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David Christopher LaneDavid Christopher Lane, Ph.D. Professor of Philosophy, Mt. San Antonio College Lecturer in Religious Studies, California State University, Long Beach Author of Exposing Cults: When the Skeptical Mind Confronts the Mystical (New York and London: Garland Publishers, 1994) and The Radhasoami Tradition: A Critical History of Guru Succession (New York and London: Garland Publishers, 1992).
If there's a singular topic Integral students need to be educated on it is evolutionary theory, given their frequent but uninformed use of the term "evolution". These short biographical chapters about evolutionary theorists have been written by different philosophy students of professor David Christopher Lane. (FV)

Glimpses into the Life and Work of Great Thinkers in Evolutionary Biology

Theodosius Dobzhansky

Ethan Li

The evolutionary biologist Theodosius Dobzhansky, originally named Feodosy Grigorevich Dobrzhansky, was born in Nemyriv, Russia on January 25, 1900 to Sophia Voinarsky and Grigory Dobzhansky. He would later immigrate to Kiev, Ukraine at the age of ten, then to America later in his life to develop works that solidified him as a key geneticist in evolutionary thinking. Dobzhansky's achievements won him the Daniel Giraud Elliot Medal in 1941, the National Medal of Science in 1964, and the Franklin Medal in 1973, two years before his death on December 18, 1975 at the age of 75.

Theodosius Dobzhansky
Theodosius Dobzhansky

Being the son of a mathematics teacher, schooling for Theodosius was emphasized for him at a very young age. From a child to his high school years, he developed his own interests in biology; he collected butterflies and beetles to study intensively. He would later enroll and graduate from the University of Kiev from 1917 to 1921, then teach at the same college till 1924. During his professorship at Kiev, he met the geneticist Natasha Sivertzeva studying evolutionary morphology who he would then marry in August of 1924. It was Natasha's studies that influenced Theodosius to pursue the Theory of Evolution and implement his own genetic hypotheses. They had a daughter Sophie and continued to work in Kiev till 1927 when he accepted a Rockefeller fellowship to continue his research in the United States. It is here at Columbia University and later the California Institute of Technology that he developed his monumental discoveries in genetics later to be known as “The Modern Synthesis”.

Theodosius' modern synthesis writings are based in part on his studies with fruit flies which was first established by Thomas Hunt Morgan. In his experiments with the flies, he observed correlations between mutation rates and population sizes; both deduced to be directly proportional. Before his studies, most scientists believed that individual members of their respective species had identical genes. During Dobzhansky's analysis of wild fruit fly populations between Canada and Mexico, he found that different populations had different sets of genes. The chromosomes displayed in contrasting fly samples highlighted distinguishing markers that in turn differentiated one population from another. Because genetics could no longer properly identify a species group from another (with holistically patterned reproduction of data) due to genetic variation (for example, two different species of grass), Dobzhansky was perplexed with what defined or separated one species from another. He realized that the answer was simple: sexual reproduction between entities defined what species group they belonged to.

Theodosius' definition of a species developed into “a group of animals or plants that reproduce primarily within themselves; animals of different species are not likely to mate, but in the unlikely chance that they do, results in incompatible and unproductive hybrids that do not result in offspring.” An example of incompatibility between cross species breeding is between the king penguin (aptenodytes patagonicus) and the Antarctic fur seal (arctocephalus gazella). To test his theories, he demonstrated through two differing fruit fly species that the incompatibility between them stemmed from the specific genes carried by each fly leading to a clash with one another. Dobzhansky published his findings in his groundbreaking book Genetics and the Origin of Species in 1937, which complimented Charles Darwin's The Origin of Species. It is here where he redefined the term “evolution” through a more genetic point of view, “a change in the frequency of an allele within a gene pool” (Genetics and the Origin of Species).

His writings explained how natural selection was determined and motivated by genetic mutations in a species' DNA over periods of time. For a new species to come into existence, mutation is necessary whether they be beneficial or detrimental. If flies reproduce with one another, they create variability in their genes that can differ from the same species of fly. Within this isolated fly population, if continued reproduction between the same group occurred where a separation of that respective population develops (both naturally and unnaturally, such as separation caused by natural disasters), they would slowly diverge from their parent genetics. Now that the isolated flies are only breeding within their own population, any mutations developed would not be passed to their previous parent species and in turn, a new species would develop from increasingly different genetic makeups. These differing genes would grow incompatible with the genes of the original group they derived from.

Dobzhansky argued that if isolation between the same population groups occurred long enough, interbreeding with the separated groups would become impossible and a new species would be created. These developments crystallized the Modern Synthesis and its implementations in the overall theory of evolution. Dobzhansky's findings allowed for an evolutionary theory that can be predictable. Because mutations are the seed to natural selection and evolution according to the Modern Synthesis, the predictability of arising species can be observed. Knowing that mutations between the isolation of the same species will lead to genetic drift and given enough time, a new species. The Modern Synthesis itself was not coined by Dobzhansky, instead it is the combination of Darwin's theory of evolution and Gregor Mendel's genetics that Dobzhansky greatly influenced.

Though he only worked with fruit flies (drosophila pseudoobscura), Dobzhansky's evolutionary genetics gave a definitive definition to evolution and natural selection; all stemming from his chromosome research. The zoologist Julian Huxley, the first to use the term “the Modern Synthesis”, contributes his own evolutionary ideas to Dobzhansky in his book Evolution: The Modern Synthesis. Other writings that delve more into Theodosius' theories and findings are in his books Mankind Evolving: The Evolution of the Human Species where he explores the evolution of mankind a and Genetic Diversity and Human Equality where he addresses correlations between genetic inheritances in human beings and the false implications of race.

Further Reading

1. Genetics and the Origin of Species, 1937

2. Mankind Evolving: The Evolution of the Human Species, Yale University Press (March 11, 1962)

3. The roving naturalist: Travel letters of Theodosius Dobzhansky, American Philosophical Society (1980)

MSAC Philosophy Group

The Evolutionary Scientists

The theory of evolution has a long history. However, it was not until Charles Darwin and Alfred Russel Wallace discovered that the wide variety of species we presently see were largely the result of natural selection did evolutionary studies have a solid, scientific basis. In the past one hundred and sixty years, a number of eminent biologists have contributed to our understanding of how complex life forms emerged from simpler, more rudimentary ones.
This small book provides a glimpse into the life and work of twenty-two outstanding evolutionary thinkers, ranging (in alphabetical order) from Jerry Coyne to Edward O. Wilson. This is by no means an exhaustive list since it is designed to show the wide diversity of scientists interested in evolutionary studies.
Each entry, written by a different author, describes the life and work of the evolutionist and why he is significant and what contributions he has made to the field. (MSAC Philosophy Group)

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