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Scientists Take Peek Behind Those Sad Puppy Dog Eyes

Associated Press

   NEW YORK - What's behind those hard-to-resist puppy dog eyes?

   New research suggests that over thousands of years of dog
   domestication, people preferred pups that could pull off that
   appealing, sad look. And that encouraged the development of the facial
   muscle that creates it.

   Today, pooches use the muscle to raise their eyebrows and make the
   babylike expression. That muscle is virtually absent in their
   ancestors, the wolves.

   "You don't typically see such muscle differences in species that are
   that closely related," said Anne Burrows of Duquesne University in
   Pittsburgh, an author of the study released Monday by the Proceedings
   of the National Academy of Sciences.

   Dogs differ from wolves in many ways, from having shorter snouts,
   smaller sizes and more expressive faces. And unlike wolves, dogs
   heavily rely on human eye contact, whether to know when someone's
   talking to them or when they can't solve a problem, like hopping a
   fence or getting out the door.
   Burrows and her colleagues examined the eye muscles in the cadavers of
   six dogs and two wolves. They found dogs have a meaty eye muscle to
   lift their eyebrows and make puppy dog eyes. But in wolves, the same
   muscle was stringy or missing.

   The scientists also recorded 27 dogs and nine wolves as each stared at
   a person. Pet pooches frequently and intensely pulled back their
   eyebrows to make sad expressions, while the wolves rarely made these
   faces, and never with great intensity.
   The researchers believe dogs, over their relatively short 33,000 years
   of domestication, used this eye muscle to communicate, possibly goading
   people to feed or care for them -- or at least take them out to play.
   And people, perhaps unwittingly, obliged.

   'Profound' implications
   Dog experts not involved with the study were impressed.

   "The implications are quite profound," said Brian Hare from Duke
   University, who edited the article. Hare wrote in an email that these
   muscles almost certainly developed because they gave dogs an advantage
   when interacting with people, and people have been unaware of it.

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