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.

Blood Types PBS
Lori Dorn
Lori Dorn

Lori is a Laughing Squid Contributing Editor based in New York City who has been writing blog posts for over a decade. She also enjoys making jewelry, playing guitar, taking photos and mixing craft cocktails.