Everybody Loves Virii

The release of the Facebook programming platform sparked a new gold rush for the web. All of a sudden the blogosphere was humming with promises of riches in them 'thar hills, and programmers descended on Facebook in thick swarms. Now that the dust has started to settle, there are 18,553 Facebook Apps, and if you decided to install one new Facebook App a day, just, y'know, to check it out, it would take you more than 50 years to go through them. What's up with the frenzy?

Facebook apps are a prime example of Granovetter's theory. They spread through both strong and weak links but what actually enables them to spread to the widest audience is through bridges. Whenever you log in to Facebook, your home page/feed automatically inundates you with information about any of your "friends", who may or may not be actual friends. While you already share interests and therefore know about what your close friends are doing, what groups they're joining or applications they are downloading, it is through your weak links that you find more applications that you probably wouldn't have heard of before.

The viral spread of Facebook Apps neatly avoids one of the fundamental trip-wires of digital viruses (or evolutionary replicating programs). The weakest link in any algorithmic evolutionary scheme is always the so-called "fitness function" — the equation that maps certain characteristics of the program to its chances of surviving until the next round. In most systems, like Tierra, like Alife, like ECJ, you must mechanically, algorithmically, mindlessly determine whether your critters will live or die. For Facebook Apps, their future is fundamentally indeterminate: maybe they'll catch on with the cool kids in the right clique, maybe not; maybe they'll find a passionate advocate who can't wait to spread it to all their friends, maybe they'll be surpassed by a competitor's rival version on day two. Because human desire rules the fitness function, Facebook Apps will not only continue to spread and grow virally, but will also display an astonishing diversity of functionality and form. More like a virus in nature than a virus in some formal system.

— Su-Yee Lin and Jeremy Ashkenas