Got a lot of friends? Thank your amygdala! A new study may shed light on how this brain structure, often associated with fear, may regulate our social lives as well.
The study, first published in Nature Neuroscience and also reported in the AP, looked at the size and complexity of people's social networks by measuring both the number of friends a person had and the number of networks those friends belonged to. They found that large network size and high network complexity were both linked with a larger amygdala, a brain area that the study authors say may have "evolved, in part, under the pressures of increasingly complex social life." They write,
Humans are inherently social animals. We play, work, eat and fight with one another. A larger amygdala might enable us to more effectively identify, learn about and recognize socioemotional cues [...], allowing us to develop complex strategies to cooperate and compete.
Social life is fucking difficult, as another recent study can attest. Quail who were "subjected to social stress" not only had higher stress hormone levels, they also seemed to pass the stress on to their offspring, who were smaller, hatched later, and behaved more cautiously. According to EurekAlert, they also "tend to move about more, which can be interpreted as increased attempts to escape from threats or to seek more social contact." So, stressed mama quails may give birth to chicks who crave more friends.
This is an interesting counterpart to the amygdala study because the amygdala is also linked to fear. SM, the woman who gleefully pokes tarantulas because she feels no fear, has a rare condition which has damaged this brain structure. The amygdala also appears to be involved in our response to others' fearful faces. So might stress or fear lead us to seek out more friends and deeper networks? Or might a better-functioning amygdala (say the study authors, "the size of a brain region is one indicator of its processing capacity") lead to less social anxiety and better relationships? I talked to Clay Lacefield, neuroscience researcher at Columbia University — and while he's not an expert on the amygdala itself, he suspects the latter hypothesis is correct. He says, "maybe a larger amygdala would allow someone to be more in control of their emotion, such as by being able to use their prefrontal cortex (their 'higher' brain) to control the expression of emotion." He speculates that perhaps "affable/gregarious people are better able to appropriately express emotions under control of their higher brain, which allows them to use them to further their long-term goals." Whatever the case, given that social interaction can so easily both freak us out and calm us down, it's no surprise that it's linked to the parts of our brain that make us afraid.