Biology subjects

Brooker, J. S.

Publications and source records attributed to Brooker, J. S..

3 recordsLinked to original sources

bioRxiv2024

ChimpanSEE, ChimpanDO: Grooming and play contagion in chimpanzees

Behavioural contagion--the onset of a species-typical behaviour soon after witnessing it in a conspecific-- forms the foundation of behavioural synchrony and cohesive group living in social animals. Although past research has mostly focused on negative emotions or neutral contexts, the sharing of positive emotions in particular may be key for social affiliation. We investigated the contagion of two socially affiliative interactive behaviours, grooming and play, in chimpanzees. We collected naturalistic observations of N = 41 sanctuary-living chimpanzees at Chimfunshi Wildlife Orphanage, conducting focal follows of individuals following observations of a grooming or play bout, compared with matched controls. We then tested whether the presence and latency of behavioural contagion was influenced by age, sex, rank, and social closeness. Our results offer evidence for the presence of grooming and play contagion in sanctuary-living chimpanzees. Grooming contagion appeared to be influenced by social closeness, whilst play contagion was more pronounced in younger individuals. These findings emphasise that contagion is not restricted to negatively valenced or self-directed behaviours, and that the predictors of contagious behaviour are highly specific to the behaviour and species in question. Examining the factors that influence this foundational social process contributes to theories of affective state matching and is key for understanding social bonding and group dynamics.

animal behavior and cognition↗

bioRxiv2024

Getting to the bottom of social learning: Chimpanzees copy arbitrary behavior from conspecifics

Studying animal culture has been crucial for understanding the complexities of knowledge transmission and tracing human cultures evolutionary origins1. Defined as the use of tools to provide clear practical benefits to individuals, well-documented examples of material culture include nut-cracking2 and termite fishing3 in chimpanzees. Additionally, there is growing interest in animal social traditions, which appear crucial for social interaction and group cohesion. We have previously documented such a tradition, in which chimpanzees copied inserting blades of grass in their ears from one persistent inventor4. Now, over a decade later, we have observed an unrelated group of chimpanzees where 5/8 individuals began wearing grass in their ears and 6/8 from their rectums. As of 2024, one newly introduced chimpanzee has adopted the grass-in-ear behavior. Given that the behaviors were not observed in seven other groups in the same sanctuary (N=148), we conclude that social learning of arbitrary behavior occurred and discuss our findings considering the larger scope of animal culture.

animal behavior and cognition↗

bioRxiv2024

Within-species variation eclipses between-species differences in Pan consolation

Empathy and its subcomponents are well documented throughout the animal kingdom, indicating the deep evolutionary origins of this socioemotional capacity. A key behavioural marker of empathy is consolation, or unsolicited bystander affiliation directed towards distressed others. Consolation has been observed in our closest living relatives, bonobos (Pan paniscus) and chimpanzees (P. troglodytes). However, systematic comparisons are absent, despite potential for interspecific differences. Bonobos are often considered less aggressive, more emotionally sensitive, and more socially tolerant than chimpanzees--key characteristics purported to drive consolation. Furthermore, social and individual factors also appear to drive intraspecific variation in empathy. To address within- and between-species variability in Pan consolation, we systematically tested the consolatory tendencies of large sanctuary-living groups of both species. Bonobos and chimpanzees exhibited similar consolation tendencies; however, within-species analyses revealed further similarities and variation. Bonobo consolation was most often directed towards and received by younger individuals, while chimpanzee consolation was most often directed towards close social partners. In addition, males and females of both species showed decreased consolation with age, with some evidence for chimpanzee males consoling more than young females. Our findings support the notion that within-species variation in Pan socio-emotional abilities is greater than between-species differences, highlighting the presence of striking behavioural diversity across our two closest cousins.

animal behavior and cognition↗