On YouTube:

Published on May 27, 2014 by SciShow
Quick Questions explains why, when it comes right down to it, there are really only eight kinds of people in the world.
———-
Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records: http://dftba.com/artist/52/SciShow
Or help support us by subscribing to our page on Subbable: https://subbable.com/scishow
———-
Looking for SciShow elsewhere on the internet?
Facebook: http://www.facebook.com/scishow
Twitter: http://www.twitter.com/scishow
Tumblr: http://scishow.tumblr.com
Thanks Tank Tumblr: http://thankstank.tumblr.com

Sources:
http://www.ncbi.nlm.nih.gov/books/NBK2261/
http://www.nobelprize.org/educational/medicine/landsteiner/readmore.html
http://anthro.palomar.edu/blood/Rh_system.htm
http://www.nlm.nih.gov/medlineplus/ency/article/002223.htm
http://www.rcsb.org/pdb/101/motm.do?momID=21
http://learn.genetics.utah.edu/content/inheritance/blood/
http://www.northshore.org/community-events/donating-blood/blood-types/
http://www.redcrossblood.org/learn-about-blood/blood-types