AbstractsAnthropology

This thesis explores the various adaptive strategies used by female gorillas to compete effectively with other females for limited and/or defendable resources, and to test the general hypothesis that such strategies have an evolutionary origin. Based on competitive strategies observed in mountain gorillas (Gorilla gorilla beringei) in the wild, seven predictions were made regarding competitive interactions between adult females in three large captive groups of western lowland gorillas (G. g. gorilla) housed at Howletts Wild Animal Park in Kent, England.Four of the predictions were supported, and a fifth partially. As predicted, older/greater tenured females at Howletts were generally of higher rank than younger/shorter tenured females; agonism generally went down the hierarchy while submissive behaviour was directed up; and in each group, the most recent female ("immigrant") received a greater proportion of the female harassment. In addition, the Howletts females appear to have developed a supportive clique of familiar, long-tenured high status females (HSFs), which, along with the tendency of low status females (LSFs), immatures and the silverback to also support the HSFs, seems to have enabled them to maintain their high-ranking positions. This pattern suggests a possible mechanism by which long-tenured, older females maintain their high status. Finally, reconciliations between females in higher than average levels of agonism only occurred with opponents of different status class, with LSFs reconciliatory towards HSFs.Some other findings also emerged. Females at Howletts appeared to use infants in their competitive interactions ("Infant-Use"). Infant kidnapping by LSF kidnappers of infants of HSF mothers was the most common form, and resulted in a temporary rank reversal of the two females involved. Infant-Use by LSFs may also be a form of indirect agonism, or tit-for-tat, against HSFs for the high levels of harassment the former receive from the latter – because HSFs have allies, direct retaliation is risky. Finally, possible cases of tactical deception were also observed among the Howletts gorillas, such as, for example, deceptive solicitations for help against an "innocent" opponent; and some cases of consolation of victims of unprovoked attacks suggested a capacity for empathy. The overall pattern of interactions suggests that gorillas are capable of moral reasoning.Thus, the Howletts females have competitive strategies evident in mountain gorillas, which supports the hypothesis that female gorilla competitive strategies have an evolutionary origin. They have also revealed the capacity for an even wider repertoire, including political alliances, Infant-Use, reconciliation, and moral reasoning. Thus, gorillas appear to have evolved a high cognitive capacity for complex social maneuvering, apparently more evident in captivity, and comparable to that observed in chimpanzees.