In Western music of the past four centuries the minor mode has been variously associated with sadness, seriousness, anger, or fear. An exception is found in Bulgarian folk music where the minor mode appears to have no such associations. The prevailing interpretation suggests that the relationship between major/happy and minor/sad is an arbitrary association that is maintained by cultural reinforcement. Drawing on research in ethology, evolutionary psychology, and cross-cultural experiments, I will suggest that the minor/sad relationship is not arbitrary -- despite it's obvious culture-specific limitation. The contrast between major and minor echoes general principles in speech prosody and emotional display.