Woman of the Day biologist and geneticist Nettie Stevens born OTD 1861 in Vermont. She discovered the chromosomes we now know as X and Y, and published a research paper in 1905 establishing that XX chromosomes = female and XY = male.
Nettie’s father was keen for his daughters to… pic.twitter.com/VLiLviWKuG
— The Attagirls (@TheAttagirls) July 7, 2024
