At first, I attributed this tendency to the “population explosion” and the relentless Malthusian logic that if twice as many people inhabit the planet now as did twenty years ago, each of us has half as much space. Recently, I’ve wondered if it’s the season: T-shirt weather ________make proximity more alluring (or much, much less). Or perhaps the proliferation of coffee bars in Manhattan — the number seems to double every three months — is infusing so much caffeine into the already jangling locals that people can no longer keep to themselves .