Thursday, August 04, 2011

food for thought

Most of us in the well-fed world give little thought to where our food comes from or how it's grown. We steer our shopping carts down supermarket aisles without realizing that the apparent bounty is a shiny stage set held up by increasingly shaky scaffolding. We've been hearing for some time about the loss of flora and fauna in our rain forests. Very little, by contrast, is being said or done about the parallel erosion in the genetic diversity of the foods we eat. The world has become increasingly dependent upon technology-driven, one-size-fits-all solutions to its problems. Yet the best hope for securing food's future may depend on our ability to preserve the locally cultivated foods of the past.

In the United States an estimated 90 percent of fruit and vegetable varieties have vanished. Of the 7,000 apple varieties that were grown in the 1800s, fewer than a hundred remain. In the Philippines thousands of varieties of rice once thrived; now only up to a hundred are grown there. In China 90 percent of the wheat varieties cultivated just a century ago have disappeared. Experts estimate that we have lost more than half of the world's food varieties over the past century. As for the 8,000 known livestock breeds, 1,600 are endangered or already extinct. Why is this a problem? Because if disease or future climate change decimates one of the handful of plants and animals we've come to depend on to feed our growing planet, we might desperately need one of those varieties we've let go extinct.

One of wheat's oldest adversaries, Puccinia graminis, a fungus known as stem rust, is spreading across the globe. The pestilence's current incarnation is a virulent and fast-mutating strain dubbed Ug99 because it was first identified in Uganda in 1999. It then spread to Kenya, Ethiopia, Sudan, and Yemen. By 2007 it had jumped the Persian Gulf into Iran. Scientists predict that Ug99 will soon make its way into the breadbaskets of India and Pakistan, then infiltrate Russia, China, and—with a mere hitch of a spore on an airplane passenger's shoe—our hemisphere as well. Roughly 90 percent of the world's wheat is defenseless against Ug99. Were the fungus to come to the U.S., an estimated one billion dollars' worth of wheat would be at risk. Scientists project that in Asia and Africa alone the portion of wheat in imminent danger would leave one billion people without their primary food source.

It took more than 10,000 years of domestication for humans to create the vast biodiversity in our food supply that we're now watching ebb away. Selectively breeding a wild plant or animal species for certain desirable traits began as a fitful process of trial and error motivated by that age-old imperative: hunger. Wild wheat, for example, drops its ripened kernels to the ground, or shatters, so that the plant can reseed itself. Early farmers selected out wheat that, due to a random genetic mutation, didn't shatter and was thus ideal for harvesting.

Farmers and breeders painstakingly developed livestock breeds and food crops well suited to the peculiarities of their local climate and environment. Each domesticated seed or breed was an answer to some very specific problem—such as drought or disease—in a very specific place. The North American Gulf Coast Native sheep, for example, thrives in high heat and humidity and has broad parasite resistance. On the remote Orkney Islands, North Ronaldsay sheep can live on nothing but seaweed. Zebu cattle are more resistant to ticks than other cattle. In Ethiopia a small, humpless, short-horned cattle breed called the Sheko is a good milk producer that withstands harsh conditions and has resistance to sleeping sickness. Such adaptive traits are invaluable not only to local farmers but also to commercial breeders elsewhere in the world. Finnsheep, for example, long raised only by a small group of Finnish peasants, have become vital to the sheep industry because of their ability to produce large litters. The Fayoumi chicken, an indigenous Egyptian species dating back to the reign of the pharaohs, is in great demand as a prodigious egg layer with high heat tolerance and resistance to numerous diseases. Similarly, the rare Taihu pig of China is coveted by the world's pig breeders for its ability to thrive on cheap forage foods and its unusual fertility, regularly producing litters of 16 piglets as opposed to an average of 10 for Western breeds.

The drive to increase production is pushing out local varieties, diluting livestock's genetic diversity in the process. As a result, the world's food supply has become largely dependent on a shrinking list of breeds designed for maximum yield: the Rhode Island Red chicken, the Large White pig, the Holstein cow. In short, in our focus on increasing the amount of food we produce today, we have accidentally put ourselves at risk for food shortages in the future. Current efforts to increase food production in the developing world—especially in Africa, largely bypassed by the green revolution—may only accelerate the pace at which livestock breeds and crop species disappear in the years to come.

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