Evolution.

Society for Experimental Biology

Date:: 1953

Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Evolution. Source: Wellcome Collection.

453/484 (page 421)

SOCIAL BEHAVIOUR AND PRIMATE EVOLUTION 423 animal does not result from stimulus ranking, which leaves a predominant stimulus; both the positive and negative aspects of the situation are in balance, and determine the locomotor behaviour of the subordinate male primate, and appear as negative and positive gradients with the properties demonstrated by Miller. We can infer, therefore, (1) That a trigonal relation between a dominant male, a subordinate male and female develops by virtue of the sexual attraction exerted by the female for all the males, (2) That the continual movement of the animals imposes a constant fluctuation in the spatial relations between the members of a heterosexual group which is continually assessed by the subordinate animal : (a) in order to avoid fights with the overlord, (b) in order to take any opportunities for mating. (3) That the trigonal relation is the basis of the spatial distribution of animals in primate societies. From it can be forecast the spatial distribution of males within the group, dependant upon their relative dominance characteristics, and their position within heterosexual groups. From it can be forecast the spatial distribution of females within a group depending upon the rhythm of their oestrous cycles, and it is also a factor restricting the freedom of movement of the developing young as they recede from the parent female. Carpenter (private communication) draws the following generalization from his observations to explain the spatial distribution of primates: 'Individuals in organised groups deploy themselves in space in inverse ratio to the strength of positive interactional motivation and conditioning, and, in direct ratio to the degree of negative interactional motivation and conditioning.' In this statement Carpenter identifies the same elements as postulated here. It is necessary to distinguish, however, between the motivational and conditioned elements in assessing the nature of these interactions. An animal may tend to move away from another to which it is negatively conditioned, and thus in a group of which it is a member to remain at a distance from the first. This does not imply a conflict component, but merely an avoidance reaction. The relations within the trigonal sphere, on the other hand, involve true antagonistic motivational forces in balance with one another. Carpenter maintains that 'any single relationship involves a complex of both negative and positive elements' (1942). Mother, young, or consort relations, however, cannot involve negatives of the type normally causing spatial deployment of individuals within the group. In such relations the positive elements