Anthropologists have recently revised their view of how early human societies were structured. This shift ultimately brings new insights into the evolution of humans from apes. This new belief is concerned with how early human groups would have been more cooperative and willing to learn from one another than the chimpanzees from which our ancestors split.
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 R. Hill of Arizona State University and Robert S. Walker 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.
The finding corresponds to an influential new view of early human origins proposed by Bernard Chapais, a primatologist at the University of Montreal. Dr. Chapais showed how a simple development, the emergence of a pair bond between male and female, would have allowed people to recognize their relatives, something chimps can do only to a limited extent. When family members dispersed to other bands, they would be recognized and neighboring bands would cooperate instead of fighting to the death as chimp groups do.