1. Animal behavior is intrinsically interesting (Mehlman) 2. Animals, especially those reared in the laboratory, are genetically more similar to each other than are individuals of the human race 3. Ethical considerations prevent us from exploring the effect of physiological manipulations (such as brain lesions) and severe behavioral manipulations (such as sensory deprivation) in man. The use of animals allows such studies to be carried out. 4. Starting with an organism as complex as man may prevent us from ever gaining a glimmer of understanding about behavior, but since man evolved from animals we can learn about one from the study of the other. 5. Because we can rear animals in the laboratory and completely control their experience, we can more easily tease out the particular variable re