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Origins of the Modern Mind

I have also tried to build a theory in such a way that specific details of chronology are not crucial to its central hypothesis, which is essentially concerned with cognitive succession, and consequent modern cognitive structure. Finally, I have chosen to construct my succession hypothesis around a fairly simple unifying theme, that of evolving cognitive architecture. This is based on my belief that brains store memories in and around their functional processors rather than somewhere else, as most computers do; and therefore that radically new representational strategies signal the likelihood of a change in the underlying neuropsychological architecture (keeping in mind that such changes may be anatomically complex). Chronology, succession and transition. Chronology is important in that it helps us establish an order of succession, and determine how many major cognitive steps were taken, and roughly when. This issue was not as difficult to resolve as one might have expected, given the controversy that seems to pursue archeological finds. There is considerable stability in the basic number of hominid species that are currently interposed between humans and Miocene apes, and in their order of appearance. Moreover, there is agreement that although australopithecines undoubtedly underwent massive anatomical and cultural change in adopting erect posture, they did not leave any evidence suggesting major cognitive evolution. There appear to be only two strong candidates for a major breakpoint in hominid cognitive evolution, and these coincide with the transition periods leading to the speciation of Homo erectus (about -1.5 M years) and archaic Homo sapiens (roughly -0.3 M years), respectively. Four recent books on this subject have all agreed on this basic point. The relative brain size of Homo erectus was much larger than that of previous hominids, eventually exceeding 70% of the modern human brain. The linear upward trend of hominid brain size accelerated sharply during the transition to Homo erectus, and was sustained until Homo sapiens emerged (Lieberman, 1991). This rapid increase in cerebral volume was concentrated in the association cortex, hippocampus, and cerebellum. Even taken in isolation of cultural artifacts, these anatomical facts would suggest a significant cognitive change. But the cultural evidence left by Homo erectus strongly confirms the presence of major cognitive evolution: Homo erectus manufactured quite sophisticated stone tools, devised long-distance hunting strategies, and migrated out of Africa over much of the Eurasian landmass. A second major transition period preceded the speciation of Homo sapiens and was marked by another large brain expansion and the descent of the larynx has argued, the latter probably coincided with the emergence of spoken language as we know it, that is, with the arrival of a high-speed vocal communication system driven by a large lexicon containing thousands of entries. T