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:

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  • 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


  • Michael Harris
    Michael Harris   4 days ago

    "There was blood everywhere". Great video thanks for informing me, the public, about the amazing world we exist in, if only for awhile.

  • tapsa nelikettu
    tapsa nelikettu   1 weeks ago

    So is blood older than oxygen (seas lost iron when oxygen became massively produced) ?

  • Kevin Dean
    Kevin Dean   1 weeks ago

    I went to school for science. Now I’m a mail man and a pool shark and a guitarist. And a dork. But I still love science. Its’ stepwise approach to explanations of natural phenomenon that can be tested and disproved seems as interesting as it was when I was in tenth grade biology. That’s why I’m watching this I suppose.

  • Eugene S
    Eugene S   3 weeks ago

    Hank, what is up with that tire around your waist??

  • Ed Me
    Ed Me   3 weeks ago

    I have always wondered about the fluids in plants being considered blood?

  • Kuzeyli
    Kuzeyli   3 weeks ago


  • Tom Kast
    Tom Kast   3 weeks ago

    When you say an animal "goes away" or "arrives" it is misleading. First off, you are talking about some identifiable set of characteristics that you consider to be "a specific animal". Then if that animal has a baby that is different, and that difference fitter or less fit, the genetic line (can) changes a bit. So that is what is really happening nothing is "going away" or "arriving". Everything is always changing. Makes sense? So Big Bars did not go away, Neanderthals did not go away, yes?

  • Jorgen Tacetta
    Jorgen Tacetta   3 weeks ago

    People always say that hemoglobin is more efficient, but is it really? Different hemoglobins have different oxygen affinities. From the charts I've seen hemoglobin in a carp is almost exactly as efficient as hemocyanin. And hemocyanin is more efficient than crocodile hemoglobin. Just because hemoglobin in humans is more efficient does not mean hemocyanin cannot evolve to be equally as efficient if there is selective pressure for it.

  • Jonathan Root
    Jonathan Root   3 weeks ago

    What blows my mind is that for around 90% of Earth's existence we only had simple life. Larger complex life didn't arise until much more recently.

  • Gord Orvis
    Gord Orvis   1 months ago

    Amazing info. Can't understand down votes.

  • Chris Yunge
    Chris Yunge   1 months ago

    Without even listening to this ambigious crap, you have to realize this.line of fantasy states that the veinous system in everything on the planet is not a predisposed pipeline of nutrient carrying waste disposal system that.carrying blood throughout everything in the planet, nope, you lying only to yourselves.if you even think that blood came before veins, our own sewer system identical, pipes first, then waste removal, even asexual microbes have waste elimination, who are you kidding dreamtrippers, your evo is lax and unrepeatable. Yet every civilization has these evacuate systems....!!!!@pay attn.!!!!!@

  • Andres piñeros
    Andres piñeros   1 months ago

    it would be great if guys make a video on RH- BLOOD

  • Daz Lolkaitis
    Daz Lolkaitis   1 months ago

    We are from Eons of Evolution, than we have Words are Power and Shenra.

  • Space Gandalf
    Space Gandalf   1 months ago

    The only things I can think about when talking about different colored blood, is Vulcans and Deviants.

  • Charles Bosse
    Charles Bosse   1 months ago

    It would be cool to have an episode that really laid out deep time to the present, maybe logarithmically going back from the present (more or less), with major points that you have talked about from your other episodes marked along the way.

  • 354sd
    354sd   1 months ago

    I like this chap he so clever

  • Ape X
    Ape X   1 months ago

    plz tell me how fungi evolved :)

  • jz35
    jz35   1 months ago

    how big was that mosquito ? it looked huge , im hoping that was just a trick of perspective or whatever i hate them so much . even 40 odd million years old ones

  • My videos.
    My videos.   1 months ago

    So maybe family original location has something to do with human blood type? I don't know.

  • Fernando Ecamp
    Fernando Ecamp   1 months ago

    this video should be restricted for younger audiences, to much blood.

  • Chad Dietmeyer
    Chad Dietmeyer   1 months ago

    I would like to know where RH Neg blood really came from? Why are we the only species on the planet that even has this separation and Incombatability?

  • Norman Petersen
    Norman Petersen   1 months ago

    Love your channel, guys. Did fish evolve from tunicates? I'd be interested at some point to hear about how fish might have evolved, and then diversified into cartilaginous, ray-finned and lobe-finned fish. Thanks!

  • Granulated
    Granulated   1 months ago

    Vulcans decended from Marrella...