Why environmentalists should be concerned: humans have dangerously destabilized the Earth's ecological system. If we now begin altering our evolved interdependence with nature, we will only accelerate the destabilization.

• Author: McKibben, Bill
• Position: Environmentalists

It's not as if environmentalists really need something new to worry about. The planet's temperature is set to rise four or five degrees--every glacial system is already in rapid retreat, and icebergs measured in units of U.S. states (the size of Rhode Island!) are calving off the Antarctic. Species disappear daily; acid rain; and you know the whole damn litany. We could be forgiven for wanting to take a pass on human genetic engineering.

And yet I think it may turn into the single greatest battle environmentalists have ever fought, the one for which the Grand Canyon and the African elephants and Amazon deforestation and Love Canal were preparing us. The real test.

Some of the reasons for thinking so are pragmatic. Changing the human germline is an almost preposterous override of the precautionary principle, the idea that if you don't know something's safe you shouldn't do it. We have rushed with blinding speed through the first phases of the biotechnological revolution--what was experimental a decade ago now grows in half the corn and soybean fields on this continent. Now we seem bent on going just as fast with our plans to tweak the human genetic code that until now we have hailed as nature's finest achievement--already teams are competing to produce the first human clone, a precursor of genetic enhancement. The ideas come thick and fast, from visionaries who foresee improving the intelligence of our offspring, or increasing their muscle mass, or bettering their character. In the words of James Watson, the first director of the Human Genome Project and co-discoverer of the double helix, "If we could make better human beings by knowing how to add genes, why shouldn't w e? What's wrong with it?"

For environmentalists with a sense of history, such words recall earlier promises of grand utopias: power "too cheap to meter" from nuclear plants. What we know about how human genetics works is dwarfed by what we don't know--and experimenting on our own genetic heritage seems unwise to say the least. If history is any guide, the experiment will come with dubious side effects, likely to be visited upon the weakest and poorest parts of society. If internal combustion, a century later, yields global warming, then what does this crash course in scientific breeding promise? At the very least, the demand that we exploit this technology immediately seems suspect (except to the venture capitalists who have made the investments). Which is not to say the...