Tasty Brazil Nuts Stun Harvesters and Scientists- page 1 | Science | Smithsonian

Tasty Brazil Nuts Stun Harvesters and Scientists

A Smithsonian biologist tracks the protein-rich nuts to understand their role in the Amazonian forest

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A single pod of brazil nuts can just about fit in a man's hand. But whenever a good-sized pod, like the ones in the National Museum of Natural History's South American exhibition, tumbles from its perch some eight stories above the forest floor, people take notice. "You sometimes see animals staggering around with large welts" where they've been struck, says Enrique Ortiz, a biologist at NMNH who has been studying Brazil nuts in Peru for more than eight years. The four- to six-pound pods hit the ground with a force that can — and does — kill a man. At times they literally plant themselves on impact.

A falling harvest is just one of the mortal dangers braved by castañeros, as people who live by collecting the nuts are known in Spanish-speaking South America. The nuts themselves are known as castañas (or castanhas in Brazil). Trying to gather Brazil nuts on a regular basis puts the castañeros in contact with vipers and jaguars, diseases like malaria and leishmaniasis, tyrannical bosses and traders, not to mention death from drowning and armed skirmishes over the possession of trees.

Brazil nuts add some $44 million annually to South American economies. Americans gobble up nearly $17 million of the nuts a year. Alone among the foods in the world economy, these nuts come almost exclusively from remote natural forests rather than more convenient plantations.

Ortiz and his colleague Adrian Forsyth describe their research goal as "getting Brazil nut forests protected based on the ecologic, economic and social viability" of collecting Brazil nuts from natural forests. They think they may be able to show that, danger of serious or fatal injury aside, castañeros can make a better living gathering nuts from a living forest year after year than from any one-shot timber harvest.

Ortiz and his team have gone to elaborate lengths with these goals in mind. Their research site is the Madre de Dios region of Peru in the Amazon's lush, upland rain forests where Peru, Brazil and Bolivia meet. This is one of the most productive areas of Brazil nut country. From Lima, it's a one-hour plane ride plus seven hours by boat. In Madre de Dios, Ortiz and a team of eight researchers keep 1,000 or so trees under surveillance, counting every pod that falls and locating the most productive areas so that castañeros can gather the nuts more efficiently. Each pod holds 10 to 25 Brazil nuts, which are technically seeds, arranged inside a pod like sections inside an orange.

Brazil nut trees flower at the start of the rainy season; each flower lasts just one day. Blossoms that open before dawn one morning fall by late afternoon. Gradually the forest floor becomes strewn with the cream-colored, marble-to-golf-ball-size flowers, which attract brocket deer and large nocturnal rodents called pacas. The mature pods fall in the rainy season.

Castañeros have to time things just right. If they come too early they waste valuable time waiting for the pods to fall. Too late and they'll lose the harvest to agoutis, cat-size brown rodents that gather up all the Brazil nut pods they can find and then bury the nuts individually, just as squirrels bury acorns for future food.

The agouti turns out to be a major player in the history of the Brazil nut. By burying the Brazil nuts, agoutis hold the key to the tree's survival in remote areas. The agouti is virtually the only animal that has teeth strong enough to open the thick husk and liberate the seeds so they can sprout. Ortiz was the first to fully understand the agouti's crucial role. To learn how many pods each agouti collected and how far it carried them, Ortiz and his team carefully opened pods that fell from 12 trees in Madre de Dios, painstakingly glued a tiny magnetic strip and a number to each seed, then glued all 120 pods back together like Russian egg puzzles.

The agoutis were completely taken in and busily began eating, or burying the doctored nuts. Ortiz's team later spent more than six months searching the forest with a magnetic locator and waiting for the seeds to sprout, a cycle that takes up to a year. Their patience is yielding a precise picture of how the Brazil nut population replenishes itself and what conditions are most favorable to its regeneration. Further research may reveal other ways in which the castañeros' harvesting could be more efficient and profitable. At present, more than 30 percent of harvested nuts spoil before they get to market.

For centuries the trees have been acquiring more and more human travel agents, those local people who found the nuts and pods useful. Many tribes, like the Yanomami, ate the nuts raw, grated and mixed into a manioc porridge. (The nuts also contain varying levels of selenium — perhaps 250 times more than most foods — depending on the soil where they're grown. Selenium may deter ovarian cancer by helping activate a powerful antioxidant, but too much can be toxic and cause balding.) Today the nuts are dried and graded, and some are shelled, before being packed in vacuum-sealed bags for shipment. They are eaten raw as well as roasted and salted. Brazil nuts contain about 14 percent protein, 11 percent carbohydrates, and 67 percent fat or oil, as well as potassium, phosphorus, calcium and Vitamin B.

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