General intelligence […] is the best-established, most predictive, most heritable mental trait ever found in psychology. Whether measured with a formal IQ test or assessed through informal conversation, intelligence predicts objective performance and learning ability across all important life-domains that show reliable individual differences.

Geoffrey Miller, ‘Mating Intelligence: Frequently Asked Questions’, in Glenn Geher and Geoffrey Miller (eds.), Mating Intelligence: Sex, Relationships, and the Mind’s Reproductive System, New York, 2008, p. 373