Stephen Jay Gould (September 10, 1941 – May 20, 2002) was a
prominent 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. Gould's greatest contribution to science was his 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 later 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. Most of Gould’s empirical research was based
on the land snails Poecilozonites and Cerion. He also
contributed to evolutionary developmental biology, and has
received wide praise for