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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


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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