Genetic analysis of farm chickens throughout the world has found that their closest living relative is the red jungle-fowl of Thailand, a finding that pushes back the point of domestication by several thousand years.
The most popular victim of the British Sunday lunch owes is existence to early farmers who lived more than 8,000 years ago in the region that is now Vietnam and Thailand.
It was here that the red jungle-fowl was domesticated for the first and only time in early human history, Japanese researchers report today in the journal The Proceedings of the National Academy of Sciences.
They found that genetic material that is inherited only through the maternal line was almost identical for domestic chickens and a sub-species of the red jungle-fowl called Gallus gallus gallus.
It was originally thought that the domestic chicken came from the Indus valley about 4,000 years ago. However, chicken bones discovered at neolithic sites along the Yellow River in north-east China pushed the date of domestication back to 8,000 years ago.
"These new findings establish that domestication took place still earlier and further to the south, in the area of Thailand and Vietnam, one region in which this the red jungle-fowl is found,'' the journal says.
The research team, led by Susumu Ohno of the Beckman Research Institute in Duarte, California, says that the domestication of wild animals "as beasts of burden, the source of protein and fat, and the instrument of war and recreation played many pivotal roles in the cultural evolution of mankind''.
One of the special interests of the research team is the domestication of the chicken because of the part it has often played as a sacrificial animal to celebrate religious festivals.
Because the red jungle-fowl is not extinct, the chicken provides a "notable exception'' to the general rule that domestication of a wild species results in the extinction of that wild ancestor, the researchers say.Reuse content