What Was the EEA Really Like?
Posted: 15 May 2010
Date Written: May 15, 2010
Evolutionary Anthropologists and Psychologists often say that humans evolved our characteristic adaptations in the Environment of Evolutionary Adaptedness, those past environments that furnished the selection pressures that shaped our brains and bodies. This is true by definition, but when and where were these environments and what were they like are open questions. It is often said, carelessly, that the Pleistocene was the EEA and that human hunter-gatherers were shaped by “the” environment over the past 2 million years. Living hunter-gathers like the San, the Ache, and the Inuit are often taken to be representative of what the EEA produced. This conventional picture does not look much like what the Pleistocene and adaptations to it were really like, insofar as we can infer from what little paleoanthropologists and paleoecologists can tell us. First, Pleistocene environments were very variable and the pattern of variability changed dramatically over the course of the Pleistocene. Adaptations of Homo erectus and related Lower Pleistocene hominins might have been very different from later form in the Middle and Late Pleistocene. Second, even late Pleistocene H. sapiens populations mostly made fairly simple Middle Paleolithic stone tools not accompanied by any art or other symbolic artifacts. Third, H. sapiens populations in West Eurasia, and perhaps our H. neandertalensis relatives in the same region, began making fancy Upper Paleolithic toolkits about 40,000 years ago in the middle of the last glacial. Earlier H. sapiens populations in Africa very occasionally made intermediate toolkits in short episodes. But the African pioneers who swept eastward into Asia and Australia seemed to have made comparatively Middle Paleolithic simple tools until very late in time. Fifth, We know next to nothing about the social organization of any Pleistocene peoples. Sixth, Last Glacial people appear to have been highly carnivorous. In the Holocene, most human populations soon switched to plant intensive diets, leading in some populations to agriculture. Populations became denser and more highly organized socially. These changes gave rise to a number of genetic changes as people adjusted to an environment that had been transformed by culture. Seventh, contemporary modern civilization is probably leading to ongoing selection on genes. Welcome to the EEA! We’re still in it.
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