One day in 1906, the british scientist Francis halton headed for a country fair in the town of plymouth where the local farmers and townspeople gathered to appraise the quality of each other's cattle, sheep, chickens, horses, and pigs. Examining workhorses and prize hogs may seem a strange way for a scientist to spend an afternoon, but there was a certain logic to it. Galton was a man obsessed with two thing: the measurement of physical and mental qualities, and breeding.