…laughter is more often prompted by banal comments than amusing jokes. That makes it even more mysterious.”

Source : New Scientist August 2009.

Laughter (or something very similar) has been observed in various different species – including chimpanzees, gorillas, bonobos, orangutans, rats, mice and dogs. Although it’s known that laughter can be induced by various situations, joy, play, relief, and humour etc - the biological function of laughter in humans (if there is one) is not known.

The evolutionary reasons for the emergence of laughter are also unknown, see : Humour evolutionplugin-autotooltip__plain plugin-autotooltip_bigHumour evolution

"There are several reasons to suppose humor and laughter could be evolutionarily adaptive. [...] the complexity of humor implicates an established genetic substrate that in turn could suggest evolutionary adaptiveness. Given that even a simple joke can utilize language skills, theory-of-mind, symbolism, abstract thinking, and social perception, humor may arguably be humankind's most complex cognitive attribute. Despite its ostensible complexity, humor is also paradoxically ref…

Note: One of the laughter inducing stimuli – humour – has its own academic journal. The International Journal of Humor Research

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