Birth of the spud

For every hot, salted, deep-fried bite of potato you've enjoyed, you have Andean farmers to thank. They were first to cultivate the spud (Solanum tuberosum), perhaps as early as 7,000 years ago. Today, from western Venezuela to northern Argentina, many primitive cultivars survive, some as weeds in commercial potato fields, others naturalized into the wild flora. The cultivars present a rich variety of shapes, colors, and growth habits. Such widespread distribution and great diversity have long led botanists to think the potato was independently domesticated several times in various places, possibly from different wild Solanum species.

Not so, say David M. Spooner, a taxonomist at the University of Wisconsin--Madison, and his colleagues from the Scottish Crop Research Institute in Dundee. After comparing the DNA of 365 specimens of Solanum from all over the Andes, including the primitive cultivars and the wild species from which they could have been derived, the team unearthed a pattern that points to a single origin in southern Peru. from the wild plant Solanum bukasovii or a close relative. Local farmers along the cordilleras then presumably developed the profusion of potatoes after the original cultivar was exported from its native soil. (PNAS 102:14694-99, 2005)

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