TALE of the Dog

Ask, Apr 2004 by Braaf, Ellen R

Tiny teacup poodles, massive Newfoundlands, squat bulldogs, sleek greyhounds, Mexican hairless dogs, bearded collies-dogs come in an amazing variety of sizes, shapes, personalities, and talents. Where did they all come from? And how did they get to be our best pals?

At the site of one of the earliest human settlements, Ein Mallaha in northern Israel, archaeologists found the skeleton of a woman buried 12,000 years ago. The remains of a puppy seem to be cradled in her hands. Not far away scientists discovered a man from the same period buried with two doglike animals. Dog fossils have been found in Germany, Italy, Russia, and Iraq, dating back at least 14,000 years. And some scientists who study the origins of the dog by looking at its DNA (the material genes are made of) think that dogs might go back much further, perhaps 135,000 years.

One thing we know for sure, dogs are our oldest animal friends. Before horses, cows, pigs, goats, sheep-and way before cats, which first became pets in Egypt about 5,500 years ago-dogs were part of human history.

Grandpaw and Grandma Wolf

So where did dogs come from? We know part of the answer. Dr. Jennifer Leonard, a biologist at the Smithsonian's Museum of Natural History, says that recent DNA studies leave no doubt that dogs evolved Scientists have even narrowed down the dog's "grandpaws" to a single species-the gray wolf. More amazing still, it now looks like all modern-day dogs can trace their roots back to just a few female wolves that once lived in East Asia, probably China. Over time, the descendents of these wolf "Eves" spread throughout the world. When early human settlers first came to North America from Asia, crossing the Bering Sea land bridge to Alaska sometime before 9000 BC, they brought their dogs with them.

But while scientists agree that wolves evolved into dogs, just how did such an amazing transformation take place? How could a wild wolf become a tame dog? The key is in wolves' relationship to humans.

The Wanderers

During the last Ice Age, about 60,000 to 12,000 years ago, ancient humans and wolves had much in common. They were hunters who shared the same lands and competed for the same prey. And both lived in well-organized social groups.

Wolves live in family groups called packs. Each pack member-from the leader, or "alpha" wolf, to the youngest pup-has a rank and a role in the group. Group needs come first. Pack members work together to hunt for food and raise the young. They obey the leader and respect each other's rank, and they are affectionate to one another.

Wolves are smart, too. To survive, the pack must learn from experience. Bringing down large prey requires intelligence and cooperation. Wolves use a complex communication system of body movements, facial expressions, gestures, and sounds to share information and let other pack members know what they are doing.

Away from the pack, wolves by nature are shy. Like other wild animals, they fear strangers and act with caution in unfamiliar situations. Scientists think that some ancient wolves, however, may have been a bit bolder and more curious about humans. Maybe these wolves learned there were advantages to hanging around the two-legged hunters. Stealing food from the humans was probably easy. And who doesn't like a free lunch? Perhaps people were curious about wolves, too, wondering whether these intelligent and skilled four-legged hunters could be of some use.

Biologists believe that after a long period, certain wolves became accustomed to the company of humans.

Friendly Foxes

Could the friendly, domesticated dogs we know and love really have come from fierce, wild wolves? In 1959 Russian scientist Dmitry Belyaev began an experiment to test the idea that a tame animal might be bred from a wild one. He worked with wild silver foxes, close cousins of the dog that had never been domesticated. For 26 years, Belyaev chose to breed only the foxes in each litter that were the friendliest and least afraid of people.

Gradually, Belyaev created a group of foxes that acted more like pet dogs than wild foxes. To his surprise, they also showed the same physical changes-curly tails, droopy ears, and different coat colors-seen in domesticated dogs.

They grew less fearful and less wild. Some of these "tame" wolves may have moved from place to place with our nomadic ancestors, not on a leash, but free to come and go as they pleased. Our ancestors may have occasionally adopted orphaned wolf pups from this group or even stolen pups from their dens, then reared these pups by hand and tamed them, choosing the gentlest and most docile to serve as hunting companions and pets.

Who Let the Dogs In?

Most scientists believe that it wasn't until about 12,000 years ago, as the Ice Age drew to a close and our ancestors began to give up their wandering ways to settle down in permanent communities, that these tame wolves evolved into dogs. Again, it was food that may have brought humans and wolves closer together. Like modern city-dwellers, ancient humans produced a lot of waste. For the wolves, human trash heaps were a kind of all-you-can-eat buffet. It was the village dump that really "split the wolf family in two," says Professor Ray Coppinger of Hampshire College. He believes that the wolves that eventually evolved into dogs were the ones that started hanging around human garbage dumps on a permanent basis. It was these roving disposal squads that villagers tamed and bred to become dogs.