Edmund_Beecher_Wilson

Edmund Beecher Wilson (October 19, 1856 – March 3, 1939) was a pioneering American zoologist and geneticist. He wrote one of the most influential textbooks in modern biology, The Cell. He discovered the chromosomal XY sex-determination system in 1905—that human males have XY and females XX sex chromosomes. Nettie Stevens independently made the same discovery the same year and published shortly thereafter.