Yvan I. Russell: Sociality in great apes: studies of reputation, food sharing, and grooming

  • Date: Oct 7, 2016
  • Time: 11:00 - 12:00
  • Speaker: Yvan I. Russell from the Middlesex University, London, GB
  • For more information, please visit: https://www.mdx.ac.uk/about-us/our-people/staff-directory/profile/russell-yvan
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Dirk Semmann
Yvan I. Russell: Sociality in great apes: studies of reputation, food sharing, and grooming


This talk will proceed in two parts. The first is an eavesdropping experiment in four great ape species. Inspired by previous studies in “image scoring” (agent-based models/behavioural economics) which showed the importance of reputation in the evolution of cooperation – this study sought to conduct an animal version of an image scoring study. While unable to show the entire sequence of positive indirect reciprocity (“A observes B help C, therefore A helps B”), the focus was on the information gathering aspect (“A observed B feed C”) and the self-interested inference (“therefore A will feed me”). We gave the apes an opportunity to eavesdrop on interactions between human actors whereupon a “nice” person gave grapes to person who begged for it and a “nasty” person refused to give grapes. The dependent variable – the apes’ expectation of which human (the nice or nasty) was more likely to offer food later – were measured by time spent with either person (who showed food but actually withheld it). Results showed that the Pan species (chimpanzees, bonobos) showed a significant preference for the nice person, whereas the gorillas and orangutans showed no preference. The second part of this talk focuses on allogrooming in a captive chimpanzee group. We investigated grooming reciprocity over different time windows. We found that time-matching, when measured precisely, occurs only during bouts of simultaneous grooming and that precise matching deteriorates with delay. This implies that grooming reciprocity, if calculated, is more of a short-term contract and in the longer-term is based on an attenuated representation.

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