You look in your dog’s eyes and feel he loves you. Or you think that’s what his face is expressing. Beauty is in the eyes of the beholder and so is beatitude: For all you know, Rover just has gas. But no question, the wolf looks at you like a cat does — at best, indifferently, and, at worst, like sausage. It cannot change the shape of its eyes to twang your heartstrings. That is not coincidence, posits an English-American team.
“Domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans,” argue Dr. Juliane Kaminski of the University of Portsmouth and the team in the U.S. Proceedings of the National Academy of Sciences.
Puppy-dog eyes, anybody? A dog can’t smile, no matter what you think, but its eyes seem to. Facial expression using the eyebrows also support speculation that when the steak vanishes from the counter, it is feeling guilty. That interpretation is based on our own intense use of eyebrow cues in communication.
However accurate our interpretations, it is unarguable that dogs and people have a remarkable level of communication — and when we communicate, our levels of the so-called “love hormone” oxytocin rise, in both person and pooch.
In other words, the dog is unwittingly taking a ride on the endocrinal element that leads parents and children to bond. Or as the researchers put it: They have “hijacked the human caregiving response.” We humans are suckers for paedomorphism — the big-eyed infantile look — and some dogs truly have the knack.
While the first dog presumably didn’t wiggle its eyebrows at a caveman who then keeled over with love, somehow communication was established. The dog moved in and we subsequently selected for exaggerated eyebrow movements in dogs, thinking they conveyed a message. And so it was that because our ancestors fell into the deep, dark pool of their eyes and sensibly selected for the most appealing characteristics, we wound up insensibly spending pretty hefty proportions of our income on dog food, vets’ fees and whatnot.
Anatomically speaking, today’s dogs possess a muscle that can raise the inner eyebrow. And they do it a lot, and intensely. Some wolves have the muscle but don’t do it a lot or intensely. Otherwise the facial musculature in domestic dogs and gray wolves is the same.
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“We hypothesize that dogs with expressive eyebrows had a selection advantage and that ‘puppy-dog eyes’ are the result of selection based on humans’ preferences,” concludes the team.
It all makes sense: What appeals more, an animal that looks you in the eye, makes his eyes look larger, sadder and more infantile, and seems to be begging for help, a caress, love? Or an animal that looks at you like you were a chair or a meal?
Sad-eyed puppies in prehistoric Europe
When the dog was domesticated, and from which species exactly, remains subject to further elucidation. The team cites a genetic analysis published in 2013 in Science, which argued that domestication of Rover began somewhere between 18,000 to 33,000 years ago.
Genetic analysis of mitochondria extracted from 18 prehistoric canids from Eurasia and the New World found that today’s dogs are all, without exception, derived from prehistoric European canids. Now, burials with dogs have been found dating back around 15,000 years, but the oldest doglike fossils found so far — in Europe and Siberia — date to about 33,000 years.
Livestock was only domesticated much later: around 12,000 to 10,000 years ago, to be very rough.
The probable conclusion from all this is that dogs were first embraced by European hunter-gatherers.
And why would they do that? Dogs today may be cute, but they weren’t then. But from the get-go, they may have simply looked at us, as opposed to just seeing us, which was unusual.
It is not news that dogs look at us in a meaningful way while wolves do not. Back in 2003, another team reported in Current Biology that socialized wolves could locate hidden food indicated by touching and, to some extent, pointing cues provided by a human they knew. But their performance remained inferior to that of dogs.
Perhaps the most intriguing difference, though, is that when stymied, dogs will look at a human for help. A wolf will not do that, not even a socialized wolf.
“Dogs, but not wolves, establish eye contact with humans when they cannot solve a problem on their own,” writes the team in the latest paper.
A separate study in 2013 found that people are especially susceptible to movements of the inner eyebrow that make eyes look bigger and sadder. And so the anatomical facial differences between dogs and wolves widened.
When did this communication begin? Was it innate to the dog all along, resulting in their uniquely advanced ability to read and use human communication? Possibly. Puppies start initiating eye contact early on, and from that point you’re toast.
Even chimps aren’t as good as dogs at interpreting human communicative cues, like pointing gestures or gaze direction, says the paper.
Some cats can also follow some human cues, including pointing and gaze direction — especially if you’re gesturing at a chicken leg. But nary a cat has asked a human for help when stymied in performing a task, as opposed to asking for food. That they will do, looking you in the eye from a strategic position on your torso. Also endearing, but it’s not the same thing.
It isn’t conclusive, but the new study notes that dogs who were adept at wiggling their eyebrows were adopted at shelters more than dogs who eschewed moving their inner eyebrow. That would indicate that producing this eye movement gives dogs a potential selection advantage — and in turn indicates that we selected for it. It may have all begun thousands and thousands of years ago when some hapless hunter-gatherer looked at a puppy, and it looked back.