Shortly after Charles Spearman’s key work in 1904, intelligence became the best-studied, best-established trait in psychology. Higher intelligence predicts higher average success in every domain of life: school, work, money, mating, parenting, physical health, and mental health. It predicts avoiding many misfortunes, such as car accidents, jail, drug addiction, sexually transmitted diseases, divorce, and jury duty. It is one of the most sexually attractive traits in every culture studied, for both sexes. It is socially desired in friends, students, mentors, co-workers, bosses, employees, housemates, and especially platoon mates. It remains ideologically controversial because its predictive power is so high, and its distribution across individuals is so unequal.

Geoffrey Miller, Spent: Sex, Evolution, and Consumer Behavior, New York, 2009, pp. 144-145