Hi guys, Joe here.
One of the most amazing things in nature is the… ahh...
Is that safe?
One of our lights is… it’s okay?
Okay!
Where was I?
One of the most amazing things in nature is the -
[OPEN]
Crap.
That was definitely one of my two favorite arms, and now I’ve just got… one left.
And if there’s one rule about losing an arm, it’s that they don’t grow back.
Unless you’re this guy.
I don’t mean Deadpool.
Well, I do.
But … I really mean...
…this guy.
The axolotl.
You guys remember Amber from our tuatara video?
Amber: Hi guys!
She also helps take care of axolotls!
Axolotls are salamanders, a type of amphibian.
Joe: It kind of looks like it’s smiling… it’s really cute.
They have happy little dopey faces.
Hi!
It’s nice to meet you.
Like other amphibians, salamanders spend their first days in the water, breathing with gills
and swimming with tails.
Most amphibians lose these traits when they become adults, when they leave the water and
start breathing– with lungs or through their skin.
But axolotls spend their whole lives in the water, so they never lose juvenile traits
like those big gills.
That’s right they’re…
Prepare to have your mind blown.
And then regenerated.
Because axoltols can do that.
Amber: But by far the coolest thing about them is that they have the ability to regenerate
lost limbs.
In the 1700s, an Italian priest started cutting body parts off animals… kind of a weird
hobby.
He noticed starfish, flatworms… these could all regrow their arms and bodies.
Cool, but they’re pretty simple invertebrates, no bones or anything like that.
When he sliced off a salamander’s arm, though, he saw something shocking: It regrew the entire
arm, bones and muscles and nerves and blood vessels and everything.
Deadpool-style.
Joe: So, cut off arms, legs, eyes, mouth, tail – anything and they regrow it?
Amber: Yeah!
Perfect copies.
Joe: That is so wild.
Amber: The juvies and babies are super cannibalistic, and so if they’re eating each other’s
limbs, toes – the ability to regrow them would be really helpful.
An axolotl can even regenerate half its own heart or part of its brain!
That is crazy.
In what is now Mexico, axolotls were known to the Aztecs for centuries…
Aztecs even occasionally ate them.
Amber: They’re native to an underground lake: the name’s a little interesting…
Joe: We’re not even going to try to pronounce it.
Amber: No!
It’s Xochimilco.
Joe: Xochimilco?
We’ll also put it right here, so we can…
Xochimilco.
Because of the growth of Mexico City, you’ll probably never see an axolotl outside of a
glass tank today.
They’re almost extinct in the wild.
But biologists are studying the animals in captivity to see if their powers of regeneration
might one day help humans regrow lost body parts.
If I cut off my arm for real, it won’t grow back...and I might bleed to death or get a
bad infection.
But an axolotl can regenerate without these problems.
We don’t have a complete understanding of how it happens, but here’s basically what
goes down:
Right after an amputation, a signal is sent to cells all over an axolotl’s body telling
them to start dividing.
Next, skin cells create a living bandaid over the wound.
Now, this is *really* important for everything that comes next.
The animal can’t regenerate without it.
After about a week, this bump called a blastema, pops up.
Everything that will become the new limb grows from that little nub.
New cartilage starts to form, notches show up where the digits–fingers or toes–will
go.
And six to ten weeks later the salamander has a complete limb where there was once a
stump.
Take a second and think about how cool that is.
We’re talking blood vessels, nerves, muscles - everything re-connected *seamlessly*
Joe: You are a magical creature.
So, obviously yeah, if people lose their limbs it would be cool if we could regenerate
them – Deadpool style – but we can’t do that.
Amber: We can’t do that.
Joe: But by studying these and how they do it, we might be able to stimulate that in
humans?
Amber: Yeah maybe we can eventually learn to do that!
Scientists think this is within reach.
Don’t try this at home, but there have been cases where young children re-grew a fingertip
after an injury.
And some of our organs, like our skin, already regenerate constantly.
The secrets to axolotl-like healing might already be hidden in our own bodies… we
just have to find them.
Think about it: Before you were born, you grew a little bud, that formed a paddle, which
eventually became an arm.
The instructions to do all that are still in your DNA when you’re an adult, we just
have to figure out how to turn those growth switches back on.
CU Of course, it’s not easy.
There’s no gene that says “arm”, “finger”, or “hand” and in your DNA you won’t
find literal blueprints for growing a limb.
It’s one of the most incredibly complex processes evolution has ever crafted, There’s
dozens of genes involved in building a limb, and they don’t work like instructions for
say, building furniture.
The genes work more like sheet music for an orchestra.
Different instruments play notes at different times, sometimes together, sometimes on their
own.
It’s the timing and where things are played that creates the symphony, not just the sheet
music itself.
Growing a limb works in a similar way.
Dozens of genes, interacting with others, each playing tiny parts in a special order
creates the whole.
The secret to remaking an arm or a leg seems to be turning back the genetic clock to the
very youngest days of an animal’s development, pausing the adult arm programming and growing
the limb like it was the first time.
And because the axolotls are “forever young” they may have a ‘leg up’.
Even if we never get to the point of regrowing complete limbs, the lessons we learn studying
axolotls could help us regrow specific tissues like muscle, which is pretty awesome on its
own.
I’d like to give you a hand.
Joe: I want to say a huge thank you to my new friend, this axolotl right here.
And to amber for giving us all of the axolotl facts.
Amber: Yeah man, you sure do axolotl questions…
Joe: well, thanksalotl for answering them.
Alright, stay curious.