Sewall Green Wright (December 21, 1889 - March 3, 1988) was one of the primary founders of population genetics which led to the modern evolutionary synthesis. In a long career, he invented much of the theory of genetic drift, and developed the inbreeding coefficient and many of its applications. Wright was the developer of adaptive surfaces (fitness landscapes), and he emphasized the importance of the interaction of genetic drift and natural selection in determining the outcome of evolution. He analogized natural selection to processes in animal and plant breeding, and his work on population genetics theory greatly influenced Jay Lush, who did the pioneering work on use of quantitative genetics in animal and plant breeding. He was born in Galesburg, Illinois. His career was spent at the United States Department of Agriculture (1915-1925), the University of Chicago (1926-1955), and the University of Wisconsin (1955-1988). Wright also did extensive breeding experiments with guinea pigs, and appreciated by 1917 that genes controlled the production of enzymes. Many of his Ph.D. students became important figures in the development of mammalian genetics.