The Secret of Regeneration in... Alligators

941 Shikime 95 mijë

Why can amphibians, fish and even some reptiles regenerate limbs, while birds and mammals can’t? Researchers think they might have found a clue on the tip of the alligator’s tail.
Hosted by: Hank Green
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Sources:
onlinelibrary.wiley.com/doi/abs/10.1002/9780470015902.a0001095.pub2
www.nature.com/articles/s41598-020-77052-8
www.sciencedaily.com/releases/2020/11/201123100952.htm
www.ncbi.nlm.nih.gov/books/NBK21070/
Image Sources:
www.istockphoto.com/photo/stranded-starfish-gm641584272-116229195
www.istockphoto.com/photo/zebra-fish-gm529402066-93256919
www.istockphoto.com/photo/axolotl-in-the-aquarium-gm533235106-94417029
www.istockphoto.com/photo/carolina-green-anole-lizard-and-reflection-gm829844516-135558993
www.istockphoto.com/photo/grass-snake-gm624626136-109809679
www.istockphoto.com/photo/blue-jay-in-fall-gm1191307973-338033081
www.istockphoto.com/photo/australian-shepherd-puppy-gm1130765875-299173268
www.istockphoto.com/photo/american-alligator-swimming-in-everglades-gm134544353-8994185
commons.wikimedia.org/wiki/File:Alligator_mississippiensis_2_babies.jpg
www.nature.com/articles/s41598-020-77052-8#Sec28
www.nature.com/articles/s41598-020-77052-8/figures/2
www.nature.com/articles/s41598-020-77052-8/figures/4
www.istockphoto.com/photo/wild-baby-alligators-everglades-national-park-gm1134581225-301530421
www.istockphoto.com/photo/close-up-snowy-owl-eye-with-wooden-background-gm986720632-267642242
www.istockphoto.com/photo/carolina-green-anole-lizard-gm829844540-135558989
www.istockphoto.com/photo/male-great-spotted-woodpecker-gm1189136390-336586470
www.istockphoto.com/photo/american-alligator-alligator-mississippiensis-gm973808230-264951484
commons.wikimedia.org/wiki/File:Macrospondylus_bollensis_Holzmaden.jpg

Komente

  1. Jonathan Williams
    Jonathan Williams
    18 minuta më parë

    or maybe the whole birds are dinos idea is nonsense we have fossilized skin impressions and what we find are scales not feathers

  2. Galaxia7
    Galaxia7
    10 ditë më parë

    No Doctor Who joke aw

  3. enter the null
    enter the null
    12 ditë më parë

    Well once we find out how we lost it we could find out how to regain it

  4. Cornbreadfed kirkpatrick
    Cornbreadfed kirkpatrick
    12 ditë më parë

    This is a true event from my family, My mom's big brother accidentally got a good bit of his finger cut off they put it in a small stuff tin and buried it, and a month later his finger grew back I had seen the scar it was a deep scar, where it was cut off on his finger no it wasn't his middle one the index on his right hand and being scared they went to where they buried it and dug it up there it was all rotted but there, proof that indeed that he did had the accident and had buried the remains.

  5. Nancy Lebovitz
    Nancy Lebovitz
    12 ditë më parë

    Children can regenerate fingertips.

  6. Gabriel Martins
    Gabriel Martins
    14 ditë më parë

    Regenerating a limb means keeping an open wound for a long time. That means high risk of infection and of bleeding out. But we still have the genes to do it, in fact, there have been clinical studies that proved we can in fact re-grow fingertips.

  7. John Smith
    John Smith
    15 ditë më parë

    Let me know when science can make me regenerate. I plan on having lots of animal powers.

  8. chasecars1savelives
    chasecars1savelives
    15 ditë më parë

    I love that “pen for scale” is useful even for the cutting edge of alligator biology

  9. Blah Smith
    Blah Smith
    16 ditë më parë

    I wish I can regenerate :(

  10. Muhammad Umair
    Muhammad Umair
    16 ditë më parë

    Imagine if humans can regenarate body parts then almost half of world circumcised male population have to do it over and over again.

  11. scifitoilet
    scifitoilet
    17 ditë më parë

    why spec into regeneration when you can spec into never taking critical damage in the first place.

  12. Ethan Gregory
    Ethan Gregory
    17 ditë më parë

    That M. Bollensis fossil is amazing

  13. Marco Tedesco
    Marco Tedesco
    18 ditë më parë

    Hypothesis off the top of my head: maybe if you have a high enough metabolism the processes of regeneration could mean a heightened risk of cancer? I think I recall something along those lines being invocated as the reason no mammals have changed the basic number of 7 cervical vertebrae except those two very low-metabolism groups, sirenians and sloths

  14. Duncan
    Duncan
    18 ditë më parë

    Fact Check: Gene study from Penn State shows that turtles are the closest living relatives . www.sciencedaily.com/releases/1999/02/990217075533.htm#:~:text=Summary%3A,available%20collection%20of%20reptile%20genes.

  15. Mino Adlawan
    Mino Adlawan
    18 ditë më parë

    Wouldn't the cost of regeneration only be present if a limb were to be cut off?

  16. Yusuf Maulana
    Yusuf Maulana
    18 ditë më parë

    Successful species just don't need a power to regrow an organ. I mean... The resource, time, and effort can be use to "grow" another offspring. It's greater good for the species as a whole.

  17. Kirstin Rose
    Kirstin Rose
    18 ditë më parë

    I only like hank. He does a better job explaining and making it fun and sometimes adorable. Thank you hank. You make learning fun.

  18. Velo1010
    Velo1010
    18 ditë më parë

    But we regenerate skin and long cells.

  19. Ryan Alexander Bloom
    Ryan Alexander Bloom
    18 ditë më parë

    It looks like you guys are all freezing in your studio lately. Everyone’s wearing coats and stuff... you not have heat in there?

  20. Tarin
    Tarin
    18 ditë më parë

    I’m surprised they didn’t as Mark Zuckerberg for a first-hand account.

  21. James 4theDoctor
    James 4theDoctor
    18 ditë më parë

    Regenerate!

  22. Lupus Macbeth
    Lupus Macbeth
    18 ditë më parë

    Hey, Hank, has anyone ever told you that you look a lot like the one nerdy kid in Jeepers Creepers 2 that almost got taken twice?

  23. The Color of Boom
    The Color of Boom
    18 ditë më parë

    Time to ramp up the inbreeding. Need me a cold-blooded, limb growing cuz

  24. MarvAlice
    MarvAlice
    18 ditë më parë

    I don't see how regeneration is a "trade off" because you only need to spend that energy if you actually lose the limb. So it's not like an animal that doesn't get injured has to pay for the ability. So the assertion is that it's a trade off between healing, or the benefits of not healing. Calling this a trade off sounds like an excuse for why we don't understand it, ngl.

  25. First Cynic
    First Cynic
    18 ditë më parë

    Mammals didn't evolve from reptiles or amphibia. We likely never had regeneration.

    1. First Cynic
      First Cynic
      15 ditë më parë

      @Sara3346 Looks like my attempt at a post with a link to other videos failed... sigh. I got that from cladistics. Our ancestors were reptilian, but not reptiles. Our earlier ancestors were amphibious, but not amphibians. I recommend you watch Aron Ra's excellent youtube video series "Systematic Classification of Life". It'll inform you about all that and far more.

    2. First Cynic
      First Cynic
      15 ditë më parë

      @Big oof Its possible they did, though there's no evidence for it (afaik). If they did, that trait almost certainly didn't continue in clade Mammalia.

    3. Big oof
      Big oof
      15 ditë më parë

      i bet our earlier synapsid ancestors had regeneration to a certain extent

    4. Sara3346
      Sara3346
      18 ditë më parë

      Where on earth are you getting that from? Do you think there was just a jump from fish to mammal?

  26. solea gaming roblox
    solea gaming roblox
    18 ditë më parë

    gg

  27. Cocomunga Productions
    Cocomunga Productions
    18 ditë më parë

    If humans could regenerate, there would be way too many of us and there already are too many.

  28. Mike Petell
    Mike Petell
    18 ditë më parë

    So now the theory of dinosaurs evolving into birds is considered fact

  29. Mike Petell
    Mike Petell
    18 ditë më parë

    Reminds of an X-files episode called Leonard Betts where he regenerated a head. Lol

  30. King David
    King David
    18 ditë më parë

    Do african spiny mouse regeneration next

  31. King David
    King David
    18 ditë më parë

    It could also show how regeneration can evolve

    1. Sara3346
      Sara3346
      18 ditë më parë

      I think the secret is that they cheat, they grow cartilage instead of bone.

  32. Samuel Brémont
    Samuel Brémont
    18 ditë më parë

    I don't care how regeneration can be lost. Quite the opposite. Precisely the opposite, actually.

    1. Sara3346
      Sara3346
      18 ditë më parë

      Well if we have a much better understanding of how it was lost then presumably we would also be able to more easily figure out how to reactivate it. I'll be at we could just fiddle around with stem cells more since that seems to have yielded humans the most results so far.

  33. Anonymous Dreamer
    Anonymous Dreamer
    18 ditë më parë

    ...scp, anyone...?

  34. Bane
    Bane
    18 ditë më parë

    Its almost as if its a "Hard to Destroy Reptile"

  35. Burner Burner
    Burner Burner
    19 ditë më parë

    Peter Parker would advise against this research.

  36. Romuland Meier
    Romuland Meier
    19 ditë më parë

    Its not that hard to figure out. The more complex a organism gets, the more drastically consequences errors in the genetic code have. The danger of tumors may increase with the increased cell division needed to heal fast. Also you age faster, which is no good trade for a K-strategist.

    1. Sara3346
      Sara3346
      18 ditë më parë

      I'm not sure an axolotl is all that more complicated than I am though I mean aside from lungs don't we share almost all organ systems, even if not in exactly the same configuration? Where to put it in another way are cockroaches and stick insects really that much less complex than butterflies? Butterflies are much worse at regeneration than them I think.

  37. Jaycee Williams
    Jaycee Williams
    19 ditë më parë

    Chop off an alligators head and it'll grow another

  38. Captain Smith
    Captain Smith
    19 ditë më parë

    That's because you sign for things, so a King had a wax seal. When you smoke, your leaving a nicotine seal, so your transient products taste like nicotine, that way you can smell things further away. But their transient materials, so an alligator has more transient components than lizarda so the seals are deemed forged coppies.

  39. GuatemalanJedi
    GuatemalanJedi
    19 ditë më parë

    Could intelligence be a factor in why evolution stop supporting regeneration? It seems to me that if an animal is smart enough to adapt their behavior to the absence of a limb, then the value of using all the energy for regeneration is greatly diminished.

  40. Anand Acharya
    Anand Acharya
    19 ditë më parë

    A whole new meaning to the phrase 'Just the Tip'.

  41. JUSTICE FOR RAVEN HOPE- LETUSHEAL
    JUSTICE FOR RAVEN HOPE- LETUSHEAL
    19 ditë më parë

    Going on personal experience only. I believe that this is related to the murky water that crocs are normally in. Due to the murky water having an over abundance of bacteria. If the croc has a lot of interaction with mimicking organisms and covers themselves in these organisms, the new replicated tail is a mimicked version.

  42. DaBlondDude
    DaBlondDude
    19 ditë më parë

    Why the assumption that mammals lost this ability (meaning they once had them)?

    1. DaBlondDude
      DaBlondDude
      18 ditë më parë

      @Sara3346 perhaps, though it still pops out as an unsupported assumption until I learn more

    2. Sara3346
      Sara3346
      18 ditë më parë

      Or free completely different example from a different group of animals for why this thinking tends to be applied, flies only have two functional wings I'm sure you've noticed this. This is not usual for insects so wouldn't it be reasonable to think that they evolved from four-winged ancestors?

    3. Sara3346
      Sara3346
      18 ditë më parë

      Because it's present in all groups besides mammals birds and snakes in a similar form, the simplest explanation for that is that it was the ancestral condition because it's shared in such a similar form across so many species. See also the pituitary eye. Most reptiles amphibians and lobe finned fish share this feature and the clothes ancestors of mammals did as well. But in short if we expected this to be a convergent trait then I think we would see a lot more variation in it than we do why should the very tips of limbs be any better at regrow than say ribs or eyes, etc if not for a common pathway.

  43. Kyle Everly
    Kyle Everly
    19 ditë më parë

    0:35, doggo! That is all, carry on

  44. Anonyfox
    Anonyfox
    19 ditë më parë

    The book Amazonia (sci-fi) goes down the rabbit hole of regeneration a bit and mentions that we may have lost regeneration in favor of being able to hold off cancer better. Don't know if there's any evidence behind that or not, but I thought it was a neat idea.

    1. Yusuf Maulana
      Yusuf Maulana
      18 ditë më parë

      That nice idea. Since "grow" a thing is similar to cancer. The system should decide to stop growing factor and start maintaining the structure.

  45. ChillsAhoy
    ChillsAhoy
    19 ditë më parë

    Gallifreyans are actually alligators?

  46. Joshua Gonzales
    Joshua Gonzales
    19 ditë më parë

    Gee I wonder why snakes can't regrow limbs

  47. Spiffo
    Spiffo
    19 ditë më parë

    interior

  48. Andre Moore
    Andre Moore
    19 ditë më parë

    Children with cut off finger tips have regrown their fingertips, this doesn't count as regeneration?

  49. Daltira
    Daltira
    19 ditë më parë

    Humans have regrown full fingers before. Including bone. Look it up.

  50. Sagacious Eagle
    Sagacious Eagle
    19 ditë më parë

    If crocs are closer to birds than lizards, then we might be closer to lizards than we are to Adam & Eve.

  51. Gertrud Bondesson
    Gertrud Bondesson
    19 ditë më parë

    What I've heard was that a wound closing with scar tissue was a faster process than regenerating limbs, and mammals basiacally traded regeneration for quicker healing to avoid infections and further injuries. I bet size also makes a difference, it'd take a lot more resources for a big dinosaur to regenerate a lost tail than it would a tiny lizard, so maybe the cost outweighed the benefits for larger species? After all, alligators seem to regenerate less of their tail the larger they are when they lose it.

  52. etmax1
    etmax1
    19 ditë më parë

    :-) it's obvious snakes can't regenerate limbs, someone must have pulled them off at birth I guess but I've never seen any with them :-)

  53. Joshua Spurgeon
    Joshua Spurgeon
    19 ditë më parë

    ❤️

  54. Aryan Sayyad
    Aryan Sayyad
    19 ditë më parë

    Hey, dna editors Thats what i'll call them Why don't you try and use the regeneration dna on a monkey or something I know it isnt that easy

  55. Edgar Smittenheighnjenkson
    Edgar Smittenheighnjenkson
    19 ditë më parë

    Damn now I want a po'boy.

  56. Ana Catarina
    Ana Catarina
    19 ditë më parë

    A cada dia eu me sinto mais pronta apta tomar vacina e virar jacaré

  57. shbunie
    shbunie
    19 ditë më parë

    ha, love the shocked owl at the dramatic reveal >

  58. I Collect Stories
    I Collect Stories
    19 ditë më parë

    This is what we get for leaving the water! We get thick-skinned to avoid drying out, but it also hinders regrowth.😥

  59. Bruce Paterson
    Bruce Paterson
    19 ditë më parë

    (Somewhat oversimplified) All the cells in a complex organism(one with many different organ types) have the same complete DNA (except sperm and egg). The different cell types differ in their epigenes (methyl groups added to DNA). As cells differentiate, divide and grow from the initial fertilized egg, at various stages, epigenes are added so different cell lines develop and organize, and the final complex mature organism results. It seems that early in evolution, so-called primitive organisms had the ability to controllably alter their epigenes in an area (say at the base of a lost limb) by removing epigenes and reverting these cells to an earlier differentiation state as well as reactivating telomerase,, and thus they can regrow lost parts good as new. This has progressively been lost, so, as Hank says, amphibians can generally regenerate well, reptiles a bit and mammals hardly at all (scar tissue is about all we can do).

  60. Carry on
    Carry on
    19 ditë më parë

    Nah, I can't be the only one thinking about SCP 682.

  61. Arcana Octonus
    Arcana Octonus
    19 ditë më parë

    Y'all need to cut the incorrect definitives like mammals do not regrow damaged limbs. It is well known that children have re-grown severed fingertips.

  62. Arcana Octonus
    Arcana Octonus
    19 ditë më parë

    What limbs r fish regrowin?

    1. Romuland Meier
      Romuland Meier
      19 ditë më parë

      Tails, fins, some even parts of the heart and nervous system.

  63. CAPSLOCKPUNDIT
    CAPSLOCKPUNDIT
    19 ditë më parë

    It still doesn't answer the main question: If you dismember, can you remember?

  64. PRASHANT BARASKAR 1
    PRASHANT BARASKAR 1
    19 ditë më parë

    I can regenerate my hairs and nails.

    1. PRASHANT BARASKAR 1
      PRASHANT BARASKAR 1
      18 ditë më parë

      @Sara3346 Wait! what parts cam deers regenerate? 😮

    2. Sara3346
      Sara3346
      18 ditë më parë

      The only mammals I know of with any significant regeneration ability are deer and yes bone is in fact living tissue.

    3. Sara3346
      Sara3346
      18 ditë më parë

      Yes, but that's not actually living tissue at all.

  65. CWLee
    CWLee
    19 ditë më parë

    If you dont spend evolution points on regeneration you can use it for other skills of course

    1. Romuland Meier
      Romuland Meier
      18 ditë më parë

      AH, a fellow player of "Outside" from the TierZoo channel. How is your robber fly build going?

  66. sirBrouwer
    sirBrouwer
    19 ditë më parë

    I wonder do we still have the mechanism/genetic information in our DNA/body to be able (so it there just not active) If so would it be something to look in to if it would be possible to reactivate it for more then our liver (the only organ that can regenerate in our case) It could be useful for people with organ say a kidney notworking well that they could grow a new kidney out of there own body. (very small chance a body will not accept it's own organs)

  67. Majart
    Majart
    19 ditë më parë

    I wonder if phantom pain is somehow linked to this as well. Like do crocodilians feel phantom pain from a severed tail, and would a regenerated tail remove that pain?

    1. Roll0112358
      Roll0112358
      19 ditë më parë

      That's a very interesting question. No idea is anyone knows the answer or how to study it, though.

  68. Art Clark
    Art Clark
    19 ditë më parë

    Deadpool approves of this video. He wants to know why he can't die.

    1. Romuland Meier
      Romuland Meier
      18 ditë më parë

      Because he is a cheater, thats why.

  69. austin bogner
    austin bogner
    19 ditë më parë

    Why do only humans wipe their butts?

    1. austin bogner
      austin bogner
      18 ditë më parë

      @Romuland Meier ok that makes a lot of sense but why are humans the only animals to wipe their butts!?!

    2. Romuland Meier
      Romuland Meier
      18 ditë më parë

      Because gut bacterias are only useful in your gut. Once they leave it they are a increased risk of illness. Thats why.

  70. Hanif Pandu
    Hanif Pandu
    19 ditë më parë

    So, how many regeneration do alligators have? 12? 13? Or infinite after certain retcons?

  71. Amit das
    Amit das
    19 ditë më parë

    Wow

  72. James Merkel
    James Merkel
    19 ditë më parë

    I wonder if metabolism and size are a factor. Most lizards are smaller or have slower metabolisms than birds and mammals. Gators have a fairly slow metabolism, but due to their size it may not be prudent to regenerate the bones in their tails. Birds on the other hand have very high metabolisms, especially small ones such as a hummingbird. It could be completely off mark or just a part of the answer, I don't know. Just a thought.

  73. Justin Abraham
    Justin Abraham
    19 ditë më parë

    Since it forms scar tissue and doesn't show specific tissue substitution, isn't that just repair, and not regeneration?

  74. John
    John
    19 ditë më parë

    Another group great at regeneration: Titanus Ghidorah

  75. hello
    hello
    19 ditë më parë

    SCP-682 is a crocodilian that regenerates well, maybe thats the missing link. 🤔

  76. CartesianColours
    CartesianColours
    19 ditë më parë

    Its phosphorous. All about the phosporous . Once optimal maturity/size is attained in creatures, cells/proteins coordinate and limit phosphorous moving into cells, preventing excessive, evolutionary disadvantaged, never ending growth. I suspect the watery, earthy, environments of some animals offers rich amounts of the atomic element if needed, and so they retained the reversal genes or immune system reaction or oxygen/nitrogen exposure triggers for regrowth. Novo Bioscience is in clinical trials now with a molecule identified (1 of 1400 molecules tested I think) thanks to dolphins that allows them amazing near scar free healing. Life is the phosporous accumulator, OR vice versa. It's DNA glue. Meantime what about the zombie starfish, horseshoe crab and lung fish with longest genomes which is likely ocean to land ancestor. Its phosphorous allowed to and into cells, and new cells. It's DNA glue. That and bump bump, bump bump, bumo bump of sonic blood pulses keeping things energetic.

  77. One Grain A Rice
    One Grain A Rice
    19 ditë më parë

    Stop talking crap about crocodile and birds are relative more than lizard and crocodile. I see u talk nonsense before, but this is stupidity

  78. Frederick Tan
    Frederick Tan
    19 ditë më parë

    Because Alligators need their tails to swim, a tailless Alligator would be bad

  79. Artsy Potato
    Artsy Potato
    19 ditë më parë

    So.. let me get this straight.. I (as a potato) can’t cut off a part of my body and regenerate?.. :(

  80. DV 8
    DV 8
    19 ditë më parë

    Yummy.

  81. Trigg Ethridge
    Trigg Ethridge
    19 ditë më parë

    are birds reptiles?

    1. Romuland Meier
      Romuland Meier
      19 ditë më parë

      No, they ear use 3 bones instead of 2, they have a way higher metobolism rate. Lung sacks for better oyxgen transfer and a faster nervous system. Also they are way more agile and intelligent (well, most of them). And have a enhanced social structure. We all love reptiles but birds have the better build.

  82. Zielosław Wiesław
    Zielosław Wiesław
    19 ditë më parë

    And why primates and guinea pigs lost the ability to make vitamin C from glucose? Mutated and broken, but still working well enough not to go extinct. That's the way I see it :)

    1. Romuland Meier
      Romuland Meier
      18 ditë më parë

      Because Vitamin C is so simple that it was in almost everything our ancestors ate. There was a benefit of saving the energy to create it. Only the modern humans suffer because they tend to eat not as many different plants.

  83. Adchoa Lulle
    Adchoa Lulle
    19 ditë më parë

    Birds do regenerate, actually. The hair cells in their inner ears. That's not so easily seen from outside, to be fair, but when I researched hearing development in chicken for my bachelor's thesis, the publications on that topic reached back to 1990s...? More than 20 years anyway.

    1. Adchoa Lulle
      Adchoa Lulle
      15 ditë më parë

      @boulderbash19700209 That's not regeneration, that's just growth. The cells that produce the nail material are not destroyed by clipping nails, so they don't need to be regenerated. The hair cells in the inner ears are the receptor cells for hearing. When they are destroyed, e.g. by way too loud music, your hearing suffers. If I remember correctly (I finished my bachelor's thesis in 2015, and I don't work anywhere near the field now), no mammal can regenerate those cells, but pretty much every other animal can.

    2. boulderbash19700209
      boulderbash19700209
      16 ditë më parë

      Yeah, and our nails are also regenerate.

  84. Miikhiel Aali
    Miikhiel Aali
    19 ditë më parë

    Maybe gators don’t have a full copy of regeneration genetic sequence which would tell cells not only to “build new cells” but also “how to do so.” Lizards may have more robust instruction set in their genomic sequence which allows cells to not only know “what needs to be made” based on things lost but also “how much, what direction, etc.” Perhaps the trade off as to why we mammals and aves lack these genes has to do with metabolism and temperature regulation.

  85. FIRE STORM 3692
    FIRE STORM 3692
    19 ditë më parë

    It takes way more mass to regenerate a big animal than a small one

  86. MunchyMeister
    MunchyMeister
    19 ditë më parë

    Scishow finally uncovers the classified details on how SCP-682 regenerates

  87. Dr Mann
    Dr Mann
    19 ditë më parë

    Si the snake is the only reptile who can not regenerate?

  88. Dave Stratton
    Dave Stratton
    19 ditë më parë

    Dr. Curt Connors was way ahead on this research in Spider-man.

  89. Dudley The Animator
    Dudley The Animator
    19 ditë më parë

    nah guys alligators are just wannabe scp 682's

  90. E. Regular
    E. Regular
    19 ditë më parë

    I feel like maybe you shouldn't tell Florida Man this. Alligators would be extinct on the next the day. Florida Man does Florida things

  91. Mike Stewart
    Mike Stewart
    19 ditë më parë

    If humans could regenerate, would you keep that severed limb around for sentimental reasons?

    1. Sara3346
      Sara3346
      18 ditë më parë

      Yes I think we would people are willing to do that right now even though they can't regenerate. I remember hearing about a guy who poses with his arm bones all the time.

    2. Romuland Meier
      Romuland Meier
      19 ditë më parë

      Maybe we would hang it over our doors as a good-luck charm (after boiling the flesh off of course).

  92. kuntamdc
    kuntamdc
    19 ditë më parë

    Its in the blood.

  93. Lyndsay Brown
    Lyndsay Brown
    19 ditë më parë

    I still haven't generated my first tail

  94. bobthebillable
    bobthebillable
    19 ditë më parë

    This was such an interesting episode!

  95. nick verdicchio
    nick verdicchio
    19 ditë më parë

    Its actually called gatoraid

  96. Coldbrew
    Coldbrew
    19 ditë më parë

    I was just thinking about the possible relation to warm-bloodedness right before it was mentioned. Would make sense, it takes a lot more energy to make all that heat. Doesn't explain why the crocs have lost some of the ability but maybe they just don't need it as much anymore.

    1. Sara3346
      Sara3346
      18 ditë më parë

      It also doesn't explain why snakes seem to be particularly bad at it either so I don't know about putting much stock in it.

  97. Joseph Magliocca
    Joseph Magliocca
    19 ditë më parë

    2:19 There’s one bird that’s surprised to be so closely related to crocodilians!

  98. stefanos tokatlidis
    stefanos tokatlidis
    19 ditë më parë

    It seems that animals with specialized body plans lose regeneration for unknown reasons. Mammals, birds, turtles, snakes, frogs all lost significant regeneration abilities.

    1. Sara3346
      Sara3346
      18 ditë më parë

      But I'm not sure that would make sense 4 generalist mammals though, I mean rats and say tree shrews has hardly lost any significant organ systems compared to reptiles even if they have changed them......

    2. Sara3346
      Sara3346
      18 ditë më parë

      Maybe it might have to do with genes being turned off to grow body parts like limbs or teeth then?

  99. Stef H
    Stef H
    19 ditë më parë

    Fun fact: humans will often regrow the tips of fingers if it is cut off before the first knuckle.

  100. Trag 1804
    Trag 1804
    19 ditë më parë

    If evolution is driven by mutation how did parents react towards their mutated offspring

    1. Sara3346
      Sara3346
      18 ditë më parë

      Mostly by not noticing at all I would imagine.

    2. Romuland Meier
      Romuland Meier
      18 ditë më parë

      You can see it in humans. Some of our childs look different like having more or less limbs, other hair structure of hight. A few even serious health problems because of it. But we still love them, protect and educate them, because they are a part of us. For animals its even more easy - keep up with the horde or die alone if your mutation is a hinderance. Also many mutaions are very subtle and only appear in certain conditions like resistance against the environment, better symbolism with your gut bacteria (more nutrients for you), increased intelligence and so on.

    3. Aryan Sayyad
      Aryan Sayyad
      19 ditë më parë

      Its happens very slow stacking from millions of years A human didn't suddenly came out of a ape or something