摘要：SummaryWhether nonhuman species can change their communicative repertoire in response to socio-ecological environments has critical implications for communicative innovativeness prior to the emergence of human language, with its unparalleled productivity. Here, we use a comparative sample of wild and zoo-housed orangutans of two species (Pongo abelii, Pongo pygmaeus) to assess the effect of the wild-captive contrast on repertoires of gestures and facial expressions. We find that repertoires on both the individual and population levels are larger in captive than in wild settings, regardless of species, age class, or sampling effort. In the more sociable Sumatran species, dominant use of signals toward single outcomes was also higher in captive settings. We thus conclude that orangutans exposed to more sociable and terrestrial conditions evince behavioral plasticity, in that they produce additional innate or innovated signals that are highly functionally specific. These findings suggest a latent capacity for innovativeness in these apes' communicative repertoires.Graphical abstractDisplay OmittedHighlights•We studied wild-captive contrasts in gestural repertoires in two orangutan species•Individual and group-level repertoires were larger in captivity than in wild•Only in Sumatrans, functional specificity was higher in captivity than in wild•Some of orangutans’ captivity-specific signals may qualify as weak innovationsWildlife behavior; Zoo animal behavior; Anthropology
