The first known crops of common millet (Panicum miliaceum) appeared in both China and the South Caucasus (Armenia, Azerbaijan and Georgia) about 7,000 years ago. No one knows exactly who was the first to domesticate this plant, but that does not mean that it is still used as food for people and animals in many tropical regions, especially in Africa.
In ancient China, this grain was cooked by boiling and steaming, producing a moist and sticky final product. Little by little its use spread westward, towards Central Asia and beyond. These cultures, however, changed the way the product was treated and preferred to grind and bake it as if it were bread.
An international team of researchers has now combined DNA analysis with the study of pottery to examine the spread of millet in Eurasia, revealing how regional culinary traditions persisted even when new crops were introduced to the prehistoric world, they explain in a paper published in Antiquity magazine.
"It was already known that staple crops had moved long distances across the Old World, while regional cuisines had persisted conservatively," says Dr. Hongen Jiang of the University of the Chinese Academy of Sciences and lead author of the study. "What we didn't know is how those two opposing trends were interconnected," he adds.
To address this issue, Chinese, British and American researchers analyzed DNA from millet remains from between 1700 BC and 1700 BC. and 700 d. C. in Xinjiang, northwest China, and compared them with vessels to reconstruct prehistoric cooking methods.
"As notable as the vast journeys that crops made across prehistoric Eurasia is the enduring persistence of the regional culinary cultures that adopted those new crops," Jiang says.
Let's look at a practical example. The stickiness of common millet is controlled by certain genetic variations. By analyzing the genetic code of grain samples, Drs Harriet Hunt and Diane Lister, from the Royal Botanic Gardens and the University of Cambridge, were able to determine that none of the Xinjiang grains had the genes that made them sticky.
This suggests that as the grain moved westward, it retained a non-sticky consistency, even though ancestral millet was already widely distributed in eastern China. This means that the crops spread further west than the culinary traditions with which they were associated.
This is also supported by ceramic evidence. While ceramic vessels from eastern China have a tripod base to facilitate boiling, those found in Central Asia have rounded bottoms, a design originating in the Altai Mountains.
This means, according to archaeologists, that while millet was introduced to Xinjiang from the east, the vessels used to cook it came from the north. The detail further indicates that culinary traditions survived the introduction of new ingredients.
The Western expansion of staple crops fundamentally changed the diets of those to whom it reached, but the culturally embedded culinary traditions likely remained the same.
Dr. Xinyi Liu of the University of Washington highlights another case. Wheat traveled east to ancient China about 4,000 years ago, but the Western tradition of grinding and baking did not.
“Conservatism in the kitchen was not eroded by prehistoric food globalization. “Persistence in culinary practice was actually a key characteristic of the environments to which moving crops would adapt,” concludes Martin Jones of the University of Cambridge.
