Inheriting social rank is not uncommon in nature, certainly not among humans. And it is also common for the offspring to inherit the social relationships of their parents, as happens with African elephants and macaques. Including hyenas, which have social structures very similar to these monkeys. A study published today has analyzed half a million interactions between hyenas over 27 years of scientific observations to reach this conclusion: hyena pups maintain the social contacts of their mothers, especially those of high rank within the group. A phenomenon that has important implications for the life of these animals.
Hyenas are one of the examples of matriarchy among mammals: they rule and the males migrate to find a new herd. Hence in this study, that publishes on its cover the magazine Science, focus on the relationships hyenas inherit from their mothers. The result leaves no room for doubt: even years after leaving the den, high-ranking hyenas maintain strong ties to the same individuals that their parents were associated with, even after they have died. Those of low social class tend to vary much more, seeking different and stronger friendships than those of their low-ranking mothers, to try to compensate for their vulnerable situation. And this has two simple consequences: the stability of the group is maintained for decades (they usually live up to 25 years), with the same families in charge, and the life expectancy of upper-class hyenas is lengthened.
For Holekamp, hyenas transmit to their young an inheritance similar to that of humans, “things less tangible, such as languages, beliefs and groups of social relationships”
Researcher Kay Holekamp, from Michigan State University (USA), believes that her study in Science suggests how something as rich and complex as the cultural heritage we see in humans can begin during the course of the evolution of other mammals, such as the social heritage learned in spotted hyenas. “In addition to the physical manifestations of wealth or poverty,” says Holekamp, “we know that what humans pass on to their children as inheritance are much less tangible things, such as languages, whole sets of cultural norms, beliefs and groups of relationships with others. members of our societies ”. Hyenas provide their litters with a similar advantage, Holekamp explains; less sophisticated, but the basic lines would be very similar.
Having the friendship of high-ranking hyenas grants priority access to food, avoiding the stress of fighting over the scarce remains left by low-status hyenas (the groups reach up to 130 members), and also allows to have more allies in conflicts, which are decided by the quality and quantity of support.
Three years ago, specialists from the Leibniz Institute for Zoological and Wildlife Research showed in a study how alliances strengthen the matriarchy of hyenas. As with bonobas, female hyenas maintain their throne not because they are stronger than the males (they are somewhat larger than them), but because of the alliances they weave in the group to face aggression. As one of the authors of that work explains, Eve davidian, showed that the number of relatives that an individual can count on and the asymmetries between individuals strongly predict the dominance relationship between two hyenas. “But it was not clear how these asymmetries arose; this study provides explanations, ”says Davidian.
“In hyenas, social rank is inherited through learning. It is not determined by physical strength or other traits that can be transmitted genetically “
Kay Holekamp, Michigan State University
The allies young hyenas have is a strong determinant of the outcomes of their disputes, explains Holekamp: “The youth of high-ranking bloodlines they have more support because they have more relatives and they also attract what we could call groupies, lower-ranking females who like to hang out with more dominant females ”.
“We already knew that in hyena societies, social rank has important effects on adaptability and that is inherited through learning. In other words, it is not determined by physical strength or other traits that can be transmitted genetically ”, explains the expert from Michigan State University, who has been studying hyenas in Africa for three decades. Now this study shows that, in addition to social rank, complete sets of relationships are also inherited from mothers, especially among high-ranking individuals. “This is also true among humans,” says the zoologist.