page_37 < previous page page_37 next page > Page 37 of Pleistocene hunter-gatherers. Evolutionary psychology typically postulates that the human brain contains a rich repertoire of such specialized mechanisms for solving problems that were adaptively relevant in the savannah-woodland habitats of Pleistocene Africa. By implication, cultural evolution in the last 10,000 years represents the exploration of a possibility space that is highly constrained by the biases we inherited from our hunter-gatherer ancestors. But on closer inspection, at least on the basis of the case we have just examined, it seems that this approach is simply producing a rather na�Żve set of �śjust-so stories.” The main significance of this debate for archaeology is in relation to the interpretation of Paleolithic site formation processes�"the processes that brought clusters of lithic artifacts and animal bones into close spatial association. Cosmides and Tooby (1989:58) cite Isaac’s (1978) �Ś�Śhome base” model of such processes to support their belief that �śPleistocene hunter-gatherers, like their modern counterparts, engaged in extensive food-sharing.” There is an unfortunate circularity to this argument, since Isaac’s model was based on the conjecture that modern hunter-gatherer land-use behavior was a suitable analogue for that of early Homo. Several other interpretations of late Pliocene and early Pleistocene site formation must also be considered, including the behavioral models of routed foraging and of stone caching, and the taphonomic model of accidental association (Potts 1992). In the extreme, Yellen (1996) has suggested that the earliest clear signs of modern hunter-gatherer camp site structure are at the Middle Stone Age site of Katanda 9 in Zaire, dating to perhaps 90,000 B.P. We certainly cannot use Isaac’s model, in itself, to validate conjectures about the EEA. BIOLOGICAL CONSTRAINTS ON DIET AND HEALTH: ANOTHER PLEISTOCENE HUNTER-GATHERER LEGACY? A similar style of argument has been adopted recently by some anthropologists, who are concerned at the high prevalence in developed countries of �śdiseases of civilization” (such as obesity, hypertension, coronary artery disease, and cancer). In this case, their emphasis is not on biological constraints on human reasoning, but on the biological constraints that determine what constitutes a healthy diet. For example, Cordain et al. (2000:682) argue that �śthe diets of modern hunter-gatherers may represent a reference standard for modern human nutrition and a model for defense against certain �Śdiseases of civilization’.” They analyze ethnographic data on the contributions of animal and plant foods to hunter-gatherer diets, and conclude that hunter-gatherers typically derive more than half of their energy requirements from animal foods, with less than one in seven ethnographically documented hunter-gatherer societies subsisting mainly on plant foods (Figure 3.4). Breaking down typical hunter-gatherer food intake into its constituent energy sources (proteins, carbohydrates, and fats), they < previous page page_37 next page >