The obsessive-compulsive personality pattern of orderliness, parsimony, and obstinacy was first described and explained by Sigmund Freud. Freud's description was sound, but his explanation was flawed. Further still, no extant etiology, psychoanalytic or otherwise, convincingly accounts for the existence, and intergenerational perpetuation, of obsessive character. Thus, herein is presented a new etiology; an evolutionary etiology that describes obsessive personality, not as a disorder, but as an extreme strategy whose imbalance is a product of post-dispersal evolution. Migration into northerly latitudes brought about a relative release from biotic selective pressures, such as conflict and conspecific competition, and a corresponding increase in abiotic selective pressures, such as cold and seasonal scarcity. Features such as (1) future-oriented thought, (2) parsimoniousness, and (3) compulsive conscientiousness become both viable and intelligible as a temperamental consequence of struggling more exclusively with the elements. After using comparative animal data to demonstrate their biogeographical distribution, the human distribution of these three traits is also shown to be concentrated within northerly latitudes.