Is rice paleo?


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 Grains are evil. The people in the paleolithic didn't eat them. Amirite? Unfortunately, that hypothesis is contradicted by archeological evidence, but now there is genetic evidence that rice may have been domesticated earlier than thought. 

Asian rice, Oryza sativa, is one of world's oldest and most important crop species. Rice is believed to have been domesticated ∼9,000 y ago, although debate on its origin remains contentious. A single-origin model suggests that two main subspecies of Asian rice, indica and japonica, were domesticated from the wild rice O. rufipogon. In contrast, the multiple independent domestication model proposes that these two major rice types were domesticated separately and in different parts of the species range of wild rice. This latter view has gained much support from the observation of strong genetic differentiation between indica and japonica as well as several phylogenetic studies of rice domestication. We reexamine the evolutionary history of domesticated rice by resequencing 630 gene fragments on chromosomes 8, 10, and 12 from a diverse set of wild and domesticated rice accessions. Using patterns of SNPs, we identify 20 putative selective sweeps on these chromosomes in cultivated rice. Demographic modeling based on these SNP data and a diffusion-based approach provide the strongest support for a single domestication origin of rice. Bayesian phylogenetic analyses implementing the multispecies coalescent and using previously published phylogenetic sequence datasets also point to a single origin of Asian domesticated rice. Finally, we date the origin of domestication at ∼8,200–13,500 y ago, depending on the molecular clock estimate that is used, which is consistent with known archaeological data that suggests rice was first cultivated at around this time in the Yangtze Valley of China.

13,500 is older than what many people consider to be the end of the paleolithic, though many consider the paleolithic era to be relative to the region and would characterize a culture eating rice 13,500 years ago to be mesolithic. 

The molecular clock also has its share of controversy, as it is based on statistical modeling, but no more than other evidence we have used to build the concept of the paleolithic diet. 

I have written about my success with rice and hope to write more about it soon. Maybe I should just start calling my diet the mesolithic diet...