Dominance and personality in stumptailed macaques

Abstract

The concept of dominance has received considerable attention in studies of non-human primates. There are many diverse opinions regarding the function and evolution of dominance. due in part to the lack of consensus as to how to define and measure dominance. Some researchers believe that dominance is a universal principle of primate social organisation. which influences all aspects of social relationships. while others consider that dominance has been overrated as a general governing principle in social behaviour. The study of personality in primates is less well documented, although the few studies which do exist have found a considerable degree of similarity between dimensions of human personality and those of primates. Recently, the study of human personality has explored the effects of the situation on the behaviour of an individual. and the complex relationship between personality and situational variables. This study considers the applicability to primate studies of human personality concepts and evaluates the extent to which the concepts of personality and dominance can increase our understanding of the behaviour of primates. The effects of changes in dominance rank were examined by an experimental manipulation, designed to give experience in up to 3 dominance positions to each of 13 animals. Preliminary observations had indicated that there were individual differences in behaviour between animals of differing dominance rank, and the manipulation phase was carried out with the object of discovering whether these characteristic differences were a function of the differences in dominance rank or in personality. The results of the manipulation indicated that changes in dominance rank affected fear and aggression levels while some behaviours remained stable over changing dominance position, suggesting stable personality dimensions. However, most of the behaviour of an individual was found to be a function of the interaction between dominance and personality. Thus the concept of dominance is useful in explaining some aspects of the behaviour of an animal and some aspects of his interaction with other animals. There was also evidence that the animals themselves differentiated other animals according to rank, in terms of how much grooming and visual monitoring they directed to animals of differing rank, suggesting that dominance rank is not only useful to human observers. Studies of primate personality can help to identify those aspects of an animal's behaviour which are independent of his dominance rank. It is proposed that dominance be defined in terms of how much limitation an animal has placed on his behaviour, but that just how aggressive a dominant animal is, or how fearful a subordinate animal is will be a function of his personality. The shotgun approach used by many researchers in trying to relate all aspects of social behaviour to dominance is misguided, since it ignores individual differences in the animals, and weakens the usefulness of the concept of dominance. The personality of an individual animal was found to be an important variable both in determining his behaviour and aspects of the social structure of the group. Both trait/state and situational specificity theories of personality were investigated but rejected in favour of an interactionist theory) although it was concluded that while behaviour is a function of the interaction of personality and the situation we are limited in accounting for why and how such interaction occurs in the behaviour of primates. In summary, the social behaviour of an animal is largely a function of the interaction between personality and dominance rank. Further studies of the social behaviour of primates would do well to investigate why animals compete for dominance) the complex interaction between dominance and personality and the effects of the personality of the animals within a group on the social structure of that group.