PI: Sergio M. Pellis, PHD

Key collaborators: Vivien C. Pellis, PHD

Project Title: The evolution of social play in primates

Area of research (e.g. behavior, cognition, biomechanics, systematics, genomics, etc.):
Behavior

Please provide brief (1-3 sentences) answers to the following questions:

1. What is your main research question?
   Social play mostly involves rough-and-tumble play or play fighting. Such play varies in complexity due to species differences in how flexible the actions are that are used and also in how vigorously they compete for the play typical advantage sought (e.g., to bite a specific area of the body gently). Our project seeks to identify the factors that account for species differences in how play varies (e.g., differences in mating system, general cognitive capacity).
2. Briefly describe your project design.
   Over the past 15 years, we have been visiting zoos and Primate Research Centers to film spontaneously occurring play fighting in juveniles of a wide range of primate species. We are developing behavioral dimensions along which play can be compared across species. The behavioral measures will then be mapped onto a tree of relatedness (i.e., cladogram) among the species to characterize the changes in different lineages of primates.
3. How will working with lemurs/lemur samples help achieve your research goals?
   Lemurs constitute a major part of one the main primate radiations and so are a critical group to evaluate changes in play that are commonly associated with particular ecological and social factors. For example, does the play of nocturnal lemurs match the play of nocturnal monkeys? Similarly, do ground-living species play alike, irrespective whether they are lemurs or monkeys?
4. What interesting results have you found?
   We are still about 10 species short of obtaining a complete data set, so we have yet to publish a comprehensive empirical paper dealing with all species. Nonetheless, we are in the process of completing a study on two closely related monkeys that vary in their social system. This study has revealed that the degree of competitiveness differs with social system and there are reliable behaviors that can be used to evaluate these subtle differences. On a broader impressionistic analysis, it appears that there is a primate wide commonality in the body targets bitten and maneuvers to gain or avoid such bites. Interestingly, some lemurs, some New World Monkeys, some Old World Monkeys and most apes, deviate from this primate-typical pattern, suggesting that major changes in the organization of play have occurred multiple times in different lineages.
5. Relevant/recent publications:
   Pellis, S. M. & Pellis, V. C. (1997). Targets, tactics and the open mouth face during play fighting in three species of primates. Aggressive Behavior, 23, 41-57.

   Pellis, S. M., & Iwaniuk, A. N. (2000).  Adult-adult play in primates: Comparative analyses of its origin, distribution and evolution. Ethology, 106, 1083-1104.

   Iwaniuk, A. N., Nelson, J. E., & Pellis, S. M. (2001).  Do big-brained animals play more? Comparative analyses of play and relative brain size in mammals. Journal of Comparative Psychology, 115, 29-41.

   Pellis, S. M. & Pellis, V. C. (2009). The Playful Brain. Venturing to the Limits of Neuroscience. Oneworld Press; Oxford, UK.

   Pellis, S. M. & Pellis, V. C. (2010). Social play, social grooming and the regulation of social relationships. In: A. Kaluev, J. I. LaPorte & C. I. Bergner (Eds.), Neurobiology of grooming behavior. Cambridge University Press; Cambridge, UK, in press.

Sergio M. Pellis, Ph.D.
Professor & Board of Governors Research Chair
Department of Neuroscience
University of Lethbridge
Lethbridge, Alberta
Canada T1K 3M4

Phone: 403 329 2078
FAX: 403 329 2775