Pitying ‘puppy eyes’: are they really caused by humans in domestic dogs?

Experts from Midwestern University in Illinois wondered if this was really the case, or if perhaps these muscles are also present in other canine species. To figure this out, the scientists dissected a deceased hyena dog of the Lycaon pictus species provided by a zoo. It turned out that not only do these animals have the same muscles for ‘puppy eyes,’ but they are just as developed as those of domestic dogs.