In the infinite variety of human minds, none is more fascinating than that of the idiot savant, or "wise idiot." These people show astonishing skill in a specific area, yet are mentally retarded, with an IQ of less than 70.
Typically, idiot savants are males (outnumbering females with this condition three to one) who can grasp complex number patterns, such as being able to name the day of the week for any date in a thousand-year span. But an idiot savant's talent may also be in art, mechanics, music, or memory of odd facts.
At 19, blind, suffering from cerebral palsy, and mentally retarded, Leslie Lemke sat down at a piano for the first time and played Tchaikovsky's First Piano Concerto, start to finish, after hearing it on the radio. A five-year old retarded child named Nadia combined a mature artist's grasp of scale and spatial relationships with an unerring visual memory to create exquisite sketches of animals in motion.
Scientists can only speculate on what causes the behaviour of an idiot savant. Somehow, he or she develops the capacity to remember certain things, coupled with an unswerving concentration that tunes out all else.
Curiously, the fields favoured by idiot savants - math, music, memory feats - also have a large share of prodigies, people with rare talents who have normal or high IQs. The brilliant German astronomer and mathematician Karl Friedrich Gauss, for example, did complex calculations in his head as a three-year-old. Musical prodigies include Mozart, Brahms, and Haydn. And prodigious memories are the mark of both idiot savants and great leaders, such as Napoleon, who knew the names of thousands of his soldiers.