[LINK] "Do Animals Laugh? Tickle Experiments Suggest They Do"

[rfmcdonald]

Liz Langley's National Geographic article takes a look at the experimental evidence that a wide variety of non-human animals, from chimpanzees to rats, laugh.

In 2009 Marina Davila Ross, a psychologist at the U.K.'s University of Portsmouth, conducted experiments in which she tickled infant and juvenile primates—such as orangutans, gorillas, and chimpanzees. The apes responded by laughing—technically called "tickle-induced vocalizations."

Ross, who studies the evolution of laughter, suggests we inherited our own ability to laugh from humans and great apes' last common ancestor, which lived 10 to 16 million years ago.

Now her latest study, published this week in PLOS ONE, goes a step further, showing that chimpanzees display "laugh faces"—smiling, with teeth bared—with or without actual laughter.

This indicates "that chimpanzees can communicate in more explicit and thus versatile ways" than we thought, she says. It's similar to how people may smile silently, while talking, or while laughing—each of which conveys a separate emotion.