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Season 3 Episode 11 | 9m 7s
| Video has closed captioning.
Humanity didn't always know about the invisible viruses, bacteria, and microbes that can cause disease. But that doesn't mean we didn't come up with some truly bizarre ideas. From the four humors and miasma theory to bloodletting and trepanation, Danielle traces humanity's winding road to the Germ Theory of Disease that revolutionized the medical profession.
