There appear to be hard limits on the soft power of friendship. In an article in The Economist last week, Facebook’s “in-house sociologist” has revealed some interesting data about behavior on the social networking site. It turns out that the average Facebook user has 120 friends in his or her network. That figure roughly corresponds to the “Dunbar number,” a hypothetical limit on the human brain’s capacity for social networks, which peaks at around 148 people. Significantly, the average Facebook man interacts with only seven of his friends on a deeper basis, by responding to postings and leaving messages of his own. The average Facebook woman is more social—but her circle of genuine friends closes for serious business at around 10.

Curiously, we’ve seen that ratio—120 options, with little more than a handful regularly selected—on display in another venue. The average American home receives 119 television channels. Yet we watch, on average, only 16 of them. The excess channels are like casual friends on Facebook: available, but not really where we want to invest our time. Whether the emotional staple is entertainment or friendship, it seems there are limits, biological or otherwise, to our appetite for more. If our brains impose a natural restraint on social networks, and shun the promiscuity of the satellite TV menu, perhaps other limits, now hidden, may ultimately be revealed to us, as well. The very idea that choice and human capabilities have boundaries seemed like defeatist heresy not long ago. But today, as we begin to dig our way out of a global collapse occasioned by seemingly infinite greed and bottomless stupidity, limits have never been more appealing. - Francis Wilkinson