( nd delighted by their results. Pe...)Biologists find regions of rice domestication

"People have moved rice around so much and the crop crosses with its wild ancestors pretty readily, so I was fully prepared to see no domestication signal whatsoever," Schaal said. "I would have expected to see clustering of the cultivated rice, but I was delighted to see geographical clustering of the wild rice. I was thrilled that there was even any sort of genetic structure in the wild rice."

In contrast to rice, other staple crops such as wheat, barley and corn appear to have been domesticated just once in history.

Rice is the largest staple crop for human consumption, supplying 20 percent of caloric content for the world.

By finding the geographic origins of rice, researchers can consider ways to improve the crop's nutritional value and disease resistance, which in turn can help impoverished populations in Asia and elsewhere that rely heavily on the crop.

Londo expects to find even more evidence for differing geographic domestication. He said that by using the database that they've gathered, they could design a sampling to target specialty rices such as the aromatic rices basmati and jasmine.

For instance, one direction that the researchers are going is Thailand, where the Karen tribe has been using multiple landraces of rice for many hundreds of years.

Landraces are localized varieties of rice that have been cultivated by traditional methods and have been passed down many generations, Schaal said.

"We're going to try to find out how landrace varieties change after domestication," Schaal said. "These landraces are ancient varieties, which are high in genetic diversity, thus valuable to breeders looking for new traits."