>> To reach this number ... searched ... for any mention of animals making noises during play sessions Too arbitrary to search only for audible laughter. As t

>> To reach this number ... searched ... for any mention of animals making noises during play sessions Too arbitrary to search only for audible laughter. As though laughter were inconceivable amongst say humans without the capacity for vocalisation. I would characterise laughter as a patterned break in any measurable intra-species communication channel. Immediately followed by reestablished communication at lowered tension. Laughter has to be cathartic. Not easy to get enough big data, and labelling those patterns would be problematic. Yet it could be feasible. I imagine that we'd eventually be remarking upon species that lacked laughter as being exceptional. Such an approach might help address long-term failures such as dolphin NLP. Rather than aiming to solve an entire species, instead aim to solve common communication patterns across many species.