Walter Stanborough Sutton (April 5, 1877 - March 10, 1916) was an American biologist whose most significant contribution to present-day biology was his theory that the Mendelian laws of inheritance could be applied to chromosomes at the cellular level. Sutton, born in Utica, New York, attended Columbia University and obtained his doctorate in medicine in 1907. He was the first scientist to prove Mendel's laws of segregation and independent assortment valid with the use of grasshopper chromosomes. In 1902 Sutton suggested that "the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reduction division ... may constitute the physical basis of the Mendelian law of heredity." He further developed these thoughts in "The Chromosomes in Heredity" in 1903. The German biologist Theodor Boveri reached the same conclusions as Sutton independently of his research, and their theory, often referred to as the Boveri-Sutton Chromosome Theory, remained controversial in the biological world until 1915, when Thomas Hunt Morgan made it universally accepted through his studies of Drosophila melanogaster.