In chimpanzee society, status matters . Being higher in the hierarchy provides access to more and better food and more opportunities to copulate with higher-ranking partners. Status is a real guarantee for the survival of one’s lineage. It was already known from various studies that male chimpanzees try to prosper socially in this hierarchical pyramid by challenging their rivals by screaming, attacking or chasing those above to try to take their place. Now we also know, thanks to a study published recently in Scientific reports, that females do not participate in these male power games. They are more likely to accept their place in the social ladder and only rise when the oldest members of the group die.
There are no challenges or competition among female chimpanzees, only the natural ladder that governs time, according to Steffen Forester, first author of the study and researcher at Duke University, in North Carolina (United States). This difference between male and female chimpanzees adds to others that were already known. For example, that males are gregarious and females are more solitary and tend to spend their time alone or taking care of their young. Only very rarely do they associate with other females.
To learn more about the social organization of these primates , the researchers have drawn on previous studies collected over 40 years on the behavior of one hundred chimpanzees that lived in the wild in Gombe National Park, in Tanzania. Through this information they deduced that males reached the peak of their power at 20 years of age, and that from then on their position began to decline. On the other hand, among females, the status continued to increase as the years passed.
In addition, the researchers observed that the starting position of males was at the lowest when they entered adult life, around 12 years of age, while in adolescent females, their hierarchical position could be indistinctly higher or lower at those ages. Although they still do not understand why, researchers believe that females whose mother is alive occupy a higher social position than the rest . This moment is crucial for them, because later on they will not be able to improve their position unless one of those above them disappears or loses their role in the group.
For scientists, the differences between males and females are due to the fact that their interests are different . And it is that if a male has a higher rank, even for a short period of time, he can be able to copulate with many females and achieve high reproductive success. For her part, each female is only capable of raising one child at a time, so her reproductive success depends a lot on how long she can live. Therefore, compared to males, females prefer a strategy of patience. It is potentially dangerous for them to challenge another, because they can injure them or kill their young. Better to stay out of the male wars.
