If your social life is a blur of friends and family, you might want to thank an almond-shaped clump of nerves at the base of your brain.

Researchers have found that part of the brain called the amygdala, a word derived from the Greek for almond, is larger in more sociable people than in those who lead less gregarious lives.

The finding, which held for men and women of all ages, is the first to show a link between the size of a specific brain region and the number and complexity of a person’s relationships.

The amygdala is small in comparison with many other brain regions but is thought to play a central role in coordinating our ability to size people up, remember names and faces, and handle a range of social acquaintances.

Researchers at Massachusetts general hospital in Boston used magnetic resonance imaging (MRI) scans to measure the amygdalas of 58 people aged 19 to 83 and found the structure ranged in size from about 2.5 cubic millimetres to more than twice that.

As part of the study, each of the volunteers completed a questionnaire giving the number of people they met on a regular basis. They also commented on the complexity of each […]