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Nettie Maria Stevens

Cavendish, Vermont 07-07-1861 ‖ Baltimore 04-05-1912

Periodo de actividad: Desde 1905 hasta 1912

Clasificación geográfica: América > Estados Unidos

Movimientos socio-culturales

Grupos por ámbito de dedicación

Científicas > Biólogas > Genetistas

Escritoras > Ensayistas

Contexto de creación femenina

In 1905, Nettie Stevens published a study that would revolutionize the world of science. Her work demonstrated that sex was determined by specific chromosomal bases. Nettie had worked all her life to make a place for herself in the complicated and sexist scientific community at the dawn of the 20th century. Although she was eventually given the recognition she deserved, her scientific work was called into question. These difficulties in finding the recognition that women scientists deserve have continued to be reproduced almost to the present day.

A century later, in 2006, upon the death of the renowned microbial geneticist Esther Lederberg, the respected molecular biology professor Dr. Stanley Falkow stated in his farewell speech regarding the unfair treatment of women scientists: "Martha Chase (1927-2003), Daisy Roulland-Dussoix (1936-2014) and Esther Lederberg (1922-2006) were women who made crucial discoveries in science".
Martha Chase showed that the hereditary material of bacteriophages is DNA, and not proteins. 
Daisy Dussoix discovered restriction enzymes.
Esther Lederberg invented the replica plate. 
Each of those discoveries have been assigned to a male member of the research group (Alfred Hershey, Werber Arber, and Joshua Lederberg, respectively). Likewise, as the final culmination of his speech, the scientist added: «Historians would do well to review the science of the mid-20th century, a time of great contributions, but also of enormous discrimination».

Reseña

Nettie Maria Stevens, American geneticist (1861-1912) was the first researcher to describe the chromosomal bases that determine sex. 
She discovered, from her research with the beetle Tenebrio molitor, that chromosomes known as X and Y were responsible for determining the sex of the individual.
Stevens found that the somatic cells of the female contained 20 large chromosomes, that is, ten major pairs, while the male cells had 19 large and 1 small, that is, 9 pairs of large chromosomes and one consisting of one large and one small.
She successfully expanded the fields of embryology and cytogenetics.

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Justificaciones

  • Nettie Maria Stevens was an American geneticist of English and Swedish descent.
  • She was the first researcher to describe the chromosomal bases that determine sex.
  • She successfully expanded the fields of embryology and cytogenetics.

Biografía

In 1905, Nettie Stevens published a study that would revolutionise the world of science. Her work came to show that sex was determined by specific chromosomal bases. Nettie had worked all her life to find a place for herself in the complicated and patriarchal scientific community of the dawn of the 20th century. Although over time she was given the recognition that she deserved, her scientific work was called into question. Her health did not accompany her either since her premature death occurred when she was beginning to achieve her dreams.
Nettie Maria Stevens was born on 7 July 1861 in the North American town of Cavendish, Vermont. Her parents, Julia Adams and Efraïm Stevens, had two children who died before Nettie was born. Emma came behind her. Nettie was just four years old when her mother died, in 1865. Shortly thereafter, her father remarried, and the family moved to Westford. Efraïm was a humble carpenter who, despite his economic situation, worked hard so that his two daughters could receive a good education. Both Nettie and Emma jumped at the chance.
But Nettie's dream, to study at the university, was far away. To achieve this, she worked for years as a teacher and librarian until she could save enough money. In 1896, at the age of thirty-five, Nettie enrolled at Stanford University. By the turn of the century she had already graduated and written her doctoral thesis.
Nettie continued her studies at Bryn Mawr College, a women's college in Philadelphia, and travelled to Europe to further her knowledge in Germany and Italy. In Philadelphia, Nettie met two leading biologists, Edmund B. Wilson and Thomas H. Morgan, with whom she worked.
The scientific interests of Nettie Stevens were focusing on the study of genetic inheritance. In those years in which it was still unknown how a living being saw its sex determined at the time of its conception, Nettie began an exhaustive investigation with different types of insects that would lead her to conclude that there were two types of chromosomes, the X and the Y, that defined the feminine and the masculine sex.
Her conclusions were published in 1905 in a study entitled Studies in spermatogenesis with special reference to the “accessory Chromosome”. Unfortunately, almost simultaneously, her colleague, Edmund B. Wilson, himself came to the same conclusion. Despite the fact that Wilson specified in the journal Science that his conclusions coincided with those of his colleague Stevens, implying that he had known his partner's study for a long time, it was him who received the most recognition.
Nettie Stevens continued her scientific work and the same year that she published her discovery about chromosomes, she got a place at Bryn Mawr as a professor and received an award for a scientific article.
Nettie's greatest enemy was her own body. At just fifty years old, breast cancer ended her life. Nettie Stevens died at the John Hopkins Hospital in Baltimore on 4 May, 1912. Bryn Mawr College had given her a research professorship that she could never enjoy.
Considered one of the best biologists and geneticists in history, her colleague and future Nobel laureate, Thomas H. Morgan, dedicated words of recognition to Nettie Stevens in Science Magazine. In 1994 her name was incorporated into the National Women's Hall of Fame.

Obras


  • Stevens, Netty Maria (1905) Studies in spermatogenesis with special reference to the “accessory Chromosome” Part I, Washington -Carnegie Insitution of Washington 
  • Stevens, Netty Maria (1906) Studies in spermatogenesis with special reference to the “accessory Chromosome” Part II, Washington -Carnegie Insitution of Washington 

Bibliografía

Enfoque Didáctico

-Biology-geology of 4th of ESO.

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