Some sociobiologists who have examined rape behavior from an evolutionary perspective hypothesize that it is adaptive behavior designed to increase the reproductive fruitfulness of the rapist, who has been frustrated or thwarted in attempts to obtain consensual sexual relations. This theory has been developed from an analysis of animal behaviors. Vaious flaws exist, however, in drawing parallels between animal and human behavior concerning rape. First, applying anthropomorphic terms such as rape to nonhuman animals is imprecise and incorrectly implies a similarity of form, function, and proximate cause between human and animal behavior which has not been documented. Further, such an analysis implies that scientists can unequivocally determine when a nonhuman animal copulation is forced or resisted. Also, sociobiologists' use of the term rape is usually different from either common usage or the legal and scientific definitions used in human studies. Sociobiologists tend to redefine terms so as to produce circular reasoning, e.g., restricting rape only to sexual assaults logically expected by the rapist to produce offspring. Two other aspects of sociobiological rape hypotheses cannot be empirically supported: (1) humans have been strongly selected to maximize their reproduction and exhibit kin selection and (2) rape behavior persists because rapists enjoy a reproductive advantage over nonrapists. Finally, sociobiological reasoning about rape contains obvious sexual and cultural biases. Sixty-one references are listed.