Chimpanzees’ socially maintained food preferences indicate both conservatism and conformity

Abstract

Chimpanzees remain fixed on a single strategy, even if a novel, more efficient, strategy is introduced. Previous studies reporting such findings have incorporated paradigms in which chimpanzees learn one behavioural method and then are shown a new one that the chimpanzees invariably do not adopt. This study provides the first evidence that chimpanzees show such conservatism even when the new method employs the identical required behaviour as the first, but for a different reward. Groups of chimpanzees could choose to exchange one of two types of inedible tokens, with each token type being associated with a different food reward: one type was rewarded with a highly preferred food (grape) and the other type was rewarded with a less preferred food (carrot). Individuals first observed a model chimpanzee from their social group trained to choose one of the two types of tokens. In one group, this token earned a carrot, while in the other, control, group the token earned a grape. In both groups, chimpanzees conformed to the trained model’s choice. This was especially striking for those gaining the pieces of carrot, the less favoured reward. This resulted in a population-level trend of food choices, even when counter to their original, individual, preferences. Moreover, the chimpanzees’ food preferences did not change over time, demonstrating that these results were not due to a simple shift in preferences. We discuss social factors apparent in the interactions and suggest that, despite seeming to be inefficient, in chimpanzees, conformity may benefit them, possibly by assisting with the maintenance of group relations.

End state copying by humans (Homo sapiens): Implications for a comparative perspective on cumulative culture.

“…It is important to note that the conservatism reported in chimpanzees appears very different from the "overimitation" observed in studies of social learning in humans, even though it may sometimes entail persistence with a socially learned solution in the face of individual experience of a more effective alternative (e.g., Hopper et al, 2011), which could be regarded as reminiscent of overimitation. As noted above, the high fidelity copying documented in the current experiment (even with regard to a relatively inefficient demonstration design) probably arises as a result of a genuine motivation to achieve an adequate, if not outstanding, score on the goal measure.…”

“…The apparent conservatism exhibited by chimpanzees within studies of social learning may provide an intriguing insight. Chimpanzees appear to show a striking tendency to perseverate with learned responses, often in the face of exposure to, or even experience of, more effective alternatives (Marshall-Pescini & Whiten, 2008;Hrubesch, Preuschoft, & van Schaik, 2009;Price et al, 2009;Hanus, Mendes, Tennie, & Call, 2011;Hopper et al, 2011).…”

“…The remarkable copying by chimpanzees has also been shown to allow introduced behavioral variants to spread through social groups under more naturalistic conditions, creating captive behavioral traditions Whiten et al, 2007). Perhaps even more strikingly, it has also been shown that the power of these social influences is such that chimpanzees will continue to use socially learned behaviors, even when they are redundant (Price, Lambeth, Schapiro, & Whiten, 2009), or when the learned behavior causes them to go against personal preferences (Hopper, Schapiro, Lambeth, & Brosnan, 2011). Consequently, it appears that, whatever the mechanism involved, for these tasks, chimpanzees seem capable of the sort of high fidelity transmission proposed by Tennie et al (2009) to be vital for cumulative culture.…”

Conformity without majority? The case for demarcating social from majority influences

“…Starting with one skilled individual (natural invention or trained skill), the rest of the group acquires the same particular way of behaving by means of social learning (Hopper et al, 2011;Perry, 2009;Whiten et al, 2005). On the other hand, the label 'conformity' has been used to describe the process by which primates would revert back to the majority strategy after discovering an alternative strategy (chimpanzees: Bonnie et al, 2007;Hopper et al, 2011;Whiten et al, 2005;capuchin monkeys: Dindo et al, 2008capuchin monkeys: Dindo et al, , 2009). Here, after socially acquiring a particular way of behaving, some individuals would occasionally explore an alternative strategy, but then change back to preferring the majority strategy.…”

“…In recent years, majority influence has become a favourable research topic for behavioural biologists. One line of research has focused on our closest living relatives, the nonhuman primates (chimpanzees, Pan troglodytes: Bonnie, Horner, Whiten, & de Waal, 2007;Haun, Rekers, & Tomasello, 2012;Hopper, Schapiro, Lambeth, & Brosnan, 2011;Whiten, Horner, & de Waal, 2005; capuchin monkeys, Cebus apella: Dindo, Thierry, & Whiten, 2008;Dindo, Whiten, & de Waal, 2009;Perry, 2009), which could enable intriguing analysis of the evolutionary roots of this human phenomenon (MacLean et al, 2012). Another line of research has aimed to investigate the possibility of convergent evolution of conformity by focusing on phylogenetically more distant species, such as fish (Day, MacDonald, Brown, Laland, & Reader, 2001;Kendal, Coolen, & Laland, 2004;Pike & Laland, 2010), rats (Galef & Whiskin, 2008;Jolles, de Visser, & van den Bos, 2011;Konopasky & Telegdy, 1977) and fruit flies (Battesti, Moreno, Joly, & Mery, 2012).…”