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.

440/484 (page 408)

410 SOCIAL BEHAVIOUR AND PRIMATE EVOLUTION A later paper by Eckstein (1949) reveals that the mating systems of mammals consist of a number of combinations of the features exhibited by the mammals as a group. The spontaneously ovulating examples mentioned above are differentiable on the presence or absence of pseudopregnancy. The advent of periods of pseudopregnancy prevents temporarily the appearance of mating behaviour and will, therefore, have a limiting effect upon the mating behaviour of a population. A similar state of affairs exists in the group of induced ovulators in that the proportion of pregnancies to matings is likely to be much higher than in spontaneously ovulating groups. A further limiting effect occurs amongst the spontaneously ovulating groups in which a seasonal period of anoestrus is characteristic. Further, it is said that the primates are characterized by the presence of at least some anovular cycles, and this has been demonstrated in the macaque (Hartman, 1930-2), which means that the mating behaviour of other spontaneous ovulators compared with the primates will be limited by pregnancy. It appears that in the primates the combination of features comprising their mating system (a continuously potent male in association with a spontaneously ovulating polyoestrous female, with no seasonal anoestrous, no pseudopregnancy and some anovular cycles) is physiologically limitless in respect of their mating behaviour. The new feature of mating behaviour in the primate is, according to Beach (1947), the 'emancipation' of the mating behaviour of the female from the cyclic control of oestrous hormones. This statement by itself is insufficiently explicit for our purposes, since two distinct elements, either of which may be present to a different degree in different primates, are responsible for the most extreme form of this new type of reproductive behaviour as it is found in man. On the one hand in the subhuman primates the postures, movements and gestures forming the mating complex have, to various degrees in different species, become part of the repertoire of behaviour at the disposal of the primates. In some of the subhuman primates these constitute a repertoire of communicative social gestures which regulate the relations between animals engaged in other types of social behaviour, other than specific sexual activities. This is most highly developed in the baboons and macaques; it is also evident in some genera of platyrrhines (howler and spider monkeys), but appears to be largely absent in gibbons. While this particular use of the sexual gestures as a means of social communication is a specific adaptation found in some species of subhuman primates, the employment of sexual gestures as one element in the social behaviour is nevertheless discernible in all primates above the lemurs.