Why There Are So Many Different Human Blood Types
In a sanguine episode of the PBS series Be Smart, host Dr. Joe Hanson explains the physiology of human blood, what it’s made of, and what it does. Hanson also explores the various types of blood and how it’s different in every person.
Across life on Earth, blood comes in red, blue, green, purple, even clear. But why? And what makes your blood different from mine? This video will teach you everything you need to know about the strange world of blood—what it does, why it varies, and why we can’t live without it.







