“What is the survival value of the involuntary, simultaneous contraction of fifteen facial muscles associated with certain noises which are often irrepressible?”—asks Koestler in his 1964 book The Act of Creation. Why do we laugh? When do we laugh more, alone or with other people? Why is it that the most inviting targets of ridicule are teachers, preachers, kings, politicians, military officers, bosses, and other members of the high and mighty? What might be the evolutionary function of laughter?