Necessity Was the Mother of Human Cultural Invention

The unique intellectual capabilities of Homo sapiens are often attributed to positive, physical evolutionary developments such as increased cranial capacity, upright posture, dexterous hands and an articulate oropharynx, despite the occurrence of similar features in other species that have not developed such capabilities. Humans are also unique, however, in lacking or ignoring instincts that define the social structures and behaviors of other animals. Genetically driven behaviors evolved to improve effectiveness in exploiting specific environmental niches. In nonhuman species, social structures, food choices, mating behaviors, child-rearing, etc. are driven strongly by pheromones and hormones and their neuronal targets, whose physiology evolves very slowly. Humans can rapidly invade new environments because they invent rather than inherit such behaviors, which cumulatively we call a culture. The invention of niche-specific social behaviors enables cultural evolution, which would otherwise be limited by the inflexibility of instinctual behavior. I explore the obverse hypothesis that down-regulation 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. Novel cultures and their social structures may conflict, however, with residual instincts. Such conflicts and their resolution will continue both to drive and to constrain cultural evolution.