According to Drs. Jane Goodall, Jennifer Williams and Anne Pusey, who have been studying chimpanzee behavior since 1960, recent findings have determined that female chimpanzees are much less dependent on male chimpanzees as a source of power than previously believed. Female chimpanzees usually control their reproductive success. Female chimpanzees, although they have frequent sex with male chimpanzees in their own colony, will leave the colony during the most fertile days of their cycle to mate with chimpanzees they consider to be superior to the local chimpanzees.
In addition, female chimpanzees have an internal hierarchy within their ranks. Those female chimpanzees who are of higher rank generally have children who live longer and are healthier than the children of those of lower rank. It is uncertain as to how the females of higher status achieved this rank, however evidence suggests it is not due to blatant acts of aggression, but due to more subtle strategies. These findings contradict earlier assumptions of male dominance in chimpanzees.