Chinese and German researchers have hypothesized that chicken domestication was widely practiced in Northern China as far back as 10,000 years ago, according to the Global Times.
The scientists found chicken bones traced to at most more than 10,000 years ago at archaeological sites in Cishan, Nanzhuangtou and Wangyin, which are said to be the areas of the earliest chicken bones found in both Northern China and the world.
Xingbo Zhao, a professor at China Agricultural University, and his team selected 39 of the chicken bones recovered from the three sites as well as from Jiuliandun Chu Tombs for DNA testing and radiocarbon dating.
According to their findings, the bones range from 2,300 to 10,500 years old.
These discoveries belie theories by scientists, including Charles Darwin's, that chicken domestication dates back to 4,000 years ago in the Indus Valley in South Asia.
The findings also corroborate suggestions by more recent research that chickens were raised in several parts of Asia, which include regions in South Asia, Southwest China and Southeast Asia.
After tracing the age of the discovered chicken bones, Xingbo's team made a comparison between their mitochondrial DNA sequences and those from Galliformes order, which include modern chickens, and found that the ancient bones belonged to the genus Gallus, to which the modern domesticated chickens belong.
"Combined phylogenetic analyses on modern ancient DNA sequences from all over the world have supported the hypothesis of multiple maternal chicken origins in South and Southeast Asia," said the team's study, which was published in Proceedings of the National Academy of Sciences, a U.S. journal.
"Our results now add northern China as another center of chicken domestication within Asia," the study said.
Researchers from Hebei Provincial Institute of Cultural Relic, Hebei's Xushui County Office for Preservation of Ancient Monuments, Germany's University of Potsdam and Jilin University helped with the research.