Life on Earth is built on biodiversity - the variety that makes each of us a little different from the next person, makes a Granny Smith apple taste different from a Golden Delicious, and makes one wheat species better than another for making bread.
Food production worldwide, however, strives against diversity. Manufacturers like consistency of raw materials and this is not served by mixing plant varieties together. Farming practice and economics as they exist today favour growing only a few crops in large quantities rather than small amounts of a variety of crops.
Cost reduction in agriculture is the powerful force driving this, explains Dr Michael Murphy, of the rural business unit with the department of land economy at Cambridge University. "We are under tremendous pressure here to reduce our costs and that is the trend that is moving in here," he says. As a result, biodiversity is being ignored in favour of healthy accounts.
"There is a conflict between profit and diversity," says Prof Matthew Harmey, of the department of botany at University College, Dublin. "One of the problems is that farming man has consistently reduced biodiversity by selecting. Man has systematically done this."
The diversity offered by nature is staggering. Between 250,000 and 300,000 plant species exist and of these between 10,000 and 50,000 are edible, according to the UN's Food and Agriculture Organisation. Yet only 150 to 200 species are actually used as human food and just three - rice, maize and wheat - supply almost 60 per cent of all the calories and proteins humans derive from plants.
Yet the monoculture approach to world agriculture is dangerous, argues Mr Quentin Gargan, spokesman for Genetic Concern. "We would see biodiversity as already being severely damaged in the western world."
Monoculture, the business of growing a single variety of a single food crop, is a risky proposition should a particularly successful plant bacterium, fungus or virus take hold, he points out. "The risks are you are reducing food security, you become vulnerable." Such an event occurred in the US in 1970, when a large fraction of the US maize crop - up to 50 per cent in some southern states - was lost to a fungus, explains Dr John Barrett, a geneticist at the University of Cambridge. He studies disease and pest resistance in plant varieties.
He has carried out research into the use of species diversity as a way to improve crop disease resistance. It involves planting a single crop, barley, but using seeds from a number of barley species, mixing them at random.
In any given year one or two plant pathogens would dominate and one or two species would become susceptible to them, he said, a catastrophe if your monoculture crop was susceptible. His research showed, however, that the mixed species approach actually delivered a 12 per cent higher yield compared to control fields even though no chemicals were used to protect against fungus attack.
In another trial, which involved mixing two crops - beans and barley - even higher yields were achieved, with a significant reduction in plant disease.
These techniques could be of real value in a Third World context, with higher yields but reduced chemical inputs. "It would work anywhere", according to Dr Barrett. While Prof Harmey does not have a problem with current Western agricultural practice, he argues strongly for the need to preserve biodiversity. "Variety is what brought us where we are. You need to keep maximum variety," he says. Plant and seed resources "represent a whole lot of genes with a whole lot of properties. It is like a bank".
Western agriculture can cope with periodic knocks such as the 1970 maize fungus, but this is not so easy for developing countries, he adds. "Whenever you go down the monopolist line of agriculture in places where you don't have good fallbacks, you have problems."
Third World farmers have struggled for years against drought, plant disease and war. Western technology's contribution to Third World agriculture is a benefit or a scourge depending on your point of view. Yet the latest development - the so-called "terminator gene", patented last March - has the potential to affect world agriculture more profoundly than anything that has come before.
Researchers at the US Department of Agriculture, in partnership with Delta & Pine Land Company, a commercial seed breeder, have developed a gene modification that sterilises the plant so that no viable seeds are produced. The food crop is produced but all seeds are sterile so the farmer cannot rely on traditional seed saving for the next season's crop. It was introduced as a way to protect the patent controls on seed varieties and Delta & Pine is reportedly ready to make the technology available to other seed breeders.
This could be hugely damaging to Third World farmers. Many are too poor to buy commercial seed every year yet these same farmers produce the food that sustains an estimated 20 per cent of the world's population. This is one technological breakthrough that the developing countries could do without.