Satellite telemetry and social modeling offer new insights into the origin of primate multilevel societies.

Bao-Guo Li,Xiao-Guang Qi,Kang Huang,Zhi-Pang Huang,Peng Zhang,Gang He,Weihong Ji,Pei Zhang,Paul A Garber,Song-Tao Guo,Xiao-Wei Wang

doi:10.1038/ncomms6296

Abstract

Multilevel societies (MLS), in which polygynous reproductive units are nested in a larger social matrix, represent a highly complex social system documented only in a small number of mammalian species. Using long-term behavioural data, satellite telemetry and social network analysis, we present a new framework for understanding the function and social dynamics of the golden snub-nosed monkey MLS. Here we show that several one-male units form a cohesive breeding band that associates with one or more all-male units to form a herd. Herds seasonally aggregate and exchange members, thus facilitating gene flow and inbreeding avoidance. This MLS evolved from the aggregation of independent one-male, multifemale units that characterize ancestral Asian colobines; the evolutionary pathway leading to this MLS contrasts with that proposed for African papionins, which appear to have undergone internal fissioning of multimale–multifemale groups. The results suggest that both environmental and phylogenetic factors are important in the evolution of a primate MLS.

Highlights

Multilevel societies (MLS), in which polygynous reproductive units are nested in a larger social matrix, represent a highly complex social system documented only in a small number of mammalian species
Despite certain similarities in the structural properties of primate MLS, studies conducted over several decades on geladas and hamadryas baboons revealed that the underlying social dynamics of their MLS are fundamentally different[9,17]
In gelada and hamadryas baboon, ancestral mixed-sex multimale multifemale groups of African papionins appear to have undergone a process of internal fissioning resulting in the formation of harem-based mating units nested within the band (Fission Model)

Summary

Introduction

Multilevel societies (MLS), in which polygynous reproductive units are nested in a larger social matrix, represent a highly complex social system documented only in a small number of mammalian species. Primate MLS differ from this pattern in that they are comprised of several socially and spatially distinct one-male, multifemale units (OMUs) that coordinate their activities and feed, forage, rest and travel together to form a single large band This social system has only been reported in geladas (Theropithecus gelada), hamadryas baboons (Papio hamadryas), some Asian colobines (in particular snub-nosed monkeys of the genus Rhinopithecus spp.) and humans[14,15,16]. Enhanced sexual dimorphism in body mass, hair patterns and pelage colour in African papionins resulting from intrasexual competition may have enabled individual males to improve their breeding success by maintaining exclusive access to several female mating partners[27,28,29,30] This Fission model assumes that a change in the spatial dispersion of feeding sites into small and scattered patches coupled with male monopolization of females[26,31] are the primary drivers of a MLS. Researchers have proposed that social pressures associated with reproductive competition by invading bachelor males[34] and ecological pressures associated with efficiently locating and harvesting widely scattered and seasonally limited resources[35] have selected for the semi-permanent aggregation of several OMUs into a large MLS (Fusion Model)

Methods

Results

Conclusion