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Scientists have transformed the way we think and live throughout the centuries. What are the most important scientific discoveries of all time? In no particular order, we present the top 100 in eight different categories.
100 Greatest Discoveries - MEDICINE
1. Human Anatomy (1538)
Andreas Vesalius dissects human corpses, revealing detailed information about human anatomy and correcting earlier views. Vesalius believes that understanding anatomy is crucial to performing surgery, so he dissects human corpses himself (unusual for the time). His anatomical charts detailing the blood and nervous systems, produced as a reference aid for his students, are copied so often that he is forced to publish them to protect their accuracy. In 1543 he publishes De Humani Corporis Fabrica, transforming the subject of anatomy.
2. Blood Circulation (1628)
William Harvey discovers that blood circulates through the body and names the heart as the organ responsible for pumping the blood. His groundbreaking work, Anatomical Essay on the Motion of the Heart and Blood in Animals, published in 1628, lays the groundwork for modern physiology.
3. Blood Groups (1902)
Austrian biologist Karl Landsteiner and his group discover four blood groups and develop a system of classification. Knowledge of the different blood types is crucial to performing safe blood transfusions, now a common practice.
4. Anesthesia (1842–1846)
Several scientists discover that certain chemicals can be used as anesthetics, making it possible to perform surgery without pain. The earliest experiments with anesthetic agents — nitrous oxide (laughing gas) and sulfuric ether — are performed mainly by 19th-century dentists.
5. X-rays (1895)
Wilhelm Roentgen accidentally discovers X-rays as he conducts experiments with the radiation from cathode rays (electrons). He notices that the rays are able to penetrate opaque black paper wrapped around a cathode ray tube, causing a nearby table to glow with florescence. His discovery revolutionizes physics and medicine, earning him the first-ever Nobel Prize for physics in 1901.
6. Germ Theory (1800s)
French chemist Louis Pasteur finds that certain microbes are disease-causing agents. At the time, the origin of diseases such as cholera, anthrax and rabies is a mystery. Pasteur formulates a germ theory, postulating that these diseases and many others are caused by bacteria. Pasteur is called the "father of bacteriology" because his work leads to a new branch of scientific study.
7. Vitamins (early 1900s)
Frederick Hopkins and others discover that some diseases are caused by deficiencies of certain nutrients, later called vitamins. Through feeding experiments with laboratory animals, Hopkins concludes that these "accessory food factors" are essential to health.
8. Penicillin (1920s–1930s)
Alexander Fleming discovers penicillin, then Howard Florey and Boris Chain isolate and purify the compound, producing the first antibiotic. Fleming's discovery comes completely by accident when he notices that mold has killed a bacteria sample in a petri dish that is languishing under a pile in his lab's sink. Fleming isolates a sample of the mold and identifies it as Penicillium notatum. With controlled experimentation, Florey and Chain later find the compound cures mice with bacterial infections.
9. Sulfa Drugs (1930s)
Gerhard Domagk discovers that Prontosil, an orange-red dye, cures infections caused by the common bacteria streptococci. The finding opens the door to the synthesis of chemotherapeutic drugs (or "wonder drugs") and sulfa drugs in particular.
10. Vaccination (1796)
Edward Jenner, an English country doctor, performs the first vaccination against smallpox after discovering that inoculation with cowpox provides immunity. Jenner formulated his theory after noticing that patients who work with cattle and had come into contact with cowpox never came down with smallpox when an epidemic ravaged the countryside in 1788.
11. Insulin (1920s)
Frederick Banting and his colleagues discover the hormone insulin, which helps balance blood sugar levels in diabetes patients and allows them to live normal lives. Before insulin, diabetes meant a slow and certain death.
12. Oncogenes (1975)
Harold Varmus and Michael Bishop discover oncogenes — normal genes that control growth in every living cell, but can contribute to converting normal cells into cancer cells if mutated or present in abnormally high amounts. Cancer cells are cells that multiply uncontrollably. Varmus and Bishop worked from the theory that the growth of cancerous cells does not occur as the result of an invasion from outside the cell, but as a result of mutations possibly aggravated by environmental toxins such as radiation or smoke.
13. The Human Retrovirus HIV (1980s)
Competing scientists Robert Gallo and Luc Montagnier separately discover a new retrovirus later dubbed HIV (human immunodeficiency virus), and identify it as the causative agent of AIDS (acquired immunodeficiency syndrome).