From wolf to whippet
We all know our pet pooches are descended from wolves, and some breeds still retain a rather wolfish appearance. But when you look at a Whippet, a Chihuahua or a French Pug, it’s hard to see the resemblance. So can that cuddly canine that curls up in front of the fire really be genetically almost identical to the fierce predators that roam the frozen North? The short answer is yes, although the explanation why is a little longer…
Let’s start at the beginning
Scientists have long debated the origins of the domestic dog – precisely where and when did that wolf first wander into a human camp? There are several competing theories, and one explanation claims that domestic dogs emerged during the agricultural revolution around 10,000 years ago, when wolves began to scavenge around human habitations. But another more recent theory suggests that dogs are related to a group of wolves that first came into contact with European hunter-gatherers around 25,000 years ago. And according to DNA gained from ancient wolf fossils, some scientists think that the original source species may have, in fact, become extinct.
So why do many of today’s dog breeds look so different from their wild cousins? The answer is that an animal’s physical characteristics are determined by a very small number of genes. So even though a Great Dane and a Shih Tzu may look like two completely different species, they’re almost genetically identical. And 99% of their original wolf DNA remains unchanged. Although evolution driven by natural selection is very slow, selective breeding guided by human intervention accelerates the process enormously - so new dog breeds can emerge quite quickly. In fact, the history of selective breeding reveals a great deal about our own human history – as people have bred dogs for a variety of purposes, from guarding horse-drawn carriages (Dalmatians), to hunting rabbits (Miniature Dachshunds) and even hunting lions (Rhodesian Ridgebacks).
The flipside of selective breeding
Traditionally, selective breeding has been used to enhance specific canine characteristics, such as stamina, strength, intelligence, loyalty and courage. But some selective breeding can result in negative side effects. In Poodles, for example, a gene related to coat colour has been linked to a rare form of cancer, so selective breeding designed to produce pups with a particular colouring can unintentionally result in generations of dogs with heightened risk of developing serious disease. And it’s well known that some high-bred flat-faced breeds can suffer from Brachycephalic Airway Obstructive Syndrome, which can cause lifelong health issues.