Edmund Beecher Wilson (1856 - 1939) was an American geneticist and zoologist. Wilson, is credited as America's first cell biologist, in 1898 he used the similarity in embyros to describe phylogenetic relationships, by observing spinal cleavage in molluscs, flatworms and annelids he concluded that the same organs came from the same group of cells, he concluded that all these organisms must have a common ancestor. He also discovered the chromosomal XY sex-determination system in 1905, Nettie Stevens also decribed the system in 1905.
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