Those Puppy Dog Eyes You Can’t Resist? Thank Evolution
You know
that face your dog makes, the one that’s a little bit quizzical, maybe a bit
sad, a bit anticipatory, with the eyebrows slanted? Sometimes you think it
says, “Don’t be sad. I can help.” Other times it quite clearly asks, “No salami
for me?”
Scientists
have not yet been able to translate the look, but they have given it a very serious
label: “AU101: inner eyebrow raise.” And a team of evolutionary psychologists
and anatomists reported Monday in Proceedings of the National Academy of
Sciences that dogs make this face more often and way more intensely than
wolves. In fact dogs, but not wolves, have a specific muscle that helps raise
those brows.
Here’s an
example of the look in a talking-dog video that nearly 200million people have
watched online. Watch for the twitch up of the inner eyebrow at 15 seconds.
The dog in
the video can do that because it has a muscle called the levator anguli oculi
medialis. It can talk because this is a YouTube video. That part has nothing to
do with science. But it hardly needs the voice-over to make its emotional
point.
Clive Wynne,
a psychologist at Arizona State University and head of the Canine Science
Collaboratory there said, “I think the study is compelling.” It is, he said,
“another piece of the puzzle of what connects dogs to people.” But Dr. Wynne,
who was not associated with the study, said that a greater number and variety
of the two species would need to be studied to learn more about the general
differences between dogs and wolves.
How humans
and other animals communicate by looking at each other is a matter of great
interest to scientists. Anne Burrows, an anatomist at Duquesne University, in
Pittsburgh, had studied chimpanzee faces. She and the other researchers,
including Juliane Kaminski, an evolutionary psychologist at the University of
Portsmouth, in England, joined together a few years ago to look at domestic
animal facial expressions and musculature.
They started
with horses and cats, and, she said, horses have facial movements similar to
dogs, but cats do not. “It turned out they just don’t really move their faces
at all.” The researchers did not explain how cats are nonetheless able to
express highly sophisticated states of mind such as skepticism, disdain, deep
self-satisfaction and world-weary ennui. That research may have to be left to
the cats themselves.
Dogs were an
obvious subject. As many dog owners have said, “Just look at that face!” There
were studies on how dogs look to their owners when they can’t solve a problem,
and evidence that dogs who indulged more in “AU101:inner eyebrow raise” were
more likely to get adopted from shelters.
So the team
tested dog and wolf behavior by videotaping their reactions, and, as expected,
dogs did raise their eyebrows more often and more intensely than wolves. Even
though wolves don’t have that muscle, they have a lot of other muscles so they
can do a bit of the look.
Researchers
dissected the heads of four wolves and six dogs, all of which they acquired
after deaths in which they had no part. As might be expected from animals so
closely related, all the musculature was exactly alike except for the levator
muscle, which none of the wolves had. One other muscle, which varied in the
wolves and dogs, was also related to eye movement.
The
scientists hypothesize that humans have unconsciously favored eyebrow-raising
dogs during fairly recent selective breeding. Dr. Burrows said that one
tantalizing hint that could lead to future study was that one of the dogs, a
Siberian husky, was more like the wolves and did not have the levator anguli
oculi medialis.
Huskies are
more closely related to wolves than some breeds, and it may also be that talent
in sled-pulling was more important than a soulful face in the breed’s
development.
Dr. Kaminski
said, “the next step is to look at more breeds” to see if the behavior and the
musculature varies. Perhaps dogs that are bred to work very closely with humans
might be more likely to show the raised eyebrows which seem to indicate that
the dog is paying attention.
And, she
said, she would want to know whether the upbringing of a dog has an effect on
this behavior.
As to what
the meaning of the look is in the mind of the dog that gives it, and what dogs
think of such studies of their facial expressions, science doesn’t have those
answers yet.
And although
animals may close one eye, and despite the vast amount of evidence on the
internet, there is no scientific evidence that dogs, or any other animals,
wink.