A novel model is presented to explain human social behavior. In recent years, a cephalo-caudal directionality to behavior has been reported in a few mammals including rodents, cattle and cats. This model shows how complex human behavior also follows this rule of cephalo-caudal directionality. The positions of the lower motor neurons mediating the specific acts in the cephalo-caudal neural axis are considered to be an important correlate of the act. The model consists of a primary layer,

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... ng of the orienting modules – eyes, head and body and a secondary layer consisting of the six transmitting channels – the eyes, facial expression, speech, upper limbs, lower limbs and the external genitalia. The model demonstrates through multiple examples that complex human behavior also follows a cephalo caudal directionality, both in the orienting modules as well as in the transmitting channels. In this paradigm, conciliatory and agonistic communications are examined as prototypes for analysis of more complex dominant and submissive behavior as well as psychiatric conditions such as mania and depression. The model is sensitive to the social context of behavior which is without precedent in the literature. Further, the concept of 'mobility gradient' is applied to human behavior to understand motor behavior in depression and mania and catatonic behavior. Finally, certain issues pertinent to difficulties of behavioral description and model building in human behavior are discussed. The model emphasizes the role of objective behavioral description paradigms that borrow from concepts in comparative psychology and animal behavior.