George Gaylord Simpson
Born in Chicago, Illinois, Simpson was raised mostly in Denver, Colorado. He got his degrees from Yale University in 1923 and 1926. His dissertation, American Mesozoic Mammalia (1929), was the first step in his lifelong interest in the evolution of mammals. After a post-doctoral year at the British Natural History Museum, Simpson returned in 1927 to take up a post in the American Museum of Natural History.