Conformity in mate choice, the overlooked social component of animal and human culture

Abstract

Although conformity as a major driver for human cultural evolution is a well‐accepted and intensely studied phenomenon, its importance for non‐human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non‐human animals. We identify gaps in knowledge and propose an evolutionary route towards the sophisticated cultural processes that characterize humanity. A landmark in the study of conformity is Solomon Asch's famous experiment on humans in 1955. By contrast, interest in conformity among evolutionary biologists has only become salient since the turn of the new millennium. A striking result of our review is that, although studies of conformity have examined many biological contexts, only one looked at mate choice. This is surprising because mate choice is probably the only context in which conformity has self‐reinforcing advantages across generations. Within a metapopulation, i.e. a group of subpopulations connected by dispersing individuals, dispersers able to conform to the local preference for a given type of mate have a strong and multigenerational fitness advantage. This is because once females within one subpopulation locally show a bias for one type of males, immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non‐preferred phenotype, which negatively and cumulatively affects fitness over generations in a process reminiscent of the Fisher runaway process. This led us to suggest a sex‐driven origin of conformity, indicating a possible evolutionary route towards animal and human culture that is rooted in the basic, and thus ancient, social constraints acting on mating preferences within a metapopulation. In a generic model, we show that dispersal among subpopulations within a metapopulation can effectively maintain independent Fisher runaway processes within subpopulations, while favouring the evolution of social learning and conformity at the metapopulation scale; both being essential for the evolution of long‐lasting local traditions. The proposed evolutionary route to social learning and conformity casts surprising light on one of the major processes that much later participated in making us human. We further highlight several research avenues to define the spectrum of conformity better, and to account for its complexity. Future studies of conformity should incorporate experimental manipulation of group majority. We also encourage the study of potential links between conformity and mate copying, animal aggregations, and collective actions. Moreover, validation of the sex‐driven origin of conformity will rest on the capacity of human and evolutionary sciences to investigate jointly the origin of social learning and conformity. This constitutes a stimulating common agenda and militates for a rapprochement between these two currently largely independent research areas.

Increased initial task difficulty drives social foragers to develop sub-optimal conformity instead of adaptive diversity

“…Conformity has been used to describe several related phenomena [ 29 , 30 ]. In the broad sense that will be used in this paper (and as commonly used in spoken language), conformity, or the tendency to conform, refers simply to ‘copying the most common behaviour’ regardless of the exact mechanism leading to it.…”

Punctuated equilibrium at 50: Anything there for evolutionary anthropology? Yes; definitely

“…Many biological processes, such as host-pathogen interactions, sexual selection, and conformity bias, 90 can all be described using the same mathematical equation for FDSan equation that is nonlinearly dependent on the frequency at which a trait occurs in a population. 91 To that end, Vidiella et al 92 built a model that directly links FDS with natural selection to explain how a punctuated pattern can emerge from the continuous accumulation of information in a population, giving sudden rise to novel paradigms (Figure 6b). In this model, the rate of invention is constant, and innovators discover new variants that might be maladaptive or beneficial.…”

“…Through FDS, demography in many cases might be linked to a pattern of rapid evolution in cultural and social institutions—or perhaps to extinction, as with the Neanderthals. Many biological processes, such as host–pathogen interactions, sexual selection, and conformity bias, 90 can all be described using the same mathematical equation for FDS—an equation that is nonlinearly dependent on the frequency at which a trait occurs in a population 91 …”

A social learning primacy trend in mate-copying: an experiment in Drosophila melanogaster

“…However, assessing mate quality through mate sampling would be far too costly, especially for unexperienced individuals [13]. Hence, using public information from other individuals' matings constitutes an effective way to circumvent the costs of individual sampling [14][15][16]. Mate-copying exists in a variety of vertebrates, as well as in the fruit fly (Drosophila melanogaster) (reviewed in [15,16]).…”

“…Hence, using public information from other individuals' matings constitutes an effective way to circumvent the costs of individual sampling [14][15][16]. Mate-copying exists in a variety of vertebrates, as well as in the fruit fly (Drosophila melanogaster) (reviewed in [15,16]). In the latter species, evidence comes from a series of experiments involving traits resulting from differential male feeding substrates [17], artificially coloured male phenotypes [17][18][19][20][21][22][23], as well as mutants with a different wing shape [24], suggesting significant levels of behavioural flexibility.…”