The nature of intelligence Intelligence can't be observed directly. The beginnings of intelligence measurement Francis Galton, the 1st to measure human abilities systematically Mental ability is inherited.
Eminence runs in families due to abilities transmitted by genes.
The Stanford-Binet test of 1916 Standardized on a large sample of children whose scores provide the norms Binet subscribed to a concept of general intelligence but was on the nurture side of the Great Intelligence Debate. Mean IQ set at 100. It stabilizes about age 6, but infant-young child intelligence scales correlate poorly with intelligence measured later. Note why this tends to be so. Potent environmental influences on measured intelligence are well known.