Greenhouse 'time machine' sheds light on corn domestication

Smithsonian archaeologist, Dolores Piperno, measures a teosinte plant growing under past climate conditions.

By simulating the environment when corn was first exploited by people and then domesticated, Smithsonian scientists discovered that corn's ancestor; a wild grass called teosinte, may have looked more like corn then than it does today. The fact that it looked more like corn under past conditions may help to explain how teosinte came to be selected by early farmers who turned it into one of the most important staple crops in the world.

The vegetative and flowering structures of modern teosinte are very different from those of corn. These and other differences led to a century-long dispute as to whether teosinte could really be the ancestor of corn.

But new findings reported in the journal Quaternary International show that teosinte may have looked very different in the past. "We grew teosinte in the conditions that it encountered 10,000 years ago during the early Holocene period: temperatures 2–3 degrees Celsius cooler than today's with atmospheric carbon dioxide levels at around 260 parts per million," said Dolores Piperno, senior scientist and curator of archaeobotany and South American archaeology at the Smithsonian's National Museum of Natural History and the Smithsonian Tropical Research Institute, who led the project. "Intriguingly, the teosinte plants grown under past conditions exhibit characteristics more like corn; a single main stem topped by a single tassle, a few, very short branches tipped by female ears and synchronous seed maturation.

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