gelotology

Laughter is defined in a multitude of ways, depending on who you ask. In general it is considered an expression of happiness or pleasure, and therefore an emotional mechanism. A chemical and biological process takes place when we prepare to and finally launch into a guffaw. There has even been evidence of laughter in primates, rats and dogs. The very human trait of self-awareness is definitely present in these species, and it therefore seems plausible that a sense of humor would be present.