Comparative Biomass Estimates and Prehistoric Cultural Ecology of the Southwest Umnak Region, Aleutian Islands

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  • Comparative Biomass Estimates and Prehistoric Cultural Ecology of the Southwest UmnakRegion, Aleutian IslandsAuthor(s): David R. Yesner and Jean S. AignerSource: Arctic Anthropology, Vol. 13, No. 2 (1976), pp. 91-112Published by: University of Wisconsin PressStable URL: .Accessed: 14/06/2014 10:00

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    While changes in faunal frequencies over time within archaeological sites can indicate the nature of changing regional settlement patterns, much may be learned about the nature of regional hunting adaptations from the pat- terning of faunal frequencies in sites as a whole. Adaptational information relates pri- marily to three areas: cultural selection of resources, dietary composition, and harvesting methods. Because of environmental stability, cultural continuity, high density and

    diversity of resources and excellent preser- vation of archaeological faunal remains, the Aleutian Islands offer an excellent model area for testing hypotheses relating to these three areas. To this end, biomass estimates are compared between the modern Aleutian ecosystem and archaeologically derived data; dietary analyses are performed; and means for deriving information on harvest- ing methods from faunal frequency data are presented.


    Archaeological faunal data can provide a good deal of information on exploitation pat- terns of hunter-gatherer populations. The "laundry list" approach of specifying which species are present in the archaeological materials indicates which species in the eco- system were being exploited, but given little or no information on hunting patterns per se. Potentially, however, a detailed quantitative approach using faunal frequency patterns can provide information on the following:

    1) Environmental change 2) Seasonality (span of occupation) and

    settlement pattern 3) Relative population change over time and

    distribution over space h) Intensity of resource exploitation 5) Cultural selection of resources 6) Dietary and nutritional patterns 7) Harvesting methods 8) Butchering patterns 9) Refuse deposition and accumulation pat-

    terns 10) Nature and spatial distribution of ac-

    tivities on discrete living floors.

    The midden sites of mari ne- adapted hunter- gatherers present a special opportunity for these ecologically-oriented archaeological studies, owing to the accumulation of vast amounts of organic materials and frequently to their excellent preservation in a highly cal- ciferous matrix. Often, however, these sites present special problems in archaeological interpretation. Because they consist primarily of refuse deposits, "microstructural" analy- sis of these sites, including reconstruction of human activities for different time periods, becomes a study of the formation of small lenses of refuse and the analysis of discrete living floors (Ambrose 1967). An ad- ditional problem is the partial intermixing of refuse deposits and living floor debris. Nevertheless, reconstruction of changing human ecological and demographic relationships based upon temporal shifts in faunal frequency pat- terns (numbers 1 through k) is possible with

    *The author wishes gratefully to acknow- ledge the opportunity provided by Drs. W. S. Laughlin and J. S. Aigner of the University of Connecticut to study Aleutian archaeological collections. A further note of thanks goes to Drs. J. S. Aigner and P. J. Pelto of the University of Connecticut for extensive review of the manuscript. Computer programs were prepared in conjunction with A. M. Bieber, Uni- versity of Connecticut, and computer facili- ties were generously made available by the University of Connecticut computer center. G. A. Sanger of the Marine Mammal Division, National Oceanic and Atmospheric Administra- tion, Seattle, kindly made available and al- losed replication of his data. This research was made possible by grants from the National Science Foundation (GB281+6, "Aleut Adaptation to the Bering Land Bridge Coastal Configura- tion" ) and the Connecticut Research Founda- tion. The author assumes responsibility for all errors contained herein.

    91 Arctic Anthropology XIII- 2, 1976

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  • 92 Arctic Anthropology XIII- 2

    careful attention to, and adequate sampling of, microstructural features within site com- ponents (these temporal trends have been out- lined in Lippold [1966] and Yesner [l9T^a, 1975]). However, certain problems (numbers 5 through 7) not only do not require this kind of detailed intrasite analysis for their illu- mination, but are more rationally tackled by dealing with whole sites within a regional framework. That is, in dealing with questions of cultural selection of resources, dietary and nutritional reconstruction, and harvesting methods, the major concerns of the present paper, the relevant data must be obtained from and analyzed in terms of regional population systems, so that confounding effects of site seasonality and mi cr environmental differentia- tion may be filtered out. An explicitly re- gional approach toward faunal analysis is often required when considering hunter- gatherers with the complex mosaic of shifting exploit at ional patterns characteristic of marine-adapted populations. While these popu- lations represent a special subset of hunter- gatherers in general, the same regional ap- proach is even more mandatory for other hunter- gatherers with even greater mobility.


    The Aleutian Islands (see Fig. 1 of Aigner this issue) serve as a good model area for the reconstruction of regional hunting adaptations from faunal analyses for several reasons. First, there is a virtual one-to-one corre- spodence between human population and environ- ment in the Aleutians. The Aleuts are found entirely within a sharply delimited ecosystem characterized by extensive reef areas support- ing large invertebrate populations, breeding grounds for sea mammals, extensive cliff areas for bird nesting, and fresh water streams and spawning lakes supporting anadromous fish populations as well as migratory waterfowl. With the exception of some roots, shoots, and berries, there are no significant terrestrial resources. To the east of the Aleutians are found Eskimo populations who have had little genetic interchange with their Aleut neighbors. In addition, the resource configuration avail- able to the Eskimos is substantially different from that available to the Aleuts; there is little in the way of invertebrate resources, but there is a substantial terrestrial mammal- ian fauna which the Eskimos exploit along with the maritime zone. The latter is within the winter ice zone, another distinction from the Aleutian ecosystem which contains virtu- ally no winter ice (Aigner 1970).

    Secondly, the high density and diversity of Aleutian resources, as well as the coastal settlement system, permitted the formation of

    high human population densities and conspicu- ous remains, and consequently high archaeolo- gical visibility. The high density of animal and human populations in the Aleutians is directly related to the presence of major up- welling systems generally concentrated in inter-island passes where cold, nutrient-rich waters of the Bering Sea mix with warmer, deeper Pacific waters bearing the strong Pacific current (Laughlin 1972:381; Aigner 1970). High densities of plankton in these areas in turn support a large biomass of birds and marine macrofauna.

    The diversity of resources in the Aleutians is the result of a combination of factors: the mixing of Nearctic and Palearctic faunas, combining seasonal, migratory species with

    year-round, sedentary forms, including the "Aleutican" avifauna native to the archipelago (Udvardy 1963) ; a central position with respect to both pinniped migration routes and the north to south Pacific flyway; the lack of winter ice; and a coastal configuration allow- ing the formation of reef systems and fresh water streams and lakes. Such a diversity of resources stimulated a variety of subsistence activities during all seasons of the year, reflected in changing frequencies of faunal remains. It also meant that when one resource was naturally depressed or over exploited, an- other could be substituted in its place. Cer- tain resources, such as invertebrates or birds , could be relied upon when more favored resources failed (Aigner 1970). In such a situation of resource density and diversity, it was unnecessary for the Aleuts to adopt such population-limiting practices as infanti- cide or senilicide that were adopted elsewhere in the arctic. Because of this, Aleut popula- tions probably responded more or less di- rectly to the nutritional changes indicated by faunal remains .

    Several additional factors contribute to making the Aleutians a model area for faunal studies. Because of their highly basic sea urchin matrix, Aleutian midden sites exhibit excellent bone preservation. Good estimates of faunal abundance are available for the modern Aleutian ecosystem. Good estimates of nutritional composition are available for na- tive Aleutian foods. Much data on the nutri- tion, seasonal cycle, and subsistence tech-

    nology of the Aleuts is available from ethno- graphic and ethnohistorical sources. Finally, cultural continuity has been demonstrated for the Aleutians for the last 9000 years (Aigner 1970, 1971).

    The southwest Umnak region of , the Aleutians was chosen as the specific focus for study for four reasons. First, the region is naturally delimited; its shape is that of an elongated triangle, bounded on two sides by the ocean and on* the third by a mountain chain. Second,

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  • Yesner and Aigner: Comparative Biomass Estimates 93

    environmental stability has "been demonstrated for the region for at least the last 1*000 years; this is the maximum age of the regional midden sites dealt with here, in order to eliminate the problem of major environmental change, which is held as a constant. Third, the southwest Umnak region was an area of high population density in prehistoric times. This was due to its unique coastal configuration, including a large number of bays , reefs , and salmon streams, the presence in nearby Samalga Pass of a major upwelling system, and the proximity of important pinniped and avian mi- gration routes. Finally, the region formed the southeastern terminus of the Bering Land Bridge at its maximal extension (Laughlin 1963, 1967; Black 1966; Laughlin, Aigner, and lack 1971; Aigner 1970, 1971).


    Archaeological data from the southwest Um- nak region were derived from site excavations depicted in Fig. 2 of Aigner this issue. Avian remains were used in the analyses for three reasons. First, because of the number of bird species and their ecological variety (i.e., differences in habitat preference), they offer the archaeologist a better data base than do other classes of faunal remains containing fewer and less ecologically- differentiated species. Second, better abun- dance estimates are available for birds than for other (modern) Aleutian faunal classes. Finally, bird remains have particularly excel- lent preservation in regional midden sites.

    An initial problem in quantifying the faunal remains for use with biological or other archaeological data is the reconstruction of "minimum numbers of individuals" as a data base for biomass or dietary analysis. Unfor- tunately, in vertebral faunal analysis calcu- lating minimum numbers of individuals rather than raw bone counts from relatively small samples tends both to exaggerate- the impor- tance of rarer taxa (Grayson 197^+a) and to suffer more from stochastic variation, even when calculations are made from individual stratigraphie units rather than entire sites. However, the problem of exaggeration of rarer taxa is mitigated to some extent in the present _ analysis by dealing with avian rather than mammalian remains (Munson 197^:8), since birds have a greater relative size uniformity than do mammals. In addition, experiments with fine-mesh (l/l6") screening of massive Aleu- tian midden flotation samples demonstrate that small birds (less than 100 grams in weight or 25 centimeters in length) were not being ex- ploited by the Aleuts, and that small avian bones that had passed through the larger (l/V) mesh screening used on most of the

    midden samples were simply smaller bones (ribs, vertebrae, and scapulae) of the larger species. Thus, the range of bird size dealt with was very narrow, increasing the relia- bility of the use of minimum numbers of in- dividuals in subsequent calculations. Lastly, there was a high correlation between raw bone counts and minimum numbers of individuals in the southwest Umnak avi faunal data, indicating that sample sizes were sufficiently large to justify the use of minimum numbers of indivi- duals in data analysis.1

    Calculation of minimum numbers of individu- als and faunal frequencies was based upon a computer program ("MIND/FREQ") developed by the author and A. M. Bieber of the University of Connecticut, which scans a matrix consist- ing of data on species, skeletal element, age, and side of the body for each specimen, and determines the largest entry in a given cate- gory or array element, with correction factors for ^the number of a given skeletal element in a given species (Yesner and Bieber 197*0. 2

    Pair-matching methods (Krantz 1968) and geo- metric models based upon such methods (Den- niston 1972) were found less effective and more time-consuming in terms of the amount of real data ge...


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