Ape cultures do not require behaviour copying

Abstract

While culture is widespread in the animal kingdom, human culture has been claimed to be special due to being cumulative. It is currently debated which cognitive abilities support cumulative culture, but behavior copying is one of the main abilities proposed. One important source of contention is the presence or absence of behavior copying in our closest living relatives, non-human great apes (apes) -especially given that their behavior does not show clear signs of cumulation. Those who claim that apes copy behavior often base this claim on the existence of stable ape cultures in the wild van Schaik et al. 2003). We developed an individual-based model to test whether ape cultural patterns can both emerge and stabilize in the entire absence of any behavior copying, but only allowing for a well-supported alternative social learning mechanism, namely socially-mediated reinnovation, where only the frequency of reinnovation is under social influence, but the form of the behavior is not. Our model reflects wild ape life conditions, including physiological and behavioral individual needs, demographic and spatial features, and the possible range of genetic and ecological variations between populations. Our results show that, under a wide range of realistic values of all model parameters, we fully reproduce the most defining features of wild ape cultural patterns van Schaik et al. 2003). Overall, our results show that ape cultures can both emerge and stabilize without behavior copying. Ape cultures are therefore unable to pinpoint behavior copying abilities, lending support to the notion that behavior copying is, among apes, unique in the human lineage. HighlightsHuman culture is cumulative: it grows in complexity and efficiency, drawing on innovations of previous generations. In contrast, ape cultures are not clearly cumulative. It has been proposed that cumulative culture depends on our ability to accurately transmit and preserve information, with behavior copying as a crucial mechanism. At the same time, researchers have claimed that non-human apes can also copy others' behavior. We show, through computer simulations, that patterns used to infer the existence of behavior copying in wild apes -ape cultures -can be reproduced in full, under realistic conditions, without any behavior copying skills necessary. This shows that the assumption that ape cultures are underlain by behavior copying cannot be proven by the mere existence of ape cultures.

Clarifying Misconceptions of the Zone of Latent Solutions Hypothesis: A Response to Haidle and Schlaudt

“…In the absence of information regarding the individual, one may, for example, inaccurately attribute the group-level pattern that arises in Schelling's model to deliberate decisions. Similarly, the ZLS approach is an empirically founded attempt to examine the individual-level processes that may produce group-level phenomena (such as wild ape cultural patterns; Acerbi et al 2020).…”

“…Note that the ZLS's principal aims explicitly include explaining group-level phenomena(Tennie et al 2009), and this work includes using agent-based modelling (e.g.,Acerbi et al 2020). 2 "Instinctive behavior has much in common with individual latent solutions, in particular that they are (partly) hereditarily determined and appear in organisms raised in isolation from others" (p. 166 in H&S).3 Haidle and Schlaudt themselves acknowledge early in their own piece that the ZLS includes cognition.…”