Long before humans in North America grew corn and beans and wheat, they were harvesting and cooking the bulbs of lilies, wild onions and other plants, roasting them for days over hot rocks, says a Texas archeologist. The evidence for this practice has long been known of in fire-cracked rock piles found throughout North America, but archeologists have tended to ignore it "because a new pyramid or a Clovis arrow point is much sexier," said archeologist Alston Thoms of Texas A&M University.
     In two new reports published online last week in the Journal of Anthropological Archaeology and the Journal of Archaeological Science, Thoms reported that cooking on hot rocks first became a substitute for cooking on hot coals around 9,000 to 10,500 years ago, then had a sudden jump in popularity about 4,000 years ago. The reason for the changes: population growth that required primitive peoples to exploit new food resources.
     Meadowlands and the forest edge were filled with wild plants. The bulbs of these plants are about as nutritious as sweet potatoes, but the only way to make them digestible was to roast them for two days or longer. Large rocks could hold heat without constant maintenance.

Source: Chicago Tribune (28 December 23008)