Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation. Gould spent most of his career teaching at Harvard University and working at the American Museum of Natural History in New York. In the latter years of his life, Gould also taught biology and evolution at New York University near his home in SoHo. Gould's greatest contribution to science was the theory of punctuated equilibrium, which he developed with Niles Eldredge in 1972. The theory proposes that most evolution is marked by long periods of evolutionary stability, which is punctuated by rare instances of branching evolution. The theory was contrasted against phyletic gradualism, the popular idea that evolutionary change is marked by a pattern of smooth and continuous change in the fossil record.