The history of science is rife with fateful meetings. The astronomer Tycho Brahe hires a young assistant named Johannes Kepler, who will go on to discover in Brahe’s observations the law of planetary motion. A bright but aimless British physicist named Francis Crick is introduced to a boisterous young American biologist named James Watson. The two soon discover they share a curiosity about a strange molecule called DNA. And on a warm afternoon in the early spring of 1838, the young Charles Darwin climbed into an orangutan’s cage.