The nature of nature

Chapter 26 covers how Sir Francis Galton was the first to apply the Shakespearian phrase “nature and nurture” to human individual differences. The so-called nature–nurture debate began as a question of whether differences among people could be attributed to in-born characteristics or environmental characteristics. Galton predated both scientific understanding of genetics and contemporary conceptualizations of behavior, but in the century that followed it was learned that: (1) the most general answer is, “both”, (2) genetic differences were more pervasive and powerful than had been anticipated, and (3) neither genetic nor environmental variance in behavior can be readily analyzed into specific mechanisms of behavior. The completion of the Human Genome Project at the turn of the current century focused attention on how the nature–nurture question had itself evolved: modern questions of nature and nurture are no longer about discriminating genetic and environmental sources of human differences, but are instead about seeking developmental mechanisms of behavior that encompass genetic and environmental inputs.