Can tardigrades survive on the Moon?

Daniel and Kelly talk about the extraordinary ability to tardigrades to survive extreme conditions, and ponder whether those abilities have kept them alive after a space craft carrying them crashed into the surface of the Moon. 

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Episode Transcript

Speaker 1 (00:06):
Watermands, lost piglets, tartar grades. They go by many names,
but I think the one thing we can all agree
on is that they're pretty much indestructible, right. I mean,
these poor teeny tiny creatures have been exposed to all
manner of unpleasant stimuli in the lab. They've been frozen
to near absolute zero, heat it up to way past boiling, irradiated,

(00:30):
squeezed at pressures you'd experience one hundred and eighty kilometers
below earths surface, exposed to the vacuum of space, and
shot into sand bands. If tartar grades ever become large
and sentient and start looking for retribution, we are in
a lot of trouble. But the good news for tartar
grades is that they survive most of these experiences surprisingly well.

(00:51):
How do they do it well? That's what we're going
to discuss today, and by the end of the episode
we'll answer a question that has no doubt kept you
up at night. Are those tartar grades that crash landed
on the Moon in twenty nineteen still alive? Let's find out.
Welcome to Daniel and Kelly's Extraordinary Universe.

Speaker 2 (01:22):
Hi, I'm Daniel, I'm a particle physicist, and I don't
like a lot of biology, but I do like hearing
about critters that only poop when they molt.

Speaker 1 (01:30):
Wait wait, wait, we'll back up that. I'm Kelly Wiersmith,
a biologist. Did you just say that you don't like
a lot of biology?

Speaker 2 (01:38):
You know, there's a reason I'm in physics. The biology
is all weird and messy. I mean, it's wonderful and fascinating,
but sometimes I just feel like there aren't really any
hard answers.

Speaker 1 (01:47):
Well, well, you guys haven't reconciled quantum mechanics or general
relativity yet, how dare you?

Speaker 2 (01:55):
But there is a hard answer. We don't have it yet,
but I think one day eventually humans or some clever
aliens will figure it out. Biology, I just don't even
know if there's an answer.

Speaker 1 (02:06):
I mean, I can't argue with that. I'm not sure
there's an answer for a lot of this stuff either,
But I still think that's exciting. And also, I will
note that you said that they only poop when they mold.
There are probably more than thirteen hundred species of tartar grades.
I don't know that it's true that all of them
only poop when they vote. I think some of them
might just poop like the rest of us.

Speaker 2 (02:28):
All right, well, I'm fascinated. I want to hear more
about it, because I'm sure there's an answer to at
least this question of when do tartar grades poop.

Speaker 1 (02:36):
I mean, it's going to depend on the species. But yes,
all right, so we had an amazing listener question. Let's
go ahead and listen to that.

Speaker 3 (02:44):
Now, Hey, Daniel and Kelly, question about tartar grades. Those
little water bears. Just curious what is it about them
that allows them to survive in basically any environment. I've
heard that there's even some on the Moon. As far
as I know, NASA has an engineered little spacesuits that small.
So yeah, just curious what is it about their physiology

(03:07):
that allows them to survive?

Speaker 2 (03:08):
Thanks?

Speaker 3 (03:10):
Also, go Virginia.

Speaker 1 (03:11):
Okay, so first off, I laughed out loud imagining NASA
engineering tiny spacesuits for the tartar grades. That was amazing.
Thank you for this question, and go Virginia. Woooo.

Speaker 2 (03:23):
I'm sorry this question is disqualified. I mean, obviously they
have no credibility from the.

Speaker 1 (03:27):
Get go, Daniel, I did ten hours of research for
this episode. We are not dropping this episode.

Speaker 2 (03:32):
And did you discover that you have to be a
tartar grade to enjoy the climate of Virginia.

Speaker 1 (03:36):
Everybody enjoys the climate of Virginia. Tim and I agree
on that. At least. There was a little bit of
snow falling the other day and I felt highly festive.
And I know that there are some places of California
that have snow, but only some.

Speaker 2 (03:51):
Well, you know, tartar grades can live on the Moon,
they can live deep underwater, they can survive when it's dry,
they can even survive Virginia winter.

Speaker 1 (03:58):
Well, hold on, can they live on the moon?

Speaker 2 (04:01):
I don't know.

Speaker 1 (04:02):
That's the whole point of this episode, trying to find
the answer to that question. So should we dig in, Yes.

Speaker 2 (04:07):
Kelly, tell us what are these tartar grades, what do
they look like, where do they stand in the context
of all biology, and what do we know about where
they can actually survive?

Speaker 1 (04:16):
Okay, all right, well, so it'll take me an hour
or so to give you that answer. But let's start
with reiterating that there are probably more than thirteen hundred species.
In fact, it's under Kingdom Animalia. There's something like thirty
phylum and tartar grade they're their own phylum whoam and
so there's a lot of them, right, But usually you're like,
tartar grades do blah blah blah, as though there's just

(04:37):
one species, but there's a lot more than just one species.

Speaker 2 (04:41):
And the fact that they're so high up in this
tree of life. I mean, it's not just like bile'll
just like to organize things because they don't really understand them.
It tells us something about.

Speaker 1 (04:50):
Like wait, wait, wait, let's listen to the particles episode
and you're like, I don't know how we categorize these things,
so anyway, little hypocritical.

Speaker 2 (04:57):
But no, seriously, I think when particle physics is feeling
is when it's just doing taxonomy. If we're just doing botany,
then we don't really understand anything. It's when we're doing philosophy,
when we're linking things together, we understand how they work underneath.
That's when I think we're really making progress. But what
I want to ask you.

Speaker 1 (05:15):
I think we need both. We'll move on.

Speaker 2 (05:16):
But what I want to ask you is how we
should interpret where people have put tartar grades in this
tree of life. The fact that they're so high up,
does that mean that they're really their own kind of thing.
They're so different from everything else, or they have their
own weird history or both.

Speaker 1 (05:30):
Let's go with both, and let's talk about why they're
so unique awesome. All right, So, first of all, these
are tiny little guys. They're multi cellular. They got lots
of cells. Big ones are about a millimeter long, so
about the size of a period. They have this hard
outer cuticle, and because it's hard, that doesn't grow with them,
so they have to molt the way like nematodes, and

(05:50):
some insects will mold the way snakes shed. Because snakes
are awesome. What's get snakes in there? You probably don't
even like snakes, do you, Daniel?

Speaker 2 (05:58):
You probably don't like like that's an outrageous thing, like,
oh yeah, snakes, rats and cockroaches. You don't like any
of that, doa Daniel?

Speaker 1 (06:07):
Do you not like those things? Daniel?

Speaker 2 (06:08):
Well, I mean I wouldn't want to like snuggle up
with them. You know. It's not like if I see
a bunch of the my bed, I go ooh cozy.
You know. They're not in the same category as like
kittens and bunnies for sure.

Speaker 1 (06:19):
All Right, all right, I won't disagree with that, but
I have seen some snugly rats. But anyway, okay, heart
outer cuticles. Sometimes when they lose that cuticle, that is
when they release the contents of their bowels that they've
been holding onto for a while. That's also sometimes they'll
release their eggs into that cuticle when they mold, and
then the eggs sort of have this like protective little
case that they're in for a while, and then when
they hatch, they have to find like the holes in

(06:39):
the cuticle to get back out.

Speaker 2 (06:41):
All right, So these things are really small. You're saying
a millimeter is the biggest one. Can I see something
with my naked eye that's just a millimeter? So like
tartar greates, you could actually, like if you squint see
one of these things.

Speaker 1 (06:51):
So it's about the size of like a period on
a printed out sheet of paper, and so like you know,
maybe you could see some like flailing limbs, but like
if you had a dissecting scope you could see them better.
But again, a millimeter is about the size of like
some of the bigger ones, and so a lot of
them are even smaller, and so you'd be better off
with like a compound microscope.

Speaker 2 (07:11):
And does everything that has this hard out or shell
have to molt when it grows? Or are there some
critters out there that can like gradually expand, Because like
our skeleton gradually expands as we grow, why can't you
gradually expand your exoskeleton as you grow? Or is that
a totally naive biology question.

Speaker 1 (07:28):
Our skeletons are inside of us, and so they can
like expand as our squishy outer parts sort of like
accommodying that. But I think that if you have a
particular kind of cuticle that's like super hard that doesn't
tend to grow and expand, I think you do usually
need to lose those all right?

Speaker 2 (07:44):
And so do all of these things look roughly the
same even though some of them are a little bigger
and some of them are smaller. Do they all roughly
look like the same critter? Like an individual non trained
biologist tell them apart by eye?

Speaker 1 (07:55):
They do have some definite characteristics that help you tell
them apart. So my question for you is, I think
when most people think of tartar grades, there is an
animated video that they saw. Is something coming to mind
for you? Or have you not seen this video?

Speaker 2 (08:08):
No? I definitely have a mental image of a tartar grade.
I think the phrase water bear has also influenced me.
So I'm imagining something that looks a little like a
fat caterpillar, but with sort of claws and then a
weird face with like a tube sticking out the front
of it. So it's a little like a possum or something.
I'm not sure exactly animal. It looks like maybe like

(08:28):
a microscopic water possum.

Speaker 1 (08:30):
Oh, I love possums. Okay, So there's this like famous
video where they're pink and they've got that like almost
a toilet paper roll on top of their face, and
it kind of like goes into the face and out
of the face over and over again as the tartar
grades eight little legs furiously have it swimmed through this water.
So I was listening to ologies and Allie Ward was

(08:50):
interviewing doctor Paul Bartel's and he was lamenting that that
is like not what they look like at all, what.

Speaker 2 (08:57):
Popular science has led us astray.

Speaker 1 (08:58):
Kelly, really, hold on, I know, I know, it's amazing. Okay,
So first of all, that toilet paper roll, nos thing
does not go out and in and out and in
and out and in That was a mistake because someone
took a special kind of microscopic picture. They used a
scanning electron microscope, and the way the sample was prepared,
one of the tartar grades had that thing sticking out

(09:20):
like it usually does, and one of them, because of
how it was prepared, it just kind of got like
sucked into the face. But I don't think that usually happens,
and so the nose thing isn't going in and out
and in and out and in and out. I think someone
just saw both of those photos and were like, oh,
it must alternate between these two states as opposed to
like the preparation process just kind of messes up specimens sometimes.

Speaker 2 (09:40):
Wow, it's like they saw two frames and just animated
the interstitial. That's crazy.

Speaker 1 (09:45):
And then the other thing is they don't swim. They
are what's called benthic, so they walk around on like
the floor of things, or like they crawl up vegetation,
but they're not swimming. They're crawling along. And that video
that most of us are, you know perhaps right now.
It has eight legs that are all like in front
of it. It's like a bear, but all of its
legs have been multiplied by two but what really happens

(10:08):
is it has six legs and like the usual configuration,
and then another two that go like straight out from.

Speaker 2 (10:13):
Its butt butt legs.

Speaker 1 (10:15):
Butt legs, Yeah, how can we get So those butt
legs hold on to stuff so that they like don't
get washed away with the current or something. And some
have claws and some don't have claws, and they're not
usually pink. A lot of them are clear or white,
or if they've got color, a lot of times it's
because they are clear, but you can see like the
algae they ate, so they look green, or you can

(10:37):
see their poop so they look brown. And so some
of them do have some colors, but they're not even
though they're moss piglets, they're not pink. Hmm.

Speaker 2 (10:45):
I see so clear, like they're invisible, like you can
see through them. They're like transparent.

Speaker 1 (10:50):
If they are starved, some of them probably are transparent.
But if they've eaten anything, you can see their digestive
tract because they've got like green in it.

Speaker 2 (11:00):
Wow, that's crazy. So like little tartar gray children when
they've been sneaking cookies from the cookie jar, it's not
a question the parents are like I see.

Speaker 1 (11:07):
That cookie exactly. Yes.

Speaker 2 (11:09):
Wow, what's the evolutionary advantage to being transparent? Is it
like a form of camouflage or is it just totally incidental?

Speaker 1 (11:16):
Everyone don't know. My first guess would be that it
does help with camouflage if like a predator just kind
of sees through you. But then the other thing is that,
like creating pigmentation, is often a process that requires some energy,
and so maybe being clear is just easier than creating pigmentation.
But if you're in an aquatic environment, probably being clear
is a good way to hide and blend into stuff.

Speaker 2 (11:36):
Wow. All right, so we have totally the wrong mental
image of a tartar grade, but it is still kind
of cute. Yeah, and it does have those fat little
legs and a toilet paper snout. But we're setting the
record straight here today.

Speaker 1 (11:48):
Well, they don't all have the toilet paper snout. Again.
There's over thirteen hundred species. Some of them look like
you little salamanders, but instead of a tail, they've got like,
you know, the two butt legs. There's some variability in
how they look, but they do have that. Like general,
there's also tons of variability and where you find them.
Some are in lakes, some are in oceans, and some
are living in like when there's a little bit of

(12:08):
water on lichens or moss, they live in that like
little water film. And there's some that you find in
like roof gutters. They're essentially anywhere where there is enough
water to keep them from like desiccating, or are there
in environments that dry out sometimes and then water comes back,
and this is what they're so well known for. They
have a bunch of different strategies for surviving that dry

(12:29):
out period.

Speaker 2 (12:30):
If you find them in large bodies of water. How
come you never find like mega tartar grades, you know,
like there are sharks and then there used to be
like huge sharks. Was there ever a tartar grade that
was like a meter long or like a one hundred
meter long or is that the next Michael Bay movie
we're looking forward to.

Speaker 1 (12:47):
There have been I believe a couple fossil tartar grades
that have been found, and I don't think we've ever
found a mega big one. So yeah, pass that idea
onto Michael Bay. I think it's a winner because there
are some that are carnivores and include there are some
that will eat other TURTI grades, So I think that
would make a great movie.

Speaker 2 (13:04):
Exactly. You thought they were cute and fuzzy until you
saw the big one come for you. Okay, but what
limits them from growing? Like why aren't there bigger ones?
Is there something about their geometry which doesn't scale up?
Or is an ecological thing like they can't eat enough
food to get that big? Or is there something which
will eat them if they get too big? Or do

(13:26):
we not know?

Speaker 1 (13:26):
I don't think we know. Amazing, amazing that we don't know.

Speaker 2 (13:30):
Amazing how many things biologists don't understand.

Speaker 1 (13:33):
I feel like that's a theme of the physics talks.
But all right, fair, fair, all right, okay man, it's
a battle between California and Virginia and physics and biology today.
I appreciate when you and I are both anti chemistry
and we're on the same team, but because today we're
doing battle, all right, So let's start with their abilities

(13:53):
to survive desiccation, which means like drying out.

Speaker 2 (13:56):
So this is something you hear about a lot in
popular science. Are you going to ruin this for us also?
Or is this something they really can do?

Speaker 1 (14:02):
They really can, well, not all of them, So again,
many many species the ones that tend to live in
like mosses and lichens and roof gutters, like places that
are wet sometimes but dry other times. They're able to
form this stage known as a ton state, where they
essentially it's like almost go dormant. Some of them describe
it as like it's near death. So they're able to

(14:22):
like go into this like super resistant form. And when
they're in this super resistant form, this is when scientists
have done all manner of horrible things to them, like
dip them in liquid nitrogen, shoot them out of guns
just to see like how much can they handle when
they're in this state.

Speaker 2 (14:36):
So this is what they're famous for. When it's not
like a nice and cozy and damp time to be
a Tarta grade, you like convert into this like weird
long lasting state where you're basically immortal, and then you
can just like unfurl and be a Tarta grade again
later it's like time traveling to the future.

Speaker 1 (14:51):
So immortal, no, when they go into this state, they
can survive for like years, maybe decades. But so one
thing you might have heard is they can stay in
this stage for hun ndreds of years. Actually that seems
to be possibly a misreading of a study. So there
was like a museum specimen where we knew when it
was collected, and one hundred years later it got taken
out of like some drawer and they found some tartar

(15:11):
grades and they added some water, and it looked like
part of an arm kind of moved a little. This
was written in Italians, either Italian or French in some
Romance language, and so it was like an arm moved
a little, but then nothing else.

Speaker 2 (15:25):
Well, you know, in Italian hand gestures are super duper important,
So maybe that was interpreted as communication, you know, that's right.

Speaker 1 (15:32):
It could be. As a biologist, I've had to look
at a lot of specimens where like, oops, the ethanol
dried out, and now this animal's totally dried, and I'm
going to try to like get it back in its
normal shape by adding like water or more ethanol. And
when that happens, they often like move in response to
the rehydrating And it's not that they're alive, that's just

(15:52):
the molecules responding to the presence of water. And if
it did do a like hello, guys, hand gesture, it
died right afterwards. Maybe it's impressive, but probably it's just
an artifact of it, like rehydrating.

Speaker 2 (16:04):
That could you poured water on a dried up belief,
it would change its shape also, and you might interpret
that its motion, but it's definitely not alive.

Speaker 1 (16:10):
Yes, exactly, and so that's a possible scenario. But there
has been a specimen collected from Antarctica where it was
two Tarta grades that had entered this dormant state and
an egg that hadn't hatched yet, and the specimen was
put in cold storage at life think negative twenty for
thirty years and then removed and they came out of
their ton state, became adults. One of them croaked, but

(16:32):
the egg hatched, and then the two individuals who were
still alive went on to like reproduce I think more
than once even, and so they were like definitely alive,
like not maybe waved at you and then croaked, like
they're definitely alive, so decades.

Speaker 2 (16:47):
Now the adult. That's really impressive, right to freeze an
adult and have it then reanimate and survive. That's amazing.
Eggs are a different story, right, because like human eggs,
you can freeze. That's not such a big deal. But
why is that I've never really understood. Like I thought,
if you freeze any cell, the water inside of it
expands and bursts the cell membranes. And that's why it's
like hard to freeze a cow and then like reanimate it.

(17:09):
Why is it possible to do for eggs or sperm
or stuff like that. Why doesn't that same physics supply?

Speaker 1 (17:15):
Yeah, so I am not an expert on cryopreservation, but
I think that it has something to do when you're
freezing human eggs, If you freeze them really fast, the
cells don't lice the same way. This is part of why,
like if you get meat, you don't want to like
slowly freeze it and then defrost and do that over
and over again because the cells lice and the meat
taste less good. I think something about freezing them really quick,

(17:38):
but I don't know why it is that they can
come back after that.

Speaker 2 (17:41):
Yeah, because even human embryos can do that, right, even
fertilized eggs. It's sort of amazing.

Speaker 1 (17:46):
It is. We should have a whole episode on cryopreservation.

Speaker 2 (17:48):
Yes, let's do it right, but it's definitely not something
you can do to like a human adult, right, Yeah,
at least not yet. If people are working on that, right,
preserving the brains of old baseball players for the future.
All Right, so you're telling us that this is real,
that tartar grades really can't go into this crazy state
and then survive insanely long exposure to really difficult conditions

(18:13):
and then be alive again and reproduce and be happy.
What's going on during that state? Like are they alive
or are things paused? Like is there some metabolism happening? Like,
what's going on?

Speaker 1 (18:23):
I'm going to tell you the answer to that, Daniel
after the break. Okay, So you wanted to know what

(18:44):
happens when the tartar grades go into this like semi
dormant state. So first of all, they like kind of
squish up into a ball, and so they like pull
their heads in that they pull their legs in, and
they like expel and they lose almost all their water.
By the end, they have something like two to three
percent of the water they started with. Just to be clear,
that would kill humans. Like we're like, what seventy percent

(19:05):
water or something. If we went down to three percent,
we'd be gonners. We'd be gunners way before then. So
as they lose that water, they start producing something called trehlos,
which is a sugar, and it ends up forming kind
of like a glass like structure that holds everything together
and gives it like structural integrity. And this has long
been the explanation for why tartar grades are able to

(19:28):
survive such incredible conditions, including the explanation you gave five
years ago on Daniel and Jorge Explained the Universe. When
I listened to that episode.

Speaker 2 (19:36):
Oh all right, doing some research.

Speaker 1 (19:38):
Yeah, yeah, well, you know, I needed something to listen
to while I was walking around the other day. But so,
here's the thing though about trehelos. Lots of tartar grade species.
Some of them make trehelos when they go into this
ton state. Some of them make quantities so small that
we're not actually sure that it can do the function
of making this glass structure that protects organism. And some

(20:01):
of them don't appear to even have the equipment at
all to make trehillos, which suggests maybe it's part of
the picture for some species. But that's not like an
across the board answer for how tartar grades are able
to do this, So it's complicated, and they make a
bunch of other proteins So cryptobiosis is a term. It
means hidden life, and so it's another way for describing

(20:22):
this ton state. And I found a line in a
twenty seventeen paper that said, mechanisms that protect tartar grade
cells during cryptobiosis are still poorly understood or completely unknown.

Speaker 2 (20:33):
Ooh, that sounds like a fair description of all biology
and physics.

Speaker 1 (20:37):
And physics and you guys only have like six questions
you need to answer. Get to work on that, guys.

Speaker 2 (20:47):
And that's my favorite thing about the universe, that it's
poorly understood or completely unknown, because otherwise it would be boring, right, I.

Speaker 1 (20:54):
Feel the same way about biology, dude.

Speaker 2 (20:57):
All right, So some of these guys have the these
weird glass like proteins called trehillosies, which maybe provide some
internal scaffolding that like support the cell when it's all
dried out. But some of them don't even have it,
but they can still do this ton state weird survive
for everything.

Speaker 1 (21:14):
Yeah, right, and so we don't really know what's happening there.
We felt like we had a handle on it, and
then we were like, oh, wait, some of these don't
make that at all. So I don't know. Back to
the drawing board.

Speaker 2 (21:22):
Do you think that means that other target grades have
different strategies or that this glass like structure has no
connection to their ability to survive.

Speaker 1 (21:31):
I bet it's both. So it could depend a lot
on the ecology of the animal. So some animals that
are in these environments with no water for longer might
need sort of more extreme solutions to this problem. And
so it could be something about like what kind of
environment you tend to be in, Whereas if, like I
don't know, maybe you're at the edge of a lake

(21:51):
and you know, every once in a while you find
yourself dry for five minutes, you can just kind of
like get through that. And so it might depend on
your ecology how frequently you encounter these weird situation, or
it could be different solutions entirely. I don't think we
know yet, all right, And then I.

Speaker 2 (22:04):
Have a basic biology question, which is, like, in biology,
how do you answer the question this is how they're
doing it, or that's how they're doing it. Do you
have to develop an alternative where you're like knocked out
that capability and show that like, if they don't have
this protein, then they can no longer do this thing.
And that's how we know. Because biology is such a huge,
complicated roup Goldberg machine. How can you point to any
one bit and say this is the essential bit.

Speaker 1 (22:26):
Yeah, so it's super complicated. So sometimes you can say, like,
you know, if trehelos is produced by a gene or something,
you could go in and turn that gene off and
then put the tartar grade through a drying cycle and
see how it does and measure like, Okay, definitely it
didn't make trehelos anymore and it died.

Speaker 2 (22:46):
But even then, maybe trehelos is just a precursor to
something else which is actually doing the crucial function. Right.
I mean, there's just such a complicated series of events.
It seems to me hard to ever point to one
and say this is the explanation. Do you think it's
just that we always want to simple explanation and there
really aren't any, or that sometimes there really are simple
explanations and we can find them.

Speaker 1 (23:06):
There are probably rarely simple explanations, but I think that's
pretty rare. Like when we did the human genome project,
I think we expected we would like immediately understand the
cause of cancer and a bunch of other diseases because
now we have the whole genome and it's going to
be super easy. But no, it depends on like how
the genome is expressed, lots of complicated extra bits, and
you know, like for the Trehelos example, if you knocked

(23:28):
out trechlos and the tartar grades died, maybe it's because
Trehlos does something else earlier, like even when it's not
in desiccation mode and you've killed it in some way
that has nothing to do with desiccation. So ideally you
try to address the question from a bunch of different
angles and see what the picture you put together tells you.
But usually the answer is like it involves five thousand

(23:49):
different genes that are all upregulated and different in and
you know some of them are cell signaling genes. It's
almost never like the answer is X. But you know,
you guys have complicated answers to Sometimes.

Speaker 2 (24:01):
Yeah, we do, absolutely, And sometimes you look at a
big complicated system and there is no simple story that
you can tell or model that you can use to
understand it. But sometimes you can, right like ten to
the twenty nine little molecules can all fly through the
air together following F equals M. It's a very simple
story about a lot of complicated things that are all
happening in concert, and somehow simplicity emerges. So I was

(24:25):
sort of wondering how often that happens in biology, that
you can pull one strand of a story and say
this is the role this is playing, or if it's
always just a huge courus.

Speaker 1 (24:35):
Yeah, no, it never happens that it's one string, Like
I like to joke that an ecology, like, you know,
the only quote unquote theory that we have is it depends.

Speaker 2 (24:47):
See that's my problem with biology exactly.

Speaker 1 (24:50):
But you know, if you don't try to figure out
all the things it depends on, then you never cure
cancer or you know, you never save the endangered animals
or whatever. So you know, you got to dig in anyway, know.

Speaker 2 (25:00):
Exactly biology has no clear answers, but the questions are
super duper important and interesting and so they're worth going after.

Speaker 1 (25:06):
Anyway, I appreciate the effort you're making to understand my perspective.
You're doing a great job. You're doing a great job,
all right, So I forgot to answer a question that
you had earlier, which was like, what is happening to
metabolism and stuff when they're in this tot and the
answer is it depends. Right, This might be pretty straightforward,

(25:27):
all right, tell me. They reduce their metabolism, they reduce
their oxygen use, and it's almost like they're frozen in time.
So they're not doing a lot of biological stuff when
they're in this desiccated state.

Speaker 2 (25:37):
But to me, there's a difference between actually frozen like
there's no motion and very slow like are they alive?
Is there some consumption of energy? Are they going to
run out of energy at some point or is it
really just paused.

Speaker 1 (25:52):
I think it's got to be the case that there's
still some consumption of energy, so one otherwise you'd expect
that they could like live forever, and so I think
at some point they kind of run out their stores.
But of course during that time they're also like accumulating
radiation damage and other sorts of problems of just being alive.
They're amp in it down, but I don't think it's
completely zero.

Speaker 2 (26:10):
Yeah, amazing, Yeah.

Speaker 1 (26:11):
And so because they're resistant to things like desiccation. Actually,
I wish I knew the history of the first time
somebody was like, let's throw these guys in liquid nitrogen.
Doesn't seem super nice, but they've got this sort of
reputation for being super environmentally resistant. We've exposed them to
pressures of seven and a half gigapasscals, which is equivalent
to being one hundred and eighty kilometers below the surface

(26:33):
of the Earth, and this is an environment that I
just can't imagine you would expect that selection would be
preparing these organisms for it, because it just doesn't come up.
But they mostly did. Okay, at six hours, they were alive.
And so here's the thing. You'll hear like a list
of like they can survive seven point five giga pass
scales of pressure, blah blah blah. They can survive seven
point five gigapascals of pressure for six hours.

Speaker 2 (26:56):
That's pretty good, though six hours is a long time,
Like we're talking the same like a hydraulic press. You know, yes,
this is serious stuff.

Speaker 1 (27:03):
No, that's a good point. Like so every once in
a while, though, you'll see like a YouTube headline that's
like they're immortal. This is incredible. You're right, it's incredible.
They can survive this, but they can't survive it for long.
If they're exposed to it for twenty four hours, they've
kicked the bucket, all right.

Speaker 2 (27:17):
And I can understand why evolution wouldn't need them to
be able to survive one hundred kilometers underground for a
thousand years. But it's not that hard to imagine why
it would be useful to survive high pressure briefly, right,
you can imagine some high pressure situation comet impact, dinosaur
steps on you. I don't know, right, these things do happen.

(27:37):
I suppose evolution can select for them. No, you're looking
skeptical over there.

Speaker 1 (27:41):
So if you are a tartar grade living in the
Marianna's Trench, and I don't know if we have tartar
grades in the Marianna's Trench, then you would have experienced
selection for being able to handle extreme pressures. But I
don't know if like a once in many millions of years,
commet would still be exerting selection pressure now for seven

(28:02):
point five gigapas skials of pressure.

Speaker 2 (28:04):
Well, if we had like lots of pianos dropping out
of buildings on people's heads the way I always thought
we were going to have when I was a kid,
I thought that was like a feature of adult life,
you know, quicksand pianos and anvils, dropping on people. Wow,
that was happening more often than you would expect evolution
to somehow select humans to be able to survive you know,
anvils and pianos and stuff like that, so you know
there must be some biological equivalent to an bills and pianos.

Speaker 1 (28:26):
First of all, I think Looney Tunes gave you a
distorted view of adulthood.

Speaker 2 (28:29):
But fair, fair, I feel like.

Speaker 1 (28:31):
The strategy could just be like you have eye spots
that detect a shadow overhead, and when that happens, your
brain is just like piano move and you get out
of the way. That seems like an easier path for
selection to take than being able to withstand a piano
dropping on your head.

Speaker 2 (28:46):
Also, it probably takes a while to get into this
ton state, so it's not like target grade is swimming
along sees a comet coming down and then like switches
into ton state like a superhero. This is like already
happens to be in this state and then survives the impact, right.

Speaker 1 (29:00):
Yep, yes, exactly, Okay, they can get into it, like
I think a couple hours pretty quick, but not like immediately,
not like snap in your fingers. It takes some work.

Speaker 2 (29:07):
A couple hours. Isn't great for our superhero movie plot.

Speaker 1 (29:09):
Yeah, that's true. But you know, if Michael Bay contacts us,
we can like change some biology stuff. Like, as we've
talked about in the past, what's important is your consistent
so you know, we will consistently change their biology. Another
incredible stressor they've been able to survive is a bunch
of different kinds of radiation at levels that certainly would
have killed people. Amazing, and we think that we know

(29:33):
partly how they do this one. So tartar grades produce
a class of proteins called intrinsically disordered proteins. And you're like,
why are you making me hear that multi syllabic phrase
that is, in.

Speaker 2 (29:46):
Fact exactly what was going through my mind.

Speaker 1 (29:47):
Yes, I know, I've gotten to know you pretty well.
But so the fact that they're disordered and like kind
of all over the place is important. And so if
you think of this like blobby thing, this blobby protein
is attracted to DNA, so your genetic material that codes
for everything else, and it binds to the DNA like electrostatically.
And because it's sort of like this blobby all over thing,

(30:10):
and you know, I wish the listeners could see the
beautiful things I'm doing with my arms right now.

Speaker 2 (30:14):
You're basically Italian right now.

Speaker 1 (30:16):
I was just gonna say that, Yeah, you beat me
to it. And so this blobby thing is able to
just kind of like fall over the DNA like a coat,
and then it appears to provide like a physical barrier
to the radiation and protect the DNA from breaking. And
in fact, they were able to get bacteria by like
moving some genes around to produce these proteins, and then

(30:37):
they mix them in to human cells, and these proteins
bound to human DNA. And when you blasted the human
DNA with radiation, they were protected by these disordered, blobby
kinds of proteins that were like coats for the DNA,
radiation shielding for the DNA.

Speaker 2 (30:55):
Oh my god, this is our superhero origin story. Bitten
by a radioactive chartic D, Kelly gained that critter's ability
to withstand radiation.

Speaker 1 (31:05):
It's gonna be amazing coming it's fall.

Speaker 2 (31:09):
Tart to Kelly. So let's reminder of listeners exactly what
radiation is and how it damages to sell because we're
talking about X rays and ultraviolet light and gamma radiation.
Those all sound like very different things, but they're all
just photons. Talking about very high energy photons, photons like
the ones emitted by your lamp or your screen or
by the sun, just higher energy, so they like penetrate deeper.

(31:32):
And the problem, of course, is that when these things
penetrate into your cells, they can like blast open delicate
stuff like your DNA, and that's how you get cancer, right,
Or also sometimes that's how your kids end up being
like amazing cross country runners even though you have no
athletic skills yourself. Hypothetically speaking, right, mutations are sometimes good
and sometimes bad. You never know, But it's like going

(31:53):
into computer code and just like randomly changing a few
things and hoping that it gets better. Yeah, sometimes it
gets worse, And so that's what we're protecting against, right,
that's right.

Speaker 1 (32:01):
And the study that I was reading it was looking
at breaks in the DNA. So DNA is like a
double stranded helix. It's almost like you took a ladder
and that sort of twisted it so that it's like
a spiral staircase, and they're looking at do you get
one break in the ladder or two breaks in the ladder.
So does one of the like long poles break or
both of them, And so they were able to find
that you get fewer breaks overall when you have this

(32:24):
like radiation coat protecting it.

Speaker 2 (32:27):
So why don't we all have this radiation coat. Is
it like good to be susceptible to radiation because then
you get these mutations? Or is this radiation coat like
expensive in some other way that's usually not worth it.

Speaker 1 (32:38):
I think it'll probably surprise some people to learn that
usually when you get blasted with radiation, you get like cancer,
but not superpowers. You probably generally want to avoid it.
But to be clear, we don't actually know the answer
to this because we don't understand the system very well.
But one hypothesis that I read about was that, you know,
probably we don't all have these because if you've got
something that's like a coat for your DNA, you know,

(33:01):
like the way your DNA replicates is like stuff comes
in and opens up the double strand, and like there's
machinery that starts replicating stuff, and if you've got like
a big coat covering it, you can't do that stuff
and like gets in the way, And so it might
be nice to protect you during a period where you're
not doing a lot of replicating your DNA because you're
just kind of hanging out waiting for the awful situation
you find yourself into. Pass.

Speaker 2 (33:22):
So it's sort of like you're locking down your DNA,
but then you can't really use it. It's like when
you freeze your credit and then you can't like open
a new bank account because you've protecting yourself against yourself.

Speaker 1 (33:31):
That's right. You shouldn't have sent your Social Security number
to that person over email. Kelly from the past anyway.
So they're surprisingly radiation resistant. Let's talk about what happens
when you dip them in liquid nitrogen or expose them
to the vacuum of space next. All right, we're back.

(34:04):
We've talked about how tartar grades are amazingly resistant to
high pressures, amazingly resistant to radiation, although not completely resistant.
You can kill them eventually, but they're impressively resistant. Also, weirdly,
we've been very interested in exposing them to temperature extremes,
and so, Daniel, I have a question for you. There's
this commonly made claim that you can expose tartar grades

(34:27):
to very close to absolute zero and they survive cool
This was from a paper in the nineteen fifties in
a language I don't speak, and I couldn't find the original.
How long have we been able to create temperatures close
to absolute zero? Has it been since the nineteen fifties?

Speaker 2 (34:46):
So the history is that colder, earlier than you might expect.
Like Faraday, Michael Faraday, who did so much amazing work
on electromagnetism, he got stuffed down like negative one hundred
and thirty s, so that's one hundred and forty degrees
above app flue zero. That was in eighteen forty five.
And then a guy named Doer after which the Doers
are named liquified hydrogen down to twenty one kelvin in

(35:09):
eighteen ninety eight. Right, So this is already just twenty
degrees above absolute zero in the eighteen hundreds, and then
it was just ten years later we got down to
four degrees kelvin when the Nobel Prize in nineteen thirteen
for that one.

Speaker 1 (35:23):
Oh wow.

Speaker 2 (35:23):
And the current record, the closest we've ever gotten is
one hundred pico kelvins. That's zero point zer zero zero
zers or zero zerzero zero one kelvin. And there's an
instrument on the International Space Station that's going to try
to get to one pico kelvin is called the cold
Atom Lab.

Speaker 1 (35:41):
All right, okay, so definitely by the nineteen fifties you
could be testing how tartar grades survived too close to
absolute zero? And Daniel, what is absolute zero? I believe
that's the temperature at which molecular stuff just stops and
everything's frozen in place. Is that right?

Speaker 2 (35:55):
Absolute zero is a theoretical limit we've never achieved and
don't know if it's act actually possible. And essentially the
argument is when things get colder, velocities internally slow down.
It's a model of temperature that says things are hot
because the stuff inside it is moving fast or wiggling
a lot. And so what happens when things get colder,
They move slower, They wiggle less. Okay, make them colder,

(36:17):
all right, they wiggle less. Is there a point at
which all wiggling stops? And so sort of the way
like when you learn calculus in high school, you could
never actually approach infinity. You like approach it and see
what the tendencies are. In that same way, we estimate
that absolute zero might be the place where everything stops.
But that's extrapolating, and it's all kind of classical physics
and quantum mechanics says you could never actually get there

(36:39):
because there's a minimum energy to all the fields in
the universe, so everything has to be buzzing because if
anything was ever completely motionless, they would have no uncertainty,
and there's a minimum uncertainty to the fabric of the universe.
So we don't know if anything can ever get to
absolute zero, if it's a real thing or not. But
we've gotten pretty close.

Speaker 1 (36:58):
Okay, and grades were able to handle it for at
least a little while, even though I couldn't find the
original paper.

Speaker 2 (37:04):
Wow, So how cold did they get these heartigrades?

Speaker 1 (37:06):
So the paper that I was able to find both
because it was online and in my native language. They
dipped them in liquid nitrogen, So that's negative one hundred
and ninety six degrees celsius. Pretty cold, super cold, and
ninety percent of them survived.

Speaker 2 (37:22):
Wow.

Speaker 1 (37:22):
Yeah, it was for fifteen minutes.

Speaker 2 (37:24):
I don't think many Californians would survive at that temperature
for that.

Speaker 1 (37:27):
Long, you know, even though Virginians are a hardier bunch
than you all Californians, I don't think we could have
survived that either.

Speaker 2 (37:33):
That's because you have to wrap your heart in so
many layers of protection that it's not available during normal use. See,
that's why Californians are friendlier.

Speaker 1 (37:41):
That doesn't make sense. No, no, no, no, no, that's
not how this works, all right. But one point that
I want to make here is that some of the
Tartar grades that were not in the Ton state also survived,
and that was also true during the radiation experiments too.

Speaker 2 (37:58):
Oh wow, and.

Speaker 1 (37:59):
That makes us like those disordered proteins that we were
talking about, maybe they help, but maybe that's not the
whole picture, because you wouldn't expect the active, untunned individuals
to be surviving if those proteins were the whole picture,
because they're not making a bunch of those when they're
not in the Ton state. So everything's complicated. Okay, But

(38:21):
now let's get to the juicy stuff. Space. Some scientists
have wanted to figure out if Tarte grades can survive
the super extreme environment of space. So first we sent
them up into spacecraft and expose them to microgravity and
some space radiation. But they were still like in this
temperature controlled container thing. They did pretty well. In response

(38:41):
to microgravity. Like, whereas humans are bones and our muscles
fall apart in the ton state, they're just kind of
chillin And.

Speaker 2 (38:47):
Let's remind ourselves what is the extreme environment of space?
What's difficult about space? So this high radiation because we
don't have the magnetic field of Earth to bend those
particles away, and we don't have the atmosphere to shield us.
Then there's microgravity that's not so extreme. But then there
could also be low temperatures if you're out in space,
low pressure, and then of course no oxygen.

Speaker 1 (39:07):
Yes, And so this first experiment was replicating the microgravity problem,
but they weren't exposed to the vacuum of space, they
weren't experiencing full radiation, and they were in low Earth orbit,
so they were still protected by the magnetosphere, and they
weren't experiencing the kind of temperatures extremes you usually experience
in space. Okay, So another experiment or a set of
experiments amped things up. They put them in a container

(39:30):
that had holes in it, and then they had a
variety of UV filters on top of the different containers.
So some of the tartar grades were exposed to the
vacuum of space well, having their temperature controlled but not
being exposed to UV radiation. And then others experienced various
kinds of UV radiation well being exposed to the vacuum
of space while still having their temperatures controlled in a

(39:52):
nice way. Does that all make sense? Vacuum of space
they rocked at which, to be clear, it would kill people, right.
The three Soviet cosmonauts who were exposed to the vacuum
of space did not survive the experience, and that's pretty
much what you should expect for the rest of us too.

Speaker 2 (40:10):
The thing that first kills you there is what is
it the low pressure that like, your eyeballs are boiling
and your blood is boiling because you're used to being
squeezed in by all the air.

Speaker 1 (40:18):
I think what killed them in particular is that the
nitrogen boiled out of their blood and it happened in
their brains and they had a bunch of brain hemorrhaging.

Speaker 2 (40:25):
That does not sound good, no, And.

Speaker 1 (40:27):
So TARTA grades don't have the same circulatory system, the
internal goo that keeps these little guys going. It's not
the same system as ours. So you might not have
to worry about nitrogen bubbles, but also they've gotten like
a bunch of the water out already, and so you're
probably not going to have like stuff that could bubble out.
So they did great in the vacuum of space, but
as soon as you opened those filters so that you

(40:47):
reradiation could get them too, they started dying in droves.
Like I think, oh, really, maybe four of the like
sixty survived that exposure, and that wasn't fair, like a
whole lifetime. I think it was. Like one of the
things that frustrates me about papers that are published in
really high impact journals is that they give you a
short page limit and so important details get left out.

(41:08):
And I couldn't figure out how long they were exposed,
but it couldn't have been more than ten days, because
that's how long the entire mission lasted.

Speaker 2 (41:15):
Said, we heard earlier that they can survive UV radiation
on its own, and we heard just now that they
can survive the vacuum of space. But you're saying that
you combine them, then that snuffs them out, so they
can't survive the combination.

Speaker 1 (41:27):
So here's the problem. All these studies that we've been
talking about, yeah, all looking at different species of tartar grades.
So because a tartar grade could survive some high radiation
doesn't mean that the next species that you expose it
to could survive. And also, not all of these studies
have the exact same experimental design, so it could be
that a bunch of the tartar grades that were exposed

(41:47):
to radiation were exposed to it for like five minutes,
but when you're exposed to it for ten days, then
you start dying. And so you know, when you hear
someone like rattling off a list of all the extreme
stuff that tartar grades can do, so some species can
do some of those things for some lengths of time,
but it's not like all of them can do all
of those amazing things indefinitely.

Speaker 2 (42:07):
So that's like saying, oh, polar bears can swim in
cold water and grizzly bears can run really fast, and
doesn't mean that they can do.

Speaker 1 (42:14):
Both, yes, exactly, or that they could do both like forever.
Like eventually, the polar bear is going to need to
find land and stop swimming. So the space people don't
invite me to their parties. The tartar grade people aren't
going to invite me to their parties anyway, It's all right,
I'm a downer.

Speaker 2 (42:26):
Physicists will always invite you to their parties, killing because
we don't have any.

Speaker 1 (42:30):
Oh, oh, that's probably not true. Maybe, So here is
the question everybody's been dying to know the answer to.
In twenty nineteen, the Bearasheet Lunar Lander crashed on the Moon.
It contained tartar grades, although the government officials who approved
that launch did not know that because the company that

(42:52):
had bought space on the lander did not disclose that
they were sending biological specimens, which they are supposed to do.

Speaker 2 (42:59):
And why were they sending biological specimens? Was this some
can tartar grades survive experiment? Or were they hoping to
populate the Moon?

Speaker 1 (43:06):
I hope that it was a can tartar grade survive experiment,
and also like that probably would have been a pretty
cool pr move for their mission to be able to
be like, oh, tartar grades in space, they really can
survive everything. But for whatever reason, they decided to not
disclose that it was happening, and I was not able
to figure out what species they sent. I spent a
long time asking. I asked Blue Sky. Nobody knew and

(43:30):
if you know, let me know. But so part of
figuring out whether or not they can survive involves knowing
the tolerances for that species in particular, right, But I
don't know what species it is.

Speaker 2 (43:40):
So the answer is it depends.

Speaker 1 (43:42):
Well, we were talking about biology, so of course the
answer is it depends. Biology. Doesn't disappoint but I think
probably not. And here's why. All right, So, first somebody
decided to stick tartar grades in bullets and then shoot
them at sandbags to try to figure out if they
could survive the impact and the subsequent shock wave that
would have been experienced when the lander crashed into the moon.

Speaker 2 (44:05):
This was an experiment done in response to the crash,
like just to answer this question, not an independently motivated experiment.

Speaker 1 (44:11):
That's exactly right. Wow, it doesn't say that in the paper,
but I found an interview with the authors it sounds
like that's true. And so there's a sentence in the
paper that says, accordingly, we have fired tartar grades at
high speed in a gun onto sand targets, subjecting them
to impact shocks and evaluating their survival. Actually, this paper
was all about if something hit the Earth and dislodged

(44:32):
Earth that had tartar grades. Could the tartar grade survive
base and survive so that they could land on the
Moon or Mars or populated. So it was a study
about pants spermia on the possibility of the tartar grades
becoming you know, interplanetary before the rest of us. I
found an interview where the author said, probably they wouldn't
have survived because of the shockwave. So it seems unlikely

(44:55):
that they survived. But let's go ahead and assume that
maybe they got lucky and they survived the initial shockwave, because.

Speaker 2 (45:02):
We don't know the speed of the descent of the lander, right,
it depends on when it failed. If it fails just
before it hits the surface, it's going to be a
pretty gentle crash. If it fails really far away, then
it's going to plummet towards the surface. But the Moon's
gravity is still not very strong, so it's not going
to be going that fast, right, But still it depends.

Speaker 1 (45:20):
This paper that I read had a bunch of different
impact speeds and shockwaves that they looked at, and I
looked on the internet to figure out what we think
the impact speed was of the bearsheet lander and based
on their table, I think it's possible it survived. But
then in an interview with the authors they said, no, no, no,
the shockwave, it wouldn't have survived. But then I found
another paper that was like, no, it might have survived

(45:42):
based on the info and the table. So you know,
it depends.

Speaker 2 (45:45):
Were any of these papers written by anonymous authors from
the Moon?

Speaker 1 (45:48):
Oh, I don't know. Yeah, the TARTI grades achieved sentience.
I think we have to worry about them sending like
moon rocks down at us as punishment for all the
things that we've done to them in the lab.

Speaker 2 (45:58):
All right, so you think it's unlikely they survey the
impact on the Moon once they're on the Moon, say
they happen to survivor if you do, then what did
they have to put up with?

Speaker 1 (46:06):
So now they've got to worry about radiation. So the
Moon doesn't have a strong planet wide magnetosphere like Earth
does or a thick atmosphere, so they'd be exposed to
all of the space radiation. And as we saw in
those earlier studies, base radiation, solar radiation is bad for them,
so that would kill them if they were exposed to it.
But let's say, well, what if maybe when they crashed,

(46:28):
the little container that was holding them ended up burying
itself under the regolith, and so now the regolith is
protecting them from radiation. Creative, let's imagine that. Okay, so
now you've got to deal with temperature. We know they
can handle really cold temperatures. The moon at night has
about a two week period where it's negative one hundred
and thirty three celsius, which is negative two hundred and

(46:49):
eight fahrenheit. That's at the equator. We know that they
survived negative one hundred and ninety six celsius, which is
more than that, but for fifteen minutes, So we don't
know if they could survive the law long polar nights,
which are the equivalent of two weeks on Earth. But
I think the bigger problem is one temperature swings back
and forth between extreme heat and extreme cold, but two

(47:10):
the fact that the moon does get really hot, so
without that atmosphere, things just heat up a lot. So
without an atmosphere, things get really hot and really cold.
There's nothing to sort of dampen the temperature swings. And
as we saw previously, tartar grades don't do great at
really high temperatures. They do pretty well with cold temperatures,
but with hot temperatures they can't survive for super long.

(47:30):
But let's imagine, Hey, we said that they're underneath the regolith.
They're protected from radiation. Underneath the regolith, you're also to
some extent protected from temperature extremes. So maybe they're still
alive there. But now you've got a problem with water.
So in order to come out of their ton state,
they need to be hydrated, and the lunar regolith is

(47:52):
as wet as cement, so not super wet. So say
it got hit by a comet that was bringing water, Well,
I think that impact and the like heating up that
happens when the comet hits the surface could kill the
tartar grades. But also if you get water, you're only
going to get it temporarily and then it's going to
like be lost to the vacuum of space. So I

(48:12):
don't see them getting out of their ton state. And
then the final big problem is food. If they did
get out of their Ton state, they don't have anything
to eat, Like, I don't know what species this is.
If this is the carnivorous ones and there was enough
of a size variability, maybe the big ones could eat
the little ones, but eventually you're gonna run out of it.
So I don't see the tartar grades permanently settling the Moon.

Speaker 2 (48:34):
So it's unlikely that the tartar grades are like water,
bearing around, being cute and bouncing around the surface of
the Moon, living happily. But it's possible that some of
them are in the ton state, survive the impact, are
buried in the regolith and don't need water or food
because they're just basically paused for a long time, but
maybe not forever.

Speaker 1 (48:54):
I feel like that is a very low probability scenario,
but it depends. I don't know that I can rule
it out entirely. Maybe they're still in their ton state.
We'll find them. I mean, we know that they can't
be in that state for forever, and it's already been
like five years, so I'm not super hopeful.

Speaker 2 (49:09):
Sorry, But if a huge impactor slams into the Earth
and like completely demolishes it so there's no record of
life left on Earth, there could still be on the
Moon some basically like frozen proof that there was once
life on Earth. So that aliens visiting in the deep
future could be like, oh, look, there was something here once.

Speaker 1 (49:29):
Maybe, or those incredible temperature swings have killed them and
the bacteria that live in their guts have consumed them
and they've become liquid munch because biologies grows.

Speaker 2 (49:39):
Also, all right, well, I guess we're just gonna have
to wait millions of years for a huge impact and
alien arrival to find out the answer to that one.

Speaker 1 (49:46):
Ah, and people say I'm the negative one.

Speaker 2 (49:49):
All right, well, thank you Tim for your really fun question.
I think Kelly had a lot of fun digging into
the research on tartar grades.

Speaker 1 (49:56):
I did. It distracted me while I was sick and
couldn't get out of bed, So thank you for this
wonderful question. I had a blast.

Speaker 2 (50:02):
If you have a question about something in the universe
that fascinates you, physics, biology, even gasp, chemistry, right to us,
we'd love to dig into it. We love hearing from
all of you at questions at Daniel and Kelly dot org.

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Speaker 2 (50:28):
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