Cognitive capacity of non-human primates has become a popular topic in recent years. Humor is an important indicator of mental function. For the four stages of humor development in children: 1.) inappropriate action. 2.) incongruous labels. 3.) incongruous features. and 4.) multiple word meanings, examples are presented from ape behavior. Apes appreciate and produce humor in a manner comparable to humans.While investigation into the cognitive capacities and mental functioning of non-human primates has become popular over the last thirty years, few researchers have pursued the topic of humor in apes. This may be because of the dangers of making assumptions with human biases about the causes of other animals' actions or because of the elusive nature of the subject of humor itself. This paper, however, will attempt to explore objectively the capacity for humor in the apes, speci®cally gorillas and chimps, ®rst by de®ning the characteristics and possible biological functions of humor, and then by searching for evidence of these attributes and the need for humor in wild and captive apes.
De®nition of humorAt the most fundamental level, humor involves the recognition of inconsistency between one's previous experience with some situation or stimulus and his/her current experience with a similar stimulus. McGhee claimed,``something unexpected, out of context, inappropriate, unreasonable, illogical, exaggerated, and so forth, must serve as the basic