SciShow on Instagram: "People have been trying to prevent the spread of infectious disease forever, yet we only got germ theory in the 19th century. Except for one 16th century Italian doctor, who got it exactly right and was immediately forgotten. This video was inspired by Air-Borne: The Hidden History of the Life We Breathe, a new book by Carl Zimmer. If you’d like to check it out, head to the SciShow Bookshop page. Made in partnership with The Alfred P. Sloan Foundation"