View full lesson: http://ed.ted.com/lessons/how-a-few-scientists-transformed-the-way-we-think-about-disease-tien-nguyen

For several centuries, people though diseases were caused by wandering clouds of poisonous vapor. We now know that this theory is pretty ridiculous, and that diseases are caused by specific bacteria. But how did we get to this new idea of germ theory? Tien Nguyen describes the work of several scientists who discredited a widely accepted theory in a way that was beneficial to human health.

This video was made in collaboration with U.S. Office of Research Integrity: http://ori.hhs.gov.

Lesson by Tien Nguyen, animation by Brandon Denmark.