The 85th Annual Meeting of the American Association of Physical Anthropologists (2016)

Infant handling and urinary oxytocin in sub-adult bonobos (Pan paniscus): support for the learning to mother hypothesis


1Anthropology, University of Oregon, 2Columbus Zoo, Columbus, Ohio

April 15, 2016 2:00, Imperial Ballroom B Add to calendar

Natal attraction is widespread across the primate clade and non-maternal infant care (allocare) includes a variety of behaviors collectively known as ‘infant handling.’ Several hypotheses have been proposed to explain the adaptive function of infant handling, namely those associated with kin selection and learning to mother. The purpose of this study is to describe the basic pattern of expression and to investigate the function of infant handling in sub-adult bonobos. Data were collected on the Columbus Zoo bonobo colony (N=19 individuals) where handling was observed in 9 sub-adults (adolescents and juveniles) toward 4 infants and primarily consisted of carrying and grooming behaviors. Mothers of infants mostly permitted handling attempts and male and female infants were handled equally (F=0.030, df=1, p=0.874). Sub-adults handled infants significantly more than adults (F=15.385, df=1, p<0.001) and while there was no significant difference in handling between male and female juveniles (F=1.750, df=1, p=0.317), a significant sex difference was found among adolescents where females expressed handling significantly more than males (F=37.733, df=1, p<0.01). Furthermore, nulliparous females engaged in handling behaviors significantly more than parous females (F=97.372, df=1, p<0.001). Additionally, urine samples from all sub-adults were analyzed to examine the relationship between infant handling and oxytocin, a known facilitator of maternal behavior in mammals. Preliminary analyses suggest a significant positive relationship between mean oxytocin and handling behavior in sub-adult females (p<0.05) but not in sub-adult males (p=0.1057). Together these results support the hypothesis that infant handling functions as a mechanism by which females learn maternal behavior in bonobos.

Support: Nacey Maggioncalda Foundation; the Bray Fellowship and Department of Anthropology, University of Oregon.