Female gelada monkeys of Ethiopian rapidly mature in the presence of an incoming breeding male. While the biological father of the gelada monkey is present in the life of a female offspring she suppresses her maturation but on the arrival of a new breeding male, she rapidly matures. The conclusion is that the female monkeys are controlling the development of their maturity to avoid inbreeding with their biological fathers.
The researchers discovered this by measuring the levels of oestrogen in the feces of the females concerned. Also they develop “sexual swellings” on their chests and necks. They found that oestrogen levels surged in immature females of all ages just after a new male took over the group. This surge in oestrogen even occurred in females who were too young to mature.
The females are avoiding sex with their fathers to prevent inbreeding. They wait for an incoming male to oust their father and then are prepared to mate with him to create more healthy offspring. That is my interpretation of the study which has been published in Current Biology.
The geladas monkey is a relative of baboons. It had been known for a while that females of the species hurry up their maturation when a male enters the scene. The study confirms what is going on. The study was conducted by scientists at Michigan University. The research covered 80 monkeys over 14 years.
The information may help us understand humans. The scientists suggest that such a process may even exist in humans.
Some more on primates