The more social relationships we have, the more specific our brain structures become. This is what French researchers have just shown, and published in Science Advances Magazine.

“Social Group Capture”

The connections between social network and brain volume have already been the subject of previous studies in the field of neuroscience. For example, scientists were interested in the difference in the size of the amygdala in the human brain depending on the number of Facebook friends an individual has. To complete this research and try to better understand the organization and functions of neural networks in humans, teams from Inserm and Claude Bernard Lyon University 1 worked with an animal species that has brain characteristics similar to those of humans: macaques.

And so they studied a group of these primates in their natural state for several months before imaging their brains. “Studying animals in the wild allowed them to understand the social group in all its intricacies. Thus scientists were able to measure the intensity of interactions with other individuals or even determine the animal’s social hierarchical position. Within the group, Inserm explains in a press release.

Scanners

In parallel with this behavioral monitoring work, the scientists analyzed brain scans of individuals in the group, which consisted of 68 adults and 21 young macaques under the age of 6. Then they discovered that in adults, the more companions an animal has, the more areas of its brain are located in the temporal lobe. More specifically, it was the anterior and middle part of the superior temporal sulcus – areas considered essential for representing other people’s feelings and perceptions of their behaviors.

To better understand how this phenomenon develops, the scientists were also able to collect brain scans of 21 newborn baby macaques. Thus their work showed that they were not born with these differences in the size of brain structures but were held in place as they evolved.

“This aspect is interesting, because if we observed the same association in young macaques, it could mean that their birth to a very famous mother (who has a lot of interaction with the group), could have predisposed the offspring to become common in the macaques. On the contrary, our data suggest that the differences we observe in adults will be determined more strongly by our social environments, perhaps more than by our innate predisposition,” concludes Jerome Salé, Director of Research at Inserm.