When James Watson was 24 years old, he spent more time thinking about women than work, according to his memoir "Genes, Girls and Gamow." His hair was unkempt and his letters home were full of references to "wine-soaked lunches." But when Mr. Watson wasn't chasing after girls, he was hard at work in his Cambridge lab, trying to puzzle out the structure of DNA. In 1953, when Mr. Watson was only 25, he co-wrote one of the most important scientific papers of all time.

Scientific revolutions are often led by the youngest scientists....