Evolution of human intelligence

This chapter focuses on the evolution of intelligence and Richard D. Alexander's 1989 paper that explains how the human psyche has evolved. Alexander's prescient paper was one of the first studies to comprehensively seek to explain the “why” question of human consciousness and other core facets of the human mind. Alexander proposes a new hypothesis that human mental capacities evolved in the context of selection for ability to “play” in the mind—to build and permute, consciously and unconsciously, alternative social strategies and tactics in a world where evolutionary success is strongly contingent on skills for social navigation. Language, brain size, the “social” components of the brain, complex cognition and affect, social-network structures, the neurological “default mode” system of functional brain activation—all follow naturally from Alexander's model for the evolution of the human psyche.