 In this early study Darwin raises further questions about who laughs and why they laugh; the myriad responses since then illustrates the complexities of this behaviour.To understand laughter in humans and other primates, the science of gelotology (from the Greek "", meaning laughter) has been established; it is the study of laughter and its effects on the body from both a psychological and physiological perspective.While jokes can provoke laughter, laughter cannot be used as a one-to-one marker of jokes because there are multiple stimuli to laughter, humour being just one of them.