How Blood Evolved (Many Times)

  • Published on: 15 January 2019
  • Blood is one of the most revolutionary features in our evolutionary history. Over hundreds of millions of years, the way in which blood does its job has changed over and over again. As a result, we animals have our familiar red blood. But also blue blood. And purple, and green, and even white.

    Thanks to Julio Lacerda, Lucas Lima, Franz Anthony of Studio 252mya for several illustrations throughout this episode. You can find more of their work here:

    Produced in collaboration with PBS Digital Studios:

    Super special thanks to the following Patreon patrons for helping make Eons possible:

    Katie Fichtner, Anthony Callaghan, Renzo Caimi Ordenes, John Vanek, Neil H. Gray, Marilyn Wolmart, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, الخليفي سلطان , Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Colin Sylvester, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ruben Winter, Ron Harvey Jr, Jacob Gerke, Alex Yan

    If you'd like to support the channel, head over to and pledge for some cool rewards!

    Want to follow Eons elsewhere on the internet?
    Facebook -
    Twitter -
    Instagram -

  • Runtime : 10:28
  • dinosaurs dinos paleo paleontology scishow eons pbs pbs digital studios hank green john green complexly fossils natural history triploblastic diploblastic burgess hemoglobin hemocyanin hemerythrin blood circulatory systems evolution burgess shale cambrian Marrella bilateral symmetry globin heme globin fold purple red green white blue


  • Cam Miller
    Cam Miller   1 days ago

    Eons and Space-Time are the best things on YouTube. Thanks PBS.

  • Elias Håkansson
    Elias Håkansson   2 days ago

    "We have animals with our familiar red blood..."Me: Yup"..but we also have blue blood..."Me: um what?"..purple blood..."Me: Okay?" blood..."Me: Wtf?"...and even white blood"Me: ?????

  • takitaki rumbah
    takitaki rumbah   1 weeks ago

    Then how can there be no life on other planets when some kind of fish that lived 600m years ago developed blood from copper

  • Fae B.
    Fae B.   1 weeks ago

    Ahhhhh homestuck

  • Glob Animations
    Glob Animations   1 weeks ago

    Pbs Eons:living things have bloodMe: DO PLANTS HAVE BLOOD

  • mem Sisters
    mem Sisters   2 weeks ago

    Need to know connection between hemoglobin, and cytochromes, myoglobins, ISC iron sulpher cluster in mitochondri

  • Donny Sandley
    Donny Sandley   2 weeks ago

    I just saw a girl cooking a horseshoe crab and I'll tell you they don't look anything like I thought they would on the inside 😳

  • BookUnbinder
    BookUnbinder   3 weeks ago

    Snails evolving hemocyanin like that queen on Drag Race who doesn't know how to sew, meanwhile octopodes are LIVING.

  • Topten Dawg
    Topten Dawg   3 weeks ago

    Omgosh like what is these guys life like.Guys: ok finished report of newly discovered species...nothing new apparently... next!

  • A. N.
    A. N.   3 weeks ago

    Biliverdin sounds sick as h*ck.

  • hagala
    hagala   3 weeks ago

    no what gives blood the read colour is communism

  • Robert Eischen
    Robert Eischen   4 weeks ago

    I learned word hemoglobin is pretty fun to say. I'm not too bright though. 😅

  • HonorisCreed
    HonorisCreed   4 weeks ago

    Thank you for teaching me that I have a slight fear of blood.

  • first last
    first last   1 months ago

    But arthropods don't have a circulatory system I thought? That's why insects can't grow too thick because they need to get oxygen from opening in their exoskeleton which can't penetrate very deep, I thought?

  • Corleone
    Corleone   1 months ago

    I didn't expect a cuckold to be commentating for PBS

  • M P
    M P   1 months ago

    We were squids, THEN we were kids.

  • Gustavo Pomar
    Gustavo Pomar   1 months ago

    After the second or third "improvement" (mutation), who might've been the lucky ones that survived and were even able to reproduce!!! One really needs lots, I mean loooooots of faith to believe this.

  • _R.N.04_ Bluefaceb
    _R.N.04_ Bluefaceb   1 months ago

    Anyone else smart that watches videos at 2x speed and still understands them, you can get thru so many videos

  • jacob reww
    jacob reww   1 months ago

    How can you dislike everything?! XD

    BAD PUPPET   1 months ago

    5:44 LOL!!! Did you know shells of living snails carbon date to 100,000 years old?

  • Helljumper
    Helljumper   1 months ago

    Can a human lose their consciousness?

  • Zane Finlay
    Zane Finlay   1 months ago

    Evolution of sap and other mechisms that plants/trees/fungi use

  • Gender Woman
    Gender Woman   1 months ago

    What's the difference between a tapeworm and a human embryo?Tapeworm has other kind of blood than his host...

  • Gender Woman
    Gender Woman   1 months ago

    There's an iron.So that's why fresh blood smells like warm metal...

  • Gender Woman
    Gender Woman   1 months ago

    4:23-What's that colorful painting? Is it Picasso's?-It's blood.

  • JustSay That
    JustSay That   1 months ago

    A Mosquito that was hacking internet just found this video!

  • magnum opus
    magnum opus   1 months ago

    Looks likes Piccolo's blood has hemerythrin who knew 😀

  • Nime Ano
    Nime Ano   1 months ago

    This is what youtube shall be use for 👍🏿