title: Co-residence between males and their mothers and grandmothers is more frequent in bonobos than chimpanzees.
abstract: In long-lived social mammals such as primates, individuals can benefit from social bonds with close kin, including their mothers. In the patrilocal chimpanzee (Pan troglodytes spp.) and bonobo (Pan paniscus), sexually mature males reside and reproduce in their natal groups and can retain post-dependency bonds with their mothers, while immatures of both sexes might also have their paternal grandmothers available. However, quantitative information on the proportion of males and immatures that co-reside with both types of these close female relatives is limited for both species. Combining genetic parentage determination and group composition data from five communities of wild chimpanzees and three communities of wild bonobos, we estimated the frequency of co-residence between (1) mature males and their mothers, and (2) immature males and females and their paternal grandmothers. We found that adult males resided twice as frequently with their mothers in bonobos than in chimpanzees, and that immature bonobos were three times more likely to possess a living paternal grandmother than were immature chimpanzees. Patterns of female and male survivorship from studbook records of captive individuals of both species suggest that mature bonobo females survive longer than their chimpanzee counterparts, possibly contributing to the differences observed in mother-son and grandmother-immature co-residency levels. Taking into account reports of bonobo mothers supporting their sons' mating efforts and females sharing food with immatures other than their own offspring, our findings suggest that life history traits may facilitate maternal and grandmaternal support more in bonobos than in chimpanzees.
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany ; Epidemiology of highly pathogenic microorganisms, Robert Koch Institute, Berlin, Germany.
authors.forename: Grit
authors.initials: G
authors.lastname: Schubert
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Vigilant
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Christophe
authors.initials: C
authors.lastname: Boesch
authors.affiliation: Department of Conservation Biology, UFZ, Helmholtz Centre for Environmental Research, Leipzig, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Klenke
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany ; Department of Anthropology, Boston University, Boston, United States of America.
authors.forename: Kevin
authors.initials: K
authors.lastname: Langergraber
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Roger
authors.initials: R
authors.lastname: Mundry
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Surbeck
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Hohmann
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D019974:Pan paniscus; D002679:Pan troglodytes; D012919:Social Behavior