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.
Study shows 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.