Hyenas Inherit Their Moms’ Social Connections
Inherited social networks shape the spotted hyena's life and survival.
Posted July 15, 2021 | Reviewed by Vanessa Lancaster
- Using data from 27 years of observations of wild spotted hyenas, researchers found evidence for social network inheritance.
- The degree of similarity between mother and offspring’s social networks increases with the mother’s social rank.
- Social inheritance is likely an important process in how relationships are formed and maintained.
Using 27 years of detailed observations of spotted hyena social interactions, researchers uncovered a pattern of social network inheritance between mothers and offspring. The findings shed light on how relationships are formed and maintained and have implications for social structure, rank, and survival.
“There is a booming literature on the implications of social networks on survival, the spread of pathogens, and information transfer,” says biologist Erol Akçay, one of the authors of the study. “That is why we are interested in the formation and dynamics of networks.
“Here, we show that a simple process — social inheritance — is important to understanding network structure and dynamics.”
Social Ties in the Wild
A few years ago, when Amiyaal Ilany was a post-doc in Akçay’s lab at the University of Pennsylvania, the two researchers published a theoretical model of social network inheritance. According to the proposed framework, animals establish their networks by copying their mother’s behaviors, resulting in an offspring’s social affiliations resembling those of its parent.
“The model showed some interesting predictions about social inheritance being potentially relevant to the formation of networks,” says Ilany, who is now at Bar-Ilan University. “We thought, that’s nice, but do any animals actually inherit their connections?”
In a new study published in Science, Ilany and Akçay evaluated their model of social inheritance in spotted hyena society, which is highly structured and female-dominated.
They were fortunate to have access to a unique dataset collected by coauthor Kay Holekamp of Michigan State University, consisting of more than 73,000 social interactions among a clan of wild hyenas collected over 27 years. Researchers from Holekamp’s team have tracked the social interactions within this hyena clan, including who spent time with whom and the social rank of each member, through year-round, almost daily fieldwork.
Using these data, the researchers compared the social networks of mother hyenas to those of their offspring.
Secrets of Sociality
The researchers found that in the first year out of the den, social inheritance was strong for the offspring of all mothers. After this period, however, social inheritance was more substantial for offspring born to higher-ranking mothers.
“It could be a silver spoon effect,” says Ilany. “If you are born to a higher-ranking mother, you can copy them, including their social connections, to be successful. If you are born to a lower-ranking mother, you might want to try other things.”
Offspring of low-ranked mothers tended to be more social than their mothers. Offspring of low-ranked mothers could compensate for their low rank (also inherited from mom) by socializing more and forming different social bonds than those of their mothers.
What’s more, the results showed that social inheritance is associated with the longevity of both mothers and female offspring. Mother-offspring pairs with more similar social networks lived longer.
Ilany and Akçay say the results provide support for their model, and they are curious for more researchers to look for evidence of social inheritance in other species. They note that social inheritance likely contributes to a group’s stability and affects how behaviors are learned and spread through groups. Ilany and Akçay hypothesize that in species with stable social groups, the inheritance of social connections from parents is the cornerstone of social structure.
“Many traits in social species, from hyenas to humans, are influenced by social connections and interactions,” says Ilany. “The network you inherit plays an immense role in your life’s trajectory, but in humans, this is complicated to study.
“We show in hyenas — which are very socially sophisticated, but simpler than humans — how social inheritance might work in a complex society.”
Ilany A, Holekamp KE, and Akçay E. (2021). Rank-dependent social inheritance determines social network structure in spotted hyenas. Science 373(6552): 348-352. Doi: 10.1126/science.abc1966.