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The Woof at the Door

Dogs may have been man’s best friend for thousands of years longer than we realized

Pat Shipman

Breuil's cave tracing watercolor of a wolfClick to Enlarge Image It’s funny how much difference a single letter makes. A “woof” at the door is a very different thing from a wolf at the door. One is familiar, domestic, reassuring; the other is a frightening apparition of imminent danger. The distinction between our fond companions and the ferocious predator of northern climes goes back a long way.

Dogs are descended from wolves, probably the gray wolf. Some scientists argue that, because dogs and wolves can and do interbreed, they shouldn’t be considered to be separate species at all. They believe that domestic dogs are only a subspecies or variant of the gray wolf, Canis lupus, and ought to be called Canis lupus familiaris (the familiar or domestic wolf) instead of Canis familiaris (the familiar or domestic dog). Although the ability to interbreed and produce fertile offspring is a tried-and-true criterion for recognizing that two populations are really variants of a single species, the reality is more nuanced. We cannot know whether dog-wolf hybrids will thrive and survive, or die out, in the long run.

Certainly we expect to be able to distinguish a dog from a wolf if we see one. Of course, domestic dogs are wildly variable in size and shape, thanks to several hundred years of selective breeding. Some have long, fluffy coats; others have tightly curled, nearly waterproof coats and webbed feet. Some are leggy and swift, whereas others are solid, stoutly built guard dogs. Some fit neatly into a pocketbook, but others barely fit into a compact car. As Robert K. Wayne of the University of California at Los Angeles declares, “Dogs show more diversity in appearance than any other mammal.”

What is it that tells us this animal is “dog” and that one is “wolf?”

Modern wolves and dogs can be distinguished reasonably easily by their appearance. The most telling feature of dogs is the snout, which is significantly shorter and wider than wolves’ snouts. Only a few dog breeds with extremely elongated, slender snouts, such as Irish wolfhounds, surpass wolves in “snoutiness.”

But a crucial part of the difference we perceive is in the animals’ manner and attitude towards humans. Domesticated dogs are just that: canids that live in the house or domicile of humans. They are genetically disposed to seek out human attention and approval and to accept human leadership. Wolves are not.

How did this important change come about? Probably in the distant past, humans took in a wolf cub, or even a whole litter of cubs, and provided shelter, food and protection. As the adopted cubs matured, some were aggressive, ferocious and difficult to handle; those probably ended up in the pot or were cast out. The ones that were more accepting of and more agreeable to humans were kept around longer and fed more. In time, humans might have co-opted the natural abilities of canids, using the dogs’ keen noses and swift running skills, for example, to assist in hunting game. If only the most desirable dogs were permitted to breed, the genes encoding for “better” dogs would continue to be concentrated until the new domesticated species (or subspecies) was formed.

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