An experimental analysis of a mother-daughter rank reversal in Japanese macaques (Macaca fuscata)

This paper describes in detail how a 2.5-year-old female belonging to the second-ranking family in a captive group of three families managed to outrank her healthy, three-times heavier mother with the aid of the two immature daughters of the alpha female who was not herself directly involved. After the outranking was completed, the two active allies were removed. This had no effect on the rank relation between the female and her daughter. It is only after the mother of the two allies was removed (in addition to her daughters) that the mother recovered her rank above her daughter. This case study and the few other reported cases of changes in rank among females are discussed in relation to the issue of the stability of rank relations in hierarchical systems where rank is socially inherited rather than based solely on dyadic power contests. On the basis of this combined evidence, it appears that when attempting to rise in rank, females do not challenge dominants by allying with subordinates, but that they rather ally with an individual ranking above the target. This phenomenon, together with the fact that support is given to other females downwards the hierarchy, might explain the stability of female dominance relations and be the manifestation of an Evolutionarily Stable Strategy.