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 reflexive — people typically laugh without consciously appreciating all the causal factors."

Source : The First Joke: Exploring the Evolutionary Origins of Humor Evolutionary Psychology, Vol. 4 issue 1.

The question of why humour has evolved - with the implication that it gives evolutionary advantages to the species - has not been answered. There are various theories, for example that it evolved, after language, as a way of maintaining 'group bonding', but without the need for physical contact.

The paper cited above lists the progress-so-far in the attempts to explain humour.

Note: Humour has its own peer-reviewed academic journal. The International Journal of Humor Research

Also see : Laughterplugin-autotooltip__plain plugin-autotooltip_bigLaughter

"...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 no…