Spotlight on Dr. Nettie Stevens
Dr. Nettie Stevens was an American geneticist who was the first person to describe the XY sex determination system in animals happens due to chromosomes, not some other factor like the environment. Nettie was born on July 7, 1861 in Vermont. She had an unusual childhood in the fact that she attended school until she graduated at 19, at which time she became a teacher. Eventually, after attending a teaching school, Nettie would enroll at Bryn Mawr College at the age of 39 to get her Ph.D. in cytology (the study of chromosomes). She is also one of the worst victims of the Matilda Effect.
After getting her Ph.D. in 1903, Nettie began studying sex determination in mealworms. In 1905, Nettie noticed that male mealworms would produce sperm with either an X chromosome or Y chromosome, but female mealworms would only produce eggs containing X chromosomes. However, her theory was not widely accepted in the scientific community, partially due to the fact that the chromosomal theory of inheritance was not accepted in the scientific community. However, Nettie’s gender almost certainly played a role as well. Sadly, Nettie died in 1912 at the age of 50 from breast cancer.
At a slightly later date then Nettie Stevens, a researcher named Edmund Beecher Wilson independently discovered the same thing as Nettie Stevens (that sex determination had to do with chromosomes). However, unlike Nettie, he only looked at male gametes as he found female eggs too fatty and hard to work with. He later edited his original paper to include a thank you to Nettie Stevens for her findings in female gametes. Although Wilson acknowledged her contributions, it is usually either Wilson or Thomas Hunt Morgan that get credited with the discovery of the XY sex-determination system.
Thomas Hunt Morgan was a very famous and influential American geneticist from the early 1900’s. He was a contemporary of Nettie Stevens, and used to correspond with her regularly. Usually in his letters to other scientists, Morgan would discuss his own theories with them. However, as Laura Hoope, a professor of Biology at Pomona college noted, his letters with Nettie were mostly just him asking for the details and findings from her experiments (Lee, National Geographic)
Following Nettie’s death, Morgan wrote an obituary on her for the famous and reputable science journal Nature. In it, he dismissed her importance and wrote that she didn’t have a broad view of science. This was a disgusting oversight and purposeful snub of Nettie Stevens. It is largely because of him (other factors such as misogyny in science also play a role) that Stevens does not get the recognition or credit she deserves for her crucial discovery. Stevens is also a female scientist with comparatively few things written about her (at least in comparison to scientists like Barbara McClintock and Rosalind Franklin). There is no published long form biography of her that I can find, but I encourage you to check out the sources below I have provided. As well, to honor her, teach everyone you know about Dr. Nettie Stevens and how her accomplishments were forgotten.