There is a correlation between the size of the social network and the structure of the brain


  • The brain controls all organs of the human body, motor and cognitive functions, and hormone production.
  • The human brain has the same general structure as the brains of other mammals.

The more our social relationships are, the more certain structures of our brain develop. This is what French researchers just found, published in the journal Science Advances.

“Understanding the Social Group”

The connections between the social network and the size of the brain have been the subject of previous studies in the field of neuroscience. For example, scientists were interested in the variation in the size of the human brain’s amygdala depending on the number of Facebook friends a person has. To complete this research and try to better understand the organization and functions of human neural networks, teams from Inserm and the University of Claude Bernard Lyon 1 worked with an animal species with human-like brain characteristics: rhesus monkeys.

They therefore studied a group of these primates in their natural state for several months before imaging their brains. “Studying animals in the wild has enabled them to understand the social group in all its complexity. Scientists could thus measure the intensity of interactions with other individuals or even identify the social hierarchical position of the animal. within the group, explains Inserm in a press release.


In parallel with this behavioral observation, the scientists analyzed the brain scans of the individuals in the group, which consisted of 68 adults and 21 young macaques under the age of 6 years. They then discovered that in adults, the more mates the animal had, the larger certain regions of its brain were in the temporal lobe. More specifically, it was the anterior insula and the middle part of the superior temporal sulcus—areas thought to be essential for representing the emotions and perceiving the behavior of others.

To better understand how this phenomenon occurs, the scientists were also able to collect brain scans from 21 young newborn macaques. Their work thus showed that these differences in the size of brain structures are not inherent in them, but that they were created during their development.

“This aspect is interesting because if we had observed the same correlation in young macaques, it could have meant that giving birth to a very popular mother (who had a lot of interaction with the group) could have predisposed the newborn to becoming popular On the contrary, our data suggest that the differences we observe in adults are strongly determined by our social environment, perhaps more than our innate disposition,” concludes Jérôme Sallet, Research Manager at Inserm.

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