Wolf-to-dog transition had little to do with humans, ancient skull suggests

Postmedia News  Dec 18, 2011

AFP/Getty Images; Wikipedia

Where, when and how wolves became domesticated dogs is the subject of lively debate among scientists.

By Randy Boswell
A Canadian researcher who specializes in the biology of ancient dogs co-authored one of the most significant studies of the year in canine science: a paper detailing the world’s earliest evidence of an animal in transition from wild wolf to domesticated dog.
The “extraordinary preservation” of the creature’s 33,000-year-old skull — found in a cave in southern Siberia — has helped show that dog domestication “was, in most cases, entirely natural” and not really a “human accomplishment,” says B.C. evolutionary biologist Susan Crockford.
She was part of a six-member team of researchers from Russia, Britain, the U.S. and the Netherlands that turned the clock back on wolf-dog transformations by thousands of years and showed that the phenomenon probably happened many times in many places around the globe.

Crockford, co-author of the study published recently in the journal PLoS One, said the process of domestication began when wild packs of wolves — or even just a few individuals — began living at the fringes of human encampments and scavenging meals from piles of the discarded bones of human-hunted game.
She said lead researcher Nikolai Ovodov of the Russian Academy of Science “was immediately suspicious that there was something different” about the canine skull found in the Siberia’s Altai Mountains.

Susan Crockford/Handout

A newly discovered, 33,000-year-old skull of a wolf-dog transition specimen found in Siberia.

He turned to Crockford, an expert in dog domestication among aboriginal nations in North America, for help in analyzing the specimen and comparing it with other early cases of canine evolution.
“It doesn’t meet all of the criteria for what we consider to be a fully domesticated dog,” she told Postmedia News. “It’s got some evidence that it is partway through the process. That’s why we talk about an ‘incipient’ dog, because it’s smaller than a wolf but it still has wolf-sized teeth.”

Traits typical of canines transformed by generations of interaction with human communities include a smaller, wider skull, shortened snout and smaller, more crowded teeth.
It’s believed the wolf-dog lineage seen in the Altai Mountains specimen did not continue through the Ice Age that took hold of the region beginning some 25,000 years ago.

The team’s research has added important new information to a lively debate among scientists over where, when and how dogs evolved from wolves. Some researchers have presented genetic evidence suggesting all dog lineages emerged following a particular domestication event in ancient China, though other studies point to dog origins in the Middle East.

Handout

B.C. biologist Susan Crockford with a collection of ancient canine skulls.

Crockford said that from the Siberian case and other examples of partial domestication “it seems pretty clear that if it can get started and stop that it could have happened in any number of places” at different times around the world.
Significantly, she noted, a consensus has emerged among experts refuting the traditional theory that humans orchestrated the domestication of dogs to gain companionship or worker animals.

“Traditional anthropological definitions of domestication consider the process to be a deliberate act of selection by humans,” the published study states. “However, this view has been challenged in recent years by the hypothesis that animals colonized anthropogenic environments of their own volition and evolved into new (‘‘domestic’’) species via natural evolutionary processes . . . After initial changes occurred, the resulting new species were modified during their association with people via natural adaptation, human selection, and genetic drift.”

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