Ancestors of primates lived in pairs

A study carried out by CNRS1  scientists working with an international team has revealed that around 70 million years ago, when dinosaurs existed, the ancestors of primates most commonly lived in pairs. Only 15% of them opted for a solitary lifestyle. This discovery — that our ancestors adopted variable forms of social organization — challenges the hitherto commonly accepted hypothesis that at the time of dinosaurs, the ancestors of primates lived alone, and that pair living evolved much later. Most likely, pair living offered significant benefits, such as easier reproduction and reduced costs of thermoregulation by huddling in pairs.

While several studies have already been conducted on the social organisation of primate ancestors, this is the first one to use only currently available field observations. By studying 498 populations from 223 species, the research team has built the most accurate database of primates to date. The information obtained was then coupled with innovative statistical analysis. This research, published in the Vol. 121, no.1 issue of PNAS, paves the way for a better understanding of the social evolution of the human species.

• 1Based at the Hubert Curien Pluridisciplinary Institute (IPHC) (CNRS/Université de Strasbourg).