the12thndash 14th centuries or the possibility that both hunter-gatherers and agriculturalists could have been simulta-neously impacted by environmental change The pa-leoenvironmental record for western North Americashows evidence for two intervals of prolonged droughtduring the Medieval Climatic Anomaly but the effectsof the second are more readily apparent in the archaeo-logical record than those of the first A nondeterminis-tic perspective on humanenvironmental relationshipsacknowledges that not all environmental oscillationswill force human responses The later medieval drought

seems to have been unusually severe and widespreadbut the important point is that it occurred at a uniquejuncture in the demographic history of western NorthAmerica when populations were unusually high Theimpact of a sustained drought of this magnitude onthe low-density more widely scattered populations ofthe early Holocene would probably have been much lessprofound Because so many attempts to invoke environ-ment as a primary cause of cultural change have fallento charges of mechanistic determinism (eg linking theAltithermal to events in North American prehistory)many ecologically oriented archaeologists have come toequate environmental causality with determinism andlook to other forces for explanation of cultural change

Nonetheless severe environmental downturns shouldnot be ignored as potential causes of demographic stressbecause human populations do not exist in an ecologi-cal vacuum Situations in the case studies consideredhere are best explained in terms of a convergence of rap-idly growing human populations and precipitous de-clines in environmental productivity To recognize thepotential for crises spawned by such factors and to in-corporate them into models of change is hardly deter-ministic it is simply realistic




Comments

m a r k e b a s g a l l Archaeological Research Center Department of Anthropology California State UniversitySacramento Calif 95819 USA 22 x 98

The role of environmental change in the major demo-graphic economic and social transitions of westernNorth America is an issue of fundamental importanceto prehistorians working in the region and the themeitself has broad resonance elsewhere Unfortunatelythe present treatment ends up being less than compel-ling and seems little more than a reworking of the clas-sic but flawed reasoning first articulated for the DesertWest by Baumhoff and Heizer (1965) One recognizessome correspondence between certain archaeologicaldata and inferred paleoclimatic anomalies assumesa causal connection of some sort and then developsaccommodating arguments to explain the linkage

Inasmuch as humans have the capacity to adjust to en-vironmental changes in numerous ways and the archae-ological record clearly indicates that many climaticshifts apparently had minimal impact on what past peo-ples were doing to explain a particular cultural transi-tion in these terms requires more than a gross correla-tive argument

There are in fact a fair number of inferential stepsnecessary in moving from indirect paleoclimaticlsquolsquoproxyrsquorsquo data to a point where it is possible to exploretheir actual on-the-ground implications for humanpopulations It is one thing to posit a general relation-ship between effective moisture and primary productiv-ity which is well established ecologically but quite an-

other to presume that increases or decreases in the samemust have had serious consequences for prehistorichunter-gatherers To suggest the latter it is necessaryto show how a purported change in effective moisturelevels would have directly impacted key resource pro-curement strategies settlement prerogatives or organi-zational features In the case of interior Australia forexample Pate (1986) has shown that periods of ex-tended drought in fact lead to shifts in resource produc-tivity that are counterintuitive important economictaxa actually having better crops than under normalconditions in a similar vein Lee (1979) has indicatedthat mongongo nut production tends to crash in yearsof above-average precipitation In short for these argu-

ments to be successful requires a demonstration of howcritical components of the adaptive pattern in operationat the critical time would have been adversely affectedby the environmental deterioration Anomalies such asdroughts whether of shorter or longer duration wouldlikely engender a cultural response of some kind butthis might take many forms and might not even be per-ceptible in the archaeological record

On another level the authors of this paper constructa false dichotomy between the so-called demographic-

crisis scenario outlined here and lsquolsquosimple adaptationrsquorsquo orlsquolsquointensificationrsquorsquo models In fact few if any of the latterassume relentless population growth through the Cali-fornia sequence and they do not deny that environmen-tal perturbations might have contributed to patterns ofsocial and territorial circumscription that were alreadyemerging Because the record fails to disclose associa-

tions between economic and social transformations andpaleoclimatic anomalies in other times and placessome intensification arguments have given primacy todemographic variables this is essentially what Jones etal do when they acknowledge that by the time of thelsquolsquolatersquorsquo medieval drought (ad 1150ndash1350) relationshipsbetween population resources and technology wereunable to weather conditions comparable to the onesthey had experienced during the lsquolsquoearlyrsquorsquo drought (ad900ndash1100)

Archaeologists have been bombarded in recent yearswith the claim that paleoenvironmental data have at-tained the level of resolution necessary to examine par-ticulars of the culture-environment equation The real-

ity of course is that while some kinds of lsquolsquoproxyrsquorsquo datado have excellent temporal resolution and offer rela-tively direct reflections of past environmental or cli-matic conditions many are as coarse-grained as theyever were and still require fancy inferential gymnasticsto translate and interpret Even when the resolution ofthese data is superior archaeological correlates are sel-dom of comparable quality Researchers are frequentlyforced to work at a millennial scale in western NorthAmerica regional coverage in most areas remains veryincomplete and most notions about the occupationalhistory of particular places can at best be termed edu-cated guesses It is just such problems of uneven resolu-tion that make the present argument suspect on a sub-

stantive basisLimitations of space preclude a detailed discussion of

the California record although several comments are inorder Having no firsthand experience with the Colo-rado Plateau I leave assessment of those data to others(but would note that the evidence for environment-in-duced cultural transformations seems stronger from thestandpoint of both temporal correspondence and clearlyidentified structural consequences) Looking first at pa-leoclimatic trends as portrayed one must questionwhether the records are in fact synchronous or have suf-ficiently similar levels of resolution to be meaningfulSome of the data sets have contradictory connotationsfor the same time period (tree-ring sequences from the

White Mountains and southern California indicatingmore effective moisture during much of the intervalStine [1994] assigns to his first lsquolsquoepicrsquorsquo drought) othersare clearly too coarse-grained to have any measurablesignificance (increased fire scarring in the Sierra Nevadafrom ad 1000 to 1300 enhanced aridity in Mojave De-sert woodrat midden constituents from ad 600 to1200 and a saltwater incursion at Newport Bay fromad 200 to 1500) Thus while Stinersquos documentation ofdramatic hydrologic changes in the eastern Sierra Ne-




vada is fairly compelling there is at present little sup-port for comparable concurrent deterioration in coastalCalifornia or the Mojave Desert

Much the same difficulty extends to the archaeologi-cal signatures which either are subject to a wide rangeof potential explanations show limited temporal corre-spondence or are based on questionable premises

Along the central California coast evidence of culturalstress takes the form of a shift in hunting technologychanges in the occupational profiles of residential sitesand a fall-off in obsidian importation all at around ad1200 There is no reason to relate these changes to envi-ronmental deterioration the bow and arrow became adominant weapon system at about this time acrossmuch of California (almost certainly because of its stra-tegic advantages) the sudden shift in site locationsmight not reflect continued expansion in diet breadthbut it could mark a change in settlement organizationthe better to exploit different microenvironments (in-tensification after all can be marked by increased useof high-cost resources shifts to more labor-intensive ex-

tractive technologies or enhanced exploitation of sub-optimal resource tracts) and the sudden decrease in ob-sidian access (which is hardly a trade horizon in itself)tracks a general trend in production at most or all of thewestern Great Basin quarries not just Coso There havebeen any number of better explanations for the shape ofthese quarry production curves people still need toolseven under drought conditions

The southern California data are equally equivocalsettlement disruption on certain of the Channel Islandsand the emergence of offshore bead-manufacturing cen-ters have been attributed to various factors other thanenvironmental deterioration increasing exploitation ofmarine resources on the mainland does not necessarily

follow from the fact that terrestrial productivity de-creased the evident changes in health and rates of inter-personal violence began around ad 300 well beforethese medieval droughts (only a single cemetery popula-tion dates to the critical interval) Trade with the South-west was never very important in this region and inter-action spheres can shift for a multitude of reasonsFinally the Mojavean data are clearly the most suspectcomposite radiocarbon curves being problematic in thebest situations as an indicator of population levels Theproblem is compounded here by the fact that researchacross the region has been haphazard and of uncertaincoverage in fact data from Fort Irwin the most system-atically examined tract in this region indicate a dra-

matic increase in assays after ad 500 that continuesinto early historic times If desert populations were con-strained by water during this period as Jones et al sug-gest the spring-poor Fort Irwin environment is hardlya likely destination

There can be little argument with the position that itwould be foolish to ignore the potential effect of cli-matic change and environmental deterioration onhunter-gatherer populations in western North Americaor anywhere These kinds of relationships however

need to be examined closely with an eye to identifyingcrucial structural connections between climatic trendsenvironmental consequences and those aspects of thecultural systems that articulated directly with re-sources and landscapes Gross correlations and asser-tions will not resolve this problem which has hinderedprocessual archaeology since its beginnings The Medi-

eval Climatic Anomaly may well have had profoundimpacts on native populations of coastal California andthe Mojave Desert but this paper falls short of demon-strating it

r o b e r t l b e t t i n g e rDepartment of Anthropology University of California Davis Calif 95616-8522 USA 26 x 98

The hypothesis that severe drought drastically reducedlate prehistoric populations in western North Americahas attracted much archaeological attention of late andJones et al are to be applauded for formalizing the argu-

ment so neatly and summarizing the relevant data inbroad geographical perspective I was surprised how-ever to find myself cast as a neo-Darwinian whosearguments about subsistence change lsquolsquoignore en-vironmental fluxrsquorsquo Neo-Darwinian or not my interpre-tations of late prehistoric adaptive change in the west-ern Great Basin have never ignored lsquolsquoenvironmentalfluxrsquorsquo (eg Bettinger 198216ndash19 1991670ndash72 nd)They simply do not accord that flux the importancethese authors believe it deserves My reservation de-rives in part from evidence suggesting that while thefrequency of extremely cold warm wet and dry yearshas varied over time during the Holocene the severityof annual extremes has not (Curry 1969) I find this

point crucial since as far as the hunter-gatherers ofCalifornia and the Great Basin are concerned one badyear is just as bad as two consecutive bad years and intheory one bad year per generation should be enough tokeep population in check In fact fine-grained paleocli-matic data establish that severe years occurred quiteregularly throughout the late Holocene (eg Brown etal 1992 Graumlich 1993 Hughes and Graumlich 1995Swetnam 1993) Indeed from Graumlichrsquos data it isquite difficult to discern the Medieval Climatic Anom-aly as a separate event at all even when the data aresmoothed by averaging (Graumlich 1993 fig 4) Pa-leoclimatic data of course are commonly smoothedthis way to accentuate trends Those trends however

are of little relevance to hunter-gatherers who cope notwith long-term climatic trends but with conditions oneyear at a time Following Testart (1988) Jones et al ar-gue that reliance on storage would have rendered groupsin California and the Great Basin more susceptible tolong-term drought This is sensible of course sincestoring permits population to grow larger (Keeley 1988)Here again however one bad year is quite enough toupset the applecart since very few of the groups inquestion consistently laid up stores for more than one




winter Belovsky (1987) argues on theoretical groundsthat the maximum shortfall period that can be coveredby regular hunter-gatherer storage is about 47 monthsStores larger than this may occur (eg for trade or feast-ing) but will have very little if any effect on local orregional population

A related but more fundamental objection to the

lsquolsquomedieval hypothesisrsquorsquo as currently articulated by Joneset al is that it fails to draw the essential connectionsbetween climatic conditions and human populationsThe key problem here is that in almost none of thecases mentioned do we have anything like a clear un-derstanding of precisely what is actually limiting popu-lation There is certainly a basic connection betweenpopulation and food supply but the relationship is sel-dom direct and cannot simply be assumed to be so It isquite thinkable for instance that unproductive (colddry) summers followed by long winters would have thegreatest impact but a substantial body of data includ-ing those provided in this paper seems to indicate thatpopulation levels rebounded during the so-called Little

Ice Age during which those conditions likely obtainedIt is unlikely in any case that drought would have hada uniformly adverse effect on all food sources of interestto human foragers in part because in regions of highlyvariable climate successful species typically maintainsubstantial genetic variety including drought-resistantstrains Indeed Graumlichrsquos data show quite clearlythat response to (inferred) drought varies substantiallyboth by individual tree and by location which is in ac-cord with the data compiled by Koenig (1994 et al) sug-gesting that California oak (Quercus) masting patternsvary dramatically by species and independently of tem-perature and precipitation (although the sample periodwas relatively short) Finally drought may well create

as many exploitative opportunities as it destroys asPate (1986) has demonstrated with reference to hunter-gatherers in desert Australia

What I am arguing is not that the Medieval ClimaticAnomaly did not occur or that it did not adversely affecthuman populations but rather that this has not beenconvincingly demonstrated Jones et al have put to-gether an interesting circumstantial case that clearlymerits further archaeological attention To proceed fur-ther will require a more detailed understanding of boththe human systems and the climatic anomalies thatwere involved

k a t a l i n t b i r oHungarian National Museum Mu zeum krt 14ndash16Budapest H-1088 Hungary 16 xi 98

Jones et al have chosen a very complex problem howclimatic change influenced the cultural development ofdifferent human populations living under rather differ-ent ecological conditions in four study regions acrosswestern North America In the Old World the time-span studied AD 800ndash1350 saw the development and

flourishing of the feudal statesmdashthat is the formationof modern Europe Meanwhile the pre-Columbian his-torical development of western North America was pro-ceeding under completely different social and economicconditions providing us the opportunity to study re-sponses to stress in very different ecosystems reminis-cent in their complexity of the MesolithicNeolithic

cultures of our region Especially interesting for stu-dents of European prehistory is how hunters in contrastto farmers responded to subsistence stress under con-trolled conditions within various ecosystems

In Central Europe we face similar problems of thespreaddevelopment of productive economies but thetemporal dimensions and the scale of paleogeographicobservations are different the coexistence of hunter-gatherer and farming economies dates back at least7000 years (6th millennium bc in the Carpathian Ba-sin) and the geographic setting is more restricted Thedevelopment of Central Europe seems to have beenmuch more homogeneous different economic systemswere much more widely separated and coexisted within

a narrower time-span Neolithisation in Europe is un-derstood as a gradual northward lsquolsquoslidingrsquorsquo of ideas andor people and the mosaic-like coexistence of differenteconomies over an extended period can be observedonly in isolated cases The reason can probably be foundin ecological niche size and variety

Another marked difference for us is that we have onlyindirect evidence of population dynamics since mostfinds come from settlements and there is very little an-thropological evidence from the period of hunter-gathererfarmer coexistence Thus it is easier to demon-strate periods of bounty than periods of stress and theconcrete response to climate deterioration is typicallythe absence of something that was once abundant large

mammals are missing by the end of the Pleistocene andthe number of settlements datable to the earliest Holo-cene correspondingly declines The Atlantic climate op-timum brought about a striking development of farm-ing economies in the formation of tell settlements inthe Carpathian Basin the northernmost limit of theirexpansion Again stress (climate deterioration mainlythe droughts of the Subboreal phase) is reflected by theabandonment of the tell settlements and the collapse ofthe old settlement system and wetland-based agricul-ture It seems that the natural endowments of Transda-nubia made it less vulnerable to sudden changes TheLengyel culture (phase 3) and the subsequent closely re-lated probably descendant Balaton culture population

survived in the western half of the Carpathian Basinwhile the world to the east of the Danube was beingshaken to its very rootsmdashwith a change of economy(the appearance of pastoral populations) the disappear-ance of tells and the scarcity of settlements in generalthe appearance of tribal cemeteries and a completechange in raw-material supply patterns

Thus on a much smaller scale and despite a scarcityof details we can corroborate Jones et alrsquos conclu-sion about the importance of economic factors and the




varying role of these factors depending on local condi-tions

j o n a t h a n h a a s a n d w i n i f r e d c r e a m e rThe Field Museum Roosevelt Rd and Lake ShoreDr Chicago Ill 60605-2496 Department of

Anthropology Northern Illinois University DeKalbIll 60115 USA 15 x 98

Jones et al are making a valiant effort to synthesize andintegrate large bodies of both environmental and ar-chaeological data from western North America Theirprimary point which they articulate convincingly isthat there is a complex causal and nonlinear relation-ship between people and their environments They spe-cifically make an effort to correlate in a general waycommon kinds of adaptive patterns between hunter-gatherers and agriculturalists in response to climaticchanges associated with the Medieval Climatic Anom-aly Their study parallels other interesting work being

done in Europe today and fits well within the devel-oping field of historical ecology which lsquolsquoexplores com-plex chains of mutual causation in human-environmentrelationsrsquorsquo (Crumley 1996558 see also 1994)

We are in substantial agreement with the main thrustand conclusions of the paper but a number of specificissues are in need of clarification and emendation Per-haps the most critical issue relates to the comparabilityof the data sets from the different areas examined Infigure 11 we see that in the two areas that have beenwell dated with tree-ring data the southern Sierra Ne-vada and the Colorado Plateau the periods of droughtare much shorter than in areas without tree-ring datesIt remains a big question whether these are real differ-

ences or artifacts of varying kinds of data On the Colo-rado Plateau alone the environmental reconstruction isbased on literally thousands of tree-ring dates In con-trast for the Mono Lake area where figure 11 showstwo long stretches of drought the data base consists ofonly 17 radiocarbon dates taken from relict stumps(Stine 1994) Our intent here is not to disparage theMono Lake data set but to point out that the resolutionprovided by an accurate dendrochronological recon-struction gives a much more refined and accurate pic-ture of prehistoric climate

Although Jones et al argue for broad patterns of envi-ronmental similarity during the Medieval ClimaticAnomaly their own data would indicate that when ac-

curate data are available there is considerable local vari-ability at any given time (see Dean 1994) Again thehigher resolution provided by tree rings also indicatesthat the Medieval Climatic Anomaly was not environ-mentally monolithic The data presented in the papershow there was actually a lot of variability in the onsetduration and frequency of drought episodes in differentparts of western North America Looking more closelyat the Colorado Plateau where there are strong paleocli-matological data for the period in question there werecyclical periods of high and low areal variability in local

environmental conditions (what Dean et al [1985] referto as lsquolsquohigh-frequency variationrsquorsquo [see also Gumerman1988]) During periods of high areal variability two ad-joining areas could receive significantly different levelsof annual precipitation and have commensurately dif-ferent annual crop yields Such inequalities in yield inturn provide circumstances conducive to either in-

creased integration between cooperating neighbors orincreased raiding and warfare between haves and have-nots

A related issue concerns the inferred causal relation-ships between periods of drought and broad patterns ofcultural adaptation Looking again at the Colorado Pla-teau the combination of a precise tree-ring record anda huge data set of surveyed and excavated sites demon-strates that the relationship between culture changeand environmental phenomena such as droughts ishighly complex Our own data on warfare in the Kay-enta subregion (Haas and Creamer 1993) illustrates thecomplexity of the relationship at the local level Theavailable evidence indicates that a low-frequency cycle

of environmental degradation began at roughly ad1150 (Dean et al 1985) Then as noted the lsquolsquoGreatDroughtrsquorsquo descended on the area from 1276 to 1299 Incontrast intergroup violence first arises in the 1240s(long after the start of the environmental downturn) andintensifies for the next 30 years (well before the onset ofthe Great Drought) The outbreak of warfare is clearlyrelated to the deteriorating environmental conditionsraiding developed as an adaptive strategy for acquiringauxiliary resources in the face of localized shortagesHowever the relationship between war and the envi-ronment is complex and contingent on specific histori-cal and geographical circumstances Rather than contra-dicting the conclusions of Jones et al this kind of local

information based on extensive dendrochronologicaland archaeological records illustrates more clearly howenvironmental forces come to play a causal role in thedecision making of human populations

The authors have taken an important first step in thispaper in trying to cross boundaries between traditionalculture areas and between ecological studies and ar-chaeology In doing so they have effectively shown thatthere were broad patterns in the development of humansystems in western North America These patternscrosscut geographical areas local ecology and substan-tial cultural differences between different populationsWhile higher-resolution environmental and archaeolog-ical records for different parts of the region indicate sig-

nificant temporal and areal diversity such data help torefine rather than refute their arguments

j o s e l u i s l a n a t aDepartment of Anthropology University of Buenos

Aires Av Rivadavia 5141 13D 1424 Buenos Aires Argentina (illanatafiloubaar) 27 x 98

Although the use of paleoenvironmental data has be-come standard in archaeology its role is usually estab-




lishing a general framework for past human behaviorJones and colleagues clearly indicate this in the firstpart of their article The use of these data has contrib-uted to the delimitation of periods with specific cli-matic characteristics but little attention has been givento environmental variability as a component of culturaland ecological change Jones et al show how a global

climate alteration such as the Medieval ClimaticAnomaly might be seen as one possible trigger of cul-tural dynamic and change The major goal of their paperis to alert us to the variability in human responses tothe same environmental stress More traditional inter-pretive models assume the environment as a constantfocusing mainly on the crystallization of culturalchange rather than on its possible causes This is a con-sequence of the adaptationist approach in archaeologyThe important issue here is to understand that climateand environment are not fixed but constantly changingBy applying an ecological and evolutionary perspectiveas the authors do archaeologists can explore underwhat circumstances cultural change is important and

or just an accommodation to brief climate pulses andminor environmental adjustments I look forward to asimilar contribution by these authors on their interpre-tation of the cultural change produced by the followingLittle Ice Age in the same area

i a n l i l l e y Aboriginal and Torres Strait Islander Studies UnitUniversity of Queensland Brisbane 4072 Australia(ililleymailboxuqeduau) 11 x 98

This is a timely article It (re)focuses archaeological at-tention on environmental constraints on past human

behaviour while acknowledging the value of recentlsquolsquopostmodernrsquorsquo attempts to break free from the environ-mental determinism which has long characterizedhunter-gatherer archaeology The insights it offers re-garding the response to environmental stress of peopleon both sides of the supposed divide between farmersand foragers add to its value as this is an area towardswhich socially oriented postmodernists have been di-recting their attention for some time (eg Bender 1978)I must take the authors at their word about the archaeo-logical and climatological evidence as I am only pass-ingly familiar with their North American materialHaving said this I will move on to some broader impli-cations of their findings as they relate to my Australian

experienceAustralian archaeology was shaken up in the 1980s

by the publication of Lourandosrsquos (1983 1984 1985) re-search on socioeconomic intensification in the mid- tolate Holocene (see also Lourandos and Ross 1994) Opin-ion remains somewhat polarized with loose clusters ofscholars producing evidence and arguments for andagainst each otherrsquos position (eg pro- Barker 1991Lourandos 1996 David and Lourandos 1997 anti- Bea-ton 1983 1985 Bird and Frankel 1991 Cosgrove 1995)

The pro- scholars have concentrated on demonstrat-

ing that recent archaeological trends to do not track en-vironmental changes and thus must be caused by some-thing lsquolsquosocialrsquorsquo In their view it comes down to scales ofanalytical resolution At a coarse scale of analysis theyare happy for long-term palaeoenvironmental and cul-tural trends to coincide They suggest that it is only atmore refined levels of analysis however that what re-

ally went on at a human scale can be detected Here so-cial factors will always cause a dramatic divergence be-tween environmental and archaeological trends becauseof the proximal causal priority of the social in humanaffairs This position is neo-Marxist to the core and inmany respects reminiscent of Braudel (eg 1972)though he is rarely if ever mentioned in the Australianliterature

The position adopted by Lourandos (1996) and his co-workers (eg David and Lourandos 1997) places thosewho seek causal correlations between environmentaland archaeological trends at fine-grained scales of analy-sis (eg Cosgrove 1995) in a bind If one finds such acorrelation onersquos data are necessarily insufficiently

fine-grained seemingly regardless of how fine-grainedthey may be A paper they use to support their positionon the grounds that its lsquolsquofiner-grained [though still quitecoarse] data have allowed the detectionrsquorsquo of cultural di-vergence from palaeoenvironmental trends (David andLourandos 199715) actually concludes lsquolsquoBased on cor-relations with a late Glacial sequence from Pulbeenaswamp the southwest caves appear to have been usedless frequently every 3 Ka during periods of relativelycolder and drier climatersquorsquo (Holdaway and Porch 199581) How does all this relate to the work of Jones et alIn two ways First contra Lourandos and co-workersthey demonstrate that very fine-grained analysis canproduce convincing correlations between cultural and

environmental trends Second they clearly show that toexplore adequately the possibility of such correlationsrequires not only that scales of archaeological resolu-tion be matched among sites or regions but that suchscales also match those of relevant palaeoenvironmen-tal analyses This may seem self-evident but both thediscussion in Jones et alrsquos paper and my experience inAustralia suggest that such matters are not always up-permost in the minds of all our colleagues in hunter-gatherer archaeology By and large Australian palaeoen-vironmental data for the mid- to late Holocene are ascoarse-grained as those for more ancient periods Thuseven if an Australian scholar has finer-grained archaeo-logical data than others it is highly likely that the

palaeoenvironmental data will be equally coarse-grained Little wonder that mid- to late Holocene cul-tural trends diverge from the environmental record

This is not to say that Lourandos et al will not even-tually be proved right about intensification in Australiaat least with regard to parts of the continent Howeverit is the implications of the research reported by Joneset al for problems such as those just described thatmakes me think their work has a lot to offer in this partof the world and indeed in many others including theirown To my admittedly inexpert eyes they do appear to




have unambiguous evidence for lsquolsquostriking correlationsrsquorsquobetween environmental and archaeological sequencesover a not insignificant area of western North AmericaThat they have approached this issue in a nondetermin-istic manner is evident from the flexibility with whichthey accommodate the differences through space andtime among the responses to the Medieval Climatic

Anomaly matters that the more mechanistic might seeas troublesome aberrations and the more lsquolsquopostmod-ernrsquorsquo at least in Australia as problems of analyticalscale Scholars around the world are right to questionmechanistic environmental determinism on thegrounds that it is a demonstrably inferior approach Itdoes not follow though that environmental factorsshould be automatically rejected in explanation becauseof an implicit or explicit ideological stance that blindsresearchers to the evidential imperatives of the archaeo-logical or palaeoenvironmental records To do so asJones and colleagues so aptly put it is simply unreal-istic

t h o m a s a w a k eZooarchaeology Laboratory Institute of ArchaeologyUniversity of California Los Angeles 405 Hilgard

Avenue Los Angeles Calif 90095 USA 16 xi 98

The arguments Jones et al make are timely and compel-ling Environmental calamities such as the 1997ndash98 ElNin ˜ o event Hurricane Mitchrsquos death toll of over11000 and drought-driven famines complicated by warin Africa have made it painfully clear that moderntechnologically complex societies are not immune tothe forces of nature and concomitant social strife Envi-ronmental perturbations clearly can affect human soci-

ety It is sobering to imagine the consequences of a fu-ture prolonged drought that might leave large treesgrowing deep below modern shorelines of large Sierranlakes (Stine 1990 1994) Such conditions have clearlyoccurred in the past and would certainly destroy mod-ern Californiarsquos valuable agricultural commodities andhave far-reaching economic and social effects Wewould be forced to adapt to such a situation one hopeswith a minimum of violence and transhumance

Jones et al weave a tangled web of important factsand observations based on the available literature andtheir own experience but I am convinced that they areonly scratching an already roughened surface Worriedthat their conclusions will be held up as purely environ-

mentally deterministic Jones et al take pains to dis-tance themselves from previous studies they and othershave proven to be overly simplistic They show con-vincingly that different environmental perturbationsand important cultural changes occurred at differenttimes in each of the separate regions they describeThese events however are not strongly linked tempo-rally region to region

The article includes a number of comments amongthem that the diet did not continue to broaden on Cali-forniarsquos central coast between ad 1000 and 1400 that

are not supported by any references I would like to seesuch comments supported since they fly in the face ofconclusions of widening diet breadths and size diminu-tion in contemporaneous San Francisco Bay and Sacra-mento Delta contexts strong indications of Late Periodvertebrate resource intensification (Broughton 1994a b1997 Simons 1991) If the medieval droughts resulted

in the general resource depression proposed then re-sponses should be discernible in dietary records avail-able in the carbonized plant remains and animal bonesleft at sites by their depositors I propose that if verte-brate resources were severely depressed as Jones et alimply then the diet breadths of people dependent onthem would have widened correspondingly No broadanalysis of Late Period dietary patterns in California yetexists but the numerous cultural resource managementand academic field investigations in California and theSouthwest over the past 20 years have generated awealth of data ripe for such a synthesis

The baseline references used to establish the environ-mental and cultural patterns during the periods high-

lighted are few and far between I do not intend to quib-ble about the results of the environmental andarchaeological studies referenced but the conclusionsdrawn from them may be premature There are manytemporal and regional gaps especially in Californiathat need to be filled before any patterns of environmen-tally stimulated punctuation of the cultural history ofwestern North America become truly convincing Theregional patterns described need to be tied togethertightly and any inconsistencies adequately explainedWhile the synthesis Jones et al provide is compellingit is only a beginning Ideally this article will serve as astimulus for further research in this arena and not as arallying cry for those who believe otherwise We can ill

afford to ignore any lessons the natural environmenthas taught past human societies if only for their poten-tial modern implications

Reply

t e r r y l j o n e s a n d g a r y m b r o w nSan Luis Obispo CalifPlacitas NM USA 23 xi 98

That our article has provoked support (Lanata and Lil-ley) amplification (Biro Haas and Creamer) and skepti-

cism (Basgall Bettinger and Wake) suggests that wehave accomplished at least some of the goals that weset for ourselves in developing the medieval-droughthypothesis Our primary objectives were to (1) reintro-duce large-scale climatic flux as a potential cause of pre-historic culture change in a nondeterministic manner(2) challenge the traditional dividing line between forag-ers and agriculturalists (3) raise a cautionary flagagainst linear adaptive arguments based on theories ofprogressive cultural evolution andor economic intensi-fication and (4) argue the specific case for drought-in-




duced crises during the late Holocene in western NorthAmerica To the degree that we have accomplishedthese goals our colleagues have described our effortsvariously as timely undemonstrated flawed and val-iant Researchers from abroad have found both theoreti-cal and empirical similarities to their work while somecommentators in our own study regions have rejected

our efforts In connection with these alternative charac-terizations commentators have raised a number of keypoints in conceptualizations of prehistoric human ecol-ogy in general and western North American archaeol-ogy in particular Foremost among these are issues ofchronological resolution economic intensification spa-tial and temporal variability and the burden of proof inarchaeological models of the past

Nearly all of the commentators raise issues of chro-nological resolution but Lilleyrsquos discussion of this topicin Australia is perhaps most insightful In Australianeo-Marxists argue that correlations between environ-mental variation and changes in human behavior are ap-parent only when paleoenvironmental and archaeologi-

cal records are coarse-grained As resolution improvesthis school predicts an inevitable lack of correlationthat is taken as evidence for the primacy of social fac-tors in forcing cultural change Lilley points out thatthis position allows for no alternative interpretationsas any sequence suggesting a correlation between envi-ronment and cultural change is automatically dis-missed as too coarse Comments by Haas and Creamerhowever are extremely important on this issue as theirinterpretations are drawn from what are probably themost detailed sequences in the worldmdashthe tree-ring-based archaeological and paleoclimatic chronologies ofthe American Southwest in particular the Kayenta re-gion in the central Colorado Plateau With the precision

afforded by what is essentially an annual calendricchronology Haas and Creamer see an outbreak of in-tergroup raiding that they believe is related to environ-mental deterioration during the late Medieval ClimaticAnomaly but they also caution that the relationshipbetween warfare and environment is complex and atleast partially stochastic The Kayenta study and ourmore general Southwestern case study are instructive indisproving the Australian neo-Marxist position summa-rized by Lilley A relationship between droughts and re-gional abandonments was recognized by pioneeringSouthwesternists long ago but subsequent increase inthe quantity and resolution of chronometrically con-trolled archaeological and paleoenvironmental data has

produced even closer correlations This trend runsstrongly counter to the predictions of Lourandos (1996)The development of paleoclimatic sequences of annualresolution has resulted in a highly complicated database that is not easily linked to patterns in humanen-vironment relationshipsmdasha fact well-recognized bytree-ring researchers who attempt to smooth out sto-chastic fluctuations and focus on longer-term (eg de-cadal) variability It is for this reason that researcherssuch as Dean (1988a) stress the need for collateral pa-leoenvironmental data to help reduce noise and identify

processes of sufficient magnitude and duration to applyto archaeological models

Our reason for considering both farmers and hunter-gatherers was to address a broad range of human re-sponses to drought Basgallrsquos reminder that lsquolsquohumanshave the capacity to adjust to environmental changes innumerous waysrsquorsquo and that lsquolsquomany climatic shifts appar-

ently had minimal impactrsquorsquo simply echoes the pointsmade repeatedly in our article His reluctance to con-sider prehistoric agriculture on either a theoretical or anempirical level further reveals his limited understand-ing of our major pointmdashthat despite the enormousrange of technological and behavioral options some cli-matic processes require cultural changes even if simplythe innovation of new technology or behavior Both Bas-gall and Bettinger further point out that some plant spe-cies produce abundantly under drought conditions Cer-tainly some plants flourish during brief droughts butthe welfare of most plant and animal populations (espe-cially domesticates) is clearly linked to effective mois-ture Paleoclimatic records of the late medieval period

from both California and the Colorado Plateau suggestanomalously prolonged periods of drought that wouldhave severely depressed effective moisture for extendedperiods We find it hard to believe that these conditionspresented a subsistence bonanza for either hunter-gath-erers or agriculturalists Furthermore while we ac-knowledge a possible range of responses to such diffi-cult conditions we emphasize the potential fordemographic problems and negative behaviors whichare often lacking in linear adaptationistintensificationmodels

While focusing on agricultural lifeways Haas andCreamer greatly expand upon the theoretical and empir-ical discussion we initiated Their Kayenta case study

provides a fascinating example of conflict rather thancooperation in the context of environmental stressTheir comment is also one of two (the other by Biro)that emphasizes spatial variability in paleoenvironmen-tal trends and its implications for human responseHaas and Creamer suggest that raiding andor warfare ismost likely to be successful when high areal variabilitycreates situations in which some groups are consider-ably better off than others Warfare in the Kayenta re-gion in the 13th century occurred during a period whenspatial variability was consistently low (Plog et al 1988)and raiding may not have been productive Kayentawarfare may therefore defy a purely functional interpre-tation but we agree with Haas and Creamer that the

increase in raiding must be viewed in the context of en-vironmental decline Decrease in localized Kayenta ex-change networks is also probably best understood inthis light as well as the context of low spatial variabil-ity which would have reduced spatial inequity in sur-pluses and the possibility of profitable trading

Biro provides yet another example of the importanceof spatial variability in prehistoric humanenvironmen-tal relationships Her description of events in easternEurope suggests that climate flux was linked to a widerange of human responses partially reflecting a grada-




tion in the effects of climatic events Some areas wereimpacted severely while other better-endowed prov-inces (eg Transdanubia) were less affected Ulti-mately the situation in western North America duringthe Medieval Climatic Anomaly should show parallelswith that in Europe in that favorably watered regions(eg major river valleys or Lake Cahuilla) could have

served as refugia where temporary population increaseswere experienced

The comparatively low resolution of the hunter-gath-erer sequences of central and southern California istroubling to Bettinger and Basgall We acknowledge thesignificant drop-off in the precision of cultural and envi-ronmental chronologies from the Colorado Plateauto California On a coarse-grained temporal scaleeconomic intensification (linked in western NorthAmerica not to neo-Marxism but to optimal foragingand population growth) provides a powerful explanationfor many diachronic patterns in hunter-gatherer settle-ment and subsistence (eg Erlandson 1991 Broughton1994) Several of us have contributed to broad-scale eco-

nomic-intensification models (Jones 1991 1992 Raab1996) and we suspect that these will continue to dem-onstrate their value when more detailed paleoenviron-mental data become available We concur with Basgallthe author of the most significant publication on eco-nomic intensification in California (Basgall 1987) thatin many cases hunter-gatherers could transcend low-intensitylow-frequency environmental flux Where wediverge however and where we feel justified in raisinga flag of caution is in our unwillingness to relate allchanges to linear trajectories of successful economic ad-aptation or to ignore major paleoclimatic change Wefeel that intensification provides a predictive frame ofreference the value of which is demonstrated by archae-

ological cases that match the predictions as well asthose that do not In the latter instances investigatorsshould consider alternative explanations (eg environ-ment) but change often continues to be viewed interms of increasingly intensified adaptation ignoringthe character of specific transitions and any possiblesynchrony with environmental events Basgall for ex-ample suggests that the bow and arrow came to domi-nate weapon assemblages in California ca ad 1200simply because of its effectiveness but by most ac-counts this improved technology had been present inwestern North America for nearly a millennium and itspresumed superiority should have been apparent fromthe outset Its sudden domination of weapon systems

ca ad 1200 seems more than a simple product of in-cremental intensification More troublesome is Bas-gallrsquos acknowledgment of the decline in production atwestern obsidian sources during the Medieval ClimaticAnomaly This decline is synchronous with markedlyreduced exchange to distant consumers who used thiscommodity as a nonessential supplement to morereadily available stone from other sources We contendas has at least one other researcher (see Gilreath 1995254) that this drop-off is not consistent with the pre-dicted outcome of intensification which only provideseffective explanation for increases in obsidian produc-

tion and exchange through the Holocene up to the onsetof the Medieval Climatic Anomaly

Basgallrsquos concerns are echoed by Wake who chal-lenges our statements about central California dietarytrends pointing out that subsistence intensificationacross the Medieval Climatic Anomaly has ostensiblybeen documented in faunal assemblages from San Fran-

cisco Bay shell mounds We do not deny these trendsbut emphasize that they are accompanied by significantdisruption in settlement (widespread abandonmentsand reoccupations) during the MiddleLate transitionand Late Period (Lightfoot and Luby 1998) that is sug-gestive of something other than simple adaptiveadjustmentintensification When the faunal recordsuggests intensification possible underlying causes canbe evaluated only when the faunal trends are examinedin the context of settlement and environment Thisseems particularly true in light of Wakersquos suggestionthat drought-related subsistence problems might resultin increasing diet breadth If both incremental popula-tion growth and demographic crises can result in wider

diets indices other than fauna need to be investigatedOne specific region where Late Period diets are not

broader than earlier (Middle Period) ones is the Big Surcoast alluded to in our discussion of central CaliforniaIn that area Late assemblages show fewer species ex-ploited and a proportional decrease in small labor-in-tensive taxa (eg fish sea otters and rabbits) from theMiddle through the Late Period (Jones 1995) Other ar-eas where faunal remains from Late Period deposits donot conform with linear schemes of intensification in-clude several of the Channel Islands where the LatePeriod is characterized by rebounds in previouslysuppressed highly ranked marine taxa (Jones and Hilde-brandt 1995) These rebounds seem to reflect decreased

predatory pressure during the Medieval ClimaticAnomaly due to drought-related abandonments of themore poorly watered islands

Finally we have the issue of the burden of proof andthe question of whether we have conclusively demon-strated that western North America experienced wide-spread demographic crises between ad 800 and 1350due to prolonged and severe drought Of course we havenot provided a full account of the situation but we seelittle reason to characterize this as a failure We fullyacknowledge that what we have detected is a highlysuggestive correlation between archaeological and pa-leoenvironmental sequences Any argument relying onthese two sources will of necessity amount to little

more than a correlation Models asserting no influencefrom environment are no more secure than those as-serting a causal relationship especially since the formerare heavily dependent upon negative evidence The cor-relation stands as a hypothesis that provides at leasttwo very different implications for local and regionalhistories of settlement and exchange Contra Basgallwe see significant intellectual value in developingbroad-scale predictive models that encompass bothwell-studied and poorly known regions we see littlevalue in waiting until detailed settlement histories aredeveloped for all localities of western North America




Our ultimate concern was to encourage the develop-ment of fine-grained archaeological and paleoenviron-mental records that facilitate such comparisons

References Cited

a g e n b r oa d l a r r y d j i m i m e a d e m i l e e d m e a da nd di a na elder 1 9 8 9 Archaeology alluvium and cavestratigraphy The record from Bechan Cave Utah Kiva 54335ndash49

a lli son j a m es r 1 9 9 6 Comments on the impacts of cli-matic variability and population growth on Virgin Anasazi cul-tural development American Antiquity 61414ndash18

a m b ler j r i c ha r d 1 9 6 6 Caldwell Village University ofUtah Anthropological Papers 84

a nde r son r y 1 994 lsquolsquoLong-term changes in the frequencyof occurrence of El Nino eventsrsquorsquo in El Nin o historical and pa-

leoclimatic aspects of the Southern Oscillation Edited byH F Diaz and V Markgraf pp 193ndash200 Cambridge Cam-bridge University Press

antevs e 1948 Climatic changes and pre-white man Univer-

sity of Utah Bulletin 38168ndash91mdashmdashmdash 1953 Climatic history and the antiquity of man in Cali-fornia University of California Archaeological Survey Reports1623ndash31

arnold j e 1987 Craft specialization in the prehistoricChannel Islands California University of California Publica-tions in Anthropology 18

mdashmdashmdash 1992a Complex hunter-gatherer-fishers of prehistoric Cal-ifornia Chiefs specialists and maritime adaptations of theChannel Islands American Antiquity 5760ndash84

mdashmdashmdash 1992b lsquolsquoCultural disruption and the political economy inChannel Islands prehistoryrsquorsquo in Essays on the prehistory of maritime California Edited by T L Jones pp 129ndash44 Centerfor Archaeological Research at Davis Publications 10

a r n o l d j e r h c o l t e n a n d s p l e t k a 1 9 9 7 Con-texts of cultural change in insular California American Antiq-uity 62300ndash318

aschmann h 1959 The evolution of a wild landscape and itspersistence in southern California Annals of the Associationof American Geographers 334ndash57

b a r b o u r m i c h a e l g j h b u r k e a n d w d p i t t s 1987 Terrestrial plant ecology Menlo Park Calif BenjaminCummings

bar ker b 1991 Nara Inlet 1 Coastal resource use and the Ho-locene marine transgression in the Whitsunday Islands centralQueensland Archaeology in Oceania 26102ndash9 [il ]

b a sga ll m e 1 987 Resource intensification among hunter-gatherers Acorn economies in prehistoric California Research

in Economic Anthropology 921ndash52b a sga ll m e a nd m c ha ll 1 9 9 2 Fort Irwin archaeol-

ogy Emerging perspectives on Mojave Desert prehistory Soci-ety for California Archaeology Newsletter 261ndash7

baumhoff m a 1978 lsquolsquoEnvironmental backgroundrsquorsquo inHandbook of North American Indians vol 8 California Ed-

ited by R F Heizer pp 16ndash24 Washington DC Smithson-ian Institution Pressb a u m h o f f m a a n d r l b e t t i n g e r 1982 The

Numic spread Great Basin cultures in competition American Antiquity 47485ndash503

b a u m h o f f m a r t i n a a n d r o b e r t f h e i z e r 1 9 6 5 lsquolsquoPostglacial climate and archaeology in the Desert Westrsquorsquo inThe Quaternary of the United States Edited by Herbert EWright Jr and David G Frey pp 697ndash707 PrincetonPrinceton University Press [meb]

b ea n l j a nd h la w t on 1 9 7 6 lsquolsquoSome explanations forthe rise of cultural complexity in native California with com-ments on proto-agriculture and agriculturersquorsquo in Native Califor-

nians A theoretical retrospective Edited by L J Bean andT C Blackburn pp 19ndash48 Menlo Park Calif Ballena Press

beatley j c 1975 Climates and vegetation pattern acrossthe MojaveGreat Basin Desert transition of southern Nevada

American Midland Naturalist 9353ndash70beaton j 1983 Does intensification account for changes in

the Australian Holocene archaeological record Archaeology inOceania 1894ndash97 [il ]

mdashmdashmdash 1985 Evidence for a coastal occupation time-lag at Prin-cess Charlotte Bay (North Queensland) and implications forcoastal colonization and population growth theories for Aborigi-nal Australia Archaeology in Oceania 201ndash20 [il ]

b elo v sk y g e 1 987 Hunter-gatherer foraging A linear pro-gramming approach Journal of Anthropological Archaeology 629ndash76 [rlb]

bender b 1978 Gatherer-hunter to farmer A social perspec-tive World Archaeology 10204ndash22 [il ]

mdashmdashmdash 1985 Emergent tribal formation in the American mid-continent American Antiquity 5052ndash62

b e r g e r r a i n e r a n d n o r m a n m e e k 1992 Radiocarbondating of Anodonta in the Mojave River Basin Radiocarbon34578ndash84

berry m s 1982 Time space and transition in Anasazi prehistory Salt Lake City University of Utah Press

b et a n c our t j uli o 1990 lsquolsquoLate Quaternary biogeography ofthe Colorado Plateaursquorsquo in Packrat middens The last 40000

years of biotic change Edited by Julio L Betancourt T R VanDevender and P S Martin pp 259ndash92 Tucson University ofArizona Press

b e t a n c o u r t j l a n d t r v a n d e v e n d e r 1 9 8 1 Ho-locene vegetation in Chaco Canyon New Mexico Science 214656ndash58

b e t a n c o ur t j u l i o l t r v a n d e v e n d e r a n dp s m a r t i n 1 983 lsquolsquoFossil packrat middens from ChacoCanyon Cultural and ecological significancersquorsquo in Chaco Can-

yon country Edited by S G Wells D W Love and T WGardner pp 207ndash18 American Geomorphological SocietyField Guidebook Albuquerque University of New MexicoPress

b et t i n ger r l 1 982 Archaeology east of the Range of Light Aboriginal human ecology of the Inyo-Mono region Cal-

ifornia Davis University of California [rlb]mdashmdashmdash 1991 Aboriginal occupation at high altitude Alpine vil-

lages in the White Mountains of eastern California American Anthropologist 93656ndash79 [rlb]

mdashmdashmdash nd lsquolsquoWhat happened in the Medithermalrsquorsquo in Models forthe millennium Great Basin anthropology today Edited by CBeck Salt Lake City University of Utah Press [ rlb]

b i r d c a nd d fr a nk el 1 9 9 1 Chronology and explana-tion in western Victoria and south-east Australia Archaeology

in Oceania 261ndash16 [il ]bouey p d 1987 The intensification of hunter-gatherer econ-

omies in the southern North Coastal Ranges of California Re-search in Economic Anthropology 953ndash101

braudel f 1972 The Mediterranean and the Mediterraneanworld in the age of Philip II Translated by S Reynolds NewYork Harper and Row [il ]

b r ought on j m 1 9 9 4a Late Holocene resource intensifica-tion in the Sacramento Valley California The vertebrate evi-dence Journal of Archaeological Science 21501ndash14

mdashmdashmdash 1994b Declines in mammalian foraging efficiency duringthe late Holocene San Francisco Bay California Journal of An-thropological Archaeology 13371ndash401 [taw]

mdashmdashmdash 1997 Widening diet breadth declining foraging effi-ciency and prehistoric harvest pressure Ichthyofaunal evi-dence from the Emeryville Shellmound California Antiquity 71845ndash62 [taw]

brown gary m 1982 Lithic exchange and production on An-derson Mesa north-central Arizona MA thesis Departmentof Anthropology Arizona State University Tempe Ariz

mdashmdashmdash 1990 Editor Technological change in the Chavez Pass region north-central Arizona Arizona State University Anthro-pological Research Papers 41

mdashmdashmdash 1991 Embedded and direct lithic resource procurementstrategies on Anderson Mesa Kiva 56359ndash84

mdashmdashmdash 1992 Archaeological investigations at the Haul




Road site 1991 excavations at La Plata Mine San JuanCounty New Mexico Technical Report 577 Albuquerque Ma-riah Associates Inc

mdashmdashmdash 1996 Transformations in Southwestern prehistory Thepaleoenvironmental context of cultural change Paper pre-sented at the 61st annual meeting of the Society for AmericanArchaeology New Orleans La

b r o w n p m m k h u g h e s c h b a i s a n t w sw et na m a nd a c c a pr i o 1 9 9 2 Giant sequoia ring-width chronologies from the Central Sierra Nevada Tree-RingBulletin 52 [rlb]

b r um fi el e m 1 992 Distinguished lecture in archaeologyBreaking and entering the ecosystemmdashgender class and fac-tion steal the show American Anthropologist 94551ndash67

cane s 1987 Australian aboriginal subsistence in the WesternDesert Human Ecology 15391ndash434

c ha r t k off j l 1 989 Exchange systems in the Archaic ofcoastal southern California Proceedings of the Society for Cali-

fornia Archaeology 2167ndash86c h a r t k o f f j l a n d k k c h a r t k o f f 1984 The ar-

chaeology of California Stanford Stanford University Pressc hr i st enson l e 1 9 9 2 lsquolsquoThe late prehistoric Yuman settle-

ment system Coastal adaptationrsquorsquo in Essays on the prehistory of maritime California Edited by T L Jones pp 217ndash30 Cen-ter for Archaeological Research at Davis Publications 10

c ohen m a r k na t ha n 1 9 7 7 The food crisis in prehistoryNew Haven Yale University Press

cole k l 1986 The Lower Colorado River Valley a Pleisto-cene desert Quaternary Research 25392ndash400

c ole k l a nd r h w eb b 1 9 8 5 Late Holocene vegeta-tion changes in Greenwater Valley Mojave Desert CaliforniaQuaternary Research 23227ndash35

colten r h 1993 Prehistoric subsistence specializationand economy in a southern California chiefdom Ph D dissUniversity of California Los Angeles Calif

mdashmdashmdash 1995 Faunal exploitation during the Middle to Late Pe-riod transition on Santa Cruz Island California Journal of Cali-

fornia and Great Basin Anthropology 1793ndash120c o r d e l l l i n d a s a n d g e o r g e j g u m e r m a n

Editors 1989 Dynamics of Southwest prehistory WashingtonDC Smithsonian Institution Press

c o r d e l l l i n d a s a n d f r e d p l o g 1 9 7 9 Escaping theconfines of normative thought A reevaluation of Puebloan pre-history American Antiquity 44405ndash29

cosgrove r 1995 Late Pleistocene behavioural variation andtime trends The case from Tasmania Archaeology in Oceania3083ndash104 [il]

c r u m l e y c a r o l e l Editor 1994 Historical ecology Cul-tural knowledge and changing landscapes Santa Fe School ofAmerican Research Press [jh wc]

mdashmdashmdash 1996 lsquolsquoHistorical ecologyrsquorsquo in Encyclopedia of culturalanthropology Edited by David Levinson and Melvin Emberpp 558ndash60 New York Henry Holt [jh wc]

c ur r ey d r a nd s r j a m es 1 9 8 2 lsquolsquoNortheastern Basinrim region A review of geological and biological evidencersquorsquo inMan and environment in the Great Basin Edited by D B Mad-sen and J F OrsquoConnell pp 27ndash52 Society for American Ar-chaeology Papers 2

curry r r 1969 Holocene climatic and glacial history of the Central Sierra Nevada Geological Society of America Spe-cial Paper 123 [rlb]

david b and h lourandos 1997 37000 years andmore in tropical Australia Investigating long-term archaeologi-cal trends in Cape York Peninsula Proceedings of the Prehis-toric Society 631ndash23 [il ]

davis j o 1982 lsquolsquoLahontan Basin paleoenvironmentsrsquorsquo inMan and environment in the Great Basin Edited by D B Mad-sen and J F OrsquoConnell pp 53ndash75 Society for American Ar-chaeology Papers 2

davis o k 1992 Rapid climatic change in coastal southernCalifornia inferred from pollen analysis of San Joaquin MarshQuaternary Research 3789ndash100

dea n j effr ey s 1 9 8 8a lsquolsquoDendrochronology and paleoenviron-

mental reconstruction on the Colorado Plateausrsquorsquo in The Ana-sazi in a changing environment Edited by George J Gumer-man pp 119ndash67 Cambridge Cambridge University Press

mdashmdashmdash 1988b lsquolsquoA model of Anasazi behavioral adaptationrsquorsquo inThe Anasazi in a changing environment Edited by George JGumerman pp 25ndash44 Cambridge Cambridge UniversityPress

mdashmdashmdash 1994 The medieval warm period on the southern Colo-rado Plateau Climate Change 26225ndash42

d e a n j e f f r e y s r o b e r t c e u l e r g e o r g e j g u m e r m a n f r e d p l o g r i c h a r d h h e v l y a n dt hor n v k a r l st r om 1985 Human behavior demog-raphy and paleoenvironment on the Colorado Plateaus Amer-

ican Antiquity 50537ndash54d e a n j e f f r e y s a n d w i l l i a m j r o b i n s o n 1 977 Den-

droclimatic variability in the American Southwest AD 680to 1970 Tucson University of Arizona Laboratory of Tree-Ring Research

d e g a r i n e i a n d g a h a r r i s o n Editors 1988 Coping with uncertainty in food supply Oxford Clarendon Press

de na r v a ez c y nt a 1995 Paleohydrology and paleotopogra-phy of a Las Vegas spring MS thesis Northern Arizona Uni-versity Flagstaff Ariz

doug la ss a e 1 929 The secrets of the Southwest solved bytalkative tree rings National Geographic 54737ndash70

drover c e 1979 The late prehistoric human ecology of thenorthern Mohave Sink San Bernardino County California Ph Ddiss University of California Riverside Calif

e l y l l y e h o u d a e n z e l v r b a k e r a n d d r cayan 1993 A 5000-year record of extreme floods and cli-mate change in the Southwestern United States Science 262410ndash12

e n z e l y e h o u d a w j b r o w n r y a n d e r s o n l d m c fa dden a nd s g w ells 1 9 9 2 Short-duration Holo-cene lakes in the Mojave River drainage basin southern Cali-fornia Quaternary Research 3860ndash73

er la n dson j m 1 991 lsquolsquoShellfish and seeds as optimal re-sources Early Holocene subsistence on the Santa Barbaracoastrsquorsquo in Hunter-gatherers of Early Holocene coastal Califor-

nia Edited by J M Erlandson and R H Colten pp 89ndash100 In-stitute of Archaeology University of California Los AngelesPerspectives in California Archaeology 1

mdashmdashmdash 1993 lsquolsquoConclusionsrsquorsquo in Archaeological investigations atCA-SBA-1731 A transitional Middle-to-Late Period site on theSanta Barbara Channel Edited by J L Gerber pp 230ndash45 Re-port prepared for Exxon Company USA Goleta Calif byDames and Moore Santa Barbara Calif

euler r c 1988 lsquolsquoDemography and cultural dynamics on theColorado Plateausrsquorsquo in The Anasazi in a changing environ-ment Edited by George J Gumerman pp 192ndash229 Cam-bridge Cambridge University Press

e u l e r r o b e r t c g e o r g e j g u m e r m a n t h o r n v k a r l s t ro m j e f f r e y s d e a n a n d r i c h a r d h hevly 1979 The Colorado Plateaus Cultural dynamics andpaleoenvironment Science 2051089ndash1101

ezzo j a 1992 Dietary change and variability at GrasshopperPueblo Arizona Journal of Anthropological Archaeology 11219ndash89

fenn em a n f n 1931 Physiography of the western UnitedStates New York McGraw-Hill

fr edr i c k son d a 1 9 7 4 Cultural diversity in early centralCalifornia A view from the North Coast Ranges Journal of California Anthropology 141ndash54

mdashmdashmdash 1994 lsquolsquoSpatial and cultural units in central California ar-chaeologyrsquorsquo in Toward a new taxonomic framework for cen-tral California archaeology Edited by R E Hughes pp 25ndash47Contributions of the University of California ArchaeologicalResearch Facility 52

f r i t t s h c d g s m i t h a n d m a s t o k e s 1 9 6 5 lsquolsquoThe biological model for paleoclimatic interpretation of MesaVerde tree-ring seriesrsquorsquo in Contributions of the WetherhillMesa Archaeological Project Edited by Bernard S Katz pp101ndash21 Memoirs of the Society for American Archaeology 19




gi lr e a t h a j 1995 Archaeological evaluations of thirteensites for the Ash Creek Project Inyo County California FarWestern Anthropological Research Group Davis CaliforniaReport prepared for the California Department of Transporta-tion Sacramento

g i l r e a t h a j a n d w r h i l d e b r a n d t 1995 Prehis-toric use of the Coso volcanic field Report prepared for theGeothermal Program Office Naval Weapons Center ChinaLake Calif

glassow m a 1991 lsquolsquoEarly Holocene adaptations on Vanden-berg Air Force Base Santa Barbara Countyrsquorsquo in Hunter-gather-ers of early Holocene coastal California Edited by J M Erland-son and R H Colten pp 113ndash24 Los Angeles University ofCalifornia Los Angeles Institute of Archaeology

g l a s s o w m a l w i l c o x o n a n d j e r l a n d s o n 1988 lsquolsquoCultural and environmental change during the early pe-riod of Santa Barbara Channel prehistoryrsquorsquo in The archaeology of prehistoric coastlines Edited by G Bailey and J Parkingtonpp 64ndash77 Cambridge Cambridge University Press

gould r a 1980 Living archaeology Cambridge CambridgeUniversity Press

gould s j 1984 lsquolsquoToward the vindication of punctuationalchangersquorsquo in Catastrophes and earth history Edited by W ABerggren and J A Van Couvering pp 9ndash34 PrincetonPrinceton University Press

gr a um li c h l j 1993 A 1000-year record of temperatureand precipitation in the Sierra Nevada Quaternary Research39249ndash55

gr ee n m a r j o r i e 1 992 lsquolsquoChipped stone raw materials fromLong House Klethla and Kayenta Valleys (Appendix C)rsquorsquo inStress and warfare among the Kayenta Anasazi of the thir-teenth century ad by Jonathan Haas and Winifred Creamerpp 181ndash200 Fieldiana Anthropology ns 21

g r i b b i n j o h n a n d h u b e r t h l a m b 1978 lsquolsquoClimatechange in historical timesrsquorsquo in Climate change Edited by JGribbin pp 68ndash82 London Cambridge University Press

gr ov e j ea n m 1988 The Little Ice Age New YorkMethuen

g u m e r m a n g e o r g e j Editor 1988 The Anasazi in a changing environment Cambridge Cambridge University Press

h a a s j o n a t h a n a n d w i n i f r e d c r e a m e r 1992 Stressand warfare among the Kayenta Anasazi of the thirteenth cen-tury ad Fieldiana Anthropology ns 21

ha y nes c v j r 1 9 6 7 lsquolsquoQuaternary geology of the TuleSprings area Clark County Nevadarsquorsquo in Pleistocene studies insouthern Nevada Edited by H M Wormington and D Ellispp 15ndash104 Nevada State Museum Anthropological Papers 13

hi ldeb r a ndt w r 1 9 9 7 The relative importance of lacus-trine and estuarine resources to prehistoric hunter-gatherer pop-ulations A view from the southern Santa Clara Valley Califor-nia Journal of California and Great Basin Anthropology 19197ndash225

h i l d e b r a n d t w r a n d t l j o n e s 1992 Evolution ofmarine mammal hunting A view from the California and Ore-gon coasts Journal of Anthropological Archaeology 11360ndash401

hoga n pa t r i c k 1 994 lsquolsquoForagers to farmers II A second lookat the adoption of agriculture in the northern Southwestrsquorsquo in

Archaic hunter-gatherer archaeology in the American South-west Edited by Bradley J Vierra Eastern New Mexico Univer-sity Contributions in Anthropology 13

holda w a y s a nd n por c h 1 9 9 5 Cyclical patterns inthe Pleistocene human occupation of southwest Tasmania Ar-chaeology in Oceania 3074ndash82 [il ]

hughes m k a nd h f di a z 1 9 9 4 Was there a medi-eval warm period and if so where and when Climate Change26109ndash42

h u g h e s m k a n d l j g r a u m l i c h 1995 lsquolsquoMultimil-lennial dendroclimatic records from western North Americarsquorsquoin Climatic variations and forcing mechanisms of the last2000 years Edited by R S Bradley P D Jones and J Jouzelpp 109ndash24 Berlin Springer-Verlag [rlb]

hughes r e 1994 lsquolsquoMosaic patterning in prehistoric Great

BasinndashCalifornia exchangersquorsquo in Prehistoric exchange systems in North America Edited by Timothy G Baugh and JonathonE Ericson pp 363ndash84 New York Plenum

hunt er k l a nd j r m c a uli ffe 1 9 9 4 Elevationalshifts of Coleogyne ramossissma in the Mojave Desert duringthe Little Ice Age Quaternary Research 42216ndash21

i n g r a m m j g f a r m e r a n d t m l w i g l e y 1 9 8 1 lsquolsquoPast climates and their impact on man A reviewrsquorsquo in Cli-mate and history Studies in past climates and their impacton man Edited by T M L Wigley M J Ingram and GFarmer pp 3ndash50 Cambridge Cambridge University Press

jackson t l 1986 Late prehistoric obsidian exchange in cen-tral California PhD diss Stanford University Stanford Calif

j a c k son t l a nd j e er i c son 1 9 9 4 lsquolsquoPrehistoric ex-change systems in Californiarsquorsquo in Prehistoric exchange sys-tems of North America Edited by T G Baugh and J E Eric-son pp 385ndash415 New York Plenum

j enn i ngs j d 1957 Danger Cave Society for American Ar-chaeology Memoir 14

jones t l 1991 Marine-resource value and the priority ofcoastal settlement A California perspective American Antiq-uity 56419ndash43

mdashmdashmdash 1992 lsquolsquoSettlement trends along the California coastrsquorsquo inEssays on the prehistory of maritime California Edited byT L Jones pp 1ndash37 Center for Archaeological Research atDavis Publications 10

mdashmdashmdash 1995 Transitions in prehistoric diet mobility exchangeand social organization along Californiarsquos Big Sur coast PhDdiss University of California Davis Calif

j o n e s t l a n d w h i l d e b r a n d t 1 995 Reasserting aprehistoric tragedy of the commons Reply to Lyman Journalof Anthropological Archaeology 1478ndash98

j ones t l a nd g w a ugh 1 9 9 5 Central Californiacoastal prehistory A view from Little Pico Creek Institute ofArchaeology University of California Los Angeles Perspec-tives in California Archaeology 3

keeley l h 1988 Hunter-gatherer economic complexity andlsquolsquopopulation pressurersquorsquo A cross-cultural analysis Journal of An-thropological Anthropology 7373ndash411 [rlb]

k elly r ob er t l 1 9 9 5 The foraging spectrum Diversity in hunter-gatherer lifeways Washington DC Smithsonian Insti-tution Press

k i n g c d t b l a c k b u r n a n d e c h a n d o n e t 1 9 6 8 The archaeological investigation of three sites on the CenturyRanch western Los Angeles County California University of California Archaeological Survey Annual Report 1968 pp 12 ndash107

king l b 1982 Medea Creek cemetery Late Inland Chumashpatterns of social organization exchange and warfare PhDdiss University of California Los Angeles Calif

kniffen f b 1939 Pomo geography University of CaliforniaPublications in American Archaeology and Ethnology 36353ndash400

k o e n i g w d r l m u m m e w j c a r m e n a n d m t sta nba ck 1994 Acorn production by oaks in central coastalCalifornia Variation within and among years Ecology 7599ndash109 [rlb]

k r e u t z k j p a m a y e w s k i l d m e e k e r m s t w i c k l e r s i w h i t l o w a n d i i p i t t a l w a l a1997 Bipolar changes in atmospheric circulation during the Lit-tle Ice Age Science 2771294ndash96

kroeber a l 1925 Handbook of the Indians of CaliforniaBureau of American Ethnology Bulletin 78

mdashmdashmdash 1955 Linguistic time depths results so far and theirmeaning International Journal of American Linguistics 2191ndash104

la m a r c he v c j r 1 9 7 4 Paleoclimatic inferences fromlong tree-ring records Science 1834129

lamb h h 1977 Climate Present past and future Vol 2London Methuen

mdashmdashmdash 1982 Climate history and the modern world LondonMethuen

lambert p m 1993 Health in prehistoric populations of the




Santa Barbara Channel islands American Antiquity 58509ndash22

la m b er t p m a nd p l w a lk er 1 9 9 1 Physical anthro-pological evidence for the evolution of social complexity incoastal southern California Antiquity 65963ndash73

larson d o 1987 An economic analysis of the differentialeffects of population growth and climatic variability amonghunters and gatherers and food producers PhD diss Univer-sity of California Santa Barbara Calif

l a r s o n d o j r j o h n s o n a n d j c m i c h a e l s e n 1994 Missionization among the coastal Chumash of centralCalifornia A study of risk minimization strategies American

Anthropologist 96263ndash99l a r s o n d o a n d j m i c h a e l s e n 1989 Climatic vari-

ability A compounding factor causing culture change amongprehistoric coastal populations MS on file Department of An-thropology California State University Long Beach

mdashmdashmdash 1990 Impacts of climatic variability and populationgrowth on Virgin Branch Anasazi cultural developments Amer-

ican Antiquity 55227ndash49l a r s o n d o h n e f f d a g r a y b i l l j m i -

c ha elsen a nd e a m b os 1 9 9 6 Risk climatic variabilityand the study of Southwestern prehistory An evolutionary per-spective American Antiquity 61217ndash42

laylander d 1994 Phase III data recovery at the ElmoreSite (CA-IMP-6427) Imperial County California San DiegoCalifornia Department of Transportation

leavitt s w 1994 Major wet interval in White MountainsMedieval Warm Period evidenced in 13C bristlecone pine treerings Climate Change 26299ndash308

lee r i c ha r d b 1 9 7 9 The Kung San Men women andwork in a foraging society Cambridge Cambridge UniversityPress [meb]

lieth h 1975 lsquolsquoPrimary production of the major vegetationunits of the worldrsquorsquo in Primary productivity of the biosphereEdited by H Lieth and R H Whittaker pp 203ndash16 NewYork Springer-Verlag

l i g h t f o o t k e n t g a n d e d w a r d m l u b y 1 9 9 8 Thelate Holocene in the greater San Francisco Bay area Temporaltrends in the use and abandonment of shell mounds in theEast Bay Paper presented at the annual meeting of the Societyfor California Archaeology San Diego Calif

l i g h t f o o t k e n t g a n d s t e a d m a n u p h a m 1 9 8 9 lsquolsquoComplex societies in the prehistoric American Southwest Aconsideration of the controversyrsquorsquo in The sociopolitical struc-ture of prehistoric Southwestern societies Edited by S UphamK G Lightfoot and R A Jewett pp 3ndash32 Boulder WestviewPress

li ndsa y la m a r w 1 9 8 6 lsquolsquoFremont fragmentationrsquorsquo in An-thropology of the Desert West Essays in honor of Jesse D Jen-

nings Edited by Carol J Condie and Don D Fowler pp 227ndash51 University of Utah Anthropological Papers 110

li pe w i lli a m d 1 9 9 5 The depopulation of the northern SanJuan Conditions in the turbulent 1200s Journal of Anthropo-

logical Archaeology 14143ndash69lourandos h 1983 Intensification A late Pleistocene-Holo-

cene archaeological sequence from southwestern Victoria Ar-chaeology in Oceania 1881ndash97 [il ]

mdashmdashmdash 1984 Changing perspectives in Australian prehistory Areply to Beaton Archaeology in Oceania 1929ndash33 [il ]

mdashmdashmdash 1985 Problems in the interpretation of late Holocenechanges in Australian prehistory Archaeology in Oceania 2037ndash39 [il ]

mdashmdashmdash 1996 lsquolsquoChange in Australian prehistory Scale trendsand frameworks of interpretationrsquorsquo in Australian archaeology rsquo95 Proceedings of the 1995 Australian Archaeological Associ-ation Annual Conference Edited by S Ulm I Lilley and ARoss pp 15ndash21 (Tempus 6) Brisbane Anthropology MuseumUniversity of Queensland [il ]

lour a ndos h a nd a r oss 1 9 8 4 The great lsquolsquointensifica-tion debatersquorsquo Its history and place in Australian archaeology

Australian Archaeology 3954ndash63 [il ]martz p c 1984 Social dimensions of Chumash mortuary

populations in the Santa Monica Mountains region PhDdiss University of California Riverside Calif

mason j a 1918 The language of the Salinan Indians Uni-versity of California Publications in Archaeology and Ethnol-ogy 141ndash154

m e h r i n g e r p e t e r j j r a n d c n w a r r e n 1 9 7 6 lsquolsquoMarsh dune and archaeological chronology Ash MeadowsAmargosa Desert Nevadarsquorsquo in Holocene environmentalchange in the Great Basin Edited by Robert Elston pp 120ndash50 Nevada Archaeological Survey Research Papers 6

meighan c w 1959 California cultures and the concept ofan Archaic stage American Antiquity 24289ndash318

m i nni s pa ul e 1 9 8 5 Social adaptation to food stress A prehistoric Southwestern example Chicago University of Chi-cago Press

moratto m j 1984 California archaeology Orlando Aca-demic Press

m o r a t t o m j t f k i n g a n d w f w o o l f e n d e n 1978 Archaeology and Californiarsquos climate Journal of Califor-

nia and Great Basin Anthropology 5147ndash61nei ly r ob er t b 1 9 8 3 The prehistoric community on the

Colorado Plateau An approach to the study of change and sur-vival in the northern San Juan area of the American South-west PhD diss Southern Illinois University CarbondaleIll

ni c k ens pa ul r 1 9 7 5 Prehistoric cannibalism in theMancos Canyon southwestern Colorado Kiva 40283ndash93

oli v e r - sm i t h a 1 996 Anthropological research on hazardsand disasters Annual Review of Anthropology 25303ndash28

pate f d 1986 Effect of drought on Ngatatjara plant use Anevaluation of optimal foraging theory Human Ecology 1495ndash115

pet er son k ennet h l 1 9 8 7 lsquolsquoSummer precipitation An im-portant factor in the Dolores project arearsquorsquo in Dolores Archaeo-

logical Program supporting studies Settlement and environ-ment Edited by Kenneth L Peterson and Janet D Orcutt pp73ndash88 Denver USDI Bureau of Reclamation Engineeringand Research Center

mdashmdashmdash 1988 Climate and the Dolores River Anasazi Universityof Utah Anthropological Papers 113

pisias n g 1978 Paleoceanography of the Santa Barbara Ba-sin during the last 8000 years Quaternary Research 10366ndash84

p l o g f r e d g e o r g e j g u m e r m an r o b e r t c e u l e rj e f f r e y s d e a n r i c h a r d h h e v l y a n d t h o rn v k a r lst r om 1988 lsquolsquoAnasazi adaptive strategies Themodel predictions and resultsrsquorsquo in The Anasazi in a changing environment Edited by George J Gumerman pp 230ndash76Cambridge Cambridge University Press

plog s 1990 lsquolsquoAgriculture sedentism and environment in theevolution of political systemsrsquorsquo in The evolution of politicalsystems Edited by S Upham pp 177ndash202 Cambridge Cam-bridge University Press

raab l m 1994 The dead at Calleguas Creek A study ofpunctuated cultural evolution during the MiddleLate Periodtransition in southern California Center for Public Archaeol-ogy California State University Northridge prepared for Envi-ronmental Division Naval Air Weapons Station Point MuguCalif

mdashmdashmdash 1996 Debating prehistory in coastal southern CaliforniaResource intensification versus political economy Journal of California and Great Basin Anthropology 1864ndash80

r a a b l m a nd k b r a dfor d 1 9 9 7 Making nature an-swer to interpretivism Response to J E Arnold R H Coltenand S Pletka American Antiquity 62340ndash41

r ub y j a nd t b la c k b ur n 1 9 6 4 Occurrence of South-western pottery in Los Angeles County California American

Antiquity 30209ndash10s a m u e l s m l a n d j l b e t a n c o u r t 1982 Modeling

the long-term effects of fuelwood harvest on pinyon-juniperwoodlands Environmental Management 6505ndash15

sc ha e fer j er r y 1986 Late prehistoric adaptations during the final recessions of Lake Cahuilla Fish camps and quarries




on West Mesa Imperial County California San DiegoMooney-Levine and Associates

mdashmdashmdash 1988 Lowland Patayan adaptations to ephemeral alkali pans at Superstition Mountain West Mesa Imperial CountyCalifornia San Diego Brian F Mooney Associates

sc hr o eder a h 1961 The archaeological excavations atWillow Beach Arizona 1950 University of Utah Anthropologi-cal Papers 50

s c h w a r tz d o u g l a s w r i c h a rd c c h a p m a n a n djane kepp 1980 Archaeology of the Grand Canyon UnkarDelta Santa Fe School of American Research Press

s c h w a r tz d o u g l a s w j a n e k e p p a n d r i c h a r d c cha pma n 1981 Archaeology of the Grand Canyon TheWalhalla Plateau Santa Fe School of American ResearchPress

s h m i d a a v i s h a i m e v e n a r i a n d i n o y - m e i r 1986lsquolsquoHot desert ecosystems An integrated viewrsquorsquo in Hot desertsand arid shrublands Edited by M Evenari pp 379ndash87 Am-sterdam Elsevier

shni r elm a n v a 1992 Crises and economic dynamics intraditional societies Journal of Anthropological Archaeology 1125ndash46

si m ons dw i ght d 1 9 9 3 lsquolsquoPrehistoric mammal exploitationin the San Francisco Bay arearsquorsquo in Essays on the prehistory of maritime California Edited by T L Jones pp 73ndash103 Univer-sity of California Davis Center for Archaeological ResearchPublications 10

spa u ldi ng w g 1 981 The Late Quaternary vegetation of asouthern Nevada mountain range PhD diss University of Ar-izona Tucson Ariz

mdashmdashmdash 1990 lsquolsquoVegetational and climatic development of the Mo-jave Desert The last glacial maximum to the presentrsquorsquo in Pack-

rat middens The last 40000 years of biotic change Edited byJ L Betancourt T R Van Devender and P S Martin pp166ndash99 Tucson University of Arizona Press

mdashmdashmdash 1991 A Middle Holocene vegetation record from the Mo-jave Desert and its paleoclimatic significance Quaternary Re-search 35427ndash37

mdashmdashmdash 1995 lsquolsquoEnvironmental change ecosystem responses andthe Late Quaternary development of the Mojave Desertrsquorsquo inQuaternary environments and deep history A tribute to PaulS Martin Edited by J I Mead and D S Steadman pp 139ndash64 Rapid City SD Fenske Printing

steward j b 1938 Basin-Plateau aboriginal sociopolitical groups Bureau of American Ethnology Bulletin 120

stine s 1990 Late Holocene fluctuations of Mono Lake east-ern California Palaeogeography Palaeoclimatology Palaeo-ecology 78333ndash81

mdashmdashmdash 1994 Extreme and persistent drought in California andPatagonia during mediaeval time Nature 369546ndash49

sulman f g 1982 Short and long-term changes in climateBoca Raton Fla CRC Press

sw et na m t hom a s w 1 9 9 3 Fire history and climate changein giant sequoia groves Science 262885ndash89

s w e t n a m t h o m a s w a n d j l b e t a n c o u r t 1 9 9 2 lsquolsquoTemporal patterns of El NinoSouthern Oscillationndashwildfireteleconnections in the southwestern United Statesrsquorsquo in ElNin o Historical and paleoclimatic aspects of the Southern Os-cillation Edited by H F Diaz and V M Graf pp 259ndash70Cambridge Cambridge University Press

testart a 1982 The significance of food storage amonghunter-gatherers Residence patterns population densities andsocial inequalities current anthropology 23523ndash37

mdashmdashmdash 1988 lsquolsquoFood storage among hunter-gatherers More or lesssecurity in the way of lifersquorsquo in Coping with uncertainty in

food supply Edited by I De Garine and G A Harrison pp170ndash74 Oxford Clarendon Press

torrey w 1978 Natural disasters social structure andchange in traditional societies Journal of Asian and AfricanStudies 13167ndash83

mdashmdashmdash 1979 Anthropology and disaster research Disasters 343ndash52

true d l 1990 Site locations and water supply A perspec-

tive from northern San Diego County California New World Archaeology 437ndash60

t u r n e r c h r i s t y g i i a n d j a c q u e l in e a t u r n e r 1990 Perimortem damage to human skeletal remains from Wu-patki National Monument Northern Arizona Kiva 55187ndash212

mdashmdashmdash 1992 The first claim for cannibalism in the SouthwestWalter Houghrsquos 1901 discovery at Canyon Butte Ruin 3 north-eastern Arizona American Antiquity 57661ndash82

upha m st ea d m a n 1 982 Polities and power An economicand political history of the Western Pueblo New York Aca-demic Press

mdashmdashmdash 1984a Adaptive diversity and Southwestern abandon-ment Journal of Anthropological Research 40235ndash56

mdashmdashmdash 1984b lsquolsquoPerspectives on labor-intensive agriculture andexchange during the fourteenth centuryrsquorsquo in Prehistoric agricul-tural strategies in the Southwest Edited by Suzanne Fish andPaul R Fish pp 291ndash307 Arizona State University Anthropo-logical Research Papers 33

u p h a m s t e a d m a n a n d f r e d p l o g 1986 The interpreta-tion of prehistoric political complexity in the central and north-ern Southwest Toward a mending of the models Journal of Field Archaeology 13223ndash38

v a n d e v e n d e r t r t l b u r g e s s r s f e l g e r a n dr m turner 1990 Holocene vegetation of the HornadayMountains of northwestern Sonora Mexico Proceedings of theSan Diego Society of Natural History 21ndash19

v a n w e s t c a r l a r a n d w i l l i a m d l i p e 1 9 9 2 lsquolsquoMod-eling prehistoric climate and agriculture in southwestern Colo-radorsquorsquo in The Sand Canyon archaeological project A progress

report Edited by William D Lipe pp 105ndash19 Crow CanyonArchaeological Center Occasional Paper 3

walker e f 1951 Five prehistoric archaeological sites in Los Angeles County California Publications of the F W HodgeAnniversary Publication Fund 6

walker p l 1986 Porotic hyperostosis in a marine-depen-dent California Indian population American Journal of Physi-cal Anthropology 69345ndash54

mdashmdashmdash 1989 Cranial injuries as evidence of violence in prehis-toric southern California American Journal of Physical Anthro-

pology 80313ndash23w a l k e r p l a n d p m l a m b e r t 1989 lsquolsquoSkeletal evi-

dence for stress during a period of culture change in prehistoricCaliforniarsquorsquo in Advances in paleopathology Edited by L Ca-passo pp 207ndash12 Chieti Marino Solfanelli

w a l k e r p l m j d e n i r o a n d p m l a m b e r t 1989 lsquolsquoThe effects of European contact on the health of AltaCalifornia Indiansrsquorsquo in Columbian consequences vol 1 Editedby David Hurst Thomas pp 349ndash64 Washington DC Smith-sonian Institution Press

w a r r en c la ude n 1 9 6 8 lsquolsquoCultural tradition and ecologicaladaptation of the southern California coastrsquorsquo in Archaic prehis-tory in the western United States Edited by C Irwin-Wil-liams pp 1ndash14 Eastern New Mexico University Contribu-tions in Anthropology 1

waters m r 1983 Late Holocene lacustrine chronology andarchaeology of ancient Lake Cahuilla California Quaternary Research 19373ndash87

weide m l 1976 lsquolsquoA cultural sequence for the Yuha Desertrsquorsquoin Background to prehistory of the Yuha Desert Edited by P JWilke pp 81ndash94 Ballena Press Anthropological Papers 5

white tim d 1992 Prehistoric cannibalism at Mancos5MTUMR-2346 Lawrenceville Princeton University Press

w i g a n d p e j o d a v i s a n d l c p i p p i n 1 9 9 0 lsquolsquoThe Lahontan Basinrsquorsquo in Studies of climatic variations andtheir impact on the Great Basin Final Report on ContractNA878A-D-CP114 submitted to National Climatic ProgramOffice NOAA Rockville Md

w i l c o x d a v i d r a n d j o n a t h a n h a a s 1994 lsquolsquoThescream of the butterfly Competition and conflict in the prehis-toric Southwestrsquorsquo in Themes in Southwestern prehistory Ed-ited by George J Gumerman pp 211ndash38 Santa Fe School ofAmerican Research Press




wilke p 1978 Late prehistoric human ecology at Lake Cahu- illa Coachella Valley California Contributions of the Univer-sity of California Archaeological Research Facility 38

wills w h 1988 Early agriculture and sedentism in theAmerican Southwest Evidence and interpretations Journal of World Prehistory 2445ndash88

w l o d a r s ki r j j f r o m a n i g r r o m a n i a n dd a la r so n 1984 Preliminary evidence of metal tool usein soapstone quarry mining on Catalina Island Jane RussellQuarry Pacific Coast Archaeological Society Quarterly 2035ndash64

w or m i ngt on h m 1 9 4 7 Prehistoric Indians of the South-west Denver Denver Museum of Natural History

w r i ght h e j r 1 9 9 3 Environmental determinism in NearEastern prehistory current anthropology 34458ndash69

yellen j 1976 lsquolsquoSettlement pattern of the Kung An archaeo-logical perspectiversquorsquo in Kalahari hunter-gatherers Edited byR B Lee and I DeVore pp 48ndash72 Cambridge Harvard Univer-sity Press




other factors do not play pivotal roles but we suggestthat the linkages between the physicalbiotic environ-ment and human subsistence and settlement are suffi-ciently tight to warrant serious consideration of envi-ronmental change as a potentially important factor inexplanations of cultural change Environment can anddid cause cultural changes in the prehistoric past and

attribution of cause to environment in archaeologicalmodels need not be deterministic A downturn in envi-ronmental productivity in particular can affect culturechange by creating demographic imbalances that re-quire some kind of response but they do not dictate thecharacter of the response in a given area Demographicstress can be felt in various ways but more often thannot its effects are negative (eg increased mortalitypoor health and decreased fecundity) Downturns re-lated to climate can simultaneously affect large por-tions of a continent or similar latitudinal zones acrosscontinents so that synchronous cultural changes maycrosscut vastly different subsistence regimes As simpleas these points may be current theories of prehistoric

humanenvironmental relationships increasingly fail toacknowledge circumstances of environmentally in-duced culture change particularly those engenderingnegative human behaviors and outright cultural fail-ures

In western North America a theoretical amalgam hasemerged from a long complex history of thought inwhich hunter-gatherers and agriculturalists have beenperceived very differently in their relationships withthe physical environment Cultural ecological theoriesfrom the early part of this century based largely on eth-nographic observations acknowledged subsistencedifficulties for both foragers and agriculturalists in aridenvironments (eg Antevs 1948 Douglass 1929 Wor-

mington 1947 Steward 1938) but envisioned a benignenvironmental past for hunter-gatherers in California(Kroeber 1925) In the 1950s and rsquo60s these perspectivesgave way to models of adaptation in which environmen-tal flux was routinely accommodated by simple culturaladjustments and or migration (Kroeber 1955) that withfew exceptions (eg Moratto King and Woolfenden1978) involved no crises stress violence or demo-graphic or environmental problems Much of westernNorth American prehistory was linked to incrementalpopulation growth and unilinear cultural evolution(Fredrickson 1974 Chartkoff and Chartkoff 1984)These perspectives have recently been supplanted byneo-Darwinian constructs and models of economic in-

tensification applied to both foragers (Baumhoff andBettinger 1982 Basgall 1987 Bouey 1987 Hildebrandt1997) and agriculturalists (Ezzo 1992) that ignore envi-ronmental flux as a cause of change and posit linear pro-gessions in human subsistence and social complexity(Fredrickson 1994)

Some types of environmental events however pro-voke changes that simply cannot be ignored Especiallycritical are those that impact the quality and abundanceof basic subsistence resources most obvious of whichare high-intensity rapidly transpiring environmental

oscillations associated with natural disasters (egfloods fires hurricanes) and short-term ecological ca-tastrophes (see Torrey 1978 1979 Oliver-Smith 1996)Such events are commonly overlooked in adaptationistmodels They may be hard to recognize in the archaeo-logical record particularly in the distant past but inter-vals of sustained andor repeated ecological and demo-

graphic instability should be detectable The thesis wedevelop here is that the interval between ad 800 and1350 known to climatologists alternatively as the Me-dieval Warm Period the Secondary Climatic Optimumthe Little Optimum (Ingram Farmer and Wigley 1981Sulman 1982) or the Medieval Climatic Anomaly(Stine 1994) was a time of increased aridity that co-incided with a unique pattern of demographic stressand frequent economic crises across much of westernNorth America Large populations of agriculturalistsand hunter-gatherers were confronted with serious andabrupt declines in productivity caused by repeated andprolonged droughts This interval is increasingly recog-nized as a time of droughts and warm temperatures in

many parts of the world (Lamb 1977 1982 Hughes andDiaz 1994) It also witnessed a profusion of widespreadcultural changes in the archaeological record many ofthem quite extreme (eg increases in interpersonal vio-lence declines in health deterioration of long-distancetrade networks population reductions andor reloca-tions site and regional abandonments and occupa-tional hiatuses) We believe that the plethora of culturalchanges and the negative character of many of them re-flect widespread crises related to populationresourceimbalances drought-related environmental deteriora-tion and shortages of food and water Many current in-terpretations of regional prehistories with some recentexceptions (eg Arnold 1992a b) largely fail to con-

sider the possibility of environmentally induced demo-graphic stress in nondeterministic ways This is partic-ularly true in California where the biotic environmenthas been portrayed as rich and reliable with no sus-tained intervals of resource shortage Recent archaeo-logical models (eg Basgall 1987 Bouey 1987 Hilde-brandt 1997) associate persistent population growthwith this perceived environmental richness but fail toconsider that economic intensification could placehunter-gatherers in positions of demographic risk simi-lar to those of sedentary agriculturalists

Our thesis begins with paleoclimatic and paleohydro-logic data demonstrating that the period between ad800 and 1350 was punctuated by lsquolsquoepic droughtsrsquorsquo (Stine

1994) These droughts and the more broadly timed epi-sodes of increased temperatures attendant upon the Me-dieval Climatic Anomaly had direct effects on terres-trial ecosystems by impacting water sources andreducing primary production and therefore harvestablebiomass The relationship between effective moistureand primary production is well documented (eg Bar-bour Bourke and Pitts 1987 Lieth 1975 Shmida Even-ari and Noy-Meir 1986) Equally important from thepoint of view of understanding the constraints on peo-ples in arid-to-semiarid regions is the steep relationship










































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited

















































































































































































































































































































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited
































































































































































































































































































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited























































































































































































































































































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited





































































































































































































































































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited



















































































































































































































































































the mojave desert









































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited








































































































































































































































































































































































California






















mainland




















Summary



























Conclusions










Comments














































































































Reply










































References Cited






























































































































































































































































































































































California






















mainland




















Summary



























Conclusions










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Environmental Imperatives ReconsideredLISTO