Behavioral Ecology and Sociobiology

, Volume 60, Issue 4, pp 536–549 | Cite as

A complex social structure with fission–fusion properties can emerge from a simple foraging model

  • Gabriel Ramos-FernándezEmail author
  • Denis Boyer
  • Vian P. Gómez
Original Article


Precisely how ecological factors influence animal social structure is far from clear. We explore this question using an agent-based model inspired by the fission–fusion society of spider monkeys (Ateles spp). Our model introduces a realistic, complex foraging environment composed of many resource patches with size varying as an inverse power law frequency distribution with exponent β. Foragers do not interact among them and start from random initial locations. They have either a complete or a partial knowledge of the environment and maximize the ratio between the size of the next visited patch and the distance traveled to it, ignoring previously visited patches. At intermediate values of β, when large patches are neither too scarce nor too abundant, foragers form groups (coincide at the same patch) with a similar size frequency distribution as the spider monkey’s subgroups. Fission–fusion events create a network of associations that contains weak bonds among foragers that meet only rarely and strong bonds among those that repeat associations more frequently than would be expected by chance. The latter form subnetworks with the highest number of bonds and a high clustering coefficient at intermediate values of β. The weak bonds enable the whole social network to percolate. Some of our results are similar to those found in long-term field studies of spider monkeys and other fission–fusion species. We conclude that hypotheses about the ecological causes of fission–fusion and the origin of complex social structures should consider the heterogeneity and complexity of the environment in which social animals live.


Fission–fusion Spider monkeys Chimpanzees Agent-based models 



Louise Barret, Colin A. Chapman, Anthony Di Fiore, S. Peter Henzi, Phyllis Lee, and Julia Lehmann provided useful comments on a previous version of this manuscript as did other participants in the workshop on Fission–Fusion Societies and Cognitive Evolution organized by Filippo Aureli, Colleen Schaffner and Cristophe Boesch and sponsored by the Wenner-Gren Foundation for Anthropological Research. We thank David Lusseau and an anonymous reviewer for fruitful suggestions during the review process. Funding was received from the following institutions: the Tomás Brody visiting scholarship from the Institute of Physics, CONACYT (Grant number 40867-F), the National Autonomous University of Mexico (UNAM), the National Polytechnic Institute of Mexico (IPN), and the Fondo Sectorial CONACYT-SEMARNAT (project 0536). All experiments comply with the current laws of Mexico.


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Gabriel Ramos-Fernández
    • 1
    Email author
  • Denis Boyer
    • 2
  • Vian P. Gómez
    • 3
  1. 1.Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional (CIIDIR), Unidad OaxacaInstituto Politécnico NacionalOaxacaMéxico
  2. 2.Departamento de Sistemas Complejos, Instituto de FísicaUniversidad Nacional Autónoma de MéxicoMéxicoMéxico
  3. 3.Instituto Latinoamericano de Comunicación Educativa (ILCE)MéxicoMéxico

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