Curiosity in wild orangutans: ecological, social, and intrinsic effects assessed during a field experiment

Abstract

The readiness to interact with, and explore, novel stimuli – i.e., curiosity – are cornerstones of innovation. Great apes show the broadest and most complex innovation repertoires. However, little is known about the factors that affect curiosity in wild apes. To shed light on wild apes’ curiosity, we measured the reactions of wild Sumatran orangutans (Pongo abelii) to an experimental apparatus. Compared to adults, immatures showed higher tendencies to visually explore and approach the apparatus but were more likely to show signs of agitation. The presence of conspecifics who approached the apparatus increased exploration and approach tendencies. Prevailing habitat food availability positively affected exploration but had a negative effect on approach tendencies. These findings show that intrinsic, social, and ecological factors affect reactions to novelty in wild orangutans and suggest that exploration, neophobia and neophilia are independently regulated. Therefore, to understand the evolution of innovative tendency, factors acting on different elements of curiosity must be considered.

Personality assessment of synanthropic rhesus macaques: implications and challenges

“…Both personality traits reported in our study have elements of within-group-level social interactions and can be interpreted as 'social personality traits' (Koski, 2011). Like several other NHPs and generally gregarious animals, rhesus macaques show complex social dynamics (Sade, 2017), where social personality traits may play crucial roles. Consistency in sociality (i.e., an individual's position in the social network) is linked to inter-individual variations in sociability in rhesus macaques (Brent et al, 2013), implying how sociability as a personality trait may shape group dynamics.…”

“…In contrast to the view of behavioral plasticity, personality or consistent inter-individual differences suggest that behavioral responses are rather 'non-flexible' and are somewhat constrained (Réale et at., 2007;Réale et al, 2010). While to what extent biological traits have plasticity or constraints is an ongoing topic of research (Dingemanse et al, 2010), inter-individual differences in the phenotypic expression of specific traits can potentially explain their 'selective' advantages with regard to certain environmental conditions and habitats (Santicchia et al, 2018;Belgrad et al, 2018;Leclerc et al, 2016). Due to the strong associations of personality traits with adaptive and survival benefits (Smith & Blumstein, 2008;Moiron et al, 2020), studying these traits in animals living close to humans can provide valuable insights into their potential functional advantages.…”