EVOLUTION OF BEHAVIORS REGULATING DENSITY AND AGE-SPECIFIC SEX-RATIOS IN A PRIMATE POPULATION

New data from a long-term study of a population of toque monkeys (Macaca sinica sinica) of Sri Lanka suggested that animals indirectly kill one another through social behaviors that involve access to resources and mates. Such mortality is not imposed randomly, but follows differences in social dominance. As dominance differs according to age, sex and kinship so do the socially imposed mortalities. The net result of these relationships is that the density and the age-sex distribution of the society (and hence of the population) are determined through social means and are regulated towards an equilibrium with the available food resources and nonsocially imposed mortality. The evolution of such behaviors are explained to elucidating phenomena that may be fundamental to the social organization of other mammalian societies [Patas monkey and baboon]. Growth, reproduction, emigration and aggressive behaviors are discussed.