Originally, most primates lived in pairs

Rather, we thought that our distant ancestors were solitary, and that other forms of social organization appeared later. But no. A remarkable study bringing together a multitude of field observations shows that 80 to 90% of ancestral primates lived in pairs.

Hervé Poirier, editor-in-chief of the scientific magazine Epsiloonexplains to us today that the first primates, our very distant ancestors, were not solitary as we thought.

franceinfo: These first primates actually lived mainly in pairs?

Hervé Poirier: It’s strange how preconceived ideas take hold. Until now, experts believed that the first primates, our distant ancestors, were overwhelmingly solitary beings. That they lived all alone, in the forest.

For the first time, this idea has been scrupulously studied. And it turns out that no. In fact, tens of millions of years ago, the social organization of primates was overwhelmingly pair life: a male and a female, possibly with her offspring as long as she was unable to mate. reproduce.

But how could this be demonstrated?

A titanic piece of work, led by Charlotte-Anaïs Olivier, from the University of Strasbourg and seven other colleagues. These specialists in animal behavior and evolution first brought together all the available field work carried out on the social organization of modern primates.

In the end, among the 493 populations of 215 species recorded (out of the 425 living), they found that the most common form is the group – like with us humans. Alone, 23% of species live in pairs, and 6% live alone.

They then integrated this data into the large tree of primate evolution. And they ran a “Bayesian phylogenetic model” which allows us to deduce, along this tree, the ways of life in the past, up to that of the common ancestor, almost 70 million years ago. To conclude that this original primate had a lifestyle largely centered on couples: only 10 to 20% of individuals were solitary.

But why have primates mostly turned to living in groups?

Very good question, which the study does not answer. Real subject of research. What we have learned today is that originally, among primates, society was the couple.