One of the first American women recognized for contributions to science, biologist and geneticist Nettie Maria Stevens (1861-1912) is credited with discovering that sex is determined by a distinct arrangement of chromosomes, known as the X and Y.

Educated at Westford Academy, one of the oldest public high schools in the United States, located in Westford, Massachusetts, Stevens excelled academically. She graduated in 1880 near the top of her class and taught for several years to earn money to further her education. Stevens enrolled in Westfield Normal School and graduated with the highest scores in her class. She went on to receive both bachelor and master degrees in biology from Stanford University and in 1903 was awarded a PhD from Bryn Mawr College, where she studied the fields of genetics, cytology and embryology.

As a research scientist, Stevens was interested in the process of sex determination, studying meal worms. Her discovery, that sex is inherited as a chromosomal factor and that males determine the gender of their offspring, was only accepted after a male colleague made a similar observation. Stevens passed away at the age of 50, publishing more than forty research papers in her lifetime. She was inducted into the National Women’s Hall of Fame in 1994 and celebrated with a Google Doodle showing her looking through a microscope at XY

The Dr. Nettie Maria Stevens Science and Innovation Center at Westfield State University is named in her honor.