Prehistoric coastal ecologies: A view from outside Franchthi Cave, Greece

Prehistoric Coastal Ecologies: A View from Outside Franchthi Cave, Greece

K.D. Thomas Department of Human Environment, Institute of Archaeology, University College London, 31 -34 Gordon Square, London, WCl H OPY,UK

Shackleton and van Andel have raised the question of past human selectivity in the collection of shellfish resources. They reconstruct, for the changing coastlines near Franchthi Cave during the post-glacial transgression, changes in availability of various species of shellfish. The model of availability is compared with the archaeological record of shellfish from the cave. Shackleton and van Andel conclude that selectivity is demonstrated and that this was, in part, “idiosyncratic.”

A critical analysis of the model leads to the conclusion that, while the reconstructions of the likely positions of past coastlines may be acceptable, the reconstructions of mollusc availability at various times in the past are highly improbable. Sea-level change is not the only important determinant of past coastal ecology although it will, of course, have an impact on the ways in which coastal ecosystems developed. Other factors (including the physical and chemical properties of the substratum, levels of productivity, and biological interactions), operating at various spatial and chronological scales, cannot be ignored or even subordinated.

The shellfish remains from the cave are the only objective evidence of man’s exploitation of past coastal resources. Taphonomic analyses of the shells from the site would allow a number of important questions to be addressed, including the reasons for their collection and the possibility of over-exploitation of certain species in the past.

INTRODUCTION

Studies of shellfish gathering by man in the past have gathered pace in recent years, spurred on by new ideas about the role of such activities in prehistoric subsistence systems (e.g., Meehan, 1982) and by detailed studies of new archaeological sites (e.g., Voigt, 1982). The studies of van Andel and his associates, especially Shackleton, of the past coastal environments near the archaeological site of Franchthi Cave in southeastern Greece have been of particular interest. These workers have attempted to assess the likely impact of past environments on the shellfish gathering be- haviors of the prehistoric inhabitants of the cave. In particular, Shackleton and van Andel (1986) argue that they are able to address the question of man’s past selectivity in exploiting a range of potential coastal resources.

Shackleton and van Andel (1986) reason that they have an objective means of establishing paleocoastline morphologies near Franchthi Cave at various times during the post-glacial transgression. From these reconstructions they infer various types of habitats for marine molluscs and predict when various

species of shellfish would have been available for human exploitation. By comparing the oc- currence and abundance of mollusc species in the closely-dated archaeological deposits of the cave with the array of species supposedly available at the contemporary coasts, they infer human selectivity in shellfish collection.

If the publications by Shackleton and van Andel which deal with the question of shellfish exploitation are critically examined (Shackleton and van Andel, 1980; Shackle- ton, 1983; Shackleton, 1985; Shackleton and van Andel, 1986), it becomes apparent that there is a need for the topic as a whole to be reviewed. The methodology and interpretive framework of the Franchthi project raise seri- ous questions. In addition, the philosophy which apparently underpins the work, as re- vealed in their most recent publication (Shackleton and van Andel, 1986), raises important issues of how ‘environmental archaeologists’ (for want of a better catch-all term) go about their work, how they use their data, how they use concepts from other disciplines, and how they use their own results in the wider context of reconstructing past human ecology.

Geoarchaeology: An International Journal, Vol. 2, No. 3, 231-240 (1987) 01987 by John Wiley & Sons, Inc. CCC 0883-6353l871030231-10$04.00

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Their work also contains a number of fun- damental inconsistencies which need to be examined. For example, they state (Shackleton and van Andel, 1986, 127-128), when criti- cizing the approaches of other workers--speci- fically Thomas (1981), that where environmental changes occur at rates for which there are no modern analogs, extrapolations from present environments are hazardous proce- dures unless they rest on a sound observa- tional basis. This is quite true, of course, but they then go on to reveal (pages 129-130) that they “have few samples from past environments. . . forcing us to extrapolate from geophysical data and rely on comparisons with modern environments.”

This analysis of the publications of van An- del and Shackleton is carried out mainly from a biological and ecological perspective. I con- sider first their attempts to reconstruct past environments using off-site sources of data; and second, the data on the shells from the site and how these relate to the environmental reconstructions. Finally, I attempt a general analysis of the shellfish-gathering activities of the successive occupants of the site in terms of past subsistence activities and the ecological setting of such activities.

RECONSTRUCTION OF PAST COASTAL ENVIRONMENTS

The stages by which Shackleton and van Andel (1986) deduce the likely availability of mollusc species in the past can be analysed at three levels, ranging from the macroscale to the microscale. At the macroscale (here termed level I) they attempt to reconstruct past coastal morphologies at various times during the post-glacial marine transgression. At the in- termediate scale (level 11) they attempt to reconstruct sedimentary environments for those coastline stages. At the microscale (level 111) they infer what associations of species of molluscs “should have been available” (Shackle- ton and van Andel, 1986,127) to man at various times in the past. They have had, of neces- sity, to make a number of assumptions and generalizations at every level of their model;

some of these are extremely problematical and are here listed in Table I.

Level I: Coastal Morphologies

Seismic reflection profiling, coupled with the use of sidescan sonar devices, was used to produce profiles of the submarine features of the Franchthi embayment (Shackleton and van Andel, 1986). The results are impressive,

Table I. Assumptions, Approximations, Omissions and Commissions in the Model of Shackleton and van Andel (1986): see text for explanations.

LEVEL I Reconstruction of coastal morphologies 1. The data are derived from remote sensing without

ground control. 2. A particular curve is assumed for sea-level rise which

has significant margins of error. 3. A constant correction factor is assumed for tectonic

movements, whereas they could have been, and probably were, episodic.

4. No consideration is given to the possibility of post- transgression warping or tectonic tilting of the sea bed.

LEVEL I1 Reconstruction of sedimentary facies Remote sensing did not give satisfactory resolution to palaeosediment types in the Franchthi embayment. Consequently, reconstructions of past sediments are mainly based on inferences from the reconstructed shore profiles. Shackleton and van Andel (1986,135) explicitly state that the effects of winds, waves, and currents on the formation of sediments can be assumed to have been effectively constant during the transgression period and up to the present day. The authors admit to being “poorly informed about which shore features may form during a very fast rise of the sea” (p, 135).

LEVEL I11 Reconstruction of Dust mollusc communities Nonquantitative modern‘data are used to infer habitat preferences for various species; it is assumed that there were no changes in ecology. Shore environments in the phase of rapid transgression may never have allowed equilibrium communities to develop, so modern data on mollusc communities could be quite irrevelant to the past. Many important aspects of mollusc ecology are ignored (e.g., changes in sea and air temperatures, changes in salinities, trophic status of the environment, presence or absence of competitors or preda- tors, etc.); it is assumed that the sedimentary environment is all-important. There is no objective evidence, apart from the shells from the archaeological site, for the past existence of any of the species of molluscs which are claimed to have inhabited the reconstructed shorelines.

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yielding evidence of drowned and buried stream channels and even of possible drowned shell middens. The methodology was, however, entirely by remote-sensing, and methods for establishing ‘ground-control’ were not used. Data from drilling were unfortunately un- available because of a lack of both coring equipment and permits (Shackleton and van Andel, 1986, 129- 130).

Having produced detailed contour maps for the drowned landscape in the Franchthi embayment, they then proceed to estimate a rate for the early Holocene marine transgression by selecting an appropriate curve. They use a “global” curve for sea-level rise, which they believe to be adequate for their rather broad chronological needs and which they assume to be appropriate for their particular area of the eastern Mediterranean. They admit (Shackle- ton and van Andel, 1986,129) an uncertainty in the chronology deduced from this curve of some 500 years for the period up to 8000 B.C. This error of some 500 years must be seen, in the light of all the other assumptions outlined in this section, to be at least a minimum likely error. Their reconstructions of coastlines at certain depths below present sea-level could, for the first two-thirds of the mollusc sequence from the archaeological site, be chronologically displaced by a significant amount either way from their proposed dating. This, in turn, would variously displace the ‘mollusc availability curves’ in their Figure 12.

The eastern Mediterranean is an area well known for tectonic instability. Van Andel and Shackleton (1982,447) note this problem and incorporate a correction factor for it in their curve for sea-level change. However, while they admit that vertical tectonic movements are usually episodic in nature, they assume a constant rate factor in their calculations. If one or more tectonic events had influenced the Franchthi area during the transgressive phase, the reconstructed coastlines could be seriously adrift from the supposed chronology. Shackleton and van Andel (1986 and else- where) have also implicitly assumed that there has been no significant warping, tilting, or other change in the morphology of the seabed in the Franchthi embayment since the

transgression. In other words, they assume that the present morphology of the seabed, stripped of its superficial deposits of mud, is essentially the same as the pre-transgression land surface.

It is always difficult to allow for such un- quantifiable variables when reconstructing past coastlines, but it is even more perilous to ignore them. I suspect that the margins of error in the chronology of the reconstructed coastlines, and in the reconstructed coastal morphologies for certain periods of time, for the Franchthi area are far greater than Shackleton and van Andel allow.

Level 11: Past Sediments

The reconstruction by Shackleton and van Andel (1986) of sedimentary environments at various times during the transgression is mostly on the basis of inference from the reconstructed shore profiles. Remote-sensing gave only limited information about various types of sediments. The seismic survey de- tected buried submerged stream channels but it could not detect the nature of the bed-load in these channels; this information would potentially be of great importance for understand- ing the types of sediments being brought into the sea at various times in the past.

Shackleton and van Andel (1986, 135) accept that the nature of any depositional shore is controlled mainly by the ways in which winds, waves, and currents sort and disperse sediments brought into the sea. They also admit that wind directions and intensities in the early Holocene cold phase could have been quite different from today, but they then proceed to assert that, for the purposes of environmental reconstruction, “no major changes need be assumed” (p. 135). They accept that the rate of sea-level rise would affect sediments because it would determine how long a shore would develop a t a particular position and how the sediments would differentiate. They also accept that for the Franchthi area, with rapid rates of sea-level change, “we are . . . poorly informed about which shore features may form during a very fast rise of the sea” (p. 135).

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In spite of all these important factors, Shackleton and van Andel (1986) elect to give them zero ratings in their model and proceed to make quite detailed inferences about local habitats for molluscs from their reconstructions of coastline morphologies.

Level 111: Mollusc Communities and Habitats

Having inferred, however tenuously, the types of sedimentary environments which might have been ‘available’ to molluscs, Shackleton and van Andel (1986) then proceed to populate these environments with various species. They use data from their own collections of recent molluscs at various locations to assess the likely habitat preferences of various species. Unfortunately they found few living specimens in the locations they vis- ited, so the data are less direct than they might appear. Also, their approach is explicitly nonquantitative and this makes the data less use- ful for reconstructing past abundances of various species. There are inconsistencies between the theoretical position they adopt, whereby extrapolation from modern suites of habitats is viewed as invalid (Shackleton and van Andel, 1986,127), and their practice (they explicitly extrapolate past mollusc availability and abundance from modern suites of habitats).

A major problem with using present-day assemblages of shells to define habitat types, and then to transpose those habitats into the past, is that one has to assume that habitat conditions at the present and in the past are, in their major features, comparable. Shackle- ton and van Andel (1986, 127-128) themselves suggest that the high rates of coastal migration with which they are concerned have no modern analogs; it must therefore follow that past coastal habitats (at least those which existed during the transgression) probably have no modern analogs in their area.

There is much more to the ecology of marine molluscs than the nature of their substratum. Species diversity and total biomass of coastal mollusc communities are greatly influenced by levels of biological productivity; Shackle-

ton and van Andel have no objective means of deducing past levels of biological productivity from their data. Individual species of molluscs are influenced by a wide range of physical, chemical, and biological factors; their distribution and abundance in various habitats is determined by the complex interaction of these ecological factors. Attempts to isolate any one factor as a prime determinant of the distribution and abundance of a species over long periods of time must assume that all the other determining factors do not vary over that time span. Many species of littoral molluscs do appear to be related to certain types of shore, but we cannot always predict that particular shores will yield specimens of particular species, or at what abundance. Shackleton and van Andel appear to be unaware of the work of marine biologists, which has clearly shown how biological interactions (such as competi- tion for space and food and inter-specific predation) can influence the distribution and abundance of species in intertidal zones. These interactions are viewed as being so important that authorities (e.g., Yonge, 1966) stress them even in their more popular writings.

Recent work by marine ecologists (e.g., Con- nell, 1985) has shown that the structure of certain intertidal communities, especially those on shores where there are low larval recruitment rates, may be the result of sto- chastic processes. In such environments, the vagaries of larval settlement rates will influence colonization sequences and community structures in unpredictable ways (see Lewin, 1986, for a recent review).

Shackleton and van Andel (1986) are forced to ignore a wide range of paleoecological factors (see Table I) which could have influenced the distribution and abundance of species of molluscs in the intertidal and subtidal zones near Franchthi Cave. In my view it is not a valid procedure to predict which species would have been available from the reconstruction of supposed sedimentary environments which might have existed during periods of rapid environmental change. It is too easy to be falsely deterministic about the relationships between animal species and their supposedly preferred habitats. Thomas (1985) has argued

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against the naive reconstruction of particular types of past habitats on the basis of particular species of molluscs; he suggests that whole assemblages be used to infer the general nature of a habitat and, within that reconstruction, particular species should be used to re- fine the reconstruction. The converse of this approach, the inference of past mollusc communities and, more particularly, the presence and abundance of individual species, from highly generalized reconstructions of sedimentary environments, seems even more ten- uous. It is, however, the approach which Shackleton and van Andel (1986) use.

It must be stated that the only objective evidence for any species of molluscs existing in the Franchthi area during the transgression comes from the archaeological deposits of Franchthi Cave-a fact acknowledged by Shackleton (1985, 226).

Evaluation of the Habitat Reconstructions

The model proposed by Shackleton and van Andel (1986) has been analyzed here in terms of three levels of interpretation which accu- rately reflect the internal structural relationships of their arguments and propositions. The three levels form a nested hierarchy of inferences, ranging from the most general to the more particular. The assumptions which are made at each level in the model are not limited to those particular levels; they apply also at lower levels. The outcome is such that, by the end of the deductive sequence, the levels of improbability have risen from a trickle to a veritable torrent.

The only factor which Shackleton and van Andel admit, at least in their analytical pro- cedures, to being a causative agent in environmental change is the post-glacial rise in sea level. All other environmental changes are deduced from the inferred consequences of the progressive rise in sea level. All other factors which could have played a dynamic role in the development of past coastal environments are dismissed as unimportant, ignored, or treated as constants. Why do they treat these factors in this way? Quite simply because their database cannot cope with them.

For Shackleton and van Andel these diverse factors (see Table I) are imponderables; they cannot be given any quantitative weighting, so they must be ignored. It is their implicit view that their model can proceed without these factors, which anyway could be incorpo- rated at a later date if suitable quantitative evidence were forthcoming. Of course, there probably is objective evidence for these factors in the deposits of the sea-bed of the Franchthi embayment, but Shackleton and van Andel base their model only on data obtained by remote-sensing and assumed rates of sea-level change. They have no independent set of objective data to provide any control over their deductions, with the exception of the shells from the cave deposits, but to use these would negate the stated objectives of their work.

It is my view that the database which Shackleton and van Andel use is not adequate to test the various high level theories that they are interested in. They have to disregard too many important environmental and ecological processes in order to make progress with their model building. Objective data must be found to substantiate or, at least, to test what they have claimed; these data are to be found under the sea.

THE MOLLUSC SHELLS FROM THE CAVE

A major problem in attempting any evaluation of the mollusc evidence from the deposits of Franchthi Cave is that the basic data have so far only been published in a very generalized form, as sawtooth histograms of the rela- tive abundance of selected taxa (Shackleton and van Andel, 1980; Shackleton, 1983; Shackleton, 1985; Shackleton and van Andel, 1986). These histograms give little idea of the total numbers of shells represented in the assemblages, although dots on them show the numbers of specimens identified. In Shackle- ton and van Andel’s 1986 paper it is difficult to make any sense of the clouds of tiny dots which appear on the right-hand side of the histogram in Figure 3. In Figure 2 of their 1980 paper the data make rather more sense. Approximately 12,000 shells were recovered from the deposits dated between 10,261 and


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7930 B.P. This represents an accumulation rate of some five to six shells a year. This grossly oversimplified calculation assumes, of course, continuous occupation and sedimenta- tion in the cave. In the absence of any information about the stratigraphic relationships of the various samples, the size of the sam- pling units, how the shells were recovered from them, and so on, it is difficult for anyone to make use of the data. It appears, however, that the cave deposits are not to be compared with high-density shell middens.

The analysis, identification, and quantifi- cation of large sets of bioarchaeological data is a lengthy procedure, but it is now six years since interpretations based on the shells were first published and it is to be hoped that full publication of the data will soon follow. Up to, and including, the 1986 paper by Shackleton and van Andel only the commonest mollusc taxa have been reported and only two of these have so far been named to species level (Cy- elope neritea Linnaeus and Cerithium vulga- tum Bruguiere). The other taxa are named only to generic level, e.g., “Patella sp., Mono- donta sp., and Gibbula s ~ . ” (Shackleton, 1985, 225). This failure to be taxonomically precise can cause problems. Cerastoderma is reported from the cave deposits; Shackleton and van Andel (1986) mention only Cerastoderma glaucum (Bruguiere) in their analysis of modern molluscs and their habitats. This species is usually found in marshy lagoonal habitats at the present day (Russell and Petersen, 1973), but in their reconstruction of the habitats of the marine molluscs from the cave deposits Shackleton and van Andel (1986, Fig- ure 11) include two possible habitats for their Cerastoderma: ‘protected marsh’ and ‘sand beach’. The latter habitat would be unusual for C . glaucum; does this mean that their cate- gory Cerastoderma includes more than one species? Taxonomic precision is vital if correct biological and ecological factors are to be inferred from the bioarchaeological record.

The data from Franchthi Cave do show interesting changes in the representation of mollusc taxa over time. As I argue below, we need more detailed information about the shells

themselves before we can evaluate the possible reasons for their collection.

COMPARISON OF OFF-SITE MODELS WITH ON-SITE DATA

Shackleton and van Andel (1986) claim, on the basis of their habitat reconstructions for molluscs, that only the shells from the latest Paleolithic and the Neolithic phases of the cave deposits reasonably represent “what should have been available in the area.” They conclude, therefore, that at certain times the inhabitants practiced “a high degree of eco- nomically, socially, or technologically controlled selectivity in the exploitation of shellfish resources at Franchthi” (p. 142). This might appear to be an unexceptionable conclusion, except that they claim it to be based on an objective evaluation of the past availability of mollusc species. In my view their models are unconvincing and do not realisti- cally reconstruct patterns of past mollusc availability. Their data do not tell us much in objective terms about mollusc selectivity; this will have to be inferred from the excavated assemblages of species, unless objective evidence can be obtained from the deposits on the seabed.

SHELLFISH IN THE PREHISTORIC SUBSISTENCE SYSTEMS AT FRANCHTHI CAVE

A number of basic questions can be asked of the shellfish remains from the excavations a t Franchthi Cave. An important one is: why are they there at all? This could be inferred, using criteria outlined by Thomas (1981, 49-50), from an examination of the condition of the shells. Do they show breakage or other damage; is any damage systematic; are there epi- zoic encrustations on the outsides and/or the insides of the shells? Such taphonomic questions can help solve problems relating to the use of shellfish for food or ornament, and even whether the shell contained a living mollusc when it was collected.

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The Cyclope Phase

The hunting and foraging activities practiced by the inhabitants of Franchthi Cave during the Cyclope phase resulted in few shellfish taxa, apart from Cyclope, being brought back to the cave in any significant numbers. The presence of Cyclope tells us that at least part of the subsistence activities of the occupants of the cave were focused on, or near to, habitats where Cyclope was living. During the Cyclope phase the coast was distant from the cave, perhaps 1.5 to 3 km away at various times (Shackleton and van Andel, 1986); it is therefore probable that food resources ac- quired in, or near, Cyclope habitats would have been consumed on the spot or a t some other nearby location. Such patterns for foraging for shellfish have been documented by Meehan (1982), who points out that women and their accompanying children may obtain a high proportion of their dietary protein in this way.

Shackleton and van Andel (1986,142) note that the shells of Cyclope from the excavations had perforations and could have been used as ornaments. This interesting observation needs elaboration: what sort of perforations are present; what could have produced them; do they tend to occur on similar parts of each shell and what proportion of the shells have them? Do the shells of Columbella, commonly found as shell beads in various prehistoric sites (Reese, 1982,85-86), also show signs of having been used as ornaments? All these questions could be answered by careful examination of the archaeological specimens.

Shackleton and van Andel (1986) assume, probably correctly, that Cyclope was not an important food resource in the past; they therefore suggest that shellfish collection in the Cyclope phase was “seemingly idiosyncratic.” Because they ‘explain-away’ an interesting observation, they miss the opportunity to make other valuable inferences. Species of edible shellfish occur consistently in the deposits of the Cyclope phase at Franchthi Cave (Shackleton and van Andel, 1986, Fig. 3). These shellfish were brought back to the cave for some purpose, possibly for consumption. If

the cave is viewed as a home-base, it is likely that some members of the social group occupy- ing the cave were not always able to take part in wide-ranging foraging activities. Nursing mothers and elderly or sick individuals are obvious examples. The shellfish remains in the cave could represent food brought back for such individuals. The low density of shells of potentially edible shellfish in the cave deposits is quite consistent with such an interpretation. Low densities of shellfish remains also suggest another possible factor: periodic exploitation. Resources in the intertidal zone have two important ecological properties for human foragers: they are both predictable and easily collected. They therefore represent a resource which could be exploited at certain times (seasons) when other foods were difficult to obtain. Seasonal or other periodic aspects of shellfish gathering a t Franchthi Cave could potentially be inferred from detailed analysis of the shells (Deith, 1985).

The Cerithiurn Phase

Shackleton and van Andel (1986, 130) are dismissive of Cerithium as a source of food: “Cerithium . . . would not have offered great food value.” As well as noting that Cerithium is widely consumed in the Mediterranean re- gion today (Davidson, 1981, 194), we might ask what, anyway, does “great food value” mean? Meehan (1977; 1982) has discussed molluscs in terms of their food value and has shown that shellfish can be a valuable protein and mineral supplement in diets which might otherwise be dominated by carbohydrates. They can be especially important in the diets of women and children, who might not have access to ‘high status’ meat hunted by the men. Furthermore, as suggested above, shellfish can be important preditable food resources when alternative foods are scarce.

Cerithium reaches high frequencies in the deposits a t Franchthi Cave when the sea has advanced from some 1.5 km away to within 0.5 km of its present-day position: the species was important enough to be brought to the cave where, perhaps, it was consumed (careful


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analysis of the actual shells might confirm or refute this specific hypothesis). Why was Ceri- thium brought to the cave in large numbers compared with other taxa? Availability or pre- ferential selection could be explanations, but there are other possibilities. As noted above, much of the shellfish consumption which might have been practiced by the inhabitants of Franchthi Cave probably took place near the coast and therefore away from the cave. Some types of shellfish are much more easily consumed than others. Limpets (Patella spp.) can easily be scooped out of their shells and eaten while bivalves (as described by Meehan, 1982) can be mixed in the embers of a fire and the valves will gape open when the animals die. Such shellfish could have been consumed away from the camp site. Others, particularly gastropods like Cerithiurn, with thick and coiled shells, present problems. Perhaps it was worthwhile transporting Cerithium from the relatively nearby coast to the cave, where the molluscs could be extracted and consumed at leisure.

The Neolithic Phase of Occupation

The shellfish assemblages in the Neolithic deposits of the cave appear to be, according to Shackleton and van Andel (19861, representa- tive of what should have been available in the area; they make little else of this observation. The coastline was close to the cave in this period and a wide diversity of shellfish was brought into the cave. It might be thought surprising that, at a time when food produc- tion was the main subsistence activity, the Neolithic inhabitants of the cave should have been exploiting a fairly broad spectrum of resources on the seashore.

The people who inhabited Franchthi Cave in the Neolithic Period were probably not con- ducting their various farming activities from the cave. They probably came to the cave at certain times (seasons?) for various reasons, including the collection of shellfish for consumption. Evidence from various parts of the world suggests that, in some circumstances, exploitation of coastal resources could have been intensified as a consequence of the adop-

tion of agriculture (e.g., Branch, 1975; Ray- mond, 1981; Troels-Smith, 1967). Branch (1975) showed that shellfish resources tended to be exploited in periods of poor crop yields. Only by considering the shellfish in the broader context of past subsistence systems are we likely to be able to infer something valid from them.

Possible Impact of Intensified Neolithic Ex- ploitation on Coastal Resources

Modern ecological studies of predation by man in the intertidal zone have shown that this can have a marked impact on the abundance of species and on the total diversity of shellfish (Branch, 1975; Castilla and DurBn, 1985; Hockey and Bosman, 1986; Moreno et al., 1984; Okera, 1976). The possible influence that such a factor might have had on the formation of the archaeological record has been summarized by Thomas (1981, 58-59). Bot- kin (1980) analyzed the shellfish remains from a midden in southern California and showed, using quantitative data on changes in the abundance and mean shell size of various species through the midden deposits, that there was a marked shift over time from the exploitation of the rock-dwelling, and readily available, bivalve Mytilus californiunus to the sand and gravel dwelling, less readily available, bivalve Protothaca staminea. These observations could not be related to changes either in sea-levels or local depositional environments. Botkin’s analysis produced compelling evidence for past over-exploitation of Mytilus, leading to a shift in foraging for the less easily obtained Protothaca.

Such arguments could also be applied to the assemblages of molluscs from Franchthi Cave, zone IV (Shackleton and van Andel, 1986, Figure 3), where there is a marked decline in the abundance of Cerithiurn (a rock-dwelling gastropod which would have been easily collected) and a rise in the numbers of bivalves such as Cermtoderm, Tapes, and the donacids (all of which live within soft substrates and are less easily collected). A detailed metrical analysis of mean shell sizes in the samples of Cerithium from the cave could cast light on

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the intriguing possibility of prehistoric over- exploitation of this taxon.

CONCLUSIONS

Shackleton and van Andel (1986) have outlined a research strategy for the study of Franchthi Cave which, if valid, could potentially be applied to other archaeological sites in coastal environments. A critical review of their model has led to the conclusion that it is too remote from their database to be reliable.

There is much valuable information to be gained from a study of the shellfish remains from Franchthi Cave; some of this has been presented and discussed by Shackleton and van Andel (1986). More detailed analyses of the shellfish remains from the cave should be made in the light of specific questions about their role in past subsistence. Taphonomic analysis of the shells would yield information on the reasons for their collection (for food, ornaments, tools, etc.) and on the ecological aspects oftheir exploitation, including the possibility of over-exploitation of certain species in the past.

All of the mollusc data from Franchthi Cave are potentially suitable for objective scientific analysis without being explained-away in terms of “idiosyncratic choices” or dismissed by asserting that their interpretation “is the task of the archaeologist” (Shackleton and van Andel, 1986, 127 and 141): We are all archaeologists now!

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Branch, G.M. (1975). Notes on the ecology of Patella concolor and Cellana capensis, and the effect of human consumption on limpet populations. Zoologica Africana 10, 75-85.

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Received December 1, 1986 Accepted for publication January 15, 1987

240 VOL. 2, NO. 3

Documents

Prehistoric coastal ecologies: A view from outside Franchthi Cave, Greece