For years, archaeologists and researchers have been trying to figure out where and when rice was first cultivated. There's evidence that rice first came from Japan, Korea, China, even Australia. Now, reports Sarah Zhang at The Atlantic, a new study suggests the process to domesticate rice from its wild form likely began in southern China.
In the early 2000s, Stephen Chen at the South China Morning Post reports, archaeologists first discovered 18 prehistoric villages in the area of Shangshan along the Yangtze river with some evidence that the people were eating and perhaps cultivating rice. Rice hulls (hard protecting coverings of grains of rice) were used to strengthen their clay pottery and researchers also discovered early agricultural tools and large mortars and pestles used to de-hull rice. But it was not clear whether these early settlers were collecting wild rice or had begun to domesticate and cultivate rice.
That’s what the current study investigates. While acidic soils decompose and destroy the organic matter from rice, including its grains and stems, rice plants produces microscopic bits of silica called phytoliths that form in distinctive patterns in rice leaves. Compared to wild rice varieties, domesticated rice has distinctive phytolith patterns. By counting the “fish scales” in these patterns, researchers can tell the difference between cultivated and wild rice since cultivated rice has more than nine scales, Chen reports.
According to a press release, the researchers examined the phytoliths in each layer of three of the village sites, finding that over time the percentage of rice with more than nine fish scales steadily increased, indicating that the villagers were producing a larger and larger percentage of cultivated rice versus the wild stock. They also sifted enough of the tiny particles to test them using carbon-14 dating, finding that the oldest rice phytoliths in Shangshan date to 9,400 years.
“We have a high confidence it is not wild rice,” Lu Houyuan, professor at the Chinese Academy of Sciences, and lead author of the study in The Proceedings of the National Academies of Science, tells Chen. “It is not the same as rice today, either. It’s a half-domestic species.”
Jiang Leping from Zhejiang’s Institute of Cultural Relics and Archaeology, tells Chen that he believes the Shangshan village sites were surrounded by rice paddies and that the team hopes to continue excavations in the area to find evidence of that.
But not everyone is convinced that these villages along the Yangtze are the epicenter of Chinese rice. Wang Zixuan, also a professor at the Chinese Academy of Sciences, tells Chen that a large scale genetic study of rice published in the journal Nature in 2012 suggested that it emerged in a single location along the Pearl River valley, not on the banks of the Yangtze. “They could spread,” Wang tells Chen. “It is likely that the early farmers along the Pearl River took the rice seeds up north to the Yangtze during migration.”
While Chinese rice may be the earliest found so far, it doesn’t mean it’s the only place rice was developed. While researchers agree the rice variety known as japonica first appeared in China, some argue that another strain, known as indica was domesticated in an area between India and Indochina. Genetic studies show a third major variety, a drought-tolerant variety known as aus rice, was likely developed in the area of India and Bangladesh from wild strains.