WEBVTT - Regenerate This!

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<v Speaker 1>Welcome to Stuff from the Science Lab from how stuff

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<v Speaker 1>works dot com. Hey guys, and welcome to the podcast.

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<v Speaker 1>This is Alison madam Ilk the science that are how

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<v Speaker 1>stuff works dot com. And this is Robert Lamb, science

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<v Speaker 1>writer at how stuff works dot com. Today we're talking

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<v Speaker 1>about the process of regeneration. And this topic comes to

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<v Speaker 1>you compliments of one Rob Chef, my colleague of ours

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<v Speaker 1>at how stuff works, and Rob send us a story

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<v Speaker 1>about a jellyfish, particular kind of jellyfish that can be

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<v Speaker 1>immortal essentially. Yeah, it's like that old saying immortality was

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<v Speaker 1>wasted on the jellyfish. Yeah, yeah, that old saying. Yeah. So,

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<v Speaker 1>the definition of regeneration is um the ability to regrow

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<v Speaker 1>lost tissue or destroyed organs or parts, and can be

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<v Speaker 1>routine or it can be sustained after injury. And the

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<v Speaker 1>regeneration is truly an amazing process. I mean, lest you

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<v Speaker 1>not regarded such, let me just regalue with a quote.

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<v Speaker 1>If there were no regeneration, there could be no life.

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<v Speaker 1>If everything regenerated, then there could be no death. And

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<v Speaker 1>that's the quote from the developmental biologist Richard Jay goss Um.

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<v Speaker 1>And goss was a pioneer in the field of developmental

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<v Speaker 1>biology and regeneration. Gossa taught up Brown for decades until

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<v Speaker 1>his death ironically from cancer actually, and a lot of

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<v Speaker 1>cellular and tissue growth. So that's pretty interesting. And Goss

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<v Speaker 1>was actually interested in antler regeneration and he published a

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<v Speaker 1>book called Deer Antlers in I was harping on this earlier,

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<v Speaker 1>but it's like, this is the guy, this guy's life work,

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<v Speaker 1>and he's just so passionate about and he just calls

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<v Speaker 1>the book dear Antlers just dear Antlers. Just sometimes the

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<v Speaker 1>topic speaks for itself, Robert, but not the complete Dear

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<v Speaker 1>Antlers or amazing or my life with Dear Antlers something.

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<v Speaker 1>I don't know. It just seems like a very gland title. Well,

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<v Speaker 1>Gas was a scientist, perhaps he felt no need for embellishment.

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<v Speaker 1>Unless the cover was a picture of himself with deer antlers,

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<v Speaker 1>then I would forgive the title. So anyway, Goss was

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<v Speaker 1>one of the main men in a pioneering regeneration um.

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<v Speaker 1>But there are some other pioneers in the field as well. Yeah,

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<v Speaker 1>I mean this is uh, the idea of regeneration is

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<v Speaker 1>is not know people have been noticing this for a

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<v Speaker 1>while Aristotle was writing about it, and if you go

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<v Speaker 1>back to the Greek myths, you might remember a certain

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<v Speaker 1>titan by the name of Prometheus, the firebringer um. And

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<v Speaker 1>his punishment UM was that he was chained to a

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<v Speaker 1>big rock and eagle would swoop down, eat his liver,

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<v Speaker 1>fly off, and then what happens, liver grows right back.

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<v Speaker 1>It's one of those eternal punishment type deals, but with

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<v Speaker 1>the bonus of livery generation um. And then also in greeknests,

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<v Speaker 1>you have the hydra, which is the multi headed serpent,

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<v Speaker 1>and every time you cut off one of its heads,

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<v Speaker 1>what happens, two of them grow back. That's correct, to

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<v Speaker 1>grow back in its place, um. And Hercules killed the

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<v Speaker 1>hydra correct, yeah, because he would, if I remember it correctly,

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<v Speaker 1>he had he realized, Hey, I just need to bring

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<v Speaker 1>a sword and a worch, and so every time he

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<v Speaker 1>cut off a head, he'd he'd cauterized the wound, burn it,

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<v Speaker 1>you know, shut. And so after a while you just

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<v Speaker 1>had this monster that was nothing but stumps, and I

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<v Speaker 1>guess it was dead. But it's a mythological creature, so

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<v Speaker 1>who knows. Who knows how these things work? As it

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<v Speaker 1>turns out, though, hydra eventually became a real thing, or

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<v Speaker 1>rather we applied that name to a living creature. Yeah,

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<v Speaker 1>it's a little tensicle microscopic animal. Yeah, I remember looking

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<v Speaker 1>at him in science class. This was discovered by Abraham

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<v Speaker 1>trimbley Um in seventeen forty and he picked the name

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<v Speaker 1>for it because every time one of the heads is

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<v Speaker 1>cut off, you can grow a new one, and as

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<v Speaker 1>it turns out, the human liver can also regenerate itself.

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<v Speaker 1>But that was an old Abraham different Abraham was main

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<v Speaker 1>really interested in the hydas. Then seventeen twelve you had

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<v Speaker 1>another guy that was really interested in this. So with

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<v Speaker 1>the last name renew and I can't say the rest

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<v Speaker 1>of it. You're gonna have to jump in with your French. Yeah,

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<v Speaker 1>I believe his name is a renee Antoine Fair. So

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<v Speaker 1>he made the first scientific observations of regeneration in crayfish,

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<v Speaker 1>which I was kind of surprised to hear that they

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<v Speaker 1>could regenerate because my wife's um of Cajun descent, so

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<v Speaker 1>I've never seen a crayfish have really a good chance

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<v Speaker 1>at surviving anything, just right in the pot. Yeah, So

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<v Speaker 1>back then a regeneration actually caught on with the public,

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<v Speaker 1>and according to Bruce Carlson, who published a textbook on

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<v Speaker 1>regenerative biology, the public just you know, went wild for

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<v Speaker 1>this concept. And so all of a sudden you have

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<v Speaker 1>members of the French nobility wandering out into their gardens

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<v Speaker 1>and chopping the heads off snails just to see the

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<v Speaker 1>poor snails grow new one. And I'm glad that's where

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<v Speaker 1>that story went, because when you first told me about it,

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<v Speaker 1>I had this vision of, um, you know, a French

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<v Speaker 1>noble has been getting all excited about regeneration, just hacking

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<v Speaker 1>off loombs, willy nilly, you know. Yeah, the French evidently

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<v Speaker 1>have a propensity for hacking off stuff, the poor snails.

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<v Speaker 1>So there are other examples of limb regeneration among animals. There's,

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<v Speaker 1>of course, the aforementioned hydra, which is that you know,

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<v Speaker 1>small to of their freshwater polyp, and the crayfish, which

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<v Speaker 1>we just talked about. There's the starfish. Do you remember

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<v Speaker 1>that scene in life that we just read about, Yeah,

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<v Speaker 1>where the crab snatches one of the limbs away. Yeah,

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<v Speaker 1>the starfish is just sitting there and minding its own

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<v Speaker 1>business and along comes this kid king crab. Don't don't,

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<v Speaker 1>don't do, and he just wrenches off the appendage. Well

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<v Speaker 1>you should. I mean, he's got he's got plenty to spare,

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<v Speaker 1>so I might as well grab one. Yeah, especially since

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<v Speaker 1>the starfish can can regrow them. Yeah, and this is um,

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<v Speaker 1>you can. You can kind of hack a starfish to

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<v Speaker 1>pieces as I recall, and each one will become a

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<v Speaker 1>new starfish pretty much. Did you do this in science class? Um? No,

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<v Speaker 1>but I remember hearing about it. We didn't have access

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<v Speaker 1>to starfish. But it's just like the SORCER's a press,

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<v Speaker 1>you know, SORCER's apprentice. Tell me Walt Disney Fantasia, Mickey

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<v Speaker 1>Mouse in a wizard costume. Mickey Mouse is practicing your generation. No,

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<v Speaker 1>he's practicing sorcery. But he has a there's like a

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<v Speaker 1>broom that gets chopped to pieces. Then all the little

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<v Speaker 1>they've turned all these little brooms and start marching everywhere. Yeah, yeah, yeah,

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<v Speaker 1>I do you remember that? Now? That's magical regeneration. That's

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<v Speaker 1>a whole different can of worms. Speaking of worms, yeah,

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<v Speaker 1>the ability to regenerate, that's a that's a good example.

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<v Speaker 1>And so regeneration is common among invertebrates, or at least

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<v Speaker 1>more common than it is among vertebrates like us, like

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<v Speaker 1>as humans, but a mind. Vertebrates. Salamanders are the kings

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<v Speaker 1>of regeneration. Yeah, they can like regenerate things like their

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<v Speaker 1>retina's right, I mean, it's just yeah, they can regenerate

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<v Speaker 1>a ton of stuff like their limbs and their tail,

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<v Speaker 1>their jaws there, and then yeah, eye tissues that you're saying,

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<v Speaker 1>that's one they had to move underground because the French

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<v Speaker 1>people were just trying to chop them up like crazy. Yeah,

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<v Speaker 1>they can even regenerate parts of the heart. And then

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<v Speaker 1>frogs they can they can survive from a broken heart then, right,

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<v Speaker 1>I guess I guess right, Yeah, his heart and he's

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<v Speaker 1>back out on the scene the next night. I'm sorry,

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<v Speaker 1>I'm getting a stuft topic, but anyway, you're to other animals, um.

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<v Speaker 1>And then, according to Scientific American, the embryos of some

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<v Speaker 1>mammals may be able to replace developing limb buds. But

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<v Speaker 1>this happens way, way, way way before the mammals are born,

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<v Speaker 1>right and then after they're born. That's so we humans

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<v Speaker 1>are capable of regeneration to just not necessarily limb regeneration.

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<v Speaker 1>But if you think about it, we're i mean human

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<v Speaker 1>limbs aren't really all that different from a salamanders, according

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<v Speaker 1>to the Scientific American story that I read. I mean,

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<v Speaker 1>they both have bones and muscles and tendons and nerves

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<v Speaker 1>and blood vessels and all this kind of things that

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<v Speaker 1>make a limb necessary. Um, mine are pretty pasty and

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<v Speaker 1>are a little freckled. Yeah, but if a salamander were

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<v Speaker 1>to lose a limb, it can regrow over and over

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<v Speaker 1>and over again. In fact, they think that this process

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<v Speaker 1>of regrowth can happen indefinitely, which is kind of crazy.

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<v Speaker 1>Whereas we just form a scar and that's the end

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<v Speaker 1>of the process by a peg lag and we're good

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<v Speaker 1>to go. So, yeah, what are the types of regeneration? Yeah,

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<v Speaker 1>as exciting as getting a whole new limb is as

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<v Speaker 1>exciting as getting a whole new limb, Maybe regeneration and

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<v Speaker 1>compasses is a lot more. In fact, you're probably doing

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<v Speaker 1>um little or a lot of regeneration right now while

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<v Speaker 1>you're listening to this. And I don't just mean the

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<v Speaker 1>salamanders out there. Um. So, here are a few different

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<v Speaker 1>ways that regeneration occurs in animals. Um, do you want

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<v Speaker 1>to take the first time? Yeah? Okay, So, according to Carlson. Um,

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<v Speaker 1>there's physiological regeneration, and that's just you know, think of

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<v Speaker 1>it as your body replacing worn out body parts. Yeah,

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<v Speaker 1>wearing out and building itself back up again. Yeah. It

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<v Speaker 1>can be as simple as replacing blood. You know, so

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<v Speaker 1>you just give blood, you know, you have to replace

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<v Speaker 1>the blood, right. Yeah. It's like they're you know, people

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<v Speaker 1>often you know, point that it's like you're not even

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<v Speaker 1>like the same person after a certain amount of time,

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<v Speaker 1>you know, because you've replaced so many different cells. Al Right,

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<v Speaker 1>I remember you talking about this. This is fascinating and uh,

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<v Speaker 1>and some people even take the extra mile and like

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<v Speaker 1>sort of talk about the how the mind changes and

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<v Speaker 1>about how you're not even the same you're not the

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<v Speaker 1>same person physically anymore after a certain amount of time,

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<v Speaker 1>and you're not the same person, uh you know mentally, uh,

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<v Speaker 1>constantly changing, constantly regenerating. Right, So the regeneration kind of

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<v Speaker 1>leading to this whole new composition of the body, and

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<v Speaker 1>that's the whole new person. Yeah. Yeah, that's really interesting.

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<v Speaker 1>Like I like to point out to you sort of

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<v Speaker 1>in a way, you're sort of building that new body

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<v Speaker 1>out of the things you buy the grocery store. So

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<v Speaker 1>which is my whole argument for why would you buy

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<v Speaker 1>a whole bunch of crappy food? You know, why don't

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<v Speaker 1>you buy a whole bunch of you know whatever kind

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<v Speaker 1>of crappy food is not in some way you know,

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<v Speaker 1>right right right? Well food food arguments aside. Um regeneration

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<v Speaker 1>also happens, you know, just on a very basic level

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<v Speaker 1>with your skin cells. You know, think about it. You're

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<v Speaker 1>constantly shedding skin cells. Did you forgear that fact about?

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<v Speaker 1>You know, if you have a mattress for a couple

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<v Speaker 1>of years, what percentage of that mattress is basically just

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<v Speaker 1>your dead skin cells filling it up? Yeah, well there's

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<v Speaker 1>a crazy fact out there, but I can't remember exactly

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<v Speaker 1>what percentages, Like your mattress just becomes your skin cells

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<v Speaker 1>or you might you need to check when you buy

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<v Speaker 1>a mattress because it's not composed only of skin cells.

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<v Speaker 1>Before we're not the ladder um. There's another form of

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<v Speaker 1>regeneration called hypertrophy, and this one is when an oregan

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<v Speaker 1>gets bigger to compensate for um. So you lost a

0:10:09.320 --> 0:10:12.200
<v Speaker 1>kidney or donated to kidney, so then you just have

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<v Speaker 1>one and it's got a whole lot more work to

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<v Speaker 1>do so it gets bigger. UM. They've also documented this

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<v Speaker 1>taking place with the lungs. UM livers. Pancreas can also

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<v Speaker 1>experience some regeneration if they're damaged. This reminds me a

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<v Speaker 1>little bit of that phenomena they've talked about in UM.

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<v Speaker 1>People who lose the sense, you know, visually impaired people,

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<v Speaker 1>and you know the other senses compensating for that. I

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<v Speaker 1>wonder like you you go blind, you're hearing gets better. UM,

0:10:37.880 --> 0:10:42.000
<v Speaker 1>you go deaf, you're smelling gets better. So the final

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<v Speaker 1>kind of regeneration is called reparative regeneration. And you might

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<v Speaker 1>find this happening and your muscle, bone, and your skin,

0:10:47.080 --> 0:10:51.120
<v Speaker 1>your heart, tissues, anything along those lines. And this is

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<v Speaker 1>also where that handy ability to form new limbs would fall.

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<v Speaker 1>And Um, this happens with courtesy of a blastema. And

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<v Speaker 1>the blastema is just a grouping of undifferentiated cells that

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<v Speaker 1>are capable of growth and later differentiation. And so by

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<v Speaker 1>differentiation we just mean you know it's going to go on.

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<v Speaker 1>It starts off life, maybe without a purpose, it's a

0:11:10.040 --> 0:11:11.840
<v Speaker 1>blank slate, and then it goes on to become a

0:11:11.840 --> 0:11:15.600
<v Speaker 1>heart cell. Say that's all we mean by differentiation. Well,

0:11:15.679 --> 0:11:19.720
<v Speaker 1>let's bring it all back to jellyfish. What about Tatopsis ah.

0:11:19.760 --> 0:11:23.520
<v Speaker 1>Tatopsis s. Neutricula is a particular species of jellyfish that

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<v Speaker 1>maybe the only animal in the world that's a maybe

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<v Speaker 1>has something in common with vampires, and that is it's

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<v Speaker 1>a it may live forever and how many do that? Well,

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<v Speaker 1>it's capable of cycling, uh, from an adult to to

0:11:35.760 --> 0:11:40.719
<v Speaker 1>an immature stage, the polyp stage, like a frog being

0:11:40.720 --> 0:11:43.880
<v Speaker 1>able to rewind to tadpole form and then advance into

0:11:43.920 --> 0:11:47.080
<v Speaker 1>frog again then rewinded the tadpole form, that kind of thing. Yeah,

0:11:47.120 --> 0:11:49.079
<v Speaker 1>So as you can imagine, if you have this kind

0:11:49.080 --> 0:11:51.800
<v Speaker 1>of ability, your numbers, your population numbers of this particular

0:11:51.840 --> 0:11:54.480
<v Speaker 1>species would probably spike, as they are. In fact with

0:11:54.720 --> 0:11:59.000
<v Speaker 1>Totopsis neutricula they were found originally in the Caribbean, I believe,

0:11:59.040 --> 0:12:01.160
<v Speaker 1>but now they've spread to waters all over the world.

0:12:01.920 --> 0:12:05.040
<v Speaker 1>And so the key in this process that allows um

0:12:05.080 --> 0:12:07.520
<v Speaker 1>a mature adult to cycle back into this immature poly

0:12:07.600 --> 0:12:11.439
<v Speaker 1>up stage lies in a cellular process called trends differentiation,

0:12:11.640 --> 0:12:14.640
<v Speaker 1>which we've just kind of touched on a little bit. So, yeah,

0:12:14.640 --> 0:12:19.280
<v Speaker 1>differentiation is the process by which an unspecified imbryonic cell

0:12:19.360 --> 0:12:22.680
<v Speaker 1>acquires the features of a specialized cell, such as a

0:12:22.720 --> 0:12:25.400
<v Speaker 1>hard liver or muscle cell, all right, and it's controlled

0:12:25.400 --> 0:12:28.480
<v Speaker 1>by an interaction of the cells genes with physical or

0:12:28.520 --> 0:12:35.960
<v Speaker 1>chemical properties. Trans Differentiation is a little different in this

0:12:36.080 --> 0:12:40.400
<v Speaker 1>adult stem cells can differentiate into cell types of scene

0:12:40.400 --> 0:12:42.720
<v Speaker 1>and organs or tissues other than those expected from the

0:12:42.760 --> 0:12:48.480
<v Speaker 1>cells predicted lineage. So like brains, like brain stem cells

0:12:48.880 --> 0:12:54.280
<v Speaker 1>might differentiate into blood cells or blood forming cells, um

0:12:54.679 --> 0:12:57.080
<v Speaker 1>into brain cells, et cetera. Yeah, I mean it's kind

0:12:57.120 --> 0:12:59.839
<v Speaker 1>of amazing. Jellyfish typically die after the propagate, but this

0:13:00.000 --> 0:13:03.040
<v Speaker 1>particular jellyfish can just i mean, keep on reproducing and

0:13:03.080 --> 0:13:05.679
<v Speaker 1>you know, carrying on its life forever. I mean, as

0:13:05.679 --> 0:13:09.679
<v Speaker 1>a mom, I find that prospect a little horrifying, the

0:13:09.720 --> 0:13:11.920
<v Speaker 1>fact that, you know, perhaps you might have to go

0:13:12.000 --> 0:13:15.240
<v Speaker 1>through childbirth numerous times. Not the jellyfish in fact go

0:13:15.280 --> 0:13:18.280
<v Speaker 1>through childbirth, but just comparing it to my own human

0:13:18.320 --> 0:13:22.040
<v Speaker 1>perspective on the reproduction cycle, Yeah, it's kind of like

0:13:23.080 --> 0:13:26.959
<v Speaker 1>it's almost like they're going through just repetitive midlife crisis.

0:13:27.240 --> 0:13:29.200
<v Speaker 1>You know. It's like, oh, I'm getting old, I'm gonna

0:13:29.520 --> 0:13:31.960
<v Speaker 1>act like a young jellyfish again. But they actually become

0:13:31.960 --> 0:13:34.480
<v Speaker 1>a young jellyfish. But the interesting thing is they have

0:13:34.480 --> 0:13:36.320
<v Speaker 1>no idea what how this happens. They don't know the

0:13:36.320 --> 0:13:39.040
<v Speaker 1>mechanism behind the life cycle. They know that cells are

0:13:39.360 --> 0:13:41.760
<v Speaker 1>able to turn from one type into another, from general

0:13:41.760 --> 0:13:44.439
<v Speaker 1>to specific, from specific to general, and keep going back

0:13:44.440 --> 0:13:46.600
<v Speaker 1>and forth, but if they don't know why, and it's

0:13:46.640 --> 0:13:49.360
<v Speaker 1>not very I mean, ultimately, it's not like a sustainable thing.

0:13:49.720 --> 0:13:52.720
<v Speaker 1>Like you mentioned the vampires um our own. Josh Clark

0:13:52.920 --> 0:13:55.800
<v Speaker 1>did a blog post a while back where some scientists

0:13:55.840 --> 0:13:57.560
<v Speaker 1>like sit down and look at the whole vampire thing,

0:13:57.559 --> 0:14:00.480
<v Speaker 1>and they're like, look, it could never happen because obviously

0:14:00.520 --> 0:14:03.040
<v Speaker 1>you'd end up with more vamps, so many more vampires

0:14:03.040 --> 0:14:05.360
<v Speaker 1>than humans. It wouldn't be any humans to feed on,

0:14:05.440 --> 0:14:08.959
<v Speaker 1>and you just have vampires and they'd starve or whatever. Right,

0:14:08.960 --> 0:14:13.480
<v Speaker 1>It's not so immortality is just not sustainable. Sustainable. Yeah, So, I,

0:14:13.600 --> 0:14:16.479
<v Speaker 1>for one, I'm very interested in regeneration and its prospects

0:14:16.480 --> 0:14:18.800
<v Speaker 1>for medicine and stem cells in the lake in the future.

0:14:18.840 --> 0:14:20.480
<v Speaker 1>So I would love to do a follow up podcast

0:14:20.480 --> 0:14:22.200
<v Speaker 1>on this. Let us know if you guys are interested

0:14:22.520 --> 0:14:25.840
<v Speaker 1>um in a in a podcast also on regeneration in

0:14:25.880 --> 0:14:28.240
<v Speaker 1>the meantime, come check out our blogs, where we'll keep

0:14:28.280 --> 0:14:31.320
<v Speaker 1>you up to date on whatever we're podcasting about for

0:14:31.320 --> 0:14:34.520
<v Speaker 1>the week and uh any other interesting scientific tidbits that

0:14:34.600 --> 0:14:37.760
<v Speaker 1>cross our desk. And if you guys have a question

0:14:37.840 --> 0:14:42.440
<v Speaker 1>about immortality, vampires, jellyfish, or regeneration in fact, send us

0:14:42.440 --> 0:14:44.440
<v Speaker 1>an email at science stuff at how stuff works dot

0:14:44.520 --> 0:14:54.400
<v Speaker 1>com for more on this and thousands of other topics

0:14:54.440 --> 0:14:57.480
<v Speaker 1>because at how stuff works dot com. Want more how

0:14:57.560 --> 0:15:00.400
<v Speaker 1>stuff works, check out our blogs on the how soworth

0:15:00.480 --> 0:15:01.440
<v Speaker 1>dot com home page.