Alfred Henry Sturtevant is the American geneticist recognized for introducing the principle of gene mapping. He was the first to suggest that the closer together genes are located on a chromosome the more likely they are to be inherited together.

Sturtevant was born in Jacksonville, Illinois in 1891 and was raised on his parent's ranch. Even as a boy Sturtevant showed a strong interest in genetics and he prepared pedigrees of his father's horses. Alfred was encouraged by his brother, Edgar, to pursue his interests by studying genetics. In 1910 Sturtevant began working with professor Thomas Hunt Morgan at Columbia University.

At the time Morgan was already performing extensive experiments on Drosophila (the common fruit fly) and his results were consistent with Gregor Mendel's theories that hereditary factors are independent of one another. However, Morgan had also observed that some genes seemed to be linked together; in other words, they...