razil nuts have long been a source of food to the indigenous people of the Amazon rainforest. The nuts are so important to these people that they have even used them as currency. But the true value of the Brazil nut is far greater, for it embodies biodiversity at work.

The Brazil nut tree, Bertholletia excelsa, which can live for 1,000 years, grows wild in Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela. Only one of the world's millions of insect species, the orchid bee (also known as the euglossine bee), can pollinate it, which causes the development of a woody pod containing about 20 nuts.

Similarly, there is only one natural way for the nuts to leave the pod. The agouti, a large rodent, breaks the tough outer shell with its extremely sharp teeth. After eating its fill, the animal buries the rest for later, inadvertently planting new trees.

People find the nuts delicious too. They are also used to make cooking oils, skin-
care products and livestock feed. The empty seed pods sometimes serve as bowls and cups, while other parts of the tree, rich in antioxidants, are brewed into tea to treat stomach aches or liver ailments.

The Brazil nut industry generates tens of thousands of jobs. Over a decade, it seems to be more profitable to harvest a forest for the nuts than to cut it for timber or clear it for pasture.

The Brazil nut tree typifies the Amazon's delicate web of life. Many plants and animals - besides orchid bees, agoutis and Brazil nut harvesters - depend on it. Damselflies, for example, breed in rainwater in the empty seed pods.

And new sustainable uses for the tree keep emerging. Scientists are now experimenting to see whether it can be used to decontaminate land because it naturally sucks up radioactivity from the ground.