Centuries of crop diversification are at risk of being lost forever, warns Jeff Bentley. In this week's Green Room, he says a growing dependency on just a few modern, high-yielding varieties is leaving the world's food supplies exposed.
A potato is not just a potato; there are thousands of local varieties still grown in their birthplace in the Andes.
Local, native varieties were safe on the farm, but as farmers turn increasingly to modern, high yielding varieties, the old ones are being abandoned
Some are long, thin and purple; others are lemon yellow and floury, or shaped like a bull's horn.
Most crops have many varieties, a rich heritage that most urban dwellers are no longer aware of.
The cultivated potato comes in six different species and perhaps 3,000 varieties, most found only in the Andes.
That is a lot of genetic information.
Until recently these local, native varieties were safe on the farm, but as farmers turn increasingly to modern, high-yielding varieties, the old ones are being abandoned.
For example, in the 1970s near Lake Titicaca, agronomists collected more than 200 varieties of quinoa, a native Andean grain. Now, no more than 50 of these are still grown.
Our generation is snuffing out ancient races of crops which fed the Incas, the Mayans, the Sumerians, and the Tang dynasty.
But it's not entirely too late to save these crop varieties, and their irreplaceable genetic information.
In 1997, the government agency responsible for Bolivia's collection of quinoa suddenly collapsed.
The drive for greater efficiency and higher yields carries a genetic cost
Many of the 1,800 accessions of this native grain were no longer found in the field, and would have been lost forever without the thoughtfulness of Alejandro Bonifacio, a native Aymara.
With no agency to care for the quinoa collection, Dr Bonifacio simply took it home.
It took him a year to find work elsewhere, but he saved these endangered crop varieties and has spent the past 10 years adding to it and describing it.
If only all crops were so lucky.
The impoverished smallhold farmers who nurture crop diversity need to sell some of their harvest to make a living, but selling can be stressful.
Villagers struggle to understand why the harvest that was so much work now fetches such a low price. The person who buys the product often gets the blame.
Researchers in Peru and Bolivia found that farmers and other people further up the food chain hardly knew each other.
But when farmers, wholesalers, even chefs and supermarket staff all sat down together they learned about each others' concerns.
Crossroad for crops
The invisible hand of the market, it seems, can favour the farmers and crop diversity. For example, heirloom potatoes are being sold to upscale Andean shoppers in smart little net bags. Because farmers can sell native spuds at a good price, they are planting more of them.
If humanity mourns the loss of wild plants, we should really worry about the extinction of cultivated ones
West Africans domesticated a native species of rice, called Oryza glaberrima
, 3,500 years ago. The grain was relative of the Asian rice Oryza sativa
Yet 450 years ago, the Asian species reached Africa and all but displaced the native rice, which had a thinner head of grain and thus brought in a smaller harvest.
By the 1990s, native African rice was reduced to a few pockets on scattered farms.
Then in the 1990s, Sierra Leonean plant breeder Monty Jones and colleagues found a way to create a fertile hybrid between African and Asian rice.
Called "Nerica" (New Rice for Africa), it could yield a bumper harvest like its Asian parent, but it was as tough as its African side, resistant to drought, pests and disease.
Scientists have bred many varieties of Nerica and farmers all over West Africa are starting to grow them.
This new rice, descended from an endangered species, is helping Africa to feed itself, yet this opportunity would have been lost if O. glaberrima
had gone extinct.
As the Earth gets warmer, we will need to breed other hardy new crop varieties. Plant breeding is like playing cards: more hands are possible with a full deck.
We'll only be able to create new varieties in the future if we save the old ones we have now.
Many rare crop varieties are now grown on just a few farms, often by elderly people. The crops will be lost forever unless young people start to grow them.
If humanity mourns the loss of wild plants, we should really worry about the extinction of cultivated ones. These plants sustain our lives.
Dr Jeff Bentley is a Cabi Associate. Cabi is a science-based development and information organisation. Jeff works as an agricultural anthropologist and is based in Cochabamba, Bolivia
The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website
Do you agree with Dr Bentley? Do people need to pay more attention to the loss of crop diversity? Are modern food and farming methods increasing the threats facing the world's food supply? Or is greater efficiency and higher yields the only way to feed a growing population?
Genetic homogenization leaves us all prone to disasters and in this case like playing poker with worldwide starvation.
Joe brown, Vancouver, Canada
Chis C, it's really pretty simple. Crop diversity = food security. It means we have a food supply that is much more resistant to disease, inclement weather, and the whims of multinational chemical companies that just happen to sell seeds, than the one we currently have. Also, traditional plant breeding is not in any way the same as genetic engineering. Breeding happens in the field. Genetic engineering happens in a lab.
anne, urbana, il
In my opinion changing the food culture will partly help solve the problem. We have evolved to choose the food by its look noy by its nutrition. Eating for tongue has to be replaced by eating for guts.
Kaphle K, Bharatpur/Chitwan, Nepal
The Irish Potato Famine (1840) in which millions of people starved to death is an example of the perils of relying on just one variety of a crop.
Mike Adams, Dorset, UK
In the grand scheme of things loss of crop biodiversity in itself would have to rank as one of the lesser of human iniquities. Ask yourself, why do we need such high crop productivity?Cranking up livestock production is one of the main reasons, where one third of all crops go to feed livestock. In addition pastoral land makes up 55% of all arable land and this area is still steadily increasing at the expense of forests. The consequence is that there is not much space left for biodiversity and mounting pressure to produce more crops on less land.
Tony, Christchurch, New Zealand
Chris C; "Overblown", you say! You can't be really serious with this comment. GMO companies like Monsanto, ravaging our diversity for profit, are a key reason our crop varieties are disappearing. And a very serious problem. Check out the short video at http://www.youtube.com/watch?v=swVjzIVqRUA In addition, there's the lack of care for the wonders of God's complete and varied creation that some people evidence and demonstrate. Blessings all, Gary In TO
Gary Patton, Toronto, ON CAN
I do not agree with Chris C. in that if the assumption is valid, invasive species would be much less a problem. Species can establish in conditions that are not optimized for them. In agriculture, what to plant is largely an economic decision rather than a result of natural selection. Unfortunately, that the economically favourable varieties can establish today, does not guarantee that they can still cope with changed climate tomorrow. Thus if they fail we had better have some forgotten varieties, originally planted in warmer or colder climate, that can be used to breed new varieties and continue to provide us with food, clothes and all the great things.
Biodiversity is not an end in itself. In principle the maintenance of the widest possible genetic pool of food crops is important - but not simply as an ideal. The reason why, for example, we now rely on about ten basic staples for the majority of our essential food supplies (e.g. wheat, maize, soya, rice, potatoes, vegetables, fruit, beef, pork, lamb) is because these have proved reliable and capable of 'improvement' in terms of their capacity to offer greater yields over time. The aims of productivity and biodiversity are not mutually exclusive, but please don't confuse the need to preserve ancient plant varieties with the ability to feed the world.
Robin Limb, Peterborough
Chris C has missed the point slightly. By preserving genetic diversity we are preserving species that may turn out to be more nutritious, better tasting, more resistant to pests or environmental insults that we haven't worried about yet. The criteria that define "superior" can and do change depending on current needs and market pressures. If we preserve the diversity, the gene pool is there for us to fall back on when we encounter new problems.
Nicola K, Cambridge, UK
Biodiversity is very important for all food crops ,by only growing limited numbers of species could lead to uncontrollable pest and diseases taking hold .In nature biodiversity there is a balance so pest and disease make very little difference . Also by limiting the choose of food crop species it may affect our health.
Dr. Bentley 's last sentence really says it all - we have a remarkable self-interest in maintaining a broad base of diversity to support our food systems. Resilient systems are always diverse, decentralized, and multi-functional in nature, and it's absurd to try to base the most fundamental of human needs on a monoculture system for converting oil into food. The BBC's last question "Or is greater efficiency and higher yields the only way to feed a growing population?" is misleading, being clearly written by someone unfamiliar with the fact that smaller, diversified farms following organic practices actually produce more food per acre and per input of energy than massively mechanized monocrop plantations. The only way that megafarms compete in "efficiency" is on a dollar per calorie basis, and even then only when they're awash in government subsidy payments and cheap oil. Of course, this is exactly how Monsanto, Cargill, ADM, and their ilk make such enormous profits, which they then use to promote such ideas as "efficiency" and "higher yields" through patented seeds, genetic engineering, and chemicals. Chris C from SLC seems unfamiliar with the nature of agricultural plant varieties. The only reason these varieties exist with such diversity is precisely because of human cultivation of them. Domesticated plants do not exist in the wild - having been selected and bred for generations to promote specific traits, and they will not survive any length of time without human intervention to plow the fields and combat weeds and pests.
Steve Morgan, Boulder, CO USA
This seems like an overblown issue. For one, if some of these crop varieties, such as O. glaberrima, are superior for a certain climate, would they not naturally outlast their alternatives in such regions anyway? It won't be mankind's cultivation that continues their existence. Furthermore, mankind has been genetically engineering crop species through artificial selection since agriculture has existed? If there is a lack of diversity, it is because mankind has settled on a very productive variety of crop, that makes the others simply not worth cultivating. I was expecting a far more compelling argument for crop diversity, like natural resistance to certain diseases (banana blight, etc.), not just diversity for diversity sake.
Chris C, Salt Lake City, USA
Yes I agree. The chemical companies and the intensive farming industry are trying to pull the wool over our eyes. Their methods are all about their quick profit at any expense including the health of the population and the environment including our flora and forna. We don't need 'cheap' food we need good food.
Alexis Wolfe, Harlech, Cymru
At last, supporting evidence that increased biodiversity is more than just a "nice idea", now if we can just get buy-in from the supermarkets, we may be able to reverse the trend towards monoculture. What's nice is that it demonstrates there's a market for crop diversity. I'm not against supermarkets per se, it's just that I believe they offer a more restricted choice for the consumer, this could be their opportunity to prove me wrong
Peter Tanczos, London UK