for National Geographic News
Editor's note: For further discussion on the origin of sunflower farming, see the Letters section of the journal Proceedings of the National Academy of Sciences.
Sunflowers were grown as a domesticated crop in Mexico more than 2,000 years ago, according to a new study.
The new findings run counter to a theory that sunflower farming began in what is now the U.S. East and then trickled south into Mexico.
Plant remains discovered in a dry cave suggest that farmers in Mexico were cultivating sunflower strains with large seeds by around 300 B.C.
A 2001 study by the same team had found evidence of Mexican sunflower domestication as early as 2600 B.C., but that finding was controversial.
A Smithsonian Institution expert on early agriculture has argued that the remains described by the team in 2001 had been incorrectly identified as sunflowers.
Eastern U.S. Origins
Sunflowers were a cultivated food crop in what is now the eastern United States 4,000 to 5,000 years ago, most experts agree.
But did sunflower farming spread south from eastern North America to Mexico and beyond? Or did ancient Mexicans develop sunflower farming on their own?
The latest evidence supports an independent origin for Mexican sunflower farming, said study leader David Lentz of the University of Cincinnati.
"We have filled in the gaps with lots of additional data that now make the Mexican sunflower [domestication] hypothesis irrefutable," Lentz said.
"Given all available data, the best explanation is that the sunflower was domesticated twice."
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