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.
decât când se joacă unii cu alţii. Similar cu râsul involuntar, de gâdilat, diferit de râsul social. Şi acustic sunt diferite: