Domestication, evolution turned wolves into dogs

June 23, 1991|By Stephen Wigler

The process of canine domestication began about 15,000 years ago when some presumably very hungry wolves sufficiently overcame their fear of man to approach his campsites to scavenge for food.

Over the next several generations, the descendants of these wolves became ever tamer. Several millenniums later, they had metamorphosed into an animal that was not a wolf, but a dog.

Genetically, the two species -- Canis familiaris (the dog) and Canis lupus (the wolf) -- are almost identical: They are about as close to each other as the mustang is to the quarter horse. But very few animals have changed as much in appearance through the process of domestication as the dog has from its wolfish original.

Dogs range in shape from the wolflike Alaskan malamute to the huge and gentle English mastiff to the high-strung, snippy Chihuahua -- but all of them are closely related to the wolf.

The wolf was changed in other significant ways, too. Take barking. All canines have the ability to bark. But the only ones that do are domestic dogs and very young and adolescent wolves.

What characterizes young wolves -- as the 2-year-old Cheyenne's behavior demonstrated -- is their friendliness. When sexual maturity arrives -- which in the wolf is much later than in the dog -- there are often personality changes that result in a much less open and more dangerous animal. In the process of domestication, the animals that retained their adolescent friendliness were favored.

Wildlife biologists theorize that mankind was able to keep dogs in a state of permanent adolescence. Hence mature dogs retain their friendliness and continue to bark.

Other important changes concern speed, strength and intelligence. The wolf's brain is almost 30 percent larger than that of its cousin, and it has intelligence superior to that of the dog. The reason is simply that it needs it to survive in the wild -- as it does its superior strength (a wolf's jaws can exert more than 1,200 pounds of pressure per square inch, compared with a German shepherd's 750); its superior speed (wolves are not as fast as greyhounds or whippets but much faster than malamutes or huskies) and endurance (it can travel 40 miles a day without tiring).

But the most important change was the predatory instinct. A frightened, running child throws a trigger that causes a dog to chase the child and perhaps tackle it. The same situation with a wolf throws the same trigger -- except that the wolf's predatory instinct may go full cycle: It runs, leaps up, tackles and may kill.

The problem with high-percentage wolf hybrids, experts say, is that they have the same trigger.

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