What is it about human brains that make some people more capable than others? In an authoritative and critical account, Professor Ian Dreary reviews historical, cognitive, and biological research on the foundations of human mental ability. Where most previous accounts of intelligence have examined how human mental ability can predict success in education, work, and social life, few books have taken as a starting point mental ability (and individual differences in intelligence), and attempted to see what factors could have influenced, and have even predicted mental ability. This book reveals what we know about the origins of intelligence. It describes research on genetic influences on intelligence, and evidence that has been obtained from biological studies, including examinations of ‘brain size’, event related potentials, and the recent profusion of studies involving functional brain imaging. Coupled with fascinating historical stories, the book provides a highly original and thought provoking guide to try and answer the age old question of why some people seem more clever than others.