Remains of a supposed dog dating to 31,680 years ago actually belonged to a wolf, according to a new study that has canine experts completely rethinking the origin and ancestry of dogs.
The study, published in the journal Scientific Reports, says that domestication of dogs happened during the Neolithic era (10,200 B.C.-2,000 B.C.) -- when people began to farm and form permanent settlements -- as opposed to the Paleolithic era (2.6 million years ago to 10,200 B.C.) , when humans and their early ancestors were hunter-gatherers.
"Previous research has claimed that dogs emerged in the Paleolithic but this claim is based on inaccurate analyses," lead author Abby Grace Drake told Discovery News. "We reanalyzed some of the fossil canids from the Paleolithic and show that they are, in fact, wolves."
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Drake and colleagues Michael Coquerelle and Guillaume Colombeau used 3-D computer imaging to study the 31,680-year-old fossil found at Goyet Cave in Belgium, as well as a 13,905-year-old fossil unearthed at a site called Eliseevichi in Russia.
The researchers then compared these fossils, which were previously identified via caliper measurements as early dogs, to other ancient and modern dogs and wolves. Features such as the muzzle and eye sockets were determined to be more wolf than dog.
The findings as a whole indicate that dogs did not gradually evolve from a wolf-like ancestor over a long period of time. Instead, Drake and her team believe that domestication of dogs likely happened "quite quickly," and did not involve direct domestication of wolves.
"Wolves are far too dangerous to have around without adequate means of controlling them," Drake said. "It is more likely that the initial stages of domestication involved at least several generations of wolves breeding in proximity to humans, lured by the 'dumps' that were present near the first permanent human settlements."
The Goyet fossil from the Paleolithic that was found in the study to be a wolf.
Raymond Coppinger, a professor emeritus of biology at Hampshire College, calls into question dog domestication itself. He says that the words "domestic" and "domesticated" should not be confused.
"Domestic means living in the presence of people," he explained. "The English sparrow lives almost exclusively in the presence of people, (but) nobody thinks humans domesticated them. Why, if dogs live in the presence of people, should anybody assume that people domesticated them?"
Dog breeders, of course, have gone to great lengths to alter the appearance and even the behavior of dogs, but it could be, as Coppinger suggests, that the earliest dogs were more domestic than domesticated.
Coppinger agrees that dogs were not around before the Neolithic, but he challenges the long-held belief that wolves or wolf-like animals were the direct ancestors of dogs. His speculation comes after 30 years of raising and taming wolves, which he says is a "difficult process taking approximately 2,000 hours of arduous work."
"Why do we think it is the wolf that was the ancestor of dogs?" he said. "I have had pet coyotes, and there are hand-raised coyotes at Wolf Park in Indiana. There have been several studies done in Europe and Asia with hand-raised jackals, and famous cross-breeding experiments for 50 years with all the species of canids."
He thinks it is "all romance" that dogs evolved from a large wolf-like ancestor. It is more likely that dogs "evolved from a small member of the genus Canis," Coppinger said.
The precise identity of that critical ancestor, for now, remains a mystery, since the new study could negate prior research on the common ancestor of today's dogs and wolves. The exact date and place where dogs became domestic, or domesticated, also remains unknown.