Dobzhansky, Theodosius, 1900-1975, American geneticist, b. Russia, grad. Univ. of Kiev, 1921. He emigrated to the United States in 1927 and was naturalized in 1937. Dobzhansky taught at the California Institute of Technology (1930-40) and was professor of zoology at Columbia (1940-62), leaving to become associated with the Rockefeller Institute (now Rockefeller Univ.). He conducted much research with Drosophila and is known for his basic work in genetics. His writings are of considerable significance and include Genetics and the Origin of Species (1937, 3d ed. 1951), a challenging summation of contemporary knowledge of genetics; Evolution, Genetics, and Man (1955); and Mankind Evolving: The Evolution of the Human Species (1962), which with great wisdom deals with cultural as well as biological evolution.

Theodosius, d. 376, Roman general under Valentinian I. He defeated (368-69) the Picts and Scots in Britain and the Alemanni in Gaul (369). He suppressed (372-74) a Berber uprising in N Africa, but was executed at Carthage by Valentinian's successor Gratian on unknown charges. His son became emperor as Theodosius I.

or Theodosius the Great in full Flavius Theodosius

(born Jan. 11, 347, Cauca, Gallaecia [Spain]—died Jan. 17, 395, Mediolanum) Roman emperor of the East (379–392) and of East and West (392–395). Born of Christian parents, he served in the military under his father, a general. He distinguished himself against the Sarmatians and was proclaimed coemperor by Gratian to rule in the eastern empire (379). To settle the contentious debate over true Christianity, he adopted the Nicene Creed as the Christian norm (380). He reached a treaty with the Visigoths (382). When the Spanish general Maximus overthrew the new coemperor in the western empire (387), Theodosius defeated the usurper (388) and claimed supreme authority over the whole empire (392). He argued with St. Ambrose over the role of the church in imperial affairs but did not grant power to the church. In 392 forces advocating paganism led by Arbogast and Eugenius took power in Rome. In 394 Theodosius defeated them and claimed the Christian God victorious over the pagan gods.

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(born April 10, 401, Constantinople—died July 28, 450) Eastern Roman emperor (408–450). In 402 he was made coemperor with his father, Arcadius (son of Theodosius I), then became sole ruler of the East at age seven, initially under a regency. A gentle, scholarly man, he allowed relatives and ministers to dominate his government. His generals twice repelled the Persians (422, 447) but failed to evict the Vandals from Roman Africa (429) and to prevent Attila's invasions (441–443, 447). The Nestorian heresy caused internal upheaval. Theodosius was credited with building the wall around Constantinople (413), founding the University of Constantinople (425), and promulgating the Theodosian Code (438).

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orig. Feodosy Grigorevich Dobrzhansky

(born Jan. 25, 1900, Nemirov, Ukr., Russian Empire—died Dec. 18, 1975, Davis, Calif., U.S.) Ukrainian-born U.S. geneticist and evolutionist. He immigrated in 1927 to the U.S., where he taught at the California Institute of Technology, Columbia University, and Rockefeller University. He laid the groundwork for a theory combining Darwinian evolution and Mendelian genetics by changing the then commonly held view that natural selection produced something close to the best of all possible results and that changes would be rare and slow and not apparent over one life span. He observed extensive genetic variability in wild populations of Drosophila, and he found that in a given population some genes would regularly change in abundance with the seasons of the year.

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orig. Feodosy Grigorevich Dobrzhansky

(born Jan. 25, 1900, Nemirov, Ukr., Russian Empire—died Dec. 18, 1975, Davis, Calif., U.S.) Ukrainian-born U.S. geneticist and evolutionist. He immigrated in 1927 to the U.S., where he taught at the California Institute of Technology, Columbia University, and Rockefeller University. He laid the groundwork for a theory combining Darwinian evolution and Mendelian genetics by changing the then commonly held view that natural selection produced something close to the best of all possible results and that changes would be rare and slow and not apparent over one life span. He observed extensive genetic variability in wild populations of Drosophila, and he found that in a given population some genes would regularly change in abundance with the seasons of the year.

Learn more about Dobzhansky, Theodosius with a free trial on Britannica.com.

Theodosius (from the Greek "Θεοδόσιος", "Giver of God") is a name which might refer to one of several people:

• One of three emperors of ancient Rome and Byzantium:
• Theodosius I (347–395; "Theodosius the Great"), son of Count Theodosius
• Theodosius II (408–450)
• Theodosius III (715–717)

• One of three Pope of the Coptic Orthodox Church
• Pope Theodosius I of Alexandria
• Pope Theodosius II of Alexandria
• Pope Theodosius III of Alexandria

Others by the name are:

• Theodosius of Bithynia or Theodosius of Tripolis (c. 160 BC– c. 100 BC) was a Greek astronomer and mathematician.
• Theodosius the Cenobiarch (c. 423-529)
• Patriarch Theodosius I of Alexandria (535–567)
• Theodosius the Deacon, an unknown 10th century Byzantine poet who wrote the poem "The Conquest of Crete"
• Patriarch Theodosius II of Alexandria (c. 12th century)
• Theodosius of Kiev, 11th century Russian saint
• Theodosius, Metropolitan of Moscow (1461–1464)
• Metropolitan Theodosius (Lazor), former primate of the Orthodox Church in America (1933– )
• Theodosius Dobzhansky, noted geneticist and evolutionary biologist