View full lesson: http://ed.ted.com/lessons/why-do-blood-types-matter-natalie-s-hodge

It’s often said that despite humanity’s many conflicts, we all bleed the same blood. It’s a nice thought, but not quite accurate. In fact, our blood comes in a few different varieties. Natalie S. Hodge defines the four major blood types and sheds light on why some bloods can mix while others cannot.

Lesson by Natalie S. Hodge, animation by Brad Purnell.