Chimpanzees ( Pan troglodytes ) stand out as highly social primates. Friendly relationships between individuals are closely related to the hierarchy of the group; a fact that acquires cabdal importance in their day to day, especially when it comes to eating and reproducing , but in what way exactly?
For years, ethologists, biologists who study animal behavior, have wondered about the reason and purpose of the friendly behaviors among these hominids. The investment of a lot of time by male chimpanzees in attitudes of cooperation and fostering alliances, they had to have some advantage, if not, why not worry about spending more time meeting basic needs, such as finding food or reproducing, instead of interacting with their peers?
A research group from the University of Michigan tried to answer this question in a study published in the journal iScience . The scientists focused on chimpanzees in western Tanzania, specifically in the Arroyo Gombe National Park, an area where Jane Goodall began her studies in 1960. Joseph Feldblum, lead author of the work, states that ” one would expect to observe these strong social ties only if they provide some kind of fitness benefit to the individuals. Males would not spend all this time grooming other males and giving up trying to find females or food unless some kind of benefit is derived from it. […] Chimpanzees cooperate frequently, and often very intensely: you see things like grooming, all kinds of complex alliance formation, and group territorial defense. The question was: what do the males get out of it and how? “
The researchers used a model that integrated the male’s age, dominance range, and genetic kinship to the mother in the success of the male’s breeding. They analyzed 56 mating events with known paternity, which occurred between 1980 and 2014.
The study findings were groundbreaking and surprising, as they found that males who maintained strong friendship ties with alpha males, or who had two or more strong association ties with other males in the group, had more than a 50% chance. of begetting offspring. Study co-author Anne Pusey says that “complimenting the boss is nothing new. With our study we show that it has always worked, even in chimpanzees ”.
But the study does not end here. They also found that creating these strong bonds within the group of chimpanzees appears to improve the rank of a certain individual within the group and also increases their chances of forming coalitions, that is, groups of allies that defend each other.
Thanks to studies like this, we can move towards a clearer idea of the benefits of social relationships in chimpanzees, but it also gives us a clue to understand the evolution of friendship in humans.
References:
Feldblum, JT, Krupenye, C., Bray, J., Pusey, AE, & Gilby, IC (2021). Social bonds provide multiple pathways to reproductive success in wild male chimpanzees. IScience, 24 (8), 102864. https://doi.org/10.1016/j.isci.2021.102864
