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PARIS: Small domesticated dogs probably originated in the Middle East more than 12,000 years ago as the descendants of grey wolves (Canis lupis).
Researchers Melissa Gray and Robert Wayne led a team from the University of California in Los Angeles that searched for variations of a gene called IGF1 which is a characteristic of small dogs.
"(The variant) probably arose early in their history," said Gray, whose paper is published online by BMC Biology, an open-access journal.
Small domestic dogs at least 12,000 years old
"Our results show that the version of the IGF1 gene found in small dogs is closely related to that found in Middle Eastern wolves and is consistent with an ancient origin."
The work concurs with archaeological work in the Middle East that has unearthed the remains of small domestic dogs dating to 12,000 years ago.
Digs in Europe have uncovered older remains, to as much as 31,000 years ago, but these are of larger dogs.
Iraq's Fertile Crescent
Canine selection may have been carried out by villagers in the Fertile Crescent of modern-day Iraq and other cradles of agriculture.
"Small size could have been more desirable in more densely packed agrarian societies where dogs may have lived partly indoors or in confined outdoor spaces," says the study.
Most of the Western barnyard animals and the cat were domesticated between 12,000 and 8,000 years ago in the Fertile Crescent.
Dogs were first domestic animal
However, dogs have been considered as an important exception, as they were thought to have been domesticated 1,000 to 5,000 years earlier, while humans were still living and hunter-gatherers.
"Domestication is a key feature of the Neolithic Revolution, a suite of cultural innovations and consequences comprising sedentism, and agricultural economy, and complex social arrangements conducive to urban living," write David MacDonald and Carlos Driscoll, in an associated opinion article published in the Journal of Biology.
"Gray et al provide evidence that early Middle Eastern dogs segregate for a character, non-adaptive in the wild, that is probably the result of long-term association with humans and must have occurred over many human generations.
"We can [also] infer from this that these human cultures were sedentary and stable … and had some loose cultural concept of tolerance for dogs, if not of caring and ownership of them."
