20th-century knowledge about the body and disease
Knowledge about the body and disease increased greatly in the 20th century. Developments ranged from the discovery of the cause of diabetes to the creation of 'test-tube' babies for previously infertile couples.
There were many scientific and medical discoveries and developments during the 20th century. The following are among the most significant:
1896: Walter Cannon (America) used a barium meal with x-rays to track the passage of food through the digestive system.
1910: Henry Dale (Britain) discovered the chemical histamine, which is produced by the body during an allergic reaction. This allowed him to understand allergic response and surgical shock.
1921: Frederick Banting and Charles Best discovered insulin, which breaks down sugar in the bloodstream. Thus he found the cause of diabetes.
1923: Edgar Allen (America) discovered oestrogen (the hormone that powers femaleness). In 1935 Ernst Laqueur isolated testosterone, the hormone that creates maleness.
1931: The invention of the electron microscope allowed doctors to see bacteria and viruses for the first time.
1951: The Mexican company Syntex developed norethisterone, which prevents ovulation - leading to production of the first contraceptive pills.
1953: Francis Crick and James Watson (Britain) discovered DNA.
1953: Leroy Stevens (America) discovered stem cells.
1970s: Patrick Steptoe (Britain) developed IVF fertility treatment; in 1978 Louise Brown became the first 'test-tube' baby.
1970s: Endoscopes - fibre optic cables with a light source - enabled doctors to 'see' inside the body.
1972: Geoffrey Hounsfield (Britain) invented the CAT scanner, which uses x-ray images from a number of angles to build up a 3D image of the inside of the body.
1980s: MRI scans were developed to monitor the electrical activity of the brain.
1986: In the Visible Human project undertaken in the US, the bodies of two criminals (a male and a female) were frozen, cut into 1mm slices, stained, photographed and stored as 3-d images on the internet.
1990s: The Human Genome project undertaken in the US mapped all the genes in the human body - 40,000 of them. Humans share their gene make-up with much of the natural world, leading scientists to joke that because of the genes we share, human beings are 60 per cent banana! In 1997 Scottish researchers bred Dolly, the first cloned sheep.
2002: Gunther von Hagens (Germany) performed live dissections on TV.
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