Prehistoric social networks - publication from Science

Stan Wasserman on The Complexity and Social Networks blog reports on a recent paper on prehistoric social networks in Science by Hill, Walker, Božičević et al:

Wasserman comments:

"A hunter-gatherer life-style is thought to have been the predominant social structure for most of human history. The common assumption is that hunter-gatherer groups consisted largely of related individuals: parents, siblings, and offspring, possibly extending to include spousal relations. In a Research Article in the 11 Mar 2011 Science, Hill et al. analyzed the kin relationships of groups in 32 contemporary hunter-gatherer societies and found that these societies display a social structure different from any other primate or vertebrate (listen to the related podcast interview with lead author Kim Hill). Although adult brothers and sisters often co-reside, most individuals in residential groups are genetically unrelated. In addition, both sexes alike can choose to leave their group or to stay, and neither the maternal lineage nor the paternal lineage is dominant within a group. These patterns produce large interaction networks of unrelated adults and suggest that inclusive fitness cannot explain extensive cooperation in hunter-gatherer bands. However, large social networks may help to explain why humans evolved capacities for social learning that resulted in cumulative culture. An accompanying Perspective by B. Chapais considered how the unique multigroup structure of human societies may have originated."

Here's the abstract: Science 11 March 2011: Vol. 331 no. 6022 pp. 1286-1289 

Co-Residence Patterns in Hunter-Gatherer Societies Show Unique Human Social Structure

Kim R. Hill1,* Robert S. Walker2,* Miran Božičević James Eder, Thomas Headland, Barry Hewlett, A. Magdalena Hurtado, Frank Marlowe, Polly Wiessner, and Brian Wood.

Abstract

Contemporary humans exhibit spectacular biological success derived from cumulative culture and cooperation. The origins of these traits may be related to our ancestral group structure. Because humans lived as foragers for 95% of our species' history, we analyzed co-residence patterns among 32 present-day foraging societies (total n = 5067 individuals, mean experienced band size = 28.2 adults). We found that hunter-gatherers display a unique social structure where (i) either sex may disperse or remain in their natal group, (ii) adult brothers and sisters often co-reside, and (iii) most individuals in residential groups are genetically unrelated. These patterns produce large interaction networks of unrelated adults and suggest that inclusive fitness cannot explain extensive cooperation in hunter-gatherer bands. However, large social networks may help to explain why humans evolved capacities for social learning that resulted in cumulative culture.