Scientists have argued for years about when rice, which now feeds more than half of the world's population, was first domesticated. A new study suggests hunter-gatherers in China started growing the grain there more than 9,000 years ago.

Why it's important: Domesticating crops was one of humans' most innovative moves. We selected for traits and put pressures on the evolution of crops that we're still trying to understand and unravel, in hopes of a) learning how civilizations arose and b) improving modern crops by potentially re-introducing wild traits for disease-resistance or tolerance to different environments that were lost over thousands of years of selection and breeding.

What they found: Researchers isolated microscopic bodies of silica found in rice (called phytoliths) from an archaeology site in the Lower Yangtze of China that appeared to represent the first efforts by modern humans to cultivate rice rather than simply harvest the wild plant. They carbon dated the rice fossils to be 9,400 years old.

The context: Earlier studies had recovered phytoliths from the site but they may have been contaminated by matter in older pottery shards. In the new study, the researchers painstakingly sorted the phytoliths from other material. The finding, if correct, aligns with other recent research into how long ago humans and crop species began interacting with each other, says NYU's Michael Purugganan.

Go deeper: Analysis of the surface patterns of the phytoliths found that the rice samples from the sites in China were more closely related to modern domesticated rice species than wild rice species.

The big question: Was this the only time rice was domesticated? There is evidence people in India began farming it there 4000 years ago but it's unclear whether that was a separate event or one with roots in China.

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