Jennifer Smith: UCLA Center for Society & Genetics and Department of Ecology and Evolutionary Biology

Cooperation is pervasive in the societies of humans and other animals, yet the current body of evolutionary theory often fails to fully explain its persistence. Because spotted hyenas (Crocuta crocuta) live in complex societies, this species provides an interesting opportunity to elucidate the evolutionary forces favoring patterns of cooperation in a group-living carnivore. Unlike most social carnivores, which live only with their kin, hyenas reside in social groups, called ‘clans’, comprised of both kin and non-kin. In fact, hyena clans are strikingly similar in their size and hierarchical structure to troops of Old World monkeys. Like groups of humans and other apes, hyena societies are further structured by fission-fusion dynamics. That is, individual hyenas regularly separate from and rejoin members of their permanent social group on an hour-to-hour basis. Here, I apply social network theory to analyze the effects of kinship and resource distribution on the social relationships among these ‘primate-like’ carnivores. This work is part of a long-term study in the Masai Mara, Kenya. The results indicate that hyenas associate most often with their kin, and that although resource competition constrains the strength of social network ties among all hyenas, kin always sustain the strongest relationships. Moreover, when forming coalitions, hyenas bias agonistic support towards kin and take the greatest risks when helping kin. Finally, I show that hyenas regularly reinforce social ties with kin, and closely associating non-kin, through ritualized reunion displays, called greetings. Overall, this work reveals the central role of kinship and signaling in the maintenance and coordination of cooperation among social allies living in dispersed social groups.
http://bec.ucla.edu/papers/JenSmithPaper1.pdfhttp://bec.ucla.edu/papers/JenSmithPaper2.pdfhttp://bec.ucla.edu/papers/JenSmithPaper3.pdfhttp://bec.ucla.edu/posters/JenSmithPaper4.pdf