Chimp Reciprocity: The Power in Triadic Social Networks

Research, Quantitative Analysis, Social Network Analysis

It is remarkable that the question of whether reciprocity exists in non-human primates is still an open question. While a strong evolutionary case for the reciprocity in chimpanzees has not been previously made, most experimental work has focused on dyads, that is, patterns of interaction between two chimps. Sarah Brosnan, a psychology professor and primatologist, asked us to think about how social network data may be analyzed in new ways in order to shed light on this puzzle.

Using food sharing data collected at the M.D. Anderson Cancer Center Science Park in Bastrop, Texas, we decomposed the chimp social networks into sub-networks of closed, reciprocal triads. In other words, we extracted out networks where Radar was friends with Moose and Nina, Moose was friends with Nina and Radar, and Nina was friends with Radar and Moose. Within these networks, we showed that reciprocity was more likely to occur. There is indeed power in the third.





We were invited to present this work at Elinor Ostrom's Workshop in Political Theory and Policy Analysis at Indiana University. Download the paper, Social Contracts on Social Networks: Local Patterns of Interaction, Local Strategy Dynamics and the Emergence of Reciprocity, here.



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