Stephen Jay Gould is an American paleontologist and writer of popular science, born in 1941. He proposed (1972), with Niles Eldredge, the theory of punctuated equilibrium, wherein evolutionary change occurs relatively rapidly in comparatively brief periods of environmental stress, separated by longer periods of evolutionary stability. He has become widely-known through his popular science essays in Natural History magazine and a number of books, including The Panda's Thumb, The Flamingo's Smile, It's a Wonderful Life, and others.
Gould is an emphatic advocate of evolution and has written prolificly on the subject, conveying an awareness of contemporary evolutionary theory to a wide audience. A recurring theme in his writings is the history and development of evolutionary (and pre-evolutionary) thinking. He is a baseball fanatic and has included mentions (including an entire essay) on that topic. His early research involved the study of the fossil record of snails (detailed in another of his essays).
Gould is considered by some to be one of the preeminent theoreticians in his field, although some evolutionary biologists who disagree with his ideas accuse him of giving the public a distorted picture of evolutionary theory. He is, of course, anathema to proponents of Creationism.
He is also the author of The Mismeasure of Man, a study of the history of psychometrics as a form of scientific racism; the most recent edition includes a refutation of the arguments of The Bell Curve.
Gould also popularized the usage of the word "spandrel" in an evolutionary context.