Walter Sutton was born in Kansas City, and graduated from Kansas University. He was E. B. Wilson's graduate student in the Department of Zoology at Columbia University. In the spring of 1902, when he was only 25, Sutton deduced that chromosomes are the basis of heredity, and that the reduction of chromosomes in meiosis is directly related to Mendel's laws of inheritance.
The behavior of chromosomes and its importance in heredity was a "hot topic" at the turn of the century. Many scientists, including Sutton's supervisor, E. B. Wilson, were working on this problem. Theodor Boveri made the connection between chromosomes and heredity by doing his own observations and experiments. Sutton, working independently in Wilson's lab, came to the same conclusions. Wilson admitted later that when Sutton first explained his theory to him, he "did not at once fully comprehend his conception or realize its entire weight."
Sutton did his observations using grasshopper cells. His paper, in 1902, clearly showed that each chromosome is different, and meiosis reduces chromosome number in the gametes. Sutton's 1903 paper, The Chromosomes in Heredity, summarized and discussed the importance of his conclusions. The paper even more strongly drew the connection between Mendel's laws of heredity and chromosomes.
Wilson was very impressed with Sutton's abilities as an investigator. Unfortunately, Sutton never finished his doctorate. Sutton left research and entered medical school. He graduated from the College of Physicians and Surgeons at New York, and became a surgeon. Sutton served in France during World War I, and distinguished himself in treatments of wounded soldiers. Sutton died following an operation for appendicitis. He was only 39.