A Papionin Multilevel Society as a Model for Hominin Social Evolution
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Abstract
Multilevel societies are unique in their ability to facilitate the maintenance of strong and consistent social bonds among some individuals while allowing separation among others, which may be especially important when social and sexual bonds carry significant and reliable benefits to individuals within social groups. Here we examine the importance of social and sexual bonds in the multilevel society of hamadryas baboons (Papio hamadryas) and apply these principles to social evolution in Plio-Pleistocene hominins. The behavior, adaptations, and socioecology of baboons (Papio spp.) have long been recognized as providing an important comparative sample to elucidate the processes of human evolution, and the social system of hamadryas baboons in particular shares even more similarities with humans than that of other baboons. Here we draw parallels between processes during the evolution of hamadryas social organization and those characterizing late Pliocene or early Pleistocene hominins, most likely Homo erectus. The higher costs of reproduction faced by female Homo erectus, exacerbated by an increased reliance on difficult to acquire, nutrient-dense foods, are commonly thought to have been alleviated by a strengthening of male–female bonds (via male provisioning and the evolution of monogamy) or by the assistance of older, postreproductive females (via grandmothering). We suggest that both of these social arrangements could have been present in Plio-Pleistocene hominins if we assume the development of a multilevel society such as that in hamadryas baboons. The evolution of a multilevel society thus underlies the adaptive potential for the complexity that we see in modern human social organization.
Keywords
Social bonds Reproductive strategies Human social evolution Homo erectus Papio hamadryas Pair bonding Grandmother hypothesisNotes
Acknowledgments
We thank Leslie Aiello, Susan Antón, Cliff Jolly, Eric Delson, Becky Ackermann, Julian Saunders, and Sue Taylor Parker for helpful discussions during the development of these ideas, and we are especially grateful to Cliff Jolly, Fred Bercovitch, and Shirley Strum for numerous constructive and insightful comments on a previous version of this manuscript. We are also indebted to two anonymous reviewers, the editors of this special issue, and Joanna Setchell for additional helpful comments that improved this manuscript. We thank the Anthropology Section of the New York Academy of Sciences and the organizers of the Darwin’s Legacy: Human Evolution in Africa conference sponsored by the New York Consortium in Evolutionary Primatology (NYCEP) for inviting L.Swedell to deliver earlier versions of this article as public lectures. Finally, we thank the Leakey Foundation, the National Geographic Society, and the Wenner-Gren Foundation for their financial support of the Filoha Hamadryas Project.
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