Crops were first developed in the Middle East about 11,000 years ago. Ever since, farmers have bred new crop varieties, resulting in great diversity.
About 3,000 plant species have been used as food at one time or another. Some 75,000 - more than a quarter of all known species - are edible. And yet only 15-20 are of major economic importance in today's globalized agriculture. Wheat, rice and maize provide half the world's food; along with barley, they occupy about 500 million hectares worldwide.
Since 1900, about 75 per cent of the genetic diversity of agricultural crops has been lost. India now has fewer than 50 rice varieties, where once it had 30,000.
It is a similar story for livestock. More than 40 mammal and bird species have been domesticated, 12 of them now important for global agriculture. Cattle, pigs, goats and sheep - the four main mammalian livestock species - have diversified into more than 4,000 recognized breeds, but many of these are also being lost.
Half of the animal breeds farmed in Europe in the 1900s are now extinct. Of the 3,800 breeds of cattle, water buffalo, goats, pigs, sheep, horses and donkeys catalogued by the Food and Agriculture Organization (FAO), 16 per cent have become extinct and another 15 per cent are considered rare.
Our food supplies depend on genetic resources, but these are disappearing as natural habitats are depleted, degraded and destroyed. The extinction of one plant can cause the loss of as many as 30 kinds of animals and insects that depend on it.
Gene banks have been established in about 60 countries but are costly. Their seeds are vulnerable to disease and cannot be stored indefinitely without deteriorating. Such banks may be useful as a genetic store, but they cannot compensate for the wild.
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