Humans and great apes have been giggling in similar ways since branching off the evolutionary tree, a new study suggests. Researchers tickled 13 captive apes and recorded the results, comparing them with the giggles of four young children while they were being tickled and playing at home.

Similarities in Laughter

The chuckles of humans and great apes follow similar rhythms, with regular timing between their laughs, a uniting thread that likely reflects their ties to a common ancestor, researchers said. According to study author Chiara De Gregorio, a primatologist at the University of Warwick in England, "In a way, we are very similar to other great apes because we’ve been laughing in a similar way for 15 million years."

Laughter communicates a playful, happy feeling without using words. Many animals can laugh too, but the giggles don’t follow human patterns as closely. When researchers tickle rats, for example, they respond with ultrasonic squeaks. Scientists trying to uncover how laughter evolved have picked apart animals’ facial expressions, but less work has been done on how laughs sound.

Compared with apes, human laughter has become faster and more complex. For one, our laughs sound different based on context — from a polite chuckle among colleagues to a full-bodied guffaw with close friends. "We are like the masters of laughter, I would say," said De Gregorio, whose findings were published in the journal Communications Biology.

These giggles evolved to best suit animals’ different social lives, said Brittany Florkiewicz, who studies animal communication at Lyon College and had no role in the new research. She said the study’s findings make sense, and point to a need for more investigation. Florkiewicz said she’d like to hear comparable recordings of other animals with playful facial expressions, like dogs, horses, and cats.

Original reporting: KTBS 3 (Shreveport) — read the source article.