The difference between a wolf and a dog depends on what we mean by ‘dogs’. Because in one important sense, wolves are dogs, in that they belong to the canid family, which also includes foxes, jackals and coyotes, among others. If we mean domestic dogs, which are also canids, then it is also the case that a dog is a wolf, because it is from wolves that dogs were domesticated.
What's the difference a wolf and a dog?
Until recently, biologists thought that dogs were domesticated from the familiar grey wolf that still prowls the wilder regions of Europe, Asia and North America. But modern genetic studies suggest otherwise. It is now thought that they are descended from another wolf lineage that is now extinct. However, while domesticated dogs and grey wolves are named as if they are different species – Canis familiaris and Canis lupus, respectively – many experts consider this distinction to be unnecessary, as they are capable of interbreeding and producing fertile offspring.
Indeed, wolves and domestic dogs are very similar genetically. This is despite the tremendous variation between dog breeds in terms of size, coat colour, facial features and body proportions. Some – huskies, say, or German shepherds – are certainly wolf-like. But the same could not be said for pugs or St Bernards. Wolves, by contrast, are far more uniform in appearance.
Remarkably, almost all of the genes responsible for this variation in modern dog breeds were already present in the ancestral wolf population. Domestication probably occurred somewhere between 15,000 and 40,000 years ago. This is a mere blink of an eye in evolutionary terms – not enough time for the line to accumulate many novel genetic mutations of its own. Instead, the differences are due to humans’ efforts to selectively breed for particular tasks, whether it’s herding sheep or looking pretty.
The cuteness factor is not to be underestimated as a driver for domestic dog evolution. A small muscle above the eyes of canids is more developed in man’s best friend than it is in wolves, enabling them to manoeuvre their eyebrows to produce facial expressions capable of plucking human heartstrings without mercy. The fact that we use the phrase ‘puppy-dog eyes’ to describe a certain melancholic look in humans might suggest that they pull it off better than we do.
Another important difference is that, compared to wolves, domestic dogs are less fearful, highly strung or aggressive. This might stem from the earliest stages of domestication, when only the least jumpy wolves would have dared to approach humans – perhaps to scavenge food from around human habitations – from where a deeper relationship between the two species could be developed.