New View of How Humans Moved Away From Apes

A nice article in the New York Times by their science correspondent Nick Wade. He reports on recent work on hunter-gatherer societies building on 2008 insights into human social organization by Bernard Chapais. Kim Hill and colleagues point out that the previously-thought pattern of females moving away from family groups, leaving male cross-generational coalitions in charge, is not by any means the rule in hunter-gatherer societies, where just as often it is the young males that move out. They call the phenomenon bilocality. This means that social groups are far less genetically related than thought so that cooperation between non-kin, as opposed to kin selection inclusive fitness cooperation of selfish genes, is the key to how humans moved away from the ape model. here's a bit of the article:

"Anthropologists studying living hunter-gatherers have radically revised their view of how early human societies were structured, a shift that yields new insights into how humans evolved away from apes.

Early human groups, according to the new view, would have been more cooperative and willing to learn from one another than the chimpanzees from which human ancestors split about five million years ago. The advantages of cooperation and social learning then propelled the incipient human groups along a different evolutionary path.

Anthropologists have assumed until now that hunter-gatherer bands consist of people fairly closely related to one another, much as chimpanzee groups do, and that kinship is a main motive for cooperation within the group. Natural selection, which usually promotes only selfish behavior, can reward this kind of cooperative behavior, called kin selection, because relatives contain many of the same genes.

A team of anthropologists led by Kim S. Hill of Arizona State University and Robert S. Walker of the University of Missouri analyzed data from 32 living hunter-gatherer peoples and found that the members of a band are not highly related. Fewer than 10 percent of people in a typical band are close relatives, meaning parents, children or siblings, they report in Friday’s issue of Science.

Michael Tomasello, a psychologist at the Max Planck Institute for Evolutionary Anthropology in Germany, said the survey provided a strong foundation for the view that cooperative behavior, as distinct from the fierce aggression between chimp groups, was the turning point that shaped human evolution. If kin selection was much weaker than thought, Dr. Tomasello said, “then other factors like reciprocity and safeguarding one’s reputation have to be stronger to make cooperation work.”"