Everyone learns at a young age that Columbus sailed the ocean blue in 1492 and discovered the New World. Then we soon learn afterwards that he didn’t really discover anything, but he still gets all the credit. During this history lesson, we discover that countless natives died, not from war with the colonists, but from the microorganisms the Europeans accidentally brought with them. But why didn’t a disease from America make countless Europeans sick when sailors returned home? CGP Grey explains the complex situation in this trending educational video.