I have long maintained that the Dunbar Number — we supposedly can only maintain a small number of close relationships, and only remain connected to 150 people in total — isn’t a constant: it’s a variable. I have been on the look out for research that supports this premise, and something new has come to light.
Lisa Feldman Barrett, working with a team at Mass General Hospital in Boston, has new research that suggests that the size of the amygdala correlates strongly with the number of close friendships that people maintain:
Ian Sample, Social whirl of a life? Thank your amygdala
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 relationship. For example, one friend might also be a boss, meaning the person had to adapt their behaviour with the person depending on the nature of their encounter.
The team, led by psychologist Lisa Feldman Barrett, found that participants with larger amygdalas typically had more people in their social lives and maintained more complex relationships.
Those with the smallest amygdalas listed fewer than five to 15 people as regular contacts, while those with the largest amygdalas counted up to 50 acquaintances in their social lives. Older volunteers tended to have smaller amygdalas and fewer people in their social group.
Writing in the journal, Nature Neuroscience, Barrett’s team cautions that the finding is only a correlation, meaning they cannot say whether there is a causal link between the size of the amygdala and the richness of a person’s social life. However, previous studies with primates show that those that live in large social groups also have bigger amygdalas. “People who have large amygdalas may have the raw material needed to maintain larger and more complex social networks,” said Barrett. “That said, the brain is a use it or lose it organ. It may be that when people interact more their amygdalas get larger. That would be my guess.
“It’s not that someone with a larger amygdala can do things that someone with a smaller amygdala cannot do. People differ in how well they remember people’s names and faces and the situation in which they met them. Someone with a larger amygdala might simply be better at remembering those details,” Barrett added.
Barrett’s conjecture about brain plasticity is supported by many other studies, like Eleanor Maguire’s research on London taxi drivers, showing that gaining ‘the knowledge’ of the city’s streets leads to the growth of the hippocampus.
Relative to Dunbar’s Number, it seems that general brain plasticity is at work again: those that exercise the amygdala — by having more close relationships, or by putting themselves in the context of meeting and knowing more people — are likely to ‘exercise’ the amygdala, allowing them to broaden and deepen their social awareness about larger numbers of people. This suggests that ‘theory of mind’ is a deep skill, like martial arts or playing an instrument.
If you want to become more deeply invested in a larger number of relationships, you need to work at it, and use tools that make it possible to do it at all.
I maintain that streaming apps like Twitter serve amplifiers of our social awareness: our theory of mind. Just like cooked food allowed early hominids’ diet to change, freeing them from the requirement of chewing for hours every day, streaming apps make it possible to remain meaningfully involved with a larger number of people than formerly possible, and probably increasing the size of our amygdalas.
Of course, these are deep skills, and will require 10,000 hours of practice before we will have achieved mastery. Roughly ten years of practice for a few hours daily.
Maybe I should have my amygdala scanned.