In a short and balanced review of Connected–”a scientific look at the ties that bind us together”–we are treated to some interesting findings on social networks and their myriad external effects–including how far these effects ‘travel’ through said networks.

Controlling for environmental factors and the tendency of birds of a feather to flock together […] Christakis and Fowler found that we really do emulate those we care about, whether we mean to or not. Being connected to a happy person, for instance, makes you 15 percent more likely to be happy yourself. “And the spread of happiness doesn’t stop there,” they note. It radiates out for three degrees of separation, so that, say, your sister’s best friend’s husband’s mood exerts a greater influence on your personal happiness than an extra $10,000 in income would. If he gains 50 pounds, it will be that much harder for you to stay slim, as the frame of reference for what’s “normal” changes through your network. Or, on the positive side, if he quits smoking, your chances of kicking the habit improve, too, even if you’ve never met him. […]

Public health workers can more effectively stop the spread of sexually transmitted diseases if they know what kind of network they’re dealing with: a hub and spoke (e.g., a prostitute with many clients) or a more transitive “ring” network where people have few partners, but many of these partners overlap (which could happen at a small high school). On another front, they point out that voting makes little sense for an individual—one vote never decides an election—but is far more rational in a network context. As with happiness and obesity, the decision to vote has repercussions through three degrees of connections. […] Since liberals and conservatives tend to form their own social networks, this means that your decision to vote can increase the likelihood of hundreds of other people voting for the same candidate.

I do wonder if these degrees of separation that exert influence on us fluctuate with the size of each ‘degree’?