Human evolution as a theoretical modelfor an extended evolutionary synthesis

Abstract

Humans have occupied a paradoxical position within the history of evolutionary studies. On one end, humans have been central to both the academic motivation of the field and the public tensions surrounding evolution. Simultaneously, humans have been cast aside as a poor model organism for understanding the processes that underlie evolutionary theory. As a result, anthropologists who work within an evolutionary context, often chided as being two decades behind mainstream biology, have come to occupy a unique position with respect to the understanding of how evolution operates on humans. Incorporating theoretical developments from a diverse set of related evolutionary fields, biological anthropologists have begun to gather empirical data on the unique evolutionary processes that have shaped our own evolutionary path. Some of the important components that have emerged in human evolutionary studies-biocultural feedback systems, culturally mediated niche construction, and technological ratchet effects-have shed new light not only on how human evolution has proceeded but also on the range of capabilities of evolution more broadly. While not rejecting traditional neo-Darwinian theory and the importance of genetic inheritance, these new developments have highlighted the tremendous complexity afforded by the cumulative action of both selective and neutral evolutionary forces across a range of inheritance modes. Rather than a poor evolutionary model, many of these evolutionary processes are best, or perhaps only, observable in humans. The traits which have structured critical transitions in our hominin past-encephalization, expanded childhood development, and generative language-open up new windows into thinking about an Extended Evolutionary Synthesis.