Duck and Dog Playing Tag

“Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, and company, when playing together, like our own children,” writes Charles Darwin in his 1872 classic, The Descent of Man. Most animals have been observed playing, and play does seem to make them happy. But research has also shown that play is a serious business, and many researchers argue that it has evolutionary significance, essential for developing a host of social, physical, and psychological skills.