(FORTUNE Magazine) – Last June, Gordon Conway, a scholarly British ecologist, walked into the Willard Hotel in Washington, D.C., for a momentous meeting with Monsanto's board. The company had invited him for a private talk about the growing furor surrounding its genetically modified, or GM, crops. It expected to get friendly advice from a biotech supporter--Conway is president of the Rockefeller Foundation, which has funded $100 million of research on bioengineered crops to help farmers in the developing world. Instead, Conway delivered a stinging rebuke.

In an eloquent speech, the scientist all but charged Monsanto with hubris--in the rush to market GM cotton, soybeans, and corn, he said, it and other purveyors had given short shrift to legitimate concerns about bioengineered crops and generated a backlash. He urged the company to make major policy changes and to forgo the use of "terminator" technology, GM plants that bear sterile seeds so that farmers are forced to buy new seeds every year. The next day Conway stunned Monsanto by going public with his recommendations. Given Conway's stature and his well-known pro-biotech leanings, the move put more heat on the company than reams of tabloid hysteria about "Frankenfoods."

Monsanto responded with a curt release saying that it had had a "frank and productive" talk with Conway--PR-speak for "infuriating confrontation." But a few weeks later, CEO Robert Shapiro promised in an open letter to Conway not to commercialize terminator technology. Then Shapiro echoed many of Conway's criticisms in a conciliatory speech to attendees at a Greenpeace meeting: "Too often we forgot to listen," he admitted.

Gordon Conway has emerged as the global food fight's leading centrist. He continues to play industry gadfly, but also has taken anti-GM zealots to task for spouting alarmist hype. Like Monsanto, they can't dismiss him as a tool of the other side. Conway happens to be a hero of the Green Revolution, the agricultural movement that more than doubled the Third World's crop yields after 1960. He spent more than 30 years in places like Borneo, India, and Thailand helping mastermind ecologically sound farming. Conway spearheaded "sustainable agriculture," a set of practices for controlling pests and boosting yields without heavy reliance on chemicals. FORTUNE's David Stipp interviewed him at his office in Manhattan to get his take on where the biofoods debate is headed:

You've spent much of your career advancing the cause of groups like Greenpeace in the developing world. Yet you sharply disagree with them about bioengineered crops. Why the parting of the ways?

We've got 800 million chronically malnourished people in the world, and we'll have about 1.6 billion more by 2020. That's over two billion more mouths to feed if everyone's going to have a decent life. We're going to need two approaches to do this. One is ecologically sound agriculture. The other is biotechnology.

Some activists argue that there's enough food in the world, and it's just a matter of distribution. But that's naive. I don't see any signs that the wealthy of the world are about to distribute their wealth. In general, aid to developing countries is declining rapidly.

The increases in crop yields we saw during the Green Revolution are slowing. They're now about half of what we saw at the peak. In some places, yields are dropping. The banana crop in Uganda and East Africa is virtually collapsing because of viruses, nematodes, and other pests. Bananas are a staple food in those countries, so it's a desperate problem. We think biotechnology could help solve it, perhaps by inserting pest-resistance genes in bananas.

About 100 million children in the developing world suffer from vitamin A deficiency, and each year some two million die as a result. Recently a Swiss researcher with Rockefeller funding introduced genes that produce beta-carotene, the precursor of vitamin A, in the rice grain. It contains sufficient beta-carotene to meet human vitamin A requirements from rice alone. Conventional plant breeding had been unable to do that.

If we're careful, biotech can help get rid of poverty and a great deal of illness in a way that's environmentally friendly.

What about activists' assertion that GM seeds sold by companies like Monsanto have little to do with feeding the world--and everything to do with dominating seed markets?

I've told the companies they shouldn't claim their biotech products will feed the world. Their interest is in crops that provide a significant return on investment. The only developing nation where they seem to be making money is China, where millions of acres have been planted with Bt cotton [which produces its own insecticide]. From everything we've heard, Bt cotton is doing spectacularly well in China. Yields have gone up, it's reduced the number of pesticide sprayings from about 12 to three per season, and pesticide poisoning is falling.

But when you talk about improving maize, rice, millet, sorghum, cassava, and all the other basic crops of small farmers in the developing world, biotech companies aren't very interested. That has to happen with public money. Still, researchers working on these crops are using many technologies developed in the private sector. If the GM controversy caused a real curtailment of private investment in biotech, a lot of the potential for using it in the developing world would be lost.

The concern about big companies capturing seed markets is legitimate. But I get irritated by critics who claim organic farming can feed the developing world. I had a meeting with President Mugabe [of Zimbabwe] two months ago. He said to me, "The Prince of Wales tells me we can feed Africa with organic food. What do you think?" I said, "Look, to do that, you need organic matter to continually put into the soil. At the moment, your crop yields are far too low to provide much left-over stalk to put back. Your livestock are not very fit and produce poor-quality manure--much of which is burned for fuel. Fifteen years from now you might be able to afford the luxury of organic farming, but only if you first put a large quantity of nitrogen into the soil with inorganic fertilizers out of bags."

What are the biggest risks posed by GM crops?

The most serious environmental risk is the possibility that implanted genes, such as those for herbicide resistance, will escape from cultivated crops into wild relatives, resulting in the production of super-weeds. It's not clear that escaped genes would remain in wild relatives and cause adverse ecological effects. Only extensive field tests will give us answers on this.

Another risk is the potential for pests to evolve resistance to Bt [an insecticide produced by a number of GM crops]. There are some well-known counterstrategies, but experience indicates they eventually will fail. So we need to carefully monitor insect pests for resistance and continuously develop alternative control strategies.

A third hazard is that crops such as Bt corn will harm beneficial insects. Recently pollen from Bt corn was shown to kill caterpillars of the Monarch butterfly. In the not-too-distant future, this problem will be avoidable by genetic techniques to prevent the expression of Bt in pollen. Nevertheless, this case demonstrates the need for more detailed monitoring of the effects of Bt crops.

How about human health risks?

Allergies are the most significant one. Transferring genes from one plant to another may introduce new allergens in foodstuffs. Known allergens can be tested for, but there may be surprises.

Other fears have less scientific basis. There's no a priori reason to suppose that ingesting pieces of DNA transferred from one plant to another is any more hazardous than ingesting the large amounts of DNA we get every day from numerous sources in normal diets. And the risks of GM foods seem pretty low compared to those posed by aflatoxin [a potent carcinogen] and E. coli [toxic bacteria] sometimes found in normal foods. Are organic peanuts guaranteed to be free of aflatoxin?

European consumers, especially in Britain, have eagerly jumped on the anti-GM bandwagon, while so far those in America haven't. Why?

One factor is worry in Europe about domination of the food chain by American companies. That partly explains why Monsanto managed to fall into the role of devil incarnate. Of course, this conveniently ignores the fact that some of the chief developers of GM technologies are based in Europe.

Another reason is that the U.S. is a very hazardous place. You have hurricanes. You have tornadoes. You have rattlesnakes. You have all kinds of tick-borne fevers. You have 250 million guns. In contrast, the sole hazard in Britain is one very rare poisonous snake. That's it. Period. It's a well-manicured country. So the American population is used to living with hazards. Most Americans are more worried about getting shot than the remote chance that some GM ingredient in food is going to affect their health.

All this makes GM risks loom larger in Europe. But there are certain paradoxes about that. When it comes to the risks of global warming, Greenpeace says that scientists are absolutely right. Yet when some of the same scientists have called for moderation on the GM issue, Greenpeace has ignored them. The classic example is Sir Robert May, the British government's chief scientist. He strongly argues that we're causing global warming and should do something about it. He also strongly argues that GM has great benefits, and we should stop being hysterical about it.

You've chided Monsanto and other GM-seed developers for mistakes that could set back crop biotech for years. What have they done wrong?

In some cases there should have been more testing before products were brought to market. Certainly, with Bt corn the companies should have known a number of adverse effects might arise, such as harm to butterfly caterpillars.

The companies' really big mistake, though, was to concentrate on things that had no benefit to the consumer. They started with pest- and herbicide-resistant crops--products with potential risks and no consumer benefits. It's not illogical for consumers to say they don't want them.

In retrospect, I think they should have started with something like low-cholesterol eggs from free-range chickens!

Perhaps your most controversial stand, from industry's point of view, is that GM-containing foods should be labeled. What's your answer to the argument that labels would provoke undue consumer alarm?

If food companies had labeled from the beginning in Europe, they wouldn't have a problem there. What people really object to is being exposed to risks without their choice. This is why I support labeling--not because I think GM foods pose significant health risks, but because it's a freedom-of-information issue. I got a flu shot yesterday--probably too late. Before I got it, I had to read this thing that said at the bottom, "You may have adverse reactions, including death." I thought, "Oh hell." Then I signed it. The point is that we don't mind taking all sorts of risks if we have a choice. Industry eventually will get dragged, kicking and screaming, into labeling. But by then it will be too late--there will be a lot of unnecessary consumer fear, and that will be a sad thing.

Recently you convinced your board to earmark $3 million to promote a "global dialogue" on GM crops. Do you see much hope for reason to prevail in this messy food fight?

There's room for consensus and win-win situations. For instance, Monsanto has a gene that can protect against a potato virus that's common in Mexico. The company is selling seed potatoes with this gene to commercial growers in Mexico's lowlands. We've helped arrange to have the technology donated to nonprofit breeders, grantees of ours, who are putting the gene into potatoes that small farmers in the uplands grow. In theory, everybody will win--as the small farmers in the hills realize the benefits, they eventually will become more prosperous and become part of the market for the commercial seeds. We're working on several other cases like this; more should be announced soon.

In addition, we're instigating fora that will bring together all the stakeholders--government people, consumer groups, scientists, environmentalists, people from developing countries. We're not trying to control anything. But outrageous statements tend to get toned down when people can sit in a room and ask their opponents, "Exactly what do you mean?" There's a whole raft of people who are thoughtful about GM issues whose views need to be heard. Not all environmental groups dismiss biotech out of hand.

How do you think the controversy will unfold over the next few years?

My guess is that sales of GM seeds will fall off some, and private development of GM crops will slow down. I don't think that will be a bad thing. The companies will concentrate on second-generation products, such as the one I described that would make Bt corn less likely to harm beneficial insects. We'll also see more work on increasing the nutritive value of foods. It will be a classic case of the second generation being safer and better than the first.

If the market for GM crops really collapses in the industrialized world, and the technology's development is sharply curtailed, there's one country that will continue to invest heavily in it and potentially emerge as the world leader. That's China. China needs this technology desperately, and it's not going to give it up.

Eventually the furor will die down. You have to understand that groups like Greenpeace are like multinational companies. They have offices all around the world. And they have sales and products. They're in the business of campaigns. The GM issue is their big campaign at the moment. After a while they'll move on to a new one.

Meanwhile, nonprofit groups and the developing world will continue to invest in biotech. As part of our focus on Africa, we're planning to fund more research on genes that make crops resistant to drought. We'll also continue to work on combining public and private interests to make sure the poor farmers of the world benefit from biotech. That's the real prize in all this. Giving up on it would be crazy.