Science in Society

IF YOU had come here 10 years ago, says Thaddeus Salah as he shows us round his tree nursery in north-west Cameroon, you would have seen real hunger and poverty. "In those times," he says, "we didn't have enough chop to eat." It wasn't just food - "chop" in the local dialect - that his family lacked. They couldn't afford school fees, healthcare or even chairs for their dilapidated grass-thatch house.

Salah's fortunes changed in 2000 when he and his neighbours learned how to identify the best wild fruit trees and propagate them in a nursery. "Domesticating wild fruit like bush mango has changed our lives," he says. His family now has "plenty chop", as he puts it. He is also earning enough from the sale of indigenous fruit trees to pay school fees for four of his children. He has been able to re-roof his house with zinc sheets and buy goods he could only dream of owning before. He even has a mobile phone.

From Salah's farm we gaze across the intensively cultivated hills which roll away towards the Nigerian border. "Ten years ago, you'd hardly see any safou [African plum, Dacryodes edulis] in this area," says Zachary Tchoundjeu, a botanist at the World Agroforestry Centre's regional office in the Cameroonian capital Yaoundé. "Now you see them growing everywhere."

The spread of African plum through these hills is one small part of a bigger movement that could change the lives of millions of Africans. The continent is home to some 3000 species of wild fruit tree, many of which are ripe for domestication. Chocolate berries, gingerbread plums, monkey oranges, gumvines, tree grapes and a host of others could soon play a role in ensuring dependable food supplies in areas now plagued by malnutrition (see "Future fruits of the forest").

One of the architects of the programme is Roger Leakey, a former director of research at the World Agroforestry Centre. He calls these fruit trees "Cinderella species": their attributes may have gone unrecognised by science and big business, but the time has come for them to step into the limelight.

"The last great round of crop domestication took place during the green revolution [in the mid-20th century], which developed high-yielding varieties of starchy staples such as rice, maize and wheat," says Leakey. "This new round could scarcely be more different." Sparsely funded and largely ignored by agribusiness, high-tech labs and policy-makers, it is a peasant revolution taking place in the fields of Africa's smallholders.

The revolution has its roots in the mid-1990s, when researchers from the World Agroforestry Centre conducted a series of surveys in west Africa, southern Africa and the Sahel to establish which indigenous trees were most valued by local people. "We were startled by the results," says Tchoundjeu. "We were expecting people to point to commercially important timber species, but what they valued most were indigenous fruit trees."

In response to this unexpected finding, the World Agroforestry Centre launched a fruit tree domestication programme in 1998. It began by focusing on a handful of species, including bush mango (Irvingia gabonensis), an indigenous African species unrelated to the Indian mango, African plum - not actually a plum but a savoury, avocado-like fruit sometimes called an afrocado - and a nut tree known locally as njansan (Ricinodendron heudelotii). Though common in the forests and as wild trees on farms, they were almost unknown to science. "We knew their biological names, but that was about all," says Ebenezar Asaah, a tree specialist at the World Agroforestry Centre. "We had no idea how long it took for them to reach maturity and produce fruit, and we knew nothing about their reproductive behaviour." Local people, in contrast, knew a good deal about them, as the trees' fruits have long been part of their diet.

Rural Africans consume an enormous variety of wild foodstuffs. In Cameroon, fruits and seeds from around 300 indigenous trees are eaten, according to a study by researchers at Cameroon's University of Dschang. A similar survey in Malawi and Zambia found that up to 40 per cent of rural households rely on indigenous fruits to sustain them during the "hungry months", particularly January and February, when supplies in their granaries are exhausted and they are waiting for their next harvest (Acta Horticulturae, vol 632, p 15).

Some of these so called "famine foods" have already been domesticated by accident, says ethnoecologist Anthony Cunningham of People and Plants International, an NGO based in Essex Junction, Vermont. He cites the example of marula (Sclerocarya birrea), a southern African tree in the cashew family with edible nutty seeds encased in a tart, turpentine-flavoured fruit. "Long before the development of agricultural crops, hunter-gatherers were eating marula fruit," he says. "They'd pick the best fruit, then scatter the seeds around their camps." These would eventually germinate and mature into fruit-bearing trees, ensuring, in evolutionary terms, the survival of the tastiest. Marula is now fully domesticated and the fruit is used to make juice, a liqueur called Amarula Cream and cosmetic oils.

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