For Dog Appreciation Month: The Origin of Domestic Dogs
April is Dog Appreciation Month, a good time for asking where in the wild these four-footed companions originally came from.
For many years, scientists interested in canine evolution speculated that some dog breeds descended from wolves and some from jackals about 10,000 to 14,000 years ago. Today, after many breakthroughs in genetic studies, biologists are probably coming much closer to the (more complex and far more interesting) truth about how dogs—from Chihuahuas to Chesapeake Bay retrievers, from dobermans to dachshunds—first came into being. Here are seven things you may not know about the origin of domestic dogs:
- What wild species was the ancestor of the domestic dog? Genetic evidence strongly suggests that dogs are descended from gray wolves and nothing but gray wolves. Your Pekinese is just a very small wolf in fluffy fur.
- When was the dog first domesticated? Bones of domestic dogs have been found at archeological sites dating back 14,000 years, when agriculture was first developed. The dog was almost certainly our first domesticated animal, making our best friend also our oldest. But in fact the dog probably has been traveling with us for far longer than 14,000 years. Genetic studies from the late 1990s indicate that dogs probably partnered with humans as long as 135,000 years ago and maybe even earlier—some human archeological sites dating back 400,000 years include the bones of wolves that may have enlisted with humankind long before evidence of their domestication showed up in their bones.
- How long would it take to domesticate the wolf? Biologists used to think that domesticating wild animals—converting them from wild creatures into docile animals distinguishable from their wild ancestors—was a slow process. Not so, Russian geneticist Dmitry Belyaev discovered in the 1960s by experimenting on silver foxes. Individual silver foxes different in personality from one another in various ones. For example, some are just naturally tamer and friendlier with humans than are others. By breeding naturally tame foxes with one another in captivity, Belyaev created a domestic version of the species in only 20 years. They differed from undomesticated foxes in a number of ways: Their brain chemistry made them more docile; they wagged their tails as no self-respecting wild fox would do; some were born with spots and other markings not found in the wild; their ears flopped, instead of standing upright; their tails shortened, and their skulls got wider; their breeding season became less well defined. The domestic dog would have arisen similarly from individual wild wolves that were tamer than average, though probably not as quickly (early hunter-gatherers presumably lacked a geneticist’s skill in selecting the right breeding stock).
- How did humans create dog breeds? Modern domestic dogs—those that are distinctly different from wolves and that are divided into breeds that differ from one another—may be a by-product of agriculture. Humans began to farm—that is, to cultivate plants rather than merely collect them from the wild—about 14,000 years ago in the Middle East and in Southeast Asia. Once people settled down to farming and the development of permanent communities, they would have learned more productive breeding techniques, giving rise to early dog breeds such as those selected for hunting and those for herding.
- Where did dogs originate? A good question that no one can answer with any certainly. The prevailing scientific speculation on this point suggests that wolves were brought into captivity at various times in various places, so that domesticated dogs have had many places of origin. Domesticated canines probably also bred through the years with neighboring wild wolves, creating more genetic diversity in the domestic animals. However, one study from 2002 used genetic evidence to suggest that domestic dogs originated in East Asia.
- How closely are wolves and domestic dogs related today? So closely that scientists have a hard time coming up with genetic criteria for distinguishing wolves from dogs. For this reason the Society of Mammalogists and the Smithsonian Institution have reclassified domestic dogs (once in their own species, Canis familiaris) as a subspecies (Canis lupus familiaris) of wolf (Canis lupus). Nevertheless, dogs and wolves are physically and behaviorally different, and these differences vary from breed to breed. In many characteristics—a more rounded face, less aggressive behavior, fuzzier hair, smaller teeth and skull, smaller brain—dogs have retained the traits of young wolves. Most breeds never fully mature into the adult physique and nature of the gray wolf, though some, such as German shepherds and Siberian huskies, come close and may have experienced a more recent influx of wolf genes (from crossbreeding) than have some other species.
- What is the oldest dog breed? Both the saluki—a rangy, silken-haired hunting dog—and the basenji—another hunting breed—appear on 5,000-year-old Egyptian friezes and have been are found mummified in Egyptian tombs, making them rivals for the title of most-ancient breed.
A Note about the Photo
This image of a Yellowstone wolf was an entry in last year’s NWF Photo Contest. You can find information about the contest and how to enter here.