Millet Domestication

"Agricultural origins and the isotopic identity of domestication in northern China"
Loukas Barton, Seth D. Newsome, Fa-Hu Chen, Hui Wang, Thomas P. Guilderson, and Robert L. Bettinger. PNAS 2009.

This paper talks about a site called Dadiwan in Gansu Province. It was occupied twice: Phase 1(7900-7200 calBP. pre-Yangshao culture) and Phase 2(6500-4900calBP. Yangshao culture). (The site was abandoned in between probably due to the bad climatic change.) The researchers used human, pigs, dogs, and other animal bones to do the stable isotope analysis. carbon and nitrogen isotope ratio were documented. Because millet is a C4 plant and there are not many edible C4 plants in the northern latitude, the increase and/or large amount of C4 in the bones will be a strong indicator of millet consumption. Nitrogen isotope shows where in the tropics the animal lies. Therefore, higher Nitrogen ratio will indicate that the animal was fed with meat, e.g. domesticated dogs fed with the meat leftovers.

Thus, the signature for millet domestication of millet and animals will be high carbon and high nitrogen ratio. This study found high carbon and nitrogen ratio during phase 1 and even higher ones during phase 2. Where these people came from and why to the area? Don't know yet. However, the stable isotope method is "probably the best means of detecting the symbiotic-human-plant-animal linkages that develop during the very earliest phases of domestication."