The unique intellectual and cultural attributes of Homo sapiens that arose during the Middle Stone Age are often ascribed to positive evolutionary development of novel physical or personality traits, but attempts to correlate cultural with genetic evolution have been unsuccessful. Humans are also unique, however, in their ability to ignore or override hormonal and pheromonal instincts that define the social structures and behaviors of other animals. Humans can rapidly invade new environments because they invent rather than inherit such behaviors, which cumulatively we call a culture. Downregulation of instincts makes the invention and learning of cultures necessary, which imposes both an opportunity and a burden on individuals and societies. Cultural evolution enables human societies to invent, promulgate, compete and evolve their social structures in a generation or two rather than the hundreds of generations required for significant genetic evolution. Nevertheless, residual instincts may conflict with and delimit novel cultures and their social structures.
Gerald E. Loeb (Mon,) studied this question.