Psychiatric disorders in the context of evolutionary biology. A functional classification of behavior.

This paper examines selected psychiatric illnesses from an evolutionary biological perspective. We present a functional classification of behavior-a classification system concerned with biological goals and behaviors which have biological consequences. The paper begins with an outline of functional views in psychiatry. This is followed by a review of the theoretical framework which serves as the basis for the classification system presented here. Biological goals are then listed and discussed. The capacity of individuals with psychiatric illnesses to achieve biological goals is reviewed briefly. Adaptive behaviors used to pursue the biologically relevant goals are then presented. The relationship between the capacity to enact adaptive behaviors and goal achievement is discussed with particular emphasis on the important role of adaptive strategies as a means of goal pursuit.