Alexander Weiss1, J.E. King2
Factor analytic studies on zoo housed chimpanzees have shown six reliable personality factors, five of which resemble the human Big Five while the sixth is a chimpanzee specific dominance factor (King, J.E. and Figueredo, A.J., 1997, Journal of Research in Personality, 31, 257-271). A recent field study showed that dominance is related to higher fertility and infant survival in chimpanzees (A. Pussey, J. Williams, and J. Goodall, 1997, Science, 277, 828-831). Personality factors in humans have a broad-sense h2 between .40 and .50. Almost all of the remaining variance is accounted for by the unshared environment (Loehlin and Rowe, 1992 cited in Rowe, D.C., 1994, The Limits of Family Influence, The Guiliford Press, New York). We calculated the heritability of six chimpanzee personality factors. We were especially interested in the dominance factor because of its established relationship to fitness. Personality data were collected on 145 zoo housed chimpanzees. Because of the complex network of relatedness within this population, we used the Symmetric Differences Squared (SDS) method to calculate h2, c2, and e2. SDS regresses the squared diffferences between the phenotypes of animals in all possible pairs onto 1-rg and any environmental variable. In our case, the latter term was determined by whether the pair were in same or different zoos. Dominance had substantial heritability. This is the first study showing that subjective personality ratings in chimpanzees may be heritable. It also supports our hypothesis that fitness benefits of high dominance would enhance this factor's heritability.
Address: Alexander Weiss, Department of Psychology, University of Arizona, Tucson, AZ 85721, 520-881-2389, aweiss@u.arizona.edu
1Department of Psychology, University of Arizona, Tucson, AZ 85721. 2Department of Psychology, University of Arizona, Tucson, AZ 85721. 3Supported by ChimpanZoo and the Jane Goodall Institute.