I’m reading The Happiness Hypothesis by Jonathan Haidt and came across a fascinating and suggestive couple of paragraphs about brain size and social networks.

Robin Dunbar has demonstrated that within a given group of vertebrate species — primates, carnivores, ungulates, birds, reptiles, or fish — the logarithm of the brain size is almost perfectly proportional to the logarithm of the social group size. In other words, all over the animal kingdom, brains grow to manage larger and larger groups. Social animals are smart animals.

Dunbar points out that chimpanzees live in groups of around thirty, and like all social primates, they spend enormous amounts of time grooming each other. Human beings ought to live in groups of around 150 people, judging from the logarithm of our brain size; and sure enough, studies of hunter-gatherer groups, military units, and city dwellers’ address books suggest that 100 to 150 is the “natural” group size within which people can know just about everyone directly, by name and face, and know how each person is related to everybody else.

One scientist’s research is not settled fact, of course, but this sounds right. And it makes me think of how quickly social media became popular: Sites like FaceBook and LinkedIn became successful so quickly, I think, because they truly suit the needs of our times. We live in a populous world and need to keep track of a never-ending stream of acquaintances, clients, customers, associates, former coworkers, and school friends. Our brains just can’t handle so many connections.

We need extra help.

The thing is, people use these social networking tools to do what people love to do most – talk about people.

Dunbar notes that people do in fact use language primarily to talk about other people — to find out who is doing what to whom, who is coupling with whom, who is fighting with whom. And Dunbar points out that in our ultrasocial species, success is largely a matter of playing the social game well.

Doctors and other medical professionals need to be part of this social game. Otherwise, they’re not part of the discussion – and not in control of their reputation.