YOU SEE SOMETHING QUITE SIMILAR WITH CHIMPANZEES CHIMPANZEES LAUGH DIFFERENTLY IF THEY'RE BEING TICKLED THAN IF THEY'RE PLAYING WITH EACH OTHER AND WE MIGHT BE SEEING SOMETHING LIKE THAT HERE INVOLUNTARY LAUGHTER TICKLING LAUGHTER BEING DIFFERENT FROM SOCIAL LAUGHTER THEY'RE ACOUSTICALLY VERY DIFFERENT THE REAL LAUGHS ARE LONGER THEY'RE HIGHER IN