Long before early humans in North America grew corn and beans, they were harvesting and cooking the bulbs of lilies, wild onions and other plants, roasting them for days over hot rocks, according to a Texas archaeologist.
In two new reports published online this week in The Journal of Anthropological Archaeology and The Journal of Archaeological Science, archaeologist Alston V. Thoms of Texas A&M University 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.
“Whatever they were eating before did not require prolonged cooking,” Thoms said. But, beginning about 10,000 years ago, “people couldn’t live off the cream of the land anymore.” The megafauna that had been a prime food source – such as the woolly mammoth – were becoming extinct, and other mammals were becoming harder to find. People had to turn to plants.
Meadowlands and the forest edge were filled with acres and acres of lilies, wild onions and perhaps two dozen other wild plants ready for the harvesting. The bulbs of these plants are about as nutritious as sweet potatoes, but their energy is locked up in a dense, indigestible carbohydrate called inulin. The only way to make the bulbs digestible was to roast them for two days or longer.
Cooking over a hot fire as people had done in the past required constant maintenance of the fire pit. But adding large rocks, some weighing more than 2,000 pounds, changed the situation. If the rocks were heated red-hot, they would hold their heat for 48 hours or longer, conserving both fuel and human energy.