Theodosius Dobzhansky
Theodosius Dobzhansky was a prominent geneticist and evolutionary biologist born in Ukraine, who played a pivotal role in shaping modern evolutionary theory. He demonstrated an early passion for biology, which led him to study ladybug beetles and later Drosophila (fruit flies) under renowned geneticist Yuri Filipchenko. After moving to the United States in 1927, he collaborated with notable scientists like Thomas Hunt Morgan and became a key figure in the development of the "modern synthesis" of evolutionary theory, which integrated genetics with natural selection.
Dobzhansky's seminal work, *Genetics and the Origin of Species*, published in 1937, outlined how changes in gene frequencies drive evolution, shifting the focus from theoretical models to empirical evidence. His influence extended beyond genetics, addressing human diversity and advocating for the recognition of individuals rather than racial classifications. Throughout his career, Dobzhansky published multiple influential texts that explored the intersection of genetics, human evolution, and culture.
Diagnosed with leukemia in 1968, he continued his work until his death in 1975, leaving a lasting impact on the fields of biology and genetics. His ideas have inspired subsequent generations of scientists, including Richard Dawkins and E. O. Wilson, who further explored the genetic and cultural dimensions of evolution.
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Theodosius Dobzhansky
- Born: 1900
- Birthplace: Nemirov, Ukraine
- Died: 1975
- Place of death: Davis, California
Ukrainian American biologist
Twentieth-century evolutionary biologist Theodosius Dobzhansky demonstrated through his experiments with fruit flies that genetics are the mechanism driving natural selection. He established the field of evolutionary genetics and introduced the modern synthesis of evolution, combining genetics and evolutionary biology.
Born: January 25, 1900; Nemyriv, Russian Empire (now Nemyriv, Ukraine)
Died: December 18, 1975; San Jacinto, California
Primary field: Biology
Specialties: Evolutionary biology; genetics
Early Life
The only child of Grigory Dobzhansky, a high school mathematics teacher, and Sophia Voinarsky, Dobzhansky announced early in life that he wanted to study biology. Dobzhansky’s family lived in Nemyriv, a small town in what is now the Ukraine. In 1910, the family moved to a location near Kiev, where they lived through the chaotic years of World War I and the Bolshevik Revolution.
Dobzhansky’s love of biology grew out of his avid collecting and his fascination with the microscope. In 1915, he met Victor Luchnik, a college dropout who advised Dobzhansky to specialize in the study of beetles; Dobzhansky chose to study ladybug beetles and wrote his first scientific paper in 1918 about them.
Dobzhansky entered the University of Kiev in 1917, from which he graduated with a degree in biology in 1921. Before he graduated, he took a position teaching zoology at the Polytechnic Institute in Kiev, where he worked until 1924, when he moved to the University of Leningrad (now St. Petersburg) to become an assistant to the Russian geneticist Yuri Filipchenko, head of the university’s new genetics department. Well acquainted with the work on Drosophila (fruit flies) performed by geneticist Thomas Hunt Morgan in the United States, Filipchenko studied these insects in his laboratory and introduced Dobzhansky to research in this area.
In August 1924, Dobzhansky married geneticist Natalia (Natasha) Sivertzev. They had one daughter, Sophie, who married Yale University anthropologist Michael D. Coe.
Life’s Work
Dobzhansky moved to the United States in 1927, after receiving a fellowship from the International Education Board of the Rockefeller Foundation. Late that year he arrived at Columbia University to work with Morgan. In 1928 Dobzhansky left Columbia and accompanied Morgan to the California Institute of Technology (Caltech). In 1929 Caltech made Dobzhansky an assistant professor of genetics, promoting him in 1936 to full professor of genetics. In 1940 he returned to Columbia University, where he became professor of zoology.
In the early part of the twentieth century, scientists struggled to understand the mechanism that drove evolution. Many biologists rejected Darwin’s idea of natural selection because it seemed to have no definite positive goal and presented nature as ruthless and chaotic. Others proposed that speciation was the engine that drove evolution, and that species developed toward a fixed goal; however, these scientists failed to provide an explanation for the ways that speciation emerged in evolutionary history. Still other scientists contended that random mutations in organisms explained the origin and evolution of species. By the 1930s, many scientists worried that the study of evolution was stagnating and wondered whether or not evolutionary research would survive.
Through his research on fruit flies, Dobzhansky discovered that genetics offers a key to understanding evolution and developed what came to be called the “modern synthesis of evolutionary theory.” Up until Dobzhansky’s most important work, various scientists such as J. B. S. Haldane and Sewall Wright had attempted to isolate genetics as the engine that drove evolution. These models influenced Dobzhansky deeply, but the models were largely mathematical and theoretical and did not offer a satisfying body of empirical evidence to support their explanations. In his early work with Morgan on Drosophila, Dobzhansky discovered the frequency with which individuals inherit various genetic traits, and he recognized that changes in gene frequency cannot be isolated to individuals but rather characterize populations and that such changes range over the whole process of evolution.
In 1937, Dobzhansky published his best-known book, Genetics and the Origin of Species, in which he argued that evolution is nothing more than a change in gene frequencies. With this groundbreaking book, Dobzhansky not only offered an explanation of the mechanism that drives evolution but he also shifted the discussion away from mathematical models of genetic change to empirical evidence for the genetic basis of natural selection. The book opens by considering biological diversity and ranges over topics from natural selection and speciation to mutation as the origin of hereditary changes. Dobzhansky’s book was so influential that he continued to revise it, and revised editions appeared in 1941 and 1951. In 1970, he published Genetics of the Evolutionary Process, which he considered the fourth edition of Genetics and the Origin of Species. This key book influenced scientists in fields as diverse as botany, paleontology, and systematic biology (dealing with the classification of organisms).
Dobzhansky extended his discussion of evolution and genetics to the evolution of humankind in much of his later work. In 1946 he cowrote Heredity, Race, and Society with L. C. Dunn; the book was so popular that it sold over one million copies. Dobzhansky argued that since humans are remarkably diverse in their genetic makeup, they should be recognized as individuals rather than as racial types or species types defined by certain racial or group traits. For Dobzhansky, human equality offers individuals the best method by which to achieve and preserve biological diversity.
In 1962, Dobzhansky published Mankind Evolving, based on lectures he delivered at Yale University on the centennial of Darwin’s publication of On the Origin of Species. Dobzhansky argued that human evolution depends on organic processes as well as on superorganic, or cultural, components of human life. He developed these ideas even further in a number of later books, including Evolution, Genetics, and Man (1955), The Biological Basis of Human Freedom (1956), and Genetic Diversity and Human Equality (1973), which was the last book he published before his death.
In 1968, Dobzhansky was diagnosed with chronic lymphatic leukemia, though he continued to work energetically on various writing projects and experiments.
He died of a heart attack on December 18, 1975.
Impact
Dobzhansky’s writings and his laboratory work found wide support among scientists. His synthesis of molecular biology, population genetics, and evolutionary theory produced the “modern synthesis” of neo-Darwinism and revived the study of evolution in the twentieth and twenty-first centuries. Evolutionary biologist Richard Dawkins has continued along the lines of Dobzhansky’s theoretical work by contending that evolution occurs at the genetic level rather than at the level of the organism or the species. Evolutionary biologist and entomologist E. O. Wilson has developed Dobzhansky’s ideas over a number of books in his attempts to show that while genetic makeup does play a role in the evolution of individuals, human evolution depends heavily on culture as well.
Raised as a Russian Orthodox Christian, Dobzhansky remained deeply interested in the meaning of human nature, life, and death, which he explored in such works as The Biology of Ultimate Concern (1967).
Bibliography
Adams, M. B., ed. The Evolution of Theodosius Dobzhansky. Princeton: Princeton UP, 1994. Print. Presents a collection of essays introducing Dobzhansky and his work.
Ruse, Michael, and Joseph Travis, ed. Evolution: The First Four Billion Years. Cambridge: Harvard UP, 2009. Print. Offers an introduction to the theory of evolution and contains a small overview of Dobzhansky and his work.
Van der Meer, J. M. “Theodosius Dobzhansky: ‘Nothing in Evolution Makes Sense Except in the Light of Religion.’” Eminent Lives in Twentieth-Century Science andReligion. Ed. Nicolaas Rupke. New York: Lang, 2007. Print. Focuses on Dobzhansky in one of a collection of religionist pieces exploring the intersections of faith and science.