Long before anyone discovered DNA, chromosomes, or genes, humans had figured out something important about the world around us. When we turned from hunting and gathering our food to growing and raising it, we realized that we could breed plants and animals to bring out desirable traits. Wild grasses became wheat under human cultivation; we domesticated and bred cows, pigs, and sheep to produce food, leather, and wool. And we also noted similarities between parents and offspring without knowing what causes these similarities. The concept of heredity preceded the science of genetics, but it is genetics that explains why all living species carry inherited traits and qualities. This timeline lists some of the key advances in thinking about heredity and genetics.
History of heredity
by John Curtis
Yale Medicine, 2015 - Spring
During the Neolithic era, about 12,000 years ago, as humans move from hunting and gathering to growing their food and raising animals, they learn to breed desirable traits into wild grasses and domestic animals.
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In the fifth century B.C.E., Hippocrates speculates that “seeds” are produced by various body parts and transmitted to offspring at the time of conception.
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Theophrastus, a Greek scholar of the late third century B.C.E., who studied under Aristotle and is considered the “father of botany,” proposes that male flowers cause the ripening of female flowers.
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Aristotle proposes in the fourth century B.C.E. that male semen and female menstrual blood mix at conception and that offspring receive traits from both mother and father.
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Abu al-Qasim, an Arab physician from about C.E. 1000, who is considered the father of modern surgery, describes the hereditary nature of hemophilia.
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William Harvey, a seventeenth-century London physician, wonders why offspring sometimes resemble the father, sometimes the mother, and sometimes progenitors both maternal and paternal.
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During the late seventeenth century, the Dutch lensmaker Antonie van Leeuwenhoek describes “animalcules” in the semen of humans and animals.
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Around 1800 the notion of heredity enters debates among physicians, animal breeders, and naturalists, and becomes a fundamental concept of biology.
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The Austrian monk Gregor Mendel describes patterns of inheritance in peas in the mid-1800s, but his theories are ignored, to be rediscovered only in 1901.
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In the mid-nineteenth century, the English naturalist Charles Darwin proposes the theory of evolution, with natural selection and heredity as its mechanisms.
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In 1869 a Swiss physician, Friedrich Miescher, discovers a microscopic substance in pus obtained from discarded surgical bandages. He isolates DNA from those samples and calls it “nuclein” because it resides in the nuclei of cells.
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Hugo de Vries, a Dutch botanist and geneticist, postulates in 1889 that “inheritance of specific traits in organisms comes in particles,” and calls the particles “(pan)genes,” a term that would later be shortened to gene.
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In 1902–03, Walter Sutton (left), an American physician, and Theodor Boveri, a German biologist, independently propose the chromosome theory of inheritance: chromosomes, which segregate in a Mendelian fashion, are hereditary units.
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William Bateson, an English geneticist, coins the term genetics in 1905.
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In 1931, Barbara McClintock, an American pioneer in cyto-genetics, provides the first proof that genes are physically positioned on chromosomes.
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In 1944, (left to right) Colin MacLeod, Oswald T. Avery, and Maclyn McCarty conducted an experiment at the Rockefeller Institute that isolated DNA as the substance that causes genetic transformation.
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(Clockwise, left to right) Francis Crick, James Watson, Maurice Wilkins, and Rosalind Franklin elucidate the structure of DNA at the University of Cambridge in 1953.2001–2003: The first draft sequences of the human genome are released by the international Human Genome Project and Celera Genomics in February 2001; two years later, the Human Genome Project is considered complete, with 99 percent of the genome sequenced to a 99.99 percent accuracy.
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