Mod­ern rice emerged 10,000 years ago

New ev­i­dence looks set to set­tle the ques­tion of rice’s first do­mes­ti­ca­tion. AMY MID­DLE­TON re­ports.

Cosmos - - Digest -

The site of the first do­mes­ti­ca­tion of rice is a hotly con­tested is­sue, with sev­eral coun­tries ea­ger to lay claim. A num­ber of lo­ca­tions in China have been put for­ward, as have the Ganges val­ley in In­dia, the south­ern slopes of the Hi­malayas and var­i­ous places in south-east Asia.

Shang­shan, in China’s Lower Yangtze re­gion, has long been one of the strong­est con­tenders: ar­chae­o­log­i­cal arte­facts un­cov­ered there con­tain some of the ear­li­est ev­i­dence of rice grown by hu­mans.

An­cient rice rem­nants in dif­fer­ent sites show up as mi­cro­scopic sil­ica bod­ies called phy­toliths. How­ever, the type – wild or do­mes­ti­cated – isn’t al­ways clear.

Re­searchers have used ra­dio­car­bon dat­ing to place these phy­toliths on a time­line, but es­ti­mates have been con­tro­ver­sial be­cause of the pos­si­bil­ity of sam­ples be­com­ing con­tam­i­nated by older car­bon present in the sur­round­ing soil.

In the lat­est study, a re­search team led by Xinxin Zuo, a geo­physi­cist at the Chi­nese Academy of Sciences in Bei­jing, ver­i­fied the age of the phy­toliths at Shang­shan by com­par­ing them with car­bon dates from arte­facts found in the same sed­i­men­tary layer.

The team then ex­am­ined the struc­ture of the rice rem­nants, and found that they “are closer to mod­ern do­mes­ti­cated species than to wild species”. This con­sti­tutes the ear­li­est known ev­i­dence of rice do­mes­ti­ca­tion.

“When the do­mes­ti­ca­tion of rice be­gan in its home­land, China, is an en­dur­ing and im­por­tant is­sue of de­bate for re­searchers from many dif­fer­ent dis­ci­plines,” the re­searchers note.

The study was pub­lished in the

Pro­ceed­ings of the Na­tional Academy of Sci­ence.


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