Alfred Henry Sturtevant Biography

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 were not independent. For example, he had noticed that white-eyed fruit flies were almost always male. Morgan and his team developed a theory to explain this cross-over of linked traits. They proposed that genes that remain together when passing from one generation to the next must be located on the same chromosome.

Sturtevant worked with Morgan in the "fly room," which was the nickname given to the lab where the fruit flies were kept. Here Sturtevant made his breakthrough discovery while researching the hereditary patterns of the flies. He took Morgan's theories one step further and proposed that genes which were close to one another on the chromosome could sometimes get passed along together because of their proximity. To support this theory, Sturtevent used his proficiency in solving mathematical puzzles to analyze how often certain genes were inherited together. From his analysis, he introduced the concept of genetic cross over. Applying his new theory, Sturtevant went home one evening in 1911 and drew the first chromosome map which detailed the gene positions on the four Drosophila chromosomes.

Sturtevant's work supported Morgan theories and together they laid the foundation for modern theories of genetic mapping. After receiving his B.A. in 1912 and his Ph.D. in 1914, Sturtevant (together with Morgan, Hermann Muller and C.B. Bridges) published The Mechanism of Mendelian Inheritance in 1915. This work established the basis for the chromosomal theory of heredity.

After leaving Columbia, Sturtevant spent his career at Caltech. He served as a professor of genetics from 1928 until 1947 and as professor of biology from 1947 until 1962. In 1965 he published A History of Genetics. It was his last work before his death in 1970.