Nature has been trying to kill off the human race with disease since the day we stood up on two legs, and for much of our history we've been powerless to stop it. It wasn't until the past 200 or so years that we really started to figure out what causes disease, how it spreads and how to treat it. Those discoveries have done wonders for improving overall health and lifespan and even given us some pretty outstanding victories.
One such discovery was made in 1854, during an outbreak of cholera in the London neighborhood of Soho, near the intersection of Cambridge and Broad streets. In just one week, some 500 people had died of the disease, which causes severe diarrhea and dehydration. Local officials dismissed it as an inevitable result of miasmas, or "bad air" tainted by particles of decomposing matter. John Snow, a London surgeon and physician, had other ideas. He began a detailed investigation in which he interviewed residents and mapped out cholera cases in the neighborhood.
The map was startlingly conclusive: it showed nearly all the deaths were clustered around — drum roll please — the Broad Street water pump. As a result of his findings, Snow convinced city officials to shut down the pump, which was later discovered to have been contaminated by nearby pools of raw sewage. The outbreak came to an end, and Snow showed that humans could sometimes outsmart disease through epidemiology, or the systematic study of patterns, causes and effects of disease [source: Kukaswadia].