Diverse species readily acquire copies of novel actions from others that are not achieved through individual learning

Abstract

The cultural transmission of behaviour patterns across animal populations and between generations has been rigorously demonstrated in diverse vertebrate species and also in insects, but controversies continue about exactly what distinguishes nonhuman from human cultural learning. A contentious contemporary debate concerns a hypothetical ‘zone of latent solutions’ (ZLS), conceptualized as all that members of a species can acquire by individual learning. The ZLS hypothesis proposes that cumulative culture is restricted to humans because of a unique ability to copy behavioural innovations beyond our species' ZLS. Apes and other taxa are argued instead to be limited to copying only behaviours that are already within their ZLS, thus constraining their capacity for cumulative culture. Here I suggest that empirical tests of this hypothesis are scattered through the research literature covering social learning experiments and I collate relevant instances. Over 20 such studies spanning mammals, birds, fish and insects demonstrate social learning of novel actions new to the species that no individual acquires through its own efforts. Many offer particularly compelling refutation of the ZLS hypothesis because in addition to documenting an absence of individual level learning, they incorporate designs showing that observers match whichever of two alternative forms of action they witnessed or include multistep actions that are clearly challenging for individuals of the species studied to acquire by individual learning.