Nettie Maria Stevens (discovery of X- and Y-chromosomes)

Nettie Maria Stevens (1861–1912) was an American scientist of the late 19 – early 20th centuries. Back at the time, women had limited career opportunities. However, Stevens made a lot of effort to become a scientist. She graduated from college at the age of 19 and became a student at Stanford University when she was 35 years old. Four years later, Stevens enrolled in Bryn Mawr College to pursue her Ph.D. When she was 38 years old, her scientific career was at its peak. When studying embryogenesis of insects, the scientist found out that sperm cells contained both X and Y chromosomes, whereas egg cells all had only an X chromosome. Thus, Stevens discovered that the gender of an organism is determined by sex chromosomes. She wrote about it in a work published in 1905. Another geneticist, Edmund Beecher Wilson, worked on a similar project simultaneously with Stevens. He read about her discovery and reissued his original paper. Although both Wilson and Stevens carried out the same study, Wilson alone was credited for the discovery.

Lise Meitner (discovery of nuclear fission)

Lise Meitner, a future physicist and radiochemist, was born in Vienna in 1878. She received her Ph.D. in 1907. Together with chemist Otto Hahn they studied the properties of radioactivity at the Kaiser Wilhelm Institute of Chemistry. In the 1920s, Meitner developed a theory of the inner constitution of nuclei and discovered the Auger effect, transitions of electrons in an excited atom. The theory was named after French scientist Pierre Auger. In 1939, Otto Hahn published the results of the collaborative research, describing nuclear fission of uranium. Meitner proposed a theoretical basis for this process. She suggested that nuclear fission could provoke a chain reaction leading to large emissions of energy. In 1945, Otto Hahn was awarded the Nobel Prize for the discovery of nuclear fission, while Meitner’s scientific contribution was recognized only in 1949, when received the Max Planck Medal.

Rosalind Franklin (discovery of double helix DNA structure)

Rosalind Elsie Franklin (1920–1958) was an English geneticist. She studied physical chemistry at Newnham College, Cambridge University. She worked on the structure analysis of X-rays. Franklin studied the trajectory of X-ray radiation as it exited through the crystal lattice. In 1951, she worked in John Randall’s laboratory, where this method was used to determine the structure of DNA. The following year, Franklin took a photo showing the spiral structure of DNA. Later, her colleagues, biologists James Watson, Francis Crick, and Maurice Wilkins, used this photograph and research data to create a world famous DNA model. The female scientist worked on the molecular structure of viruses for decades. In 1961, Wilkins, Watson, and Crick received the Nobel Prize in physiology and medicine for the discovery of the DNA structure. Rosalind Franklin did not have a chance to win an award because of her sudden death from cancer in 1958.

Cecilia Helena Payne (chemical composition of a star)

Cecilia Helena Payne was another English female scientist whose contribution to science is difficult to overestimate. She was born in Wendover, England, in 1900. She entered Newnham College, University of Cambridge, in 1919. Payne studied botany, physics, chemistry, and astronomy there. In 1923, she was accepted to the Harvard College Observatory, the United States. At the age of 25, Payne wrote a doctoral dissertation, claiming that stars were composed primarily of helium and hydrogen. However, authoritative scientists urged her not to rush to conclusions, since they assumed that the elemental composition of the Sun and the Earth was almost similar. Thus, Payne had to abandon her previous suggestions. But four years later, astronomer Henry Norris Russell came up with a similar result, confirming Payne’s theory. In his paper, Russell acknowledged the work and achievements of his colleague. Nevertheless, he alone is usually credited for the discovery. In 1956, Cecilia Payne became the first woman to become a fully tenured professor at Harvard's Faculty of Arts and Sciences and the first woman to head a department at that prestigious university.

Mary Anning (discoveries in paleontology)

Mary Anning, born in Lyme Regis, England, in 1799, made a great contribution to the development of paleontology. Anning most likely became interested in fossils thanks to her father who searched and sold them. Her first important discovery was the uncovering of an Ichthyosaurus skeleton. She sold it to Everard Home who wrote a paper about the fossil. Five years later, the skeleton was exhibited at the British Museum in London. Between 1815 and 1819, Anning found several more full ichthyosaur skeletons. Some of them ended up in local museums. At the age of 24, she discovered the first complete skeleton of a plesiosaur. Thus, Mary Anning became known in paleontological circles in Europe. In 2010, the Royal Society recognized Mary Anning as one of the ten British most influential women in science history.

Alice Ball (development of effective treatment for leprosy)

Alice Augusta Ball is recognized as a pioneer in medicine. She was born in Seattle, Washington, in 1892. Ball studied chemistry at the University of Washington, earning a bachelor's degree in pharmacy and pharmaceutical chemistry. She also studied chaulmoogra oil at the University of Hawaii. Previously, chaulmoogra oil had been the best treatment available for leprosy. Because of the bitter taste, it was difficult to take, and the high viscosity made it difficult to inject. During her research, Ball fell ill and died before she could print the results. Chemist Arthur Dean published the paper. The process for creating the extract became known as "Dean's Method." In fact, the University of Hawaii had not recognized Alice Ball’s works for 90 years. Only in 2000, the university honored Ball by dedicating a plaque to her. In March 2016, Hawai'i Magazine added Ball to the list of the most influential women in the history of the Hawaiian Islands.