Do nonhuman animals copy successful and prestigious models? Disentangling payoff-biased transmission across taxa

As the empirical literature on social learning across taxa has exploded, some claims that certain social learning strategies are uniquely human have been challenged. While enriching, the interdisciplinary nature of cultural transmission studies has also weakened semantic and conceptual congruence across fields. A theoretical gap has thus been growing between the observed animal behaviours and the hypothesized social learning strategies underlying them. This review specifically explores the taxonomic distribution of social learning strategies based on payoff correlates, like a model's success or prestige, and the possibility that these extend beyond humans. Such ‘copy-if-better model’ (i.e. indirect bias) strategies are functionally distinct from ‘copy-if-better variant’ (i.e. direct bias) strategies, although they are both often generically described as payoff-biased transmission. Perhaps most importantly, copy-if-better model heuristics may increase the risks of maladaptive transmission and have been implicated in the spread of fitness-reducing behaviours in humans. This paper first proposes broad criteria of cognitive mechanisms that are required for indirectly biased social learning strategies to be deployed. It then reviews the empirical evidence for these strategies across nonhuman animals. While several studies call into question the ability of nonhuman animals to preferentially copy a model in the absence of any immediately and directly observed relative benefits (e.g. payoffs), multiple others meet the criteria for indirectly biased transmission. Observing indirectly biased transmission dynamics across a range of different taxa could be indicative of the adaptive potential of these social learning strategies. On the other hand, species that rely on this type of social learning strategy may be vulnerable to the transmission of maladaptive information, suggesting future research into how animals mitigate the risks inherent in such a low-cost, but potentially uncertain, heuristic. • I explore cases of directly and indirectly biased social learning across taxa. • The former evaluates trait payoffs; the latter, demonstrator characteristics. • Indirectly biased learners may be more likely to adopt maladaptive information. • Insects, birds, mammals and fish seem to rely on indirectly biased social learning. • It is unclear how these species mitigate the risks of maladaptive social learning.