In an attempt to understand the social dynamics among our hunter-gatherer ancestors, anthropologists sometimes begin in the present and work backwards. And what the researchers at University College London have found adds another dimension to the unique social structure of hunter-gatherer society.

It was traditionally believed that our ancestors would have chosen to live among their closest kin. The extended family afforded protection, sharing of resources, and a vested interest in the group's survival. But studies of contemporary hunter-gatherer groups tell a different story, with many groups having low levels of relatedness among their members. The folks at UCL wanted to understand how that happens.

For two years, researchers from the Hunter-Gatherer Resilience Project in UCL Anthropology lived among hunter-gatherer populations in Congo and the Philippines, hoping to tease apart just how group members chose where they would live. They collected genealogical date on kinship relations, between-camp mobility, and residence patterns through extensive interviews among hundreds of residents. They then constructed a computer model that simulated camp assortment and the distribution of kin within the group.

Their data showed that when one sex had influence over decision-making as to where a family would live, camp relatedness was high. Such is the pattern in male-dominated pastoral or horticultural societies. But when the decision is equally split between males and females, camp relatedness tends to be low. This egalitarian decision-making results in families alternating between camps, living for periods among the male's relatives, other times among the female's, which results in low levels of relatedness within camps.

"While previous researchers have noted the low relatedness of hunter-gatherer bands, our work offers an explanation as to why this pattern emerges" lead author of the new study, Mark Dyble says. "It is not that individuals are not interested in living with kin. Rather, if all individuals seek to live with as many kin as possible, no-one ends up living with many kin at all."

And what can be learned from such studies? Although contemporary hunter-gatherers may be affected by the modern world around them, they are the closest example of how our ancestors may have lived. Social organization research provides insight into the evolution of traits that are uniquely human, such as high cognition, cumulative culture, and hyper-cooperation.

According to co-author Dr. Andrea Migliano, "Sex equality suggests a scenario where unique human traits such as cooperation with unrelated individuals could have emerged in our evolutionary past."

Which brings us one step closer to understanding the evolution of modern societies.