Thomas Hunt Morgan was a great man of science, whose research has been considered the fundamental pillar for the understanding of genetics as we understand it today, together with Gregor Mendel.

This American was an evolutionary biologist, embryologist, geneticist and author of several works who had the honor of receiving a Nobel Prize for his active scientific career. Let’s see his story in more depth through this short biography of Thomas Hunt Morgan .

Biography of Thomas Hunt Morgan

The following is an in-depth look at the life of Thomas Hunt Morgan, his relationship with various American institutions and his stance on the main evolutionary ideas of the late 19th and early 20th centuries.

First years and training

Thomas Hunt Morgan was born on September 25, 1866 in Lexington, Kentucky. At the age of sixteen he attended the State College of Kentucky, now the University of Kentucky. There he focused primarily on science, especially natural history. During his summer vacation time, he worked for the United States Geological Survey.

He graduated in 1886 with a Bachelor of Science degree. The following summer he attended the Marine Biology School in Annisquam, Massachusetts, where he would begin to take an interest in zoology at John Hopkins University .

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After two years of working and publishing, Morgan was chosen to receive a Master of Science degree from the State College of Kentucky in 1888. This same institution offered Morgan a job as a professor, although in the end he chose to remain at John Hopkins.

It was at this time that finished his thesis on the embryology of sea spiders ( Pycnogonide ), to determine their phylogenetic relationship with other arthropods . On the basis of their embryonic development, it was established that they were more related to land spiders than to crustaceans. Their publication was awarded with a doctorate in 1890. With the money he won as a prize for the publication of his thesis, Morgan took the opportunity to travel around the Caribbean and Europe to continue his research in zoology.

Career and research

In 1890 Thomas H. Morgan was hired as professor in charge of courses on morphology at the Bryn Mawr School , an institution twinned with John Hopkins University.

His working life in the institution was very intense. He gave lectures five days a week, twice a day, mainly oriented to biology in general terms. However, despite being a good teacher, he wanted to focus on research.

Stay in Europe

In 1894 he travelled to Naples to carry out research in the laboratories of the city’s Zoological Station. There he completed a study on the embryology of ctenophores, an almost microscopic life form.

While in Naples he came into contact with German researchers, who taught him the ideas of the Entwicklungsmechanik or developmental mechanics school. This school was reactionary to the ideas of naturphilosophy, which until then had been the reference point in the science of morphology during the 19th century.

At that time there was a great debate about how embryos were formed. One of the most popular explanations was the mosaic theory , which held that the hereditary material was divided among the embryonic cells, which were predestined to become concrete parts of the organism once it was mature.

Others, including Morgan at the time, thought that development was due to epigenetic factors, where interactions between the protoplasm and the nucleus of the embryonic cells affected the way the cells developed.

When Morgan returned to Bryn Mawr in 1895 he was hired as a full-time teacher. There he addressed in his research aspects such as the development of larvae and their regeneration. It was also there that he wrote his first book The Development of the Frog’s Egg (1897).

At the beginning of the 20th century, Morgan began research on sex determination , by which time Nettie Stevens, another great researcher, had discovered the impact of the Y chromosome on the determination of male sex in humans.

Columbia University

In 1904, Morgan was invited by E. B. Wilson to join Columbia University , where he could carry out his research work full time. A year earlier, he had written Evolution and Adaptation , in which he explained that, like other biologists of the time, he had found evidence of the biological evolution of species, but he was not in favour of the mechanism of Darwinian natural selection. However, years later, after the rediscovery of the findings made by Gregor Mendel, Morgan would change his position.

Although he was initially skeptical about Mendelian laws, since they were being given enough importance as a theory to explain Charles Darwin’s postulates, Morgan understood that they had quite a lot of meaning and evidence behind them.

Fruit fly studies

In 1908 Morgan started working with the fruit fly ( Drosophila melanogaster ) . He mutated, through the use of chemicals, physics and radiation, specimens of this very common fly.

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He began to cross the specimens to find mutations that were inheritable, but at first he did not achieve significant results. In addition, he had some trouble detecting which mutations were actually inherited. Later, when he detected the mutations, he saw that they followed the laws proposed by Mendel .

Morgan found a white-eyed male fly that stood out among its peers, with red eyes. When the white-eyed flies met the red ones, their progeny were red eyed. However, when the second generation, i.e. the daughter flies, were crossed with each other, white-eyed flies would emerge.

Based on his research with flies, he published an article in 1911 explaining that some traits were inherited in a sex-linked manner, and that it was likely that the particular trait was stored on one of the sex chromosomes.

Based on this research, Morgan published in 1915, together with other prestigious scientists of the time, the book The Mechanism of Mendelian Heredity , which is considered the fundamental book for understanding genetics. After the studies with the insect, Morgan returned to the field of embryology, in addition to addressing the heritability of genes in other species.

In 1915 he was critical of a new movement that had emerged from science, eugenics, especially when it defended racist ideas.

Last years

Several years later, in 1928, Thomas Hunt Morgan moved to California to take over the biology section of the California Institute of Technology (CALTECH). There he researched embryology, biophysics, biochemistry, genetics, evolution and physiology . He worked at CALTECH until 1942, when he retired and became Professor Emeritus. However, even when he retired, he would continue his research in sexual differentiation, regeneration and embryology.

Finally, Thomas Hunt Morgan would die on December 4, 1945 at the age of 79 after suffering a heart attack.

Evolutionary posture

Morgan was interested in evolution throughout his life . As a young man he wrote his famous thesis on the phylogeny of sea spiders, as well as writing up to four books in which he explained his position on Darwinian and Lamarckian evolutionary ideas.

In his book Evolution and Adaptation (1903) he is critical of Charles Darwin’s postulates. According to Morgan, selection could never produce a new species completely by only acting on differences between merely perceptible individuals . He also rejected the idea of acquired characters postulated by Neolamarckism.

It’s safe to say that Morgan was not a scientist who went against the grain. In fact, the years between 1875 and 1925 are known as ‘the eclipse of Darwinism’, since the scientific advances of the time, along with changes in positions within the natural sciences, caused some of Darwin’s original ideas to come to fruition.

However, after his studies with the Drosophila melanogaster, Morgan changed his position. Mutations have their importance for evolution , given that it is those characters that are inherited that significantly affect the anatomical and behavioural changes of the species. These characters are inherited following, many times, the laws proposed by Mendel.

Honors

Among the distinctions that Thomas Hunt Morgan obtained, we find the following:

  • Thomas Hunt Morgan received several honors during his lifetime, the most notable being
  • D. degree from the University of Kentucky.
  • Elected member of the National Academy of Sciences (1909)
  • Elected member of the British Royal Society (1919)
  • He received the Darwin Medal (1924).
  • He received the Nobel Prize in medicine and physiology (1933).

In addition, several institutions have been founded with his name, such as the Thomas Hunt Morgan School of Biological Sciences at the University of Kentucky. Also, the American Society of Genetics awards the Thomas Hunt Morgan Medal annually to members of the institution who have contributed to the field.

Bibliographic references:

  • Allen, G. E. (1978). Thomas Hunt Morgan: The Man and His Science. Princeton University Press.
  • Allen, G. E. (2000). “Morgan, Thomas Hunt.” American National Biography. Oxford University Press.
  • Kohler, R. E. (1994). Lords of the Fly: Drosophila Genetics and the Experimental Life. University of Chicago Press.