Theodosius Dobzhansky

Dobzhansky was confident that mixing races created no serious medical issues. Dobzhansky's experience with breeding fruit flies came into play when he made this conclusion. The only medical issue Dobzhansky found in this breeding was when certain crosses could lead to having infertile offspring. However, Dobzhansky noticed no such problems when humans from different populations reproduced. When anthropologists at the time were trying to compare the means of physical measurements of people from different races Dobzhansky argued that these means had no value because there was more variation between the individuals of each population than there was among the groups (Farber 2011 p. 63). However, Dobzhansky's work and beliefs on genetics and evolution created opposition with his views on race mixing. First, that race has to do with groups and not individuals and so in this instance it is not races that mix, it is individuals. Second, if races do not mix then they will become different species, so therefore they have to mix. All of the races that currently exist are products of past mixed races, so according to Dobzhansky there is no pure race. Third, when race had been discussed in the past it was all about comparing means of trait to which this made no sense to Dobzhansky (Farber 2011 p. 65-67).

By 1975, his leukemia had become more severe, and on November 11 he traveled to San Jacinto, California, for treatment and care. Working till his last day as a Professor of Genetics, Dobzhansky died (from heart failure) on December 18, 1975, in Davis, California. He was cremated, and his ashes were scattered in the Californian wilderness.

Dobzhansky's wife Natasha died of coronary thrombosis on February 22, 1969. Earlier (on June 1, 1968), Theodosius had been diagnosed with lymphocytic leukemia (a chronic form of leukemia), and had been given a few months to a few years to live. He retired in 1971, moving to the University of California, Davis where his student Francisco J. Ayala had been made assistant professor, and where he continued working as an emeritus professor. He published one of his most famous essays "Nothing in Biology Makes Sense Except in the Light of Evolution" in 1973, influenced by the paleontologist and priest Pierre Teilhard de Chardin.

His concern with the interface between humans and biology may have come from different factors. The main factor would be the race prejudice that contributed in Europe that triggered WWII. His concern also dealt with religion in human life which he speaks about in his book The Biology of Ultimate Concern in 1967. "The pervasiveness of genetic variation provides the biological foundation of human individuality". Dobzhansky talks about in great detail that "human nature has 2 dimensions: the biological, which mankind shares with the rest of life, and the cultural, which is exclusive to humans." Both of these are believed to have come from "biological evolution and cultural evolution".

Dobzhansky was elected a Foreign Member of the Royal Society (ForMemRS) in 1965. In 1970, he published Genetics of the evolutionary process.

Theodosius Dobzhansky and Ashley Montagu debated the use and validity of the term "race" over a period of many years without reaching an agreement. The debate has continued. Montagu argued that "race" was so laden with toxic associations that it was a word best eliminated from science completely. Dobzhansky strongly disagreed. He argued that science should not give in to the misuses to which it had been subjected. The two men never reached an agreement, which led Dobzhansky to say in 1961, while commenting on Montagu's autobiography, "The chapter on 'Ethnic group and race' is, of course, deplorable, but let us say that it is good that in a democratic country any opinion, no matter how deplorable, can be published" (Farber 2015 p. 3). The concept of "race" has been important in many life science disciplines; the modern synthesis revolutionized the concept of race, moving it from a strictly morphological definition based on "racial types" in humans, to a definition focused on populations differing in gene frequencies. This was done in hopes that its foundation in population genetics would undermine the deeply ingrained social prejudices associated with "race".

In the third revision of Genetics and the Origin of Species (1951), Dobzhansky rewrote all ten chapters on: Isolating Mechanisms, Mutation in Populations, Organic Diversity, Heredity and Mutation, Race Formation, Selection, Adaptive Polymorphism, Hybrid Sterility, Species as Natural Units, and Patterns of Evolution. Dobzhansky decided to remove the chapter on Polyploidy in the third edition. The new chapter on Adaptive Polymorphism highlighted Dobzhansky’s research since the second edition. He included precise, quantitative evidence on effective natural selection in laboratory and free populations.

Dobzhansky was renowned as the president of the Genetics Society of America in 1941, president of the American Society of Naturalists in 1950, president of the Society for the Study of Evolution in 1951, president of the American Society of Zoologists in 1963, a member of the Board of Directors of the American Eugenics Society in 1964, and president of the American Teilhard de Chardin Association in 1969.

In Dobzhansky’s second edition of Genetics and the Origin of Species (1941), four years had gone by and he was able to add more research and advancements made in genetics. Around half of the new research he found was added to the last two chapters in his book: Patterns of Evolution, and Species as Natural Units. In the second to last chapter, Patterns of Evolution, Dobzhansky explained how on the path to a new adaptation, a method could be used to where a species could go through a less adaptive stage. The last chapter, Species as Natural Units, Dobzhansky explained some of the contributions made in genetics to what was called “the new systematics.” Dobzhansky’s second edition of the book also had twice as many sources in the bibliography than the first edition.

He returned to Columbia University from 1940 to 1962. Among his students was geneticist Bruce Wallace. In 1941, Dobzhansky was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences. In 1943, the University of São Paulo awarded him an honorary doctorate. He was one of the signatories of the 1950 UNESCO statement The Race Question. He then moved to the Rockefeller Institute (shortly to become Rockefeller University) until his retirement in 1971. In 1972 he was elected the founding president of the Behavior Genetics Association, and was recognized by the society for his role in behavior genetics, and the founding of the society by the creation of the Dobzhansky Award (for a lifetime of outstanding scholarship in behavior genetics).

His 1937 work Genetics and the Origin of Species became a major influence on the modern synthesis. He was awarded the US National Medal of Science in 1964 and the Franklin Medal in 1973.

The first edition of Genetics and the Origin of Species (1937) highlighted the most recent discoveries in genetics and how they applied to the concept of evolution. The book starts by addressing the problem of evolution and how modern discoveries in genetics could help find a solution. The book covers the chromosomal basis of Mendelian Inheritance, how the effects from changes in chromosomes greater than gene mutations are common and acceptable, and how mutations form racial and specific differences. Dobzhansky explained how three levels could describe the processes of evolutionary population genetics: (1) the origin of raw materials by mutations of genes and chromosomes, (2) the changes in populations by changes in frequencies and combinations of mutations, (3) the fixation of changes by reproductive isolation. To support his writing and research, the bibliography was twenty-eight pages long with around six hundred sources.

He followed Morgan to the California Institute of Technology from 1930 to 1940. On the basis of his experiments, he articulated the idea that reproductive isolation can be caused by differences in presence of microbial symbionts between populations. In 1937, he published one of the major works of the modern evolutionary synthesis, the synthesis of evolutionary biology with genetics, titled Genetics and the Origin of Species, which amongst other things, defined evolution as "a change in the frequency of an allele within a gene pool". Dobzhansky's work was instrumental in spreading the idea that it is through mutations in genes that natural selection takes place. Also in 1937, he became a naturalized citizen of the United States. During this time, he had a very public falling out with one of his Drosophila collaborators, Alfred Sturtevant, based primarily in professional competition.

Dobzhansky immigrated to the United States in 1927 on a work-study scholarship from the International Education Board of the Rockefeller Foundation. Upon arriving in New York City on December 27, he joined the Drosophila Group at Columbia University working alongside Thomas Hunt Morgan and Alfred Sturtevant. Their work provided crucial information on Drosophila cytogenetics. Additionally, Dobzhansky and his team helped establish Drosophila pseudoobscura, within the genus Drosophila, as a favorable model organism in evolutionary-biological studies ever since they published their influential works. Dobzhansky’s original mindset (after studying alongside Yuri Filipchenko), was that there were serious doubts on using data obtained from phenomena happening in local populations (microevolution) and phenomena happening on a global scale (macroevolution).  Filipchenko also believed that there were only two types of inheritance: Mendelian inheritance of variation within species, and Non-Mendelian inheritance of variation in a macroevolutionary sense. Dobzhansky later stated that Filipchenko “bet on the wrong horse”.

On August 8, 1924, Dobzhansky married geneticist Natalia "Natasha" Sivertzeva, who was working with I. I. Schmalhausen in Kiev. The Dobzhanskys had one daughter, known under her married name as Sophie Coe, an anthropologist, food historian, and author, primarily known for her work on the history of chocolate.

At high school, Dobzhansky collected butterflies and decided to become a biologist. In 1915, he met Victor Luchnik who convinced him to specialize in beetles instead. Dobzhansky attended the University of Kiev between 1917 and 1921, where he then studied until 1924 specializing in entomology. He then moved to St Petersburg to study under Yuri Filipchenko, where a Drosophila melanogaster laboratory had been established.

Theodosius Grigorievich Dobzhansky (Russian: Феодо́сий Григо́рьевич Добржа́нский; Ukrainian: Теодо́сій Григо́рович Добржа́нський; January 25, 1900 – December 18, 1975) was a prominent Russian-American geneticist and evolutionary biologist, and a central figure in the field of evolutionary biology for his work in shaping the modern synthesis. Born in the Russian Empire, Dobzhansky emigrated to the United States in 1927, aged 27. He was a distant relation of the Russian writer Feodor Dostoevsky.

Dobzhansky was born on January 25, 1900, in Nemirov, Russian Empire (now Nemyriv, Ukraine), the only child of Grigory Dobzhansky, a mathematics teacher, and Sophia Voinarsky. He was given a rare name, Theodosius, because he was born after his middle-aged parents prayed for a child to St. Theodosius of Chernigov. In 1910 the family moved to Kiev.