Washington, Apr 29 : Contrary to the earlier belief, sunflowers were grown as a domesticated crop in Mexico more than 2,000 years ago, says a new study.
Previously it was believed that sunflower farming began in what is now the U.S. East and then trickled south into Mexico.
The conclusions were made after the discovery of plant remains in a dry cave, which 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.
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," National Geographic quoted Lentz, as saying.
"Given all available data, the best explanation is that the sunflower was domesticated twice," he added.
The study is published in the journal Proceedings of the National Academy of Sciences.