Scientists sequenced the genome of an ancient corn cob recovered from a cave in central Mexico. Photo by Bruce Smith/Cell Press
COPENHAGEN, Denmark, Nov. 18 (UPI) -- Scientists recently sequenced the genome of one of the oldest corn cobs in the world. Analysis of the newly sequenced 5,310-year-old corn cob, first found in in Mexico in the 1960s, suggests ancient maize was more like modern corn than its wild ancestors.
Domesticated corn is a derivative of teosinte, a wild grass. The fate of the grass was transformed by human interference. Humans began eating teosinte around 9,000 years ago.
"Over the course of several thousand years, human-driven selection caused major physical changes, turning the unproductive plant into modern maize, commonly known as corn," Nathan Wales of the Natural History Museum of Denmark, said in a news release. "Maize as we know it looks so different from its wild ancestor that a couple of decades ago scientists had not reached a consensus regarding the true ancestor of maize."
The new genomic analysis -- detailed in the journal Current Biology -- is a reminder of how quickly human impact can transform a wild plant into a domesticated crop. After just 4,000 years of its 9,000-year evolution, domesticated corn had become genetically more similar to its modern iterations than to the roots of its lineage.
Despite the genetic similarities, the ancient maize looked quite different than corn today. The 5,310-year-old corn cob measures just two centimeters and boasts just eight rows of corn, half as many as modern cobs.
Scientists hope DNA recovery efforts from similar well-preserved corn cobs will help them fill in more gaps in the history of domesticated corn.
"This is only the beginning of the story," said researcher Ramos-Madrigal. "Humans dispersed maize across the Americas very quickly and very successfully. We want to know how humans dispersed it, which routes they took, and how maize adapted to such diverse environments."