Conformity cannot be identified based on population-level signatures

Acerbi, Alberto; Leeuwen, Eduard Johannes Cornelis van; Haun, Daniel B. M.; Tennie, Claudio

doi:10.1038/srep36068

Cited by 33 publications

(74 citation statements)

References 65 publications

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“…More generally, the results of our models suggest caution when deriving individual-level mechanisms from population-level patterns (see also (Acerbi et al 2016;Barrett 2019)). Cultural systems, as many others, exhibit equifinality: the same global state can be produced by different local processes.…”

Section: Discussionmentioning

confidence: 85%

Ape cultures do not require behaviour copying

Acerbi

Snyder

Tennie

2020

Preprint

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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.

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Section: Discussionmentioning

confidence: 85%

Ape cultures do not require behaviour copying

Acerbi

Snyder

Tennie

2020

Preprint

Self Cite

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“…Do non-conformist social learning strategies generate sigmoidal curves? Acerbi et al (2016) 16 used an individual-based model to investigate when a sigmoidal relationship arises between the proportional frequency of a behavioural variant A and the probability of that a random individual will adopt A over a competing 2/12 7/12 10/12…”

Section: Resultsmentioning

confidence: 99%

“…Scaling up, the presence of a sigmoidal acquisition curve at the population level-in which the relationship between the frequency of a behavior and the overall rate at which it is adopted is sigmoidal-has generally thought been to provide evidence of conformist learning in the population in question.Yet is this approach robust? Several recent papers have argued that the answer is a firm 'no' [14][15][16] . These critiques center on the claim that sigmoidal curves can be generated without conformist learning, and therefore that the presence of such curves is not evidence for conformist learning.…”

Section: Introductionmentioning

confidence: 99%

“…In two more recent papers, van Leeuwen et al (2016) 15 and Acerbi et al (2016) 16 have issued a more direct challenge to the validity of identifying conformist transmission from population-level sigmoidal acquisition curves. In these papers, they developed a simple computational model in which populations of 100 individuals were randomly initialized with one of two behaviours.…”

Section: Introductionmentioning

confidence: 99%

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Do Sigmoidal Acquisition Curves Indicate Conformity?

Farine

2017

Preprint

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The potential for behaviours to spread via cultural transmission has profound implications for our understanding of social dynamics and evolution. Several studies have provided empirical evidence that local traditions can be maintained in animal populations via conformist learning (i.e. copying the majority). A conformist bias can be characterized by a sigmoidal relationship between a behavior's prevalence in the population and an individual's propensity to adopt that behavior. For this reason, the presence of conformist learning in a population is often inferred from a sigmoidal acquisition curve in which the overall rate of adoption for the behavior is taken as the dependent variable. However, the validity of sigmoidal acquisition curves as evidence for conformist learning has recently been challenged by models suggesting that such curves can arise via alternative learning rules that do not involve conformity. We review these models, and find that the proposed alternative learning mechanisms either rely on faulty or unrealistic assumptions, or apply only in very specific cases. We therefore recommend that sigmoidal acquisition curves continue to be taken as evidence for conformist learning. Our paper also highlights the importance of understanding the generative processes of a model, rather than only focusing solely on the patterns produced. By studying these processes, our analysis suggests that current practices by empiricists have provided robust evidence for conformist transmission in both humans and non-human animals.

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“…Conformity can be conceptualized in different ways (Van Leeuwen et al, 2015;Whiten and van de Waal, 2016a), from copying the majority, to copying a new behavioral variant while abandoning a personal preference for a previously acquired behavioral variant, to not only copying the majority but doing so with a disproportionate probability. Empirical evidence for such a disproportionate tendency is scarce in humans (Acerbi et al, 2016) and also among animals (Aplin et al, 2017). However, there is increasing evidence in primates for the other forms of conformity.…”

Section: Conformitymentioning

confidence: 99%

Evolutionary Origins of Morality: Insights From Non-human Primates

2018

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The aim of this contribution is to explore the origins of moral behavior and its underlying moral preferences and intuitions from an evolutionary perspective. Such a perspective encompasses both the ultimate, adaptive function of morality in our own species, as well as the phylogenetic distribution of morality and its key elements across primates. First, with regard to the ultimate function, we argue that human moral preferences are best construed as adaptations to the affordances of the fundamentally interdependent hunter-gatherer lifestyle of our hominin ancestors. Second, with regard to the phylogenetic origin, we show that even though full-blown human morality is unique to humans, several of its key elements are not. Furthermore, a review of evidence from non-human primates regarding prosocial concern, conformity, and the potential presence of universal, biologically anchored and arbitrary cultural norms shows that these elements of morality are not distributed evenly across primate species. This suggests that they have evolved along separate evolutionary trajectories. In particular, the element of prosocial concern most likely evolved in the context of shared infant care, which can be found in humans and some New World monkeys. Strikingly, many if not all of the elements of morality found in non-human primates are only evident in individualistic or dyadic contexts, but not as third-party reactions by truly uninvolved bystanders. We discuss several potential explanations for the unique presence of a systematic third-party perspective in humans, but focus particularly on mentalizing ability and language. Whereas both play an important role in present day, full-blown human morality, it appears unlikely that they played a causal role for the original emergence of morality. Rather, we suggest that the most plausible scenario to date is that human morality emerged because our hominin ancestors, equipped on the one hand with large and powerful brains inherited from their ape-like ancestor, and on the other hand with strong prosocial concern as a result of cooperative breeding, could evolve into an ever more interdependent social niche.

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Conformity cannot be identified based on population-level signatures

Cited by 33 publications

References 65 publications

Ape cultures do not require behaviour copying

Ape cultures do not require behaviour copying

Do Sigmoidal Acquisition Curves Indicate Conformity?

Evolutionary Origins of Morality: Insights From Non-human Primates

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