Researchers believe the yawning robot may have triggered some biological mechanism in the chimps that they associated with sleep. Image: Popular Science composite, Getty Images/ RMJM, Aline ...

A young chimpanzee will yawn when a human does, regardless of whether the face is familiar, according to a study that suggests contagious yawning grows stronger in our primate cousins as they grow up.

Humans aren't alone when it comes to yawning — all vertebrates do it too, including fish, amphibians, reptiles, birds and mammals. But why? The "evolutionarily ancient" act of yawning likely ...

Yawn next to your dog, and she may do the same. This is quite remarkable: Only a few animals exhibit such contagious behavior, and only dogs cross the species barrier. Now a study finds that dogs ...

Experts discuss the mysteries of yawning at first ever international conference. —LONDON, June 28, 2010 -- For two days last week, they came to Paris. Over two dozen experts in the field of ...