Chimpanzees demonstrate individual differences in social information use

Abstract

Studies of transmission biases in social learning have greatly informed our understanding of how behaviour patterns may diffuse through animal populations, yet within-species inter-individual variation in social information use has received little attention and remains poorly understood. We have addressed this question by examining individual performances across multiple experiments with the same population of primates. We compiled a dataset spanning 16 social learning studies (26 experimental conditions) carried out at the same study site over a 12-year period, incorporating a total of 167 chimpanzees. We applied a binary scoring system to code each participant’s performance in each study according to whether they demonstrated evidence of using social information from conspecifics to solve the experimental task or not (Social Information Score—‘SIS’). Bayesian binomial mixed effects models were then used to estimate the extent to which individual differences influenced SIS, together with any effects of sex, rearing history, age, prior involvement in research and task type on SIS. An estimate of repeatability found that approximately half of the variance in SIS was accounted for by individual identity, indicating that individual differences play a critical role in the social learning behaviour of chimpanzees. According to the model that best fit the data, females were, depending on their rearing history, 15–24% more likely to use social information to solve experimental tasks than males. However, there was no strong evidence of an effect of age or research experience, and pedigree records indicated that SIS was not a strongly heritable trait. Our study offers a novel, transferable method for the study of individual differences in social learning.

Innovation in chimpanzees

“…These studies provide valuable evidence on the characteristics of innovative individuals, as an individual's performance may be tracked across multiple studies. Indeed, it has proved possible to conduct a meta‐analysis of individual differences in social learning across multiple studies conducted at the same captive care facility, establishing quite stable variations in whether individuals tend towards learning from others, or instead rely on their own exploration of the opportunities presented (Watson et al ., 2018). Social‐learning studies are also carried out under carefully controlled conditions, with individuals in asocial control groups often having the opportunity to attempt an artificial foraging task in isolation.…”

Competition for resources can promote the divergence of social learning phenotypes

“…This provides a mechanistic explanation for the divergence of social learning phenotypes that has been observed in nature (e.g. [15,20]). Interestingly, sufficiently complex conditional social learning rules can resolve disruptive selection and so may prevent the divergence of social learning phenotypes.…”

“…Rates of social learning often differ among individuals in the same population, so that some individuals use social learning more frequently than others [14,15]. In some cases, differences in social learning phenotypes can be linked to differences in life history [16].…”

“…For example, Aplin & Morand-Ferron found differences in social learning frequency among great tits, even without clear pre-existing differences among birds [20]. Similarly, chimpanzees have different social learning frequencies within sexes, and the adaptive value of these differences remains unexplained [15].…”

Melanism influences the use of social information in a polymorphic owl

“…16,17 . However, considerably far less attention has been paid to intra-specific variation in the propensity to use social information, despite accumulated evidence showing that is not a species-specific characteristic [18][19][20] . In particular, the mechanistic basis behind such intra-specific variability remains poorly understood 21,22 .…”