TFA speculates that laughter or similar vocalizations are a signal of nonagression in play. Play is necessary for animals to learn to hunt and survive. There is

TFA speculates that laughter or similar vocalizations are a signal of nonagression in play. Play is necessary for animals to learn to hunt and survive. There is no indication that the "laughter" is due to a feeling of "joy" as humans experience it, but I guess there's no way to really know either. Do we observe animals telling jokes to each other, or laughing when another of their group slips and falls?