Rhesus monkeys have an intricate social structure. There is a dominance hierarchy, meaning that not all individuals enjoy the same rank in the group. This also effects the value that individuals gain from each of their relationships. Obviously, having powerful allies is of great value. And to maintain a powerful position requires allies. These are all features that rhesus macaques share with humans.
In a recent study, primatologists detailed the social relationships of female macaques and how they change throughout their life course. It’s generally assumed that, in a species with a dominance hierarchy, the more allies you have, the better off you are, especially if those allies are high-ranking. But this is not quite what the researchers found. Older female macaques actually spent much less time tending to their social relationships, a surprising finding given that, in primates (including humans!), social relationships are more important than ever as we get older.
But what the researchers found was that older female macaques, while an important resource of knowledge for younger macaques, really didn’t need social relationships to maintain their status and their success. Their wisdom and experience was more important than their relationships. Younger monkeys get more out of their relationships with the older females than vice versa.
This work took place at the Caribbean Primate Research Center on the island of Cayo Santiago, off the coast of Puerto Rico. Macaques are Old World Monkeys and thus not native to the Americas. This colony of macaques was brought here in the 1930s and has been thriving under the watchful eye of primatologists ever since. (The Cayo Santiago field site, like the rest of Puerto Rico, was devastated by hurricane Maria and is struggling to rebuild. Please consider helping in that effort.).
On a recent episode of This World of Humans, I spoke with two of the authors of this study, Dr. Angelina Ruiz-Lambides of the University of Puerto Rico and Dr. Laurent Brent from the University of Exeter (UK).
We discussed the history of the research site at Cayo Santiago (how did a colony of Old World monkeys get there?!) as well as the results of this recent study on the social value of relationships in aging female macaques.
Listen to the podcast episode for the full story. (Episode #04)
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-NHL
The Human Evolution Blog 
Interesting. But I wonder, for an older female macaque, whether serving as a source of knowledge and wisdom for younger ones isn’t in itself a form of social relationship, and quite a satisfying one. Don’t the females convey their wisdom by being with, touching, berating, demonstrating to the younger ones? Those are modes of socializing–for both old and young. I’m thinking of some older female humans whom I know who, although they do like to gossip and go to lunch together, feel much of their self-respect and value comes from the active roles they play in the lives of their kids, grandkids, and others.
Brock
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I suspect you are very right. I also found a parallel in how the contacts are initiated. The older females have less social contact because they don’t initiate it, but they don’t rebuff the contact. It reminds me of my own late grandparents. Of course they loved when their children and grandchildren came to visit, but they weren’t going to call and beg. 🙂
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