The zone of latent solutions and its relevance to understanding ape cultures

Abstract

The zone of latent solutions (ZLS) hypothesis provides an alternative approach to explaining cultural patterns in primates and many other animals. According to the ZLS hypothesis, non-human great ape (henceforth: ape) cultures consist largely or solely of latent solutions. The current competing (and predominant) hypothesis for ape culture argues instead that at least some of their behavioural or artefact forms are copied through specific social learning mechanisms (“copying social learning hypothesis”) and that their forms may depend on copying (copying-dependent forms). In contrast, the ape ZLS hypothesis does not require these forms to be copied. Instead, it suggests that several (non-form-copying) social learning mechanisms help determine the frequency (but typically not the form) of these behaviours and artefacts within connected individuals. The ZLS hypothesis thus suggests that increases and stabilisations of a particular behaviour’s or artefact’s frequency can derive from socially-mediated (cued) form reinnovations. Therefore, and while genes and ecology play important roles as well, according to the ape ZLS hypothesis, apes typically acquire the forms of their behaviours and artefacts individually, but are usually socially induced to do so (provided sufficient opportunity, necessity, motivation and timing). The ZLS approach is often criticized—perhaps also because it challenges the current null hypothesis, which instead assumes a requirement of form-copying social learning mechanisms to explain many ape behavioural (and/or artefact) forms. However, as the ZLS hypothesis is a new approach, with less accumulated literature compared to the current null hypothesis, some confusion is to be expected. Here, we clarify the ZLS approach—also in relation to other competing hypotheses—and address misconceptions and objections. We believe that these clarifications will provide researchers with a coherent theoretical approach and an experimental methodology to examine the necessity of form-copying variants of social learning in apes, humans and other species.

Zoo-housed female chimpanzee adopts local female-specific tradition upon immigrating into a new group

“…The reported observations and inferences warrant differential scrutiny (Sándor & Miklósi, 2020). Moni's adoption of the crossed-arm walk provides an objective account of chimpanzees' capacity to copy behavioural sequences (Hobaiter & Byrne, 2010;van Leeuwen et al, 2014), yet proponents of the "zone of latent solutions" approach (Tennie et al, 2020) would challenge this notion by arguing that the crossed-arm walk was merely individually reinvented by Moni. In our view, however, the speed at which Moni adopted the crossed-arm walk, in conjunction with the idiosyncrasy of the crossed-arm walk posture/gait, defies -probabilistically -the reinvention hypothesis.…”

Processing of novel food reveal payoff and rank-biased social learning in a wild primate

“…Note that we avoided using the term “copying” across the manuscript which is strongly associated to “imitation” by some scholars (38, 39), although not by all (9, 40). Here, we do not make any assumption and conclusion regarding the social learning mechanisms (action form copying versus non-form copying/socially mediated individual learning: 39) implied in the acquisition of the peanuts processing techniques.…”

Leveraging Social Learning to Enhance Captive Animal Care and Welfare

“…For the purposes of this article, I want to consider all the ways in which an individual animal's choices and behavior may be influenced by others (i.e., socially influenced learning), not just cases of direct observational learning in which a new skill is acquired (i.e., imitation). Indeed, some have argued that much purported imitation by nonhuman animals is actually individual learning spurred by social influence ("reinnovation"), that leads to group-level consistency in behavioral forms [32,33]. Table 1.…”

“…When social learning does occur in animals, the 'copying' is often inexact as imitation is rare, or even nonexistent, in nonhuman animals [32,33]. Animals do not tend to faithfully replicate every detail of an action, or sequence of actions, they observe (this is in contrast to humans, who often copy even seemingly redundant behaviors [60,61]).…”

“…Specifically, there is disagreement over what skills primates are capable of copying from others and whether high-fidelity copying is required for the transmission of behaviors [200,201]. Tennie and colleagues have argued that what differentiates human culture from that of apes is that we alone can copy behaviors that we could not invent ourselves, whereas apes are restricted to copy behaviors within their "Zone of Latent Solutions" [32,33,200]. This Zone of Latent Solutions hypothesis posits that apes are influenced by the behavior and presence of others to individually discover solutions ("reinnovation").…”