The Lima center, which provides seeds to communities that have lost their potato crops to diseases, freezes or a leftist insurgency, began helping Aymara improve its potato stock in 1990s.

"Our production was not good," said village leader Carlos Hidalgo, who himself grows about 180 brightly colored and oddly shaped varieties. "We said the soil must be tired. We did not realize it was the seeds."

Like other villagers, Hidalgo and his wife each eat an average of two pounds of tubers at every meal. Their four children eat almost as much. That's about 15 times what Americans consume.

Sometimes, she prepares them in a creamy soup, adding boiled eggs, dried lamb meat and crumbled Andean cheese. Usually she just boils them, choosing from dozens of varieties to produce a savory mix of flavors and nutrients. And during the harvest, the village women steam potatoes between layers of lamb in a communal underground pit called a "huatia."

"There are communities that live off only potatoes and people are healthy," said Walter Amoros, another gene researcher. "The potato is not a completely balanced food, but it has the basics for good nutrition."

Aymara's villagers complement their starch-heavy diet by loading up llamas, donkeys and horses and traveling to lower-lying communities, where they trade their prized crop for corn, barley and wheat.

Meanwhile, the women of Aymara rely on their ancestral knowledge of each tuber's virtues as they sort through hundreds of potatoes at harvest time, deciding which to eat, sell, store for seeds or trade to diversify their stock.

"Our parents and grandparents have taught us since we were children," said Susana Hidalgo Avila, a mother of six. "The knowledge is part of our nature."

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