The universal and nonrandom distribution of anxiety, fears, and depression suggests that there may have been underlying evolutionary pressures leading to adaptations for pessimistic thinking. Symptoms and processes that today we may label as psychopathology may have solved problems in an evolutionarily relevant environment, providing variations in individual behavior as a response to variations in availability of resources and vulnerability to threats and danger from predation. For example, investment strategies, the focus of this article, change with seasonal variation. Hibernation is marked by reduction of demand by limiting metabolic rates, activity, and arousal during winter months when resources are reduced, and conservation is salient, whereas manic enthusiasm focuses on short windows of opportunity, emphasizing overvaluation of pleasure, exploration, breeding, and diversification. A general theoretical model of investment strategies is proposed that accounts for sex differences in parental investments. Cognitive schemata focused on pessimistic strategies are viewed as operating through evolved algorithms that attempt to assure that behavioral and genetic investments are protected. These cognitive biases may account for male strategies of diversification and female strategies of consolidation and protection, and suggest possible determinants of a greater likelihood of females to be characterized by inhibition and depression.