Several years ago, therefore, Robin Dunbar, an anthropologist who now works at Oxford University, concluded that the cognitive power of the brain limits the size of the social network that an individual of any given species can develop.

ECONOMIST: Even online, the neocortex is the limit

Lucina Uddin, a cognitive neuroscientist at Stanford, and her colleagues are now studying whether brain imaging of this network can serve as a biological marker of autism in kids.

WSJ: When Social Skills Are a Warning