Gene CalamityJohn Carey
THE LAST HARVEST
The Genetic Gamble That Threatens to Destroy American Agriculture
By Paul Raeburn
Simon & Schuster 269pp $24
For all its vast natural resources, North America lacks one crucial asset--the genetic gold of food crops. Of the world's top 20 crops, including wheat, corn, and rice, not one has wild ancestors in the U.S. Harvests in America "are powered by foreign genes just as surely as our industry is powered by foreign oil," observes one expert quoted by Associated Press science writer Paul Raeburn in his provocative new book. What's more, the rest of the world isn't much better off.
That dependence brings the seeds of potential calamity, argues Raeburn. Food crops are constantly being threatened by new pests or plagues, from the fungus that caused the 1846 Irish potato famine to the leaf blight that wiped out 15% of the U.S. corn harvest in 1970. That's why breeders must keep adding genetic material from other varieties--or from wild ancestors--that can fight off threats better.
The problem, Raeburn writes, is that "vital genetic resources are disappearing with virtually no notice." For one thing, farmers in the U.S. and around the world are planting fewer crop varieties. Almost the entire U.S. potato harvest comes from just six types. In India, 30,000 traditional varieties ef rice have been largely replaced with only 10.
Just as ominous may be the extinction of the wild relatives of crops. Raeburn recounts the exciting 1977 find of an uncultivated corn plant in Mexico. But he points out that it could easily have gone extinct before the discovery.
Theoretically, such genetic gems can be preserved in seed banks. But Raeburn finds that many are falling down on the job. And if the loss of genes continues, "America's and the world's agriculture must ultimately suffer catastrophic losses," he concludes. "We will be unable to feed ourselves."
It's a sobering tale, marred only occasionally by hype. Along the way, Raeburn provides fascinating historical nuggets. Thomas Jefferson smuggled rice seeds out of Italy, an offense then punishable by death. Intrepid plant hunter Frank Meyer crossed deserts and fought brigands in order to bring back 2,500 new plants to the U.S. early in this century. And Russian botanists chose to starve rather than eat up the genetic treasure in Leningrad's seed bank during World War II. If Raeburn is right, that's the kind of dedication we need now to prevent gene loss from eventually causing mass starvation.