Early social exposure in wild chimpanzees: mothers with sons are more gregarious than mothers with daughters.


In many mammals, early social experience is critical to developing species-appropriate adult behaviors. Although mother-infant interactions play an undeniably significant role in social development, other individuals in the social milieu may also influence infant outcomes. Additionally, the social skills necessary for adult success may differ between the sexes. In chimpanzees (Pan troglodytes), adult males are more gregarious than females and rely on a suite of competitive and cooperative relationships to obtain access to females. In fission-fusion species, including humans and chimpanzees, subgroup composition is labile and individuals can vary the number of individuals with whom they associate. Thus, mothers in these species have a variety of social options. In this study, we investigated whether wild chimpanzee maternal subgrouping patterns differed based on infant sex. Our results show that mothers of sons were more gregarious than mothers of daughters; differences were especially pronounced during the first 6 mo of life, when infant behavior is unlikely to influence maternal subgrouping. Furthermore, mothers with sons spent significantly more time in parties containing males during the first 6 mo. These early differences foreshadow the well-documented sex differences in adult social behavior, and maternal gregariousness may provide sons with important observational learning experiences and social exposure early in life. The presence of these patterns in chimpanzees raises questions concerning the evolutionary history of differential social exposure and its role in shaping sex-typical behavior in humans.





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Publication Info

Murray, Carson M, Elizabeth V Lonsdorf, Margaret A Stanton, Kaitlin R Wellens, Jordan A Miller, Jane Goodall and Anne E Pusey (2014). Early social exposure in wild chimpanzees: mothers with sons are more gregarious than mothers with daughters. Proc Natl Acad Sci U S A, 111(51). pp. 18189–18194. 10.1073/pnas.1409507111 Retrieved from https://hdl.handle.net/10161/9282.

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Anne Pusey

James B. Duke Distinguished Professor Emerita of Evolutionary Anthropology

I have recently retired and am not taking on new students although I am continuing some research projects.  I am interested in understanding the evolution of sociality, social structure, and the patterns of competition, cooperation and social bonds in animal species, including humans. Most of my work has focused on social mammals: lions and chimpanzees. For the last twenty five years I have worked almost exclusively on the long term Gombe chimpanzee project. I have gathered the data from this study into an archive, currently housed at Duke, and I oversee the computerization of systematically collected daily data, incorporating this and related material into a relational database. I also advise on the ongoing field study at Gombe. Combined analysis of the long-term data and focused new data collection in the field enables study of a wide variety of questions. Current projects in my research group include studies of female social relationships and female settlement patterns. We also participate in collaborative work with colleagues at a number of other institutions on studies of life history, personality, and health, including studying the natural history of SIVcpz.

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