Nellissen, L. | bioRxiv Science

bioRxiv2025

Observational social learning of "know-how" and "know-what" in wild orangutans: evidence from nest-building skill acquisition

Immature great apes learn how to build their nests over multiple years, yet how they do so has remained largely unclear. We investigated the detailed role of social learning in the acquisition of nest-building skills in wild Sumatran orangutans (Pongo abelii) using data on nest-building, nest practice, and nest peering behaviour from 44 individuals, collected over 17 years. We found that nest peering (but not being close to a nesting individual without peering) is associated with a significant increase in nest practice behaviour, and mostly directed at multi-step nest elements. Dependent immatures mostly peer at their mothers and use nest tree species in common with her, independent immatures peer at a larger range of individuals and use nest tree species in common with them. Our results suggest that orangutans acquire their nest-building skills through observational social learning including selective attention to "know-how" and the transmission of "know-what" information.

animal behavior and cognition↗

bioRxiv2024

The development of social attention in orangutans: comparing peering behaviour in wild and zoo-housed individuals

Social learning is the cornerstone of all cultural processes and plays a pivotal role during the evolution of cognition. To understand how social learning evolved, we have to look at the immediate and developmental conditions affecting individuals tendencies to attend to social information. We compared peering behaviour (i.e., close-range and sustained observation of the activities of conspecifics) in wild and zoo-housed immature Sumatran orangutans (Pongo abelii) by analysing long-term data which included 3101 peering events collected at the Suaq Balimbing research site in Indonesia and at four European zoos on 35 immature individuals. Using Generalized-Additive-Mixed-Models, we tested for age-specific patterns in peering frequency, target, and context selection. We found similar age trajectories of peering in both settings but higher mean frequencies of peering in the zoos, even after controlling for varying social opportunities to peer. Wild immatures preferably peered at their mothers but zoo-housed immatures at non-mother individuals. In both settings, immatures preferred to peer at older individuals, and in learning-intense contexts. Our findings suggest a hard-wired component in the tendency to attend to social information and a considerable degree of ontogenetic plasticity - a combination that was likely foundational for the evolution of complex cultures, including human culture. HighlightsO_LIWe compared attendance to social information in wild and zoo-housed orangutans C_LIO_LIImmature orangutans peer in contexts where learning is expected C_LIO_LIPeering frequency develops similarly over age, suggesting hardwired propensities C_LIO_LIPeering target and context selection differs between the two settings C_LIO_LIOrangutans tendency to attend to social information shows plasticity C_LI

animal behavior and cognition↗