History Of Dogs: Do Pugs Really Come From Wolves?
Female pug dog painting, 1802. (Bonhams London/Wikimedia Commons)
Aside from being canine, pugs and wolves don't seem to have much in common. Really, pugs don't even have much in common with other dog breeds, from the towering Great Dane to the friendly Golden Retriever. The evolution of dogs that created a myriad breeds occurred over thousands of years, giving rise to cuddly creations that are each in their own way man's best friend.
Canis lupus, otherwise known as the big gray wolf, first appeared in Eurasia early in the Pleistocene period, about a million years ago. Shortly after that, around 750,000 years ago, it's believed that the gray wolf migrated to North America. For a brief period of a few thousands years, the gray wolf and dire wolf (Canis dirus) coexisted, but thanks to climate change and prey extinction, the dire wolf fell away and the gray wolf became the alpha canine in North America. By the time the Inuit people crossed the Beringia, the gray wolf was a well-established predator in North America.
The Evolution Of Dogs
The first step toward specific dog breeds was like an early visit to a canine adoption facility, just without the paperwork or shots. The Inuit people "adopted" wolf cubs (or just took them from their parents) and trained them to be docile, or at least as docile as a wolf can be. Referred to as "one of the most extraordinary events in human history," no one knows exactly how long it took to create the first docile canine, but the scientific community believes the animal that's closest to man's best friend has its origins somewhere in southern China, Mongolia, or Europe. By studying the D.N.A. of two Neolithic German dog fossils, dog researchers (researchers who study dogs, not dogs who have somehow scored jobs in scientific institutes) have concluded that domestication first occurred between 20,000 and 40,000 years ago.
Splitting Into Breeds
While researchers believe that dogs were domesticated in a single event, they also think multiple domestication events led to multiple types of dogs with at least three types of skulls: a dolichocephalic skull, which is common in hunting dogs; a mesocephalic skull, the most common; and a brachycephalic skull, which is flat.
These multiple versions of the domestic dog split around 14,000 years ago and then split again about 7,000 years later into East Asian and Western Eurasian dogs, many of the latter of which have gone extinct. Ancient D.N.A. tells us that those dogs then interbred to create various mutts that then interbred, creating a mess of canines that were either fine-tuned into one breed or disappeared off the map completely.
Dogs And Humans
There may not be a straight line from wolves to lap dogs, but it's not as curved as you think. Researchers believe that many wolves took part in a kind of self-domestication, allowing themselves to eat less and defer to their person. In an experiment on domesticated foxes in Russia, researchers learned that foxes who were good-tempered and skilled at picking up social cues from humans were most likely to be kept around, so this may have been a survival strategy. As those deferential wolves bred, they made friendlier animals. Thanks to this kind of domestication, dogs and humans have both evolved to need one another on a chemical level. When dogs and humans look into each other's eyes, their brains secrete oxytocin, a hormone linked to maternal bonding and trust.
So just how did the mighty wolf become the awkward pug? Researchers believe that pugs were first bred around 400 B.C.E. to be companion animals for both Chinese royalty and Buddhist monks in Tibet. It's not entirely clear how canines were bred down to the sturdy, sniffly pugs, but their small frame and lack of exercise needs makes them incredibly adaptable, which is likely why the breed has survived for thousands of years.
Pugs more than likely played a part in the explosion of dog breeds during the Victorian era, when the English became obsessed with Darwin's concept of natural selection. It was during this era that many of the conformational traits of dogs that we know today were locked in place, when pug genetics may have been used to shrink down a dog or make it somewhat more deferential, although it's just as likely that Victorians were shooting in the dark when it came to mixing breeds. Through their experiments, Victorians made dachshunds smaller and codified what breeds were supposed to look like. For example, pugs were meant to be "of a fawn colour [sic], devoid of any smut approaching blackness, [with] a coat that is sleek, shining, and soft to touch."
Whether through genetic manipulation or dumb luck, the path from gray wolves to domesticated pooches is quite straight, even if researchers can't pinpoint the moment the shift occurred.
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