Researchers trace corn’s ancient history

Children of the teosinte:  Even though maize (Zea mays) is perhaps the most important crop in the Americas (for better or worse), until recently, we didn’t know where it came from and when it was domesticated. Research by botanists, geneticists and archeologists has finally found the answers in a grass called teosinte, a river valley in southern Mexico, and tools that date back to 8,700 years ago. Teosinte has been a leading contender for maize’s oldest ancestor since early in the 20th century, even though it has a strikingly different appearance: each head of seeds has just a dozen kernels that are each covered by a hard casing. George W. Beadle, while in graduate school and after retirement, used a long series of field experiments to show that teosinte and corn were indeed closely related. More recently, DNA analysis of samples of teosinte from across its geographic range determined that the variety from the tropical Central Balsas River Valley of southern Mexico was the likely ancestor of maize. Archeological excavations of rock shelters and caves in the Balsas River Valley found maize starch on many tools dating back 8,700 years ago, providing the oldest evidence yet of the domestication of maize. Experts estimate that it took the inhabitants of the valley between several hundred and a few thousand years to create the transition from teosinte to maize, a process that would have required careful observation and dedication.  (New York Times and ScienceDaily)

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