Northern China may have served as an early center of chicken domestication, possibly dating as far back as 10,000 years, researchers from China and Germany said on Monday.

In the past, many scientists, including Charles Darwin, have suggested that chicken domestication originated about 4,000 years ago in the Indus Valley of South Asia.

However, more recent research suggests that chickens were domesticated multiple times in different parts of Asia, including regions in South Asia, Southwest China and Southeast Asia.

The bones of chickens dating from more than 10,000 years ago have been discovered in China, but it is unclear whether the specimens are related to present-day domestic species.

In the new study, Professor Zhao Xingbo of China Agricultural University and colleagues chose 39 ancient chicken bones from Cishan, Nanzhuangtou and Wangyin - three archaeological sites representing the earliest sites for chicken bones both in northern China and worldwide - as well as one later archaeological site known as the Jiuliandun Chu Tombs, for DNA analysis.

The bones range in age from 2,300 to 10,500 years, based on radiocarbon dating, the researchers said.

The researchers then compared mitochondrial DNA sequences from the ancient bones with those from modern ground-feeding birds from the Galliformes order, including pheasants, rock partridges and chickens, as well as those from ancient specimens from Spain, Hawaii and Chile, including Easter Island.

Their analysis showed that the chicken bones from northern China belong to the Gallus genus, which includes modern domesticated chickens.

"Combined phylogenetic analyses of modern and ancient DNA sequences from all over the world have supported the hypothesis of multiple maternal chicken origins in South and Southeast Asia," said the study, published in the US journal Proceedings of the National Academy of Sciences.

"Our results now add northern China as another center of chicken domestication within Asia."

The study also included researchers from the Hebei Provincial Institute of Cultural Relics, Xushui County Office for Preservation of Ancient Monuments in Hebei province, Jilin University in Northeast China's Jilin province, and the University of Potsdam in Germany.

(China Daily 11/26/2014 page5)