Bonobos Exhibit Delayed Development of Social Behavior and Cognition Relative to Chimpanzees

Phenotypic changes between species can occur when evolution shapes development. Here, we tested whether differences in the social behavior and cognition of bonobos and chimpanzees derive from shifts in their ontogeny, looking at behaviors pertaining to feeding competition in particular. We found that as chimpanzees (n = 30) reached adulthood, they became increasingly intolerant of sharing food, whereas adult bonobos (n = 24) maintained high, juvenile levels of food-related tolerance. We also investigated the ontogeny of inhibition during tasks that simulated feeding competition. In two different tests, we found that bonobos (n = 30) exhibited developmental delays relative to chimpanzees (n = 29) in the acquisition of social inhibition, with these differences resulting in less skill among adult bonobos. The results suggest that these social and cognitive differences between two closely related species result from evolutionary changes in brain development.

[1]  Brian Hare,et al.  Tolerance Allows Bonobos to Outperform Chimpanzees on a Cooperative Task , 2007, Current Biology.

[2]  D. Waal Tension regulation and nonreproductive functions of sex in captive bonobos pan paniscus , 1987 .

[3]  Josep Call,et al.  Reaching around barriers: the performance of the great apes and 3–5-year-old children , 2009, Animal Cognition.

[4]  Suehisa Kuroda,et al.  DEVELOPMENTAL RETARDATION AND BEHAVIORAL CHARACTERISTICS OF PYGMY CHIMPANZEES , 1989 .

[5]  H. Hemmer Domestication: the decline of environmental appreciation. , 1990 .

[6]  L. Trut,et al.  An Experiment on Fox Domestication and Debatable Issues of Evolution of the Dog , 2004, Russian Journal of Genetics.

[7]  Jody Hey,et al.  Divergence population genetics of chimpanzees. , 2004, Molecular biology and evolution.

[8]  M. Tomasello,et al.  Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis , 2007, Science.

[9]  A. Harcourt The Chimpanzees of Gombe. Patterns of Behavior, Jane Goodall. Belknap Press of Harvard University Press, Cambridge, Massachussets (1986), xii, +671. Price $30 , 1988 .

[10]  Daniel E Lieberman,et al.  A geometric morphometric analysis of heterochrony in the cranium of chimpanzees and bonobos. , 2007, Journal of human evolution.

[11]  B. Galdikas,et al.  All Apes Great and Small , 2001, Developments in Primatology: Progress and Prospects.

[12]  Takayoshi Kano,et al.  The Last Ape: Pygmy Chimpanzee Behavior and Ecology , 1992 .

[13]  E. Palagi Social play in bonobos (Pan paniscus) and chimpanzees (Pan troglodytes): Implications for natural social systems and interindividual relationships. , 2006, American journal of physical anthropology.

[14]  F. D. de Waal,et al.  The Other “Closest Living Relative”: How Bonobos (Pan paniscus) Challenge Traditional Assumptions about Females, Dominance, Intra‐ and Intersexual Interactions, and Hominid Evolution , 2000, Annals of the New York Academy of Sciences.

[15]  B. Hare,et al.  Testing the social dog hypothesis: Are dogs also more skilled than chimpanzees in non-communicative social tasks? , 2009, Behavioural Processes.

[16]  F. White,et al.  The last ape. Pygmy chimpanzee behavior and ecology , 1993, International Journal of Primatology.

[17]  C. Boesch,et al.  Behavioural Diversity in Chimpanzees and Bonobos: BEHAVIOURAL FLEXIBILITY , 2002 .

[18]  R. Wrangham,et al.  African Apes as Time Machines , 2002 .

[19]  M. Eens,et al.  Urinary Testosterone Metabolite Levels in Bonobos: A Comparison with Chimpanzees in Relation to Social System , 2003 .

[20]  Daniel J. Bauer,et al.  Selective breeding for differential aggression in mice provides evidence for heterochrony in social behaviours , 2001, Animal Behaviour.

[21]  G. Hohmann,et al.  How bonobos handle hunts and harvests : Why share food? , 2002 .

[22]  B. Smith,et al.  Ages of eruption of primate teeth: A compendium for aging individuals and comparing life histories , 1994 .

[23]  M. Hauser,et al.  The Evolutionary Origins of Human Patience: Temporal Preferences in Chimpanzees, Bonobos, and Human Adults , 2007, Current Biology.

[24]  Sarah R. Heilbronner,et al.  A fruit in the hand or two in the bush? Divergent risk preferences in chimpanzees and bonobos , 2008, Biology Letters.