Traumatic experiences in early childhood are reflected in social networks of adult chimpanzees (Pan troglodytes) (#913)
Adverse early life experiences are known to affect the social behaviour of human and non-human primates. We investigated the integration of adult zoo as well as re-socialised ex-laboratory chimpanzees (Pan troglodytes) by focusing on close proximity and grooming behaviour using social network analysis (SNA).We compared individual social network measures of three groups of ex-laboratory chimpanzees at the Primate Sanctuary at Gänserndorf, AT to that of two groups of zoo chimpanzees at Burgers Zoo and Dierenpark Amersfort, NL. The ex-laboratory chimpanzees experienced either early (EDs, n=10) or later (LDs, n=8) deprivation from their mothers and single caging for decades. The zoo groups comprised wild-born maternally deprived “founder” individuals (MDs, n=9) as well as non-deprived (NDs, n=16) animals. If age at onset of deprivation affects later social integration we expected social network measures to differ between individuals with traumatic experiences during early childhood, i.e. EDs and MDs, and later deprived as well as mother-reared ND individuals. If, however, duration affects social integration ex-laboratory chimpanzees are expected to differ from zoo chimpanzees. Our study revealed that proximity networks were most strongly affected by the duration of deprivation as ex-laboratory chimpanzees were much more selective regarding their association with partners subsequent to re-socialization than were zoo chimpanzees. However, ex-laboratory chimpanzees partially recovered during the second year of group life. Grooming interactions, in contrast, appeared to be more affected by the age of onset of trauma since MD chimpanzees were less well integrated in grooming networks than their zoo born and mother-reared ND conspecifics. Network measures of these founder chimpanzees were comparable to those of ED chimpanzees, even after living sometimes more than 40 years in the stable zoo groups. Thus, our data suggest that early traumatic experiences as well as lack of social experience affect social integration of chimpanzees throughout their lifetime.