Ancient cooks living in what is now the valley of Oaxaca in Mexico could have taught even Bobby Flay a thing or two, it seems. Dried out remains of chili peppers from two Oaxacan caves reveal that people of the region used at least 10 different varieties of fresh and dried chilies between 500 and 1,500 years ago.

"If you've got seven different kinds of peppers, if you're using them fresh and you're using them dried, you've got some interesting food," says archaeobotanist Linda Perry of the Smithsonian National Museum of Natural History in Washington, D.C.

She says that together with other plant remains found in the area, including maize (corn), beans, squash, avocados and the cactuslike agave, the result confirms that "all the components of what we call modern Mexican cuisine, we've got them all in the past."

Perry examined 122 chili fragments and stems excavated 30 years ago from the arid Guilá Naquitz Cave and Silvia's Cave near the Mitla River in southern Mexico. Uncovered by her colleague Kent Flannery of the University of Michigan Museum of Anthropology in Ann Arbor, the well-preserved remains dated from A.D. 600 to 1521 when area natives began settling in cities and growing crops, using the caves as overnight shelter during the harvest.

Perry distinguished seven cultivated varieties, or cultivars, from Guilá Naquitz and three from Silvia's Cave based on the shapes and sizes of the stems, according to a paper published online today by the Proceedings of the National Academy of Sciences USA.

She assigned them to two of the five species known to have been domesticated in the Americas: Capsicum frutescens and Capsicum annuum, members of which include the jalapeño, serrano, ancho and Tabasco. Some of the chilies resembled modern Tabasco and cayenne peppers, Perry says, but she adds it would take DNA testing to sort out the relationships between the ancient plants and modern ones.

Whole stems were probably pulled from fresh chilies, perhaps for ancient salsa or seasoning, whereas ripped pepper fragments may represent dried chilies used for stews and sauces, says Perry, who experimented at home by pulling off the stems of modern peppers.

Starch grains from the chilies were relatively large with a distinctive round, dimpled shape characteristic of domesticated chilies, she adds.

Domesticated Mexican chilies date to 6,000 years ago, but the new analysis marks the earliest evidence of diverse cultivated chilies, Perry says. "It's just a really nice indication," she says, "of an ancient and rich heritage of cuisine and agriculture in this region."