It’s the 200th birthday of John Snow, the father of epidemiology, the science of diseases and how they spread. In 1854, Snow mapped cases of cholera and traced the disease to its origin, and proved with a simple test that it was coming from a polluted well: he removed the pump handle, and the cholera outbreak stopped. Naturally, this conclusion was scoffed at by those with competing theories (“bad air”), producing one of my favourite history of medicine stories: to prove that cholera was not in the water, some smartypants biologist drank a glass of the stuff … and got away with it, because he just happened to be immune. It’s a great example of why “experience” is not trustworthy, and why it takes so long to settle even relatively straightforward puzzles in medicine.
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