Lack of conformity to new local dietary preferences in migrating captive chimpanzees

Abstract

Conformity to the behavioural preferences of others can have powerful effects on intragroup behavioural homogeneity in humans, but evidence in animals remains minimal. In this study, we took advantage of circumstances in which individuals or pairs of captive chimpanzees, Pan troglodytes, were 'migrated' between groups, to investigate whether immigrants would conform to a new dietary population preference experienced in the group they entered, an effect suggested by recent fieldwork. Such 'migratory-minority' chimpanzees were trained to avoid one of two differently coloured foods made unpalatable, before 'migrating' to, and then observing, a 'localmajority' group consume a different food colour. Both migratory-minority and local-majority chimpanzees displayed social learning, spending significantly more time consuming the previously unpalatable, but instead now edible, food, than did control chimpanzees who did not see immigrants eat this food, nor emigrate themselves. However, following the migration of migratory-minority chimpanzees, these control individuals and the local-majority chimpanzees tended to rely primarily upon personal information, consuming first the food they had earlier learned was palatable before sampling the alternative. Thus, chimpanzees did not engage in conformity in the context we tested; instead seeing others eat a previously unpalatable food led to socially learned and adaptive re-exploration of this now-safe option in both minority and majority participants. Author ContributionsG.L.V. collected the data and carried out the statistical analyses; G.L.V. and A.W. drafted the manuscript with all authors contributing to the final manuscript; the original conception of the methodology was the work of A.W. and E.W.; the original methodology was adapted for captive chimpanzees by G.L.V. and A.W.; S.D. conducted inter-rater reliability, S.P.L. conducted and monitored all chimpanzee 'migrations' and provided on-site logistical support along with S.J.S. Many of the daily choices faced by animals require decisions about whether to engage in personal exploration of the environment (asocial learning) or instead to exploit the existing knowledge of others by learning socially (Kendal, Coolen, van Bergen, & Laland, 2005;Kendal, Coolen, & Laland, 2009;Laland, 2004). Evolutionary theory predicts that if appropriate decision-making rules can be economically employed, social learning will itself be selective. Such selectivity may be pursued through heuristics termed social learning strategies (Laland, 2004), or transmission biases (Boyd & Richerson, 1985;Henrich, 2001), which dictate who, what, when or even how to copy. The identification of such heuristics has proved instructive in understanding how cultures evolve in humans and other species (Kendal et al., 2015;Rendell et al., 2011). A variety of social learning strategies have recently been identified in diverse animal taxa (Kendal et al., 2009;Laland, 2004;Rendell et al., 2011), such as preferentially copying 'dominant' or 'knowledgeable' in...

Population-specific social dynamics in chimpanzees

“…The latter approach would simultaneously enable the opportunity to study the mechanisms by which population-level homogeneity in interaction patterns could ensue [e.g., by means of conformity (18,23,61,62), although see refs. [63][64][65].…”

Wild primates copy higher-ranked individuals in a social transmission experiment

“…Despite promising indications of primate social-learning strategies, some inconsistencies have been reported 32,33 and the interpretations of some findings as indicative of social-learning strategies have been controversial 34 . Moreover, many previous studies tested subjects by imposing a trained model who uses one technique in a two-alternative-actions design (henceforth termed "options").…”

Social conformity affects experimental measurement of boldness in male but not female monk parakeets (Myiopsitta monachus)

“…Initially described in humans and non-human primates (Cialdini & Goldstein, 2004;Whiten et al, 2005;Dindo et al, 2009;van de Waal et al, 2013), conditional change in behaviour in response to the actions of conspecific individuals has been documented in other vertebrate groups such as rodents (Galef & Whiskin, 2008;Jolles et al, 2011), birds (Aplin et al, 2015;King et al, 2015), and fish (Day et al, 2001;Webster & Laland, 2012). One of the demonstrated selective advantages of conforming to group behaviour is acquiring behavioural norms that help them utilize local food resources, which newly immigrated individuals rely on after their dispersal into a new social group (Vale et al, 2017). For species that show sex-specific natal dispersal patterns, we would expect individuals of the emigrating sex to have a higher tendency towards conformity in response to risk-related events, so that they can better adapt to their novel environment and maximize their fitness through observation of the local preferences in their new social groups .…”