Loading...
Egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees, Pan troglodytes.
Kaburu, Stefano S. K. Newton-Fisher, Nicholas E.
Kaburu, Stefano S. K.
Newton-Fisher, Nicholas E.
Editors
Other contributors
Affiliation
Epub Date
Issue Date
2014-11-25
Submitted date
Alternative
Abstract
Biological market theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. Studies of female Old World monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees have yielded mixed results. Here we provide the strongest test of the model to date for male chimpanzees: we use data drawn from two social groups (communities) of chimpanzees from different populations and give explicit consideration to variation in dominance hierarchy steepness, as such variation results in differing conditions for biological markets. First, analysis of data from published accounts of other chimpanzee communities, together with our own data, showed that hierarchy steepness varied considerably within and across communities and that the number of adult males in a community aged 20–30 years predicted hierarchy steepness. The two communities in which we tested predictions of the grooming-trade model lay at opposite extremes of this distribution. Second, in accord with the grooming-trade model, we found evidence that male chimpanzees trade grooming for agonistic support where hierarchies are steep (despotic) and consequent effective support is a rank-related commodity, but not where hierarchies are shallow (egalitarian). However, we also found that grooming was reciprocated regardless of hierarchy steepness. Our findings also hint at the possibility of agonistic competition, or at least exclusion, in relation to grooming opportunities compromising the free market envisioned by biological market theory. Our results build on previous findings across chimpanzee communities to emphasize the importance of reciprocal grooming exchanges among adult male chimpanzees, which can be understood in a biological markets framework if grooming by or with particular individuals is a valuable commodity.
Citation
Kaburu, S.K. and Newton-Fisher, E. (2014) Egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees (Pan troglodytes). Animal Behaviour, 99 . pp. 61-71
Publisher
Journal
Research Unit
DOI
PubMed ID
PubMed Central ID
Embedded videos
Additional Links
Type
Journal article
Language
en
Description
Series/Report no.
ISSN
0003-3472
EISSN
ISBN
ISMN
Gov't Doc #
Sponsors
Wenner-Gren foundation (grant no. 8216), Leverhulme Trust (grant no. F/00236/Z), the H.F. Guggenheim Foundation.
Rights
Attribution-NonCommercial-NoDerivs 3.0 United States