Laughter is the most enjoyable form of human communication. Humans are the only animals able to appreciate all the shadings of humor; it integrates the limbic system with the frontal lobes. (Donahue, Phil. The Human Animal. NY: Simon & Schuster, 1985, 1986, pp 331-334)
The immediate involuntary action of laughter forms the most direct communication link possible between people, limbic brain to limbic brain. People who relish each other’s company laugh easily and often; those who distrust/dislike each other laugh little, if at all. (Goleman, Daniel, PhD, with Richard Boyatzis, and Annie Mckee. Primal Leadership. Boston: Harvard Business School Press, 2002, p 12)
Refer to Laughter and the Brain for additional information.