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.
Šimpanzės juokiasi skirtingai, kai jas kutena nei tada, kai žaidžia tarpusavyje, ir galime kažką panašaus matyti čia, nevalingas juokas, kutenimo juokas skiriasi nuo socialinio juoko.