Evolution of the dog: Wolf to woof
Ever wonder what events had to take place in history in order for the ferocious wolf to become man's best friend?
Wednesday, April 7, 2010 - 15:00
SEñOR PUGSLEY: My pet pug. (Photo: Maria Boland)
I had always been curious about whether my dog, who is of the pug breed, actually evolved from wolves. His pushed-in snout, curly tail and lack of dog-like personality kept me second guessing. I became interested in the evolution of dogs from wolves and what drastic changes had to take place to turn a wild wolf into my housebroken pug. After doing a little research, I found that the domestication of the dog was a 15,000 year process. This explains why there have been so many wild animal attacks while in captivity, by animals like tigers and orca whales. Some humans expect that within years, the domestication of a wild animal can be completed without any danger of a setback, but if more people understood that it takes thousands of years to fully domesticate an animal, perhaps the links between the human and animal world would be stronger.
There are two different theories that have developed as to how the wolf came to be domesticated:
1) It was traditionally believed that domestication was a conscious effort of humans. (The theory that ancient people took wolf pups from dens, adopted them, fed them, trained and tamed them.)
2) Another school of thought is that wolves domesticated themselves, which is a process that would have begun at end of the Ice Age (approximately 15,000 years ago) when people began to gather and live in one place for the first time. When humans live in the same spot for a long period of time, they create waste, including both sewage and leftovers. This leads to the behavior characteristic "flight distance."
Flight distance was crucial to the transformation from wild wolf to the ancestors of the modern dog. It represents how close an animal will allow humans (or anything else it perceives as dangerous) to get before it runs away.
Animals with shorter flight distances will linger, and feed, when humans are close by. This behavioral trait would have been passed on to successive generations, and amplified, creating animals that are increasingly comfortable around humans. (So what "domesticated" or "tame" really means is to be able to eat in the presence of human beings. This is something that wild wolves can't do.)
Evidence suggests several varieties of ancient wolves contributed to domestic dogs with deliberate or unintentional interbreeding.
Although all wolves belong to species Canis lupus, there were many subspecies that had evolved distinctive appearance, social structure and other traits. The five distinct wolf types were the Japanese Wolf, the North American Wolf, the Indian/Asian Wolf, the European Wolf and the Chinese wolf. Some still exist in limited ranges, but the Japanese and European Wolf became extinct in the early 20th century. Over time, the cross breeding of the wolf types lead to the diverse breeds of dogs we know today.
A change in personality can lead to changes in DNA and physical appearance.
As man began to select the wolves with the most "puppy-like" personalities and appearances, the physiological development of the animal was slowed or delayed. This eventually lead to adult wolves with the same personality and appearance as puppy wolves, and furthermore to the development of dogs that were able to live their entire lives with human interaction.
Dogs as pets share many physical features with immature wolves. Such puppy-like traits may have made early dogs seem "cute" and less threatening than wolves, leading to both natural and artificial selection.
Puppy-like characteristics include: soft/fuzzy fur, round torsos, large heads and eyes, ears that hang down rather than stand erect, labeled "cute" or "appealing."
There are varying degrees of puppy-like behavior retention. Herding dogs retain the most juvenile characteristics (ex: border collie). They stay close to flock rather than going out hunting. They have almost no predatory behavior. They respond to perceived threats with vocalization in attempt to alert and engage dominant individuals in their "pack," engaging in actual combat only as a last resort. Lastly, they have puppy-like physical characteristics (do not bring out fearful responses from sheep in way that appearance similar to adult wolf would).
Hunting dogs, on the other hand, retain only an intermediate degree of puppy-like behavior (ex: Labrador retriever). Members of this group of dogs share in the pack's hunting behavior but still play a junior role (don't participate in actual attacks). They identify potential prey and freeze into immobility (refrain from stalking prey). They retrieve dead or wounded prey and bring back to "pack." Their physical characteristics are closer to mature, wild canines.
To sum all of this information up for you, there is a very interesting video clip posted below that came from the environmental focus television show "Nature." This particular segment is the preview to a two-part series whose main focus is the domestication of dogs and how important they have come to be in our daily lives. If you wish to view the entire series, please follow this link.
DesertNana aka majamo/Flickr
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