One of the claims of the so-called intelligent design (ID) movement is that some aspects of life are “irreducibly complex”, and so could not have evolved. An example often given is the eye, because it contains many parts (lens, iris, retina, optic nerve), and it will not work if even one is missing. The claim is that the eye could not have evolved one step at a time, since all components have to exist for the eye to work. Since it is highly unlikely that all these different components evolved together in one step, ID proponents claim a designer must have been at work.
Of course, this argument has been debunked many times. For example, there are simpler versions of the eye on such animals as the flatworm. Clearly a primitive eye that could just tell the animal if it was in light or shadow, would be of benefit. This hasn’t stopped ID proponents and their “irreducibly complex” argument, though. And the argument, although flawed, was difficult to prove wrong. Until now.
An article in February’s Discover Magazine describes how Scientists at Michigan State University have been running an experiment where digital organisms have evolved into irreducibly complex forms. (You’ll need a subscription to read the whole article.) This is what they did. They set up bits of computer code, similar to computer viruses, as kinds of digital organisms. Each digital organism was set up so it could produce tens of thousands of copies of itself within minutes. But this is what makes it interesting: their instructions were set up so they could mutate in a similar way to how DNA mutates. A software program called Avida allowed the scientists to record the complete lifecycle of generations of the mutated digital organisms – the complete history of their actual evolution.
Physicist Chris Adami of Caltech, set out to manipulate the environment to see if the organisms could evolve the ability to do addition. He took the basic digital organisms and:
at regular intervals presented numbers to them. At first they could do nothing. But each time a digital organism replicated, there was a small chance that one of its command lines might mutate. On a rare occasion, these mutations allowed an organism to process one of the numbers in a simple way. An organism might acquire the ability simply to read a number, for example, and then produce an identical output.
Adami rewarded the digital organisms by speeding up the time it took them to reproduce. If an organism could read two numbers at once, he would speed up its reproduction even more. And if they could add the numbers, he would give them an even bigger reward. Within six months, Adami’s organisms were addition whizzes. “We were able to get them to evolve without fail,” he says. But when he stopped to look at exactly how the organisms were adding numbers, he was more surprised. “Some of the ways were obvious, but with others I’d say, ‘What the hell is happening?’ It seemed completely insane.”
Not only had they evolved the ability to do addition, they had evolved to be irreducibly complex. For example, for a digital organism to add two numbers together, it would have to read the numbers, hold them in memory, add them, and hold the sum in memory or read it out. If any of these steps was removed, addition wouldn’t happen. This is what ID proponents say is impossible to evolve.
The scientists then decided to see if they could evolve even more complex operations. They set up an experiment to evolve the operation known as “equals”, which:
consists of comparing pairs of binary numbers, bit by bit, and recording whether each pair of digits is the same. It’s a standard operation found in software, but it’s not a simple one. The shortest equals program Ofria could write is 19 lines long. The chances that random mutations alone could produce it are about one in a thousand trillion trillion.
The scientists set up the experiment so that the organisms would replicate for 16,000 generations, and then performed this experiment 50 times. Startlingly, the “equals” function, which has at least 19 irreducibly complex steps, evolved in 23 of the 50 experiments. And, in line with evolutionary theory, all 23 successful evolutions were done in completely different ways.
The researchers made their software freely available on the Internet, and allowed creationists to download it to test it for flaws. Despite this army of highly motivated bug testers, no major flaws have been found. So, now that these creationists have proved for themselves that irreducible complexity can evolve, do you think they will drop this silly objection to evolution? OK, rhetorical question.
I really recommend anyone to get hold of the magazine and read the full article. (Take out a subscription – it’s not that expensive.) It's fascinating: I’ve only scratched the surface of the story here.