Ancient Rock Piles Reveal Early American Cuisine

Dec. 22, 2008 -- Fire-cracked rock piles found across North America received little scientific attention for decades, but two new studies reveal their importance as early Native American earth ovens. For thousands of years, they were used to cook a favorite food staple: smoky, sweet camas bulbs.

Based on charred remains of plant material found at hot rock oven sites, cooked versions of this root vegetable -- somewhat like a cross between an onion and a potato -- is thought to have been the tortilla of the Stone Age.

The bulbs required up to two days to bake, due to a complex carbohydrate called inulin that is otherwise indigestible.

Alston Thoms, who conducted both studies, told Discovery News that "camas consumption preceded corn consumption everywhere in the U.S. by thousands of years."

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"Camas was mashed and pounded with a mortar and pestle into a thick dough that was then shaped into loaves that were later broken apart and cooked," added Thoms, an associate professor of anthropology at Texas A&M University.

He analyzed the fire-cracked rock assemblages and food remains throughout North America, with a particular focus on northwestern and southwestern sites. The findings have been accepted for publication in both the Journal of Anthropological Archaeology and the Journal of Archaeological Science.

Thoms found that fire-cracked rock cooking dates to anywhere from 9,000 years ago to as recent as 400 years ago, with some sites up to 9 feet in diameter containing stones weighing more than 2,000 pounds.

Before the emergence of this technology, "Native Americans and people around the world got along fine for thousands of years without any kind of heated stones for cooking or bathing," Thoms said.