Bonobo chimpanzee females are so interested in the birth of their grandchildren that they help their sons to become fathers in every possible way. Caring moms “acquaint” the heirs with fertile females, make sure that no one interferes with the “young” during mating, and even eliminate the rivals of their sons.
Such a curious behavior of powerful females in a matriarchal bonobo society was described by an international team of scientists under the leadership of Martin Surbeck (Martin Surbeck), a primatologist from the Max Planck Institute for Evolutionary Anthropology.
“This is the first time that we can show the influence of the presence of a mother on a very important feature of men’s“ professional suitability, ”namely, fecundity. We were surprised to see that mothers have such a strong direct influence on how many grandchildren they are born.” reported the researcher.
His team monitored the wild bonobo population in the Democratic Republic of the Congo, as well as the wild chimpanzee population in Côte d’Ivoire, Tanzania and Uganda. Scientists have concluded that in both populations, mothers defend the interests of their sons in conflicts with other males.
But at the same time, the bonobo females put much more effort into ensuring the birth of their grandchildren. They play the role of matchmaker and bodyguard: first they bring sons to fertile “daughters-in-law”, and then make sure that the males do not interfere with the mating process. Thus, females increase the probability of paternity of their sons three times (compared with males without maternal support).
It is curious that powerful females can join their son in a clash with his rival. In addition, they prevent the mating of other males: they attack couples and threaten “fiancés”. The latter at the same time simply run away in order not to enter into conflict: aggressive behavior is fraught with the attack of several female mothers.
At the same time, some bonobo mothers also provide their sons with a higher social status due to their own influence. In fact, several high-ranking males “monopolize mating” in their community, crowding out competitors who do not have maternal support.
“Mothers act as a“ social passport ”that allows males to get into the female core of the bonobo community. But as soon as mothers lose their high ranks, this can affect the rank of their sons,” explains Surbek.
The authors of the paper note that among ordinary chimpanzees such interactions are rare: in their communities males occupy a dominant position, and females are less influential.
In general, the behavior of mothers bonobo recalls the “grandmother effect”, which is present in people. The grandmother’s anthropological hypothesis says that at a certain period of life, caring for offspring becomes more important for women than the birth of their own children. By redirecting their energy to the support of subsequent generations, grandmothers help daughters in raising children and thereby increase the likelihood of having more grandchildren and transferring genetic material.
Mother bonobos also contribute to the birth of their grandchildren. But at the same time it is curious that they do not provide such help to daughters.
The point, apparently, is that young bonobo females, as a rule, leave their community, while young males remain with their mothers. Nevertheless, even in those rare cases where the daughter also prefers to stay, she does not receive help from her mother, notes Martin Surbek.
In the future, his team intends to better explore the benefits that the described behavior gives bonobo mothers. Scientists believe that with their actions females indirectly influence the continuation of their genetic line and, therefore, their own reproductive success, although they no longer increase the number of direct descendants.
Read more about this exciting study in the article presented in the journal Current Biology.