The Day I Played God

By Philip Elmer-DeWitt

In the beginning I created the heavens and the earth -- well, almost. I actually started with a lump of molten rock, gave it a hundred million years or so to cool off and then began to form the clear blue oceans and the landmasses that would eventually become continents. After a few billion years had gone by (it seemed like minutes to me), I created the first life-forms and triggered the start of their long evolution. Before I knew it, my world was filled with thousands of self-replicating molecules, millions of one-celled organisms, whole armies of invertebrates, crustaceans and primitive mollusks. What on earth had I done?

The name of this computer exercise is SimEarth -- The Living Planet, a new $69.95 disk for Macintosh computers that offers something no other program can. It not only shows how life may have evolved on earth, but it also let me do the one thing I've always wanted to do: play God.

And what a feeling it was! By pointing and clicking my electronic mouse, I could pick up a square of green from one corner of the screen, drop it on a barren stretch of land and watch it blossom into a prairie. I could sprinkle the forest primeval with dinosaurs, insects and birds. I could fill the seas with starfish, lobsters and whales. I could rattle my little planet with computer-generated earthquakes and hurricanes.

In SimEarth, as in the real world, the great natural processes that shape the environment -- volcanoes, erosion, continental drift -- interact with one another. Climate, vegetation and geology are represented as interrelated systems, each with controls that can be adjusted. Animals multiplying too fast? Just crank down the reproduction dial. Tired of waiting for evolution to work its wonders? Just speed up the mutation rate. Earth getting too hot for its own good? Just turn off the greenhouse effect.

Things really get interesting when the creatures on my pet planet develop intelligence. The program is set up so that the beings that become smart are not necessarily human. They can as easily be dolphins or spiders. In one game I played, it was a lizard that discovered fire. Africa was soon littered with Stone Age reptile cities.

Whatever animals get the gift of intelligence, it is the player's job to nurture and protect them, guiding their technological development by directing investments in science, medicine, agriculture and the arts. But playing the Almighty, I discover, is complicated -- and dangerous. Skimp on medical research, and your SimEarthlings are pestered by plagues. Cut back in the philosophy department, and wars break out. Let the master race linger too long in the industrial age, and the planet is choked with pollution. If, on the other hand, you steer your beings adroitly toward the ages of information and nanotechnology (molecule building), they will spontaneously load themselves into tiny spacecraft, turn the earth into a wildlife preserve and take off to colonize other planets -- the closest thing to "winning" this game.

Scientists will point out that almost every one of the program's premises is subject to debate, from its assumption that life must be based on carbon (rather than, say, silicon) to its noticeable bias against nuclear energy. The program also assumes that technology always advances and that intelligence always confers an evolutionary advantage. "We may be flattering ourselves," says the program's designer, Will Wright.

The most controversial aspect of the SimEarth model may be its reliance on the so-called Gaia hypothesis, a theory of evolution that views the earth as a single organism with various feedback mechanisms to maintain conditions suitable for life. In SimEarth this means that as the heat from the sun increases 25%, as it has during the past few billion years, changes will automatically occur in factors like the rate of cloud formation to keep the surface temperature relatively stable. The feedback loops appear most valuable when they are turned off, as they were when I played in the "hard game" mode. Suddenly, rather than "playing" God, I found myself working overtime to keep my oceans from boiling away, my jungles from bursting into flame and my populations from suffering yet another mass extinction. SimEarth may turn out to be Gaia's best advertisement. If God had to adjust all these systems by hand, he'd never get a day of rest.