Skip to main content
No. 263:
Un-natural Selection

Today, a computer visits the Garden of Eden. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

A story was popular 20 years ago, when computers were young. A programmer asked his computer, "Is there a God?" The machine hummed for an hour. Then a page of output emerged with three words on it: "There is now," the computer told its programmer.

Since then the public has become more familiar with computers. We're far less inclined to assign godlike, or even human-like, qualities to them. No more Hal from the movie 2001. Computers are classy tools but not machines that threaten to replace us or take us over.

Yet while our concern has abated, a scientist at Oxford University, Richard Dawkins, has created a disturbing computer simulation. He peoples the computer screen with little protozoan animals -- and with food particles. These little mathematical pac-men scoot about, their motions dictated by built-in probabilities. They go one way, then switch directions. Each one has its own set of probabilities. Every now and then one bumps into a food particle. But if it goes too long without food, it dies.

Dawkin's little animals can also reproduce -- but only when they're well fed. When they do, their offspring inherit similar, but not identical, probabilities for their movements.

The outcome of the experiment varies with the food supply. When food is plentiful, animals that keep shifting direction randomly do the best. But when food is scarce, the ones that move in long straight lines are more likely to find it. Then the more jittery ones bounce around in one place and starve.

We learn that natural selection breeds one kind of computer animals when they're well-fed and quite another when they're hungry. Once a species has evolved, Dawkins makes a change. He creates little patches of plenty -- he calls them Gardens of Eden. Now the survivors evolve a different movement -- the ones that keep turning in one direction have the best chance of finding food.

This computer is not some super-being, sprung complete and half-human from a writer's mind. Yet these modest little experiments somehow strike even closer to the bone of our being. Dawkins's computer may not be trying to take over humankind, but it is trying to relive the first life on Earth.

Maybe when all's said and done, this computer really is helping to control us, but not in the sense we've been talking about. This computer is helping us understand ourselves. And understanding ourselves is the first step on the road to self-control.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Dewdney, A.K., Computer Recreatons. Scientific American, May, 1989.