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.
Chimpanser ler anderledes hvis de bliver kildet end hvis de leger med hinanden, og vi ser noget lignende her, ufrivillig latter, kildende latter, som anderledes end social latter. De er ret forskellige akustisk set.