Y: Don, many mammals make facial expressions. The architecture of the face, with muscles for making facial expressions is much the same across these mammals. They probably inherited this architecture from a common evolutionary ancestor in the distant past.

D: Yaël, animal facial expressions aren’t like ours. They are inflexible and involuntary and don’t reflect sophisticated cognitive processes.

Y: That’s what scientists used to think, but increasing evidence shows that they were wrong.

D: What’s the evidence?

Y: In 2017, a team of scientists from the United Kingdom published findings that dogs actively use facial expressions to communicate with and influence humans. The experimenters put dogs in situations where a human experimenter was either paying attention to them or turned away, and either gave them food or didn’t.

D: I see. Getting food is emotionally exciting for dogs. If their facial expressions just have to do with emotional excitement, then it shouldn’t matter whether a human is paying attention to them or not. On the other hand, if dogs are actively using facial expressions to influence humans, then it should.

Y: That’s it exactly. The researchers found that the dogs showed a much wider range of facial expressions when the human was paying attention, than when they were given food without human attention.

D: Wow! Animal facial expressions are a lot more active and sophisticated than scientists thought.

Y: There’s other evidence, too. Researchers found that dogs use a special gesture involving raised eyebrows when interacting with humans. It makes their eyes look bigger, which humans find cute. In fact, dogs that use this expression are more likely to be adopted from a shelter.