In a recently released Big Questions Essay, Rabbi Jonathan Sacks comments on the seemingly unnatural selection that produces altruistic progeny. "The paradox is that selfish genes get together to produce selfless people." But when you look at emergent behavior, counterintuitive results often prevail. And as the Web has proven time and again, aggregating the selfish behavior of the individual can result in invaluable good for the whole.
In his talk "Design for the Wisdom of Crowds," Derek Powazek admonishes developers to "design for selfishness" pointing out the example of photo-sharing site Flickr, which takes the selfish act of tagging and turns it into one of the site's most useful features. When I upload a photo of an apple to Flickr, I "tag" that photo with the word "apple," typing that word into a field provided. I do this not so that other people can find the photo (at least, that need not be my motivation). I do it so I can find the photo later when I want to see it again. But because of the way Flickr is designed, someone I've never met can see a a multitude of different pictures of different apples simply by searching for that tag on Flickr because a whole lot of selfish people like me have also added that tag to their photo of an apple.
There are many examples of this in the virtual space, but they all reflect the same tendency of the Web to be very good at aggregating behavior to produce a result that, at the individual level, was never intended but can be of great benefit to others. Put simply, the Web creates ad hoc altruism.