Successful formation of a large chimpanzee group out of two preexisting subgroups (2001)

Seres, M., Aureli, F., deWaal, F. B. M.

Abstract

Nineteen chimpanzees from preexisting subgroups were introduced into a social group [two adult males, six adult females along with six dependent infants, and five unrelated juveniles, four of whom had been hand-raised in a nursery unit]. ... The introduction process itself took more than 3 weeks, and was completed without major injuries. ... During the introductions, low rates of agonistic behavior among adult females were offset by high rates of affiliative behavior. The two adult males, however, showed contact aggression during the first 10 minutes, after which such behavior virtually disappeared, whereas affiliative behavior increased. ... The frequency of aggression among all adults, including the males, increased during the 4-year period, but aggression was generally of low intensity after the first year.