If you think that your mother is very fond of having grandchildren, rest assured: at least you are not a bonobo.
We have seen bonobos mothers adopt a variety of behaviors that seem to give their sons an advantage when it comes to giving birth to a baby, according to one study published Monday in Current Biology Magazine.
What kind of behaviors? Well.
When a bonobo is mating with a female, her mother sometimes encounters interference with other males who approach too closely and attempt to interrupt their sexual relationship. .
Wingman? How about wingmom?
It has also been observed that Bonobo mothers actively broke up mating relationships between women and other men who are not their sons, recalling the title of a big-screen comedy roughly named last year.
Sometimes a bonobo mother even teams up with her son to beat his sexual rivals and help him climb the hierarchy of his social group.
Scientists have known for a long time that bonobos mothers do all these things, but so far, they have never been able to prove that the interference brought to their sons an advantage that allowed them to have more great bonobos . New research, however, has shown that wild male bonobos in Congo had three times more children when their mothers were still visible than bonobos whose mothers had died or had left their group.
In comparison, the same researchers found no such significant benefit for wild male chimpanzees in Côte d'Ivoire, Tanzania and Uganda. This is important because bonobos and chimpanzees are very close. But chimpanzee mothers usually have none of these twinning behaviors – or rather match defense – for their sons. This suggests that the increase in the number of baby candies is due, at least in part, to the mother's behavior in helping her sons and not just good genetics.
But there is also a social component. In chimpanzee groups, men still retain dominance. In bonobo groups, men and women share a dominant position and women are generally protected from male violence.
"I'm pretty sure we see these effects in bonobos because women hold high social ranks," said Martin Surbeck, biologist at the Max Planck Institute for Evolutionary Anthropology and lead author of the study. "We are less sure of the actual mechanism by which the presence of moms helps their sons."
And the only presence of mothers is important.
In a 2010 study, Surbeck and his co-authors observed that bonobos tended to stay on the periphery of the group when they did not have their mother nearby. This is bad news for the breeding rates of these men because the center of the group is the gathering place for the most reproductive females. On the contrary, even middle and lower-ranking men could safely enter the center of the group when their mothers accompanied them.
"They act as a social passport allowing men to enter the female core of bonobo society," Surbeck wrote in an email.
Mothers also seem to influence the rank of their sons, the most powerful mothers having stronger sons. "And once mothers have lost their high ranks, this can also affect the ranks of their sons," said Surbeck.
Ammie Kalan, a primatologist at the Max Planck Institute of Evolutionary Anthropology, who was not involved in the new study, described it as "fascinating" in the way she invokes comparisons with the grandmother hypothesis of human evolution.
The grandmother's hypothesis attempts to explain why women are among the very few menopausal animals. After all, if evolution depends solely on the transmission of your genes, what advantage would there be in hooking up your reproductive capacity?
The answer, according to the hypothesis, is that after a certain age, grandmothers are more likely to transmit their genes by helping their offspring rather than creating themselves more.
"That being said, I would find it very interesting to know which has greater predictive value for the reproductive success of a bonobo," said Kalan, who collaborates with some of the study's authors. "Is his mother present? The rank of his mother in the group? Or his own rank?
Cat Hobaiter, a primatologist from the University of St. Andrews, also said that she found the research interesting. "But I wonder how it's a difference between the species and the opportunity offered to couples of mothers and sons in particular," she wrote in an email.
Another 2011 study showed that bonobos mothers are less inclined to help their sons when they are pregnant, for example. And while bonobos are relegated to a relatively small part of Central Africa, chimpanzees are in pockets across the continent and there is great variation between each group.
Groups of East African chimpanzees congregate and separate frequently. For example, a mother who still lives with her son may not see him for days or even weeks. On the other hand, West African chimpanzees seem to form more cohesive social groups, offering mothers more opportunities to help their offspring.
Whatever the case may be, the new study on bonobos shows fascinating evidence of the grandmother's hypothesis at one of our closest relatives, Surbeck said.
"What's interesting, is that in humans, it was originally thought that it was thanks to the support of their daughters," said Surbeck, "while at the bonobos, c & rsquo; Is thanks to the wires. "
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