Darwin's monkey: Why baboons can't become human

Abstract

Baboons were used in the past as models for human evolution. I utilize 40 years of data from my long-term study on baboons in Kenya to suggest that baboons are once again relevant for understanding human evolution, not as a referential model but to reset the starting conditions of the human experiment. The baboon data also offer a critique of widely held ideas about how natural selection might work by looking at real lives in real time. This situates competition in a matrix of collaboration and illustrates the critical role of chance, contingency, and history in baboon survival and success. I make three methodological moves to reach these conclusions. The first is to focus on process not just outcome. The second is to look at time scales longer than usual studies but shorter than evolutionary time as a way to open the black box that currently links behavior to evolutionary value. The third is to use comparative natural history, Darwin's method, as a way to capture and comprehend how complexity is generated and how baboons deal with it in their daily lives. These empirical and methodological turns lead to conclusions that run counter to widely held ideas about baboons, about primates, and about the determinism of natural selection. I follow my own research history to illustrate these points. The discussion ranges from alternative interpretations of the male and the female dominance hierarchies, to insights from a fission that happened when the foraging strategy of raiding and nonraiding baboons diverged, to evidence of adaptation after translocation, and finally to assessing two unusual fusions of baboon groups. Altogether, these natural histories yield baboon "principles of the social" with insights about cognition, cooperation, and culture and suggest why baboons can't become human. The data also support Weiss and Buchanan's framework (The Mermaid's Tale: Four Billion Years of Cooperation in the Making of Living Things. Cambridge, MA: Harvard University Press,2009. 305 p) with its alternative view of natural selection in which there is more slippage and tolerance, multiple solutions with larger acceptability spaces, and the possibility that an adaptive fit will be "good enough" rather than seamless. However, capturing behavioral complexity "in the wild" poses methodological challenges. Long-term field studies provide critical information but the current quantitative methods should be expanded also include natural history observations of behaviors and events across time, space, groups, and landscapes. Finally, the baboon natural histories illustrate how the evolutionary game has changed in the Anthropocene yielding a cautionary tale about the future for many primate species.