Scientists at Michigan State University and Caltech have developed a speeded-up computer model of evolution that proves that "irreducible complexity" can arise from random mutation and natural selection -- so says Discover Magazine's cover story: [Subscribers only, alas, but if you're fascinated by these questions it's worth buying the magazine to read it.]
These are digital organisms—strings of commands—akin to computer viruses. Each organism can produce tens of thousands of copies of itself within a matter of minutes. Unlike computer viruses, however, they are made up of digital bits that can mutate in much the same way DNA mutates. A software program called Avida allows researchers to track the birth, life, and death of generation after generation of the digital organisms by scanning columns of numbers that pour down a computer screen like waterfalls.
The researchers wanted to see whether these "digital organisms" could evolve the ability to perform certain operations with numbers, operations a human programmer could only compose out of at least 19 lines of code. In order to do a complex operation, such as adding numbers or comparing them, a digital organism first has to be able to perform simpler steps, such as reading a number and holding it in memory. Knock out any one of those steps, and the complex operation is impossible. This is "irreducible complexity," analogous to the way the lens, iris, retina and vitreous humor of a human eye work together, and if one component is removed the whole can't work.
Whenever random mutation produced a "digital organism" that could perform any one of these simple steps, the scientists "rewarded" it the way natural selection does: by speeding up its reproduction. More complex operations got bigger "rewards." In their first experiment, out of 50 trials of 16,000 generations each, the "organisms" evolved the ability to perform the ultimate operation 23 times -- in 23 different ways. (Think of the eyes of an octopus, a bee, and a human -- each produces an image, but by very different means.) Even more startling, when the researchers limited the supply of "food" -- i.e., numbers -- thus increasing the "competition," every trial produced "organisms" that could carry out the complex routine, and they got there five times faster. And there's even weirder stuff than that.
Avida software can be downloaded for free, and lots more information is available, at Caltech's Digital Life Laboratory. According to the Discover article, numerous "creationists" (more likely Intelligent Design advocates) have downloaded the software and tried to find flaws in it; so far, none have. Well, gentlemen, what do you have to say for yourselves?
UPDATE: Here's what they have to say for themselves.