title: Chimpanzees copy dominant and knowledgeable individuals: implications for cultural diversity.
abstract: Evolutionary theory predicts that natural selection will fashion cognitive biases to guide when, and from whom, individuals acquire social information, but the precise nature of these biases, especially in ecologically valid group contexts, remains unknown. We exposed four captive groups of chimpanzees (Pan troglodytes) to a novel extractive foraging device and, by fitting statistical models, isolated four simultaneously operating transmission biases. These include biases to copy (i) higher-ranking and (ii) expert individuals, and to copy others when (iii) uncertain or (iv) of low rank. High-ranking individuals were relatively un-strategic in their use of acquired knowledge, which, combined with the bias for others to observe them, may explain reports that high innovation rates (in juveniles and subordinates) do not generate a correspondingly high frequency of traditions in chimpanzees. Given the typically low rank of immigrants in chimpanzees, a 'copying dominants' bias may contribute to the observed maintenance of distinct cultural repertoires in neighboring communities despite sharing similar ecology and knowledgeable migrants. Thus, a copying dominants strategy may, as often proposed for conformist transmission, and perhaps in concert with it, restrict the accumulation of traditions within chimpanzee communities whilst maintaining cultural diversity.
authors.affiliation: Centre for the Coevolution of Biology and Culture, Anthropology Department, Durham University, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Kendal
authors.affiliation: Centre for the Coevolution of Biology and Culture, Anthropology Department, Durham University, UK; Centre for Social Learning and Cognitive Evolution, School of Psychology and Neuroscience, University of St. Andrews, UK; Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, USA; Lester E. Fisher Center for the Study & Conservation of Apes, Lincoln Park Zoo, USA.
authors.forename: Lydia M
authors.initials: LM
authors.lastname: Hopper
authors.affiliation: Centre for Social Learning and Cognitive Evolution, School of Psychology and Neuroscience, University of St. Andrews, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Whiten
authors.affiliation: Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, USA; Language Research Center, GA State University, USA; Department of Psychology & Neuroscience Institute, GA State University, USA.
authors.forename: Sarah F
authors.initials: SF
authors.lastname: Brosnan
authors.affiliation: Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, USA.
authors.forename: Susan P
authors.initials: SP
authors.lastname: Lambeth
authors.affiliation: Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, USA; Department of Experimental Medicine, University of Copenhagen, Denmark.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schapiro
authors.affiliation: Centre for Social Learning and Cognitive Evolution, School of Biology, University of St. Andrews, UK; Department of Life Sciences, Anglia Ruskin University, UK.
authors.forename: Will
authors.initials: W
authors.lastname: Hoppitt
keywords: Chimpanzees; Cultural diversity; Culture; Social learning strategies; Transmission biases