If we look at the years 1980–2000, the main driver of rising income differences—which explains 75 percent of the variation—is whether a person has a college degree, no degree, or a graduate degree.

Intelligence predicts invention.In a Finnish study, IQ accounted for 66% of the explained variation in who becomes an inventor, far outweighing other factors like parental education. This effect is strongest at the highest levels of achievement, where cognitive ability has an increasingly potent relationship with earnings.

Top performers need intelligence.For jobs requiring innovation, leadership of smart people, and the ability to "see around corners," high intelligence is often necessary. However, intelligence alone is not sufficient - it must be combined with other traits like work ethic, creativity, and social skills to produce truly exceptional results.

Areas where intelligence matters most: