First, we have Grendel, a (very) mixed breed, who looks like the result of blenderizing DNA from a pug, a German shepherd, a pit bull, a husky, and a fireplug. He's cute, in a melancholy, "what are you so sad about, boy?" kind of way, and uses his wide range of pathetic expressions to get attention and food scraps.
Then we have Lena, whose ancestry includes redbone, blue-tick coonhound, and beagle. She's eternally cheerful, has a tail that never stops wagging, lives for chasing squirrels, and has the intelligence of a loaf of bread.
They get along pretty well, although I kind of get the impression they don't really understand each other. Grendel sometimes tries to play with Lena, in his ponderous sort of way, but it never lasts very long. Lena usually ends up capering around, trying to fit all of the toys in her mouth at the same time, and Grendel gives up, sighs heavily, and plods over to us hoping we'll give him a dog cookie for at least giving it a shot.
I've always had dogs. There's something about having a dog in my house that just seems necessary. It always comes along with bushels of pet hair, muddy pawprints, and a variety of carpet stains, but I can't imagine that part of my life being missing.
I bring all of this up because I've always wondered about how dogs were domesticated. Some people think they started out as utilitarian hunting animals, and after selection for responsiveness to human interaction, gradually morphed into what we have today. Others think that the companionship aspect was there from the beginning, perhaps from as long ago as our cave-dwelling days.
The question, of course, will probably never have much going for it other than speculation, given that we don't have much in the way of evidence on which to base an answer. However, a study by Laurent Frantz of Oxford University et al., published this week in Science, has at least given us a little more information about when and where this pivotal event took place.
According to Frantz's team, a study of DNA from the remains of 59 ancient dogs, including one from the late Neolithic Period (this particular mutt lived in Newgrange, Ireland about 4,800 years ago), dogs were domesticated at least twice -- once in Western Europe, and once in East Asia. The East Asian dogs came with their human friends during migrations, and interbred with preexisting European Paleolithic dogs to produce most of the breeds familiar in Europe and America. Says Tina Hesman Saey, who wrote about the study in Science News:
Using the Newgrange dog as a calibrator and the modern dogs to determine how much dogs have changed genetically in the past 4,800 years, Frantz and colleagues determined that dogs’ mutation rate is slower than researchers have previously calculated. Then, using the slower mutation rate to calculate when dogs became distinct from wolves, the researchers found that separate branches of the canine family tree formed between 20,000 and 60,000 years ago. Many previous calculations put the split between about 13,000 and about 30,000 years ago, but the new dates are consistent with figures from a study of an ancient wolf’s DNA.Which is a long time ago, considering that most of the distinct modern dog breeds trace back to a common ancestor only a few centuries ago. (Exceptions include some of the old Chinese breeds, such as the Pekingese, Shih-Tzu and Sharpei, which seem to be a good bit older than that.) But despite the recent diversification of shapes, sizes, colors, and behaviors, what seems pretty certain is that dogs in some form have been our friends for a long, long time.
Compare this to cats. A recent study done in Japan found that cats recognize their own names and their owners' voices, but apparently evolved not to give a damn. Their ears turn and whiskers twitch when their owners speak, but it doesn't make a lot of difference to their behavior otherwise. I find this result unsurprising. I can say from personal experience that my 18-year-old cat Geronimo considers me to be warm-blooded furniture, and his expression usually says, "I am only refraining from clawing your eyes out because you feed me expensive canned food every day." Contrast this to Lena, whose body language communicates "I LOVE YOU SOOOO MUCH" if I give her a muddy stick to chew on.
Not that I'm biased, or anything. I'm sure that a lot of this is my projecting my own emotions, thoughts, and feelings onto my pets, but when Grendel looks up at me with those big sad eyes, it's hard not to sense a bond. Maybe we've evolved into the relationship, too, because there's something primal and comforting about having a dog around.
Despite the hair, muddy pawprints, and carpet stains.