Robin Dunbar came up with his eponymous number almost by accident. The University of Oxford anthropologist and psychologist (then at University College London) was trying to solve the problem of why primates devote so much time and effort to grooming. In the process of figuring out the solution, he chanced upon a potentially far more intriguing application for his research. At the time, in the nineteen-eighties, the Machiavellian Intelligence Hypothesis (now known as the Social Brain Hypothesis) had just been introduced into anthropological and primatology discourse. It held that primates have large brains because they live in socially complex societies: the larger the group, the larger the brain. Thus, from the size of an animal’s neocortex, the frontal lobe in particular, you could theoretically predict the group size for that animal.
Looking at his grooming data, Dunbar made the mental leap to humans. “We also had humans in our data set so it occurred to me to look to see what size group that relationship might predict for humans,” he told me recently. Dunbar did the math, using a ratio of neocortical volume to total brain volume and mean group size, and came up with a number. Judging from the size of an average human brain, the number of people the average person could have in her social group was a hundred and fifty. Anything beyond that would be too complicated to handle at optimal processing levels. For the last twenty-two years, Dunbar has been “unpacking and exploring” what that number actually means—and whether our ever-expanding social networks have done anything to change it.
The Dunbar number is actually a series of them. The best known, a hundred and fifty, is the number of people we call casual friends—the people, say, you’d invite to a large party. (In reality, it’s a range: a hundred at the low end and two hundred for the more social of us.) From there, through qualitative interviews coupled with analysis of experimental and survey data, Dunbar discovered that the number grows and decreases according to a precise formula, roughly a “rule of three.” The next step down, fifty, is the number of people we call close friends—perhaps the people you’d invite to a group dinner. You see them often, but not so much that you consider them to be true intimates. Then there’s the circle of fifteen: the friends that you can turn to for sympathy when you need it, the ones you can confide in about most things. The most intimate Dunbar number, five, is your close support group. These are your best friends (and often family members). On the flipside, groups can extend to five hundred, the acquaintance level, and to fifteen hundred, the absolute limit—the people for whom you can put a name to a face. While the group sizes are relatively stable, their composition can be fluid. Your five today may not be your five next week; people drift among layers and sometimes fall out of them altogether.
But, the truth is, no one really knows how relevant the Dunbar number will remain in a world increasingly dominated by virtual interactions. The brain is incredibly plastic, and, from past research on social interaction, we know that early childhood experience is crucial in developing those parts of the brain that are largely dedicated to social interaction, empathy, and other interpersonal concerns. Deprive a child of interaction and touch early on, and those areas won’t develop fully. Envelop her in a huge family or friend group, with plenty of holding and shared experience, and those areas grow bigger. So what happens if you’re raised from a young age to see virtual interactions as akin to physical ones? “This is the big imponderable,” Dunbar said. “We haven’t yet seen an entire generation that’s grown up with things like Facebook go through adulthood yet.” Dunbar himself doesn’t have a firm opinion one way or the other about whether virtual social networks will prove wonderful for friendships or ultimately diminish the number of satisfying interactions one has. “I don’t think we have enough evidence to argue either way,” he said.
One concern, though, is that some social skills may not develop as effectively when so many interactions exist online. We learn how we are and aren’t supposed to act by observing others and then having opportunities to act out our observations ourselves. We aren’t born with full social awareness, and Dunbar fears that too much virtual interaction may subvert that education. “In the sandpit of life, when somebody kicks sand in your face, you can’t get out of the sandpit. You have to deal with it, learn, compromise,” he said. “On the internet, you can pull the plug and walk away. There’s no forcing mechanism that makes us have to learn.” If you spend most of your time online, you may not get enough in-person group experience to learn how to properly interact on a large scale—a fear that, some early evidence suggests, may be materializing. “It’s quite conceivable that we might end up less social in the future, which would be a disaster because we need to be more social—our world has become so large” Dunbar said. The more our virtual friends replace our face-to-face ones, in fact, the more our Dunbar number may shrink.
Ever feel like you need to make out with someone?
Deeply, passionately, aggressively.
Until you’re warm from the inside out, you’re face is flushed, your lips are swollen and sore from all the contact and biting. Fingers knotted up in the other ones hair, heart racing. You know, that kind of thing?
I JUST REALIZED WE DON’T EVEN KNOW WHAT DINOSAURS SOUND LIKE! THEY COULD’VE BEEN SPEAKING FLUENT GERMAN FOR ALL WE KNOW
it’s too early for this late night tumblr shit
GUTEN MORGEN HERR PTERODACTYL
WIE GEHTS FRAU MASTADON
Oh my god neither of those are dinosaurs and there’s 145 million years separating them both, this post is a palaeontological disaster.