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Can tardigrades survive on the Moon? · Daniel and Kelly’s Extraordinary Universe

0:06
Speaker 1: Watermands, lost piglets, tartar grades. They go by many names,
0:11
Speaker 1: but I think the one thing we can all agree
0:13
Speaker 1: on is that they're pretty much indestructible, right. I mean,
0:17
Speaker 1: these poor teeny tiny creatures have been exposed to all
0:21
Speaker 1: manner of unpleasant stimuli in the lab. They've been frozen
0:25
Speaker 1: to near absolute zero, heat it up to way past boiling, irradiated,
0:30
Speaker 1: squeezed at pressures you'd experience one hundred and eighty kilometers
0:34
Speaker 1: below earths surface, exposed to the vacuum of space, and
0:38
Speaker 1: shot into sand bands. If tartar grades ever become large
0:41
Speaker 1: and sentient and start looking for retribution, we are in
0:44
Speaker 1: a lot of trouble. But the good news for tartar
0:47
Speaker 1: grades is that they survive most of these experiences surprisingly well.
0:51
Speaker 1: How do they do it well? That's what we're going
0:53
Speaker 1: to discuss today, and by the end of the episode
0:56
Speaker 1: we'll answer a question that has no doubt kept you
0:58
Speaker 1: up at night. Are those tartar grades that crash landed
1:02
Speaker 1: on the Moon in twenty nineteen still alive? Let's find out.
1:06
Speaker 1: Welcome to Daniel and Kelly's Extraordinary Universe.
1:22
Speaker 2: Hi, I'm Daniel, I'm a particle physicist, and I don't
1:26
Speaker 2: like a lot of biology, but I do like hearing
1:28
Speaker 2: about critters that only poop when they molt.
1:30
Speaker 1: Wait wait, wait, we'll back up that. I'm Kelly Wiersmith,
1:34
Speaker 1: a biologist. Did you just say that you don't like
1:36
Speaker 1: a lot of biology?
1:38
Speaker 2: You know, there's a reason I'm in physics. The biology
1:41
Speaker 2: is all weird and messy. I mean, it's wonderful and fascinating,
1:44
Speaker 2: but sometimes I just feel like there aren't really any
1:46
Speaker 2: hard answers.
1:47
Speaker 1: Well, well, you guys haven't reconciled quantum mechanics or general
1:50
Speaker 1: relativity yet, how dare you?
1:55
Speaker 2: But there is a hard answer. We don't have it yet,
1:57
Speaker 2: but I think one day eventually humans or some clever
2:01
Speaker 2: aliens will figure it out. Biology, I just don't even
2:04
Speaker 2: know if there's an answer.
2:06
Speaker 1: I mean, I can't argue with that. I'm not sure
2:08
Speaker 1: there's an answer for a lot of this stuff either,
2:09
Speaker 1: But I still think that's exciting. And also, I will
2:12
Speaker 1: note that you said that they only poop when they mold.
2:16
Speaker 1: There are probably more than thirteen hundred species of tartar grades.
2:19
Speaker 1: I don't know that it's true that all of them
2:21
Speaker 1: only poop when they vote. I think some of them
2:24
Speaker 1: might just poop like the rest of us.
2:28
Speaker 2: All right, well, I'm fascinated. I want to hear more
2:31
Speaker 2: about it, because I'm sure there's an answer to at
2:33
Speaker 2: least this question of when do tartar grades poop.
2:36
Speaker 1: I mean, it's going to depend on the species. But yes,
2:38
Speaker 1: all right, so we had an amazing listener question. Let's
2:42
Speaker 1: go ahead and listen to that.
2:44
Speaker 3: Now, Hey, Daniel and Kelly, question about tartar grades. Those
2:49
Speaker 3: little water bears. Just curious what is it about them
2:54
Speaker 3: that allows them to survive in basically any environment. I've
2:58
Speaker 3: heard that there's even some on the Moon. As far
3:00
Speaker 3: as I know, NASA has an engineered little spacesuits that small.
3:03
Speaker 3: So yeah, just curious what is it about their physiology
3:07
Speaker 3: that allows them to survive?
3:08
Speaker 2: Thanks?
3:10
Speaker 3: Also, go Virginia.
3:11
Speaker 1: Okay, so first off, I laughed out loud imagining NASA
3:14
Speaker 1: engineering tiny spacesuits for the tartar grades. That was amazing.
3:19
Speaker 1: Thank you for this question, and go Virginia. Woooo.
3:23
Speaker 2: I'm sorry this question is disqualified. I mean, obviously they
3:26
Speaker 2: have no credibility from the.
3:27
Speaker 1: Get go, Daniel, I did ten hours of research for
3:30
Speaker 1: this episode. We are not dropping this episode.
3:32
Speaker 2: And did you discover that you have to be a
3:34
Speaker 2: tartar grade to enjoy the climate of Virginia.
3:36
Speaker 1: Everybody enjoys the climate of Virginia. Tim and I agree
3:39
Speaker 1: on that. At least. There was a little bit of
3:42
Speaker 1: snow falling the other day and I felt highly festive.
3:45
Speaker 1: And I know that there are some places of California
3:47
Speaker 1: that have snow, but only some.
3:51
Speaker 2: Well, you know, tartar grades can live on the Moon,
3:53
Speaker 2: they can live deep underwater, they can survive when it's dry,
3:56
Speaker 2: they can even survive Virginia winter.
3:58
Speaker 1: Well, hold on, can they live on the moon?
4:01
Speaker 2: I don't know.
4:02
Speaker 1: That's the whole point of this episode, trying to find
4:04
Speaker 1: the answer to that question. So should we dig in, Yes.
4:07
Speaker 2: Kelly, tell us what are these tartar grades, what do
4:09
Speaker 2: they look like, where do they stand in the context
4:12
Speaker 2: of all biology, and what do we know about where
4:15
Speaker 2: they can actually survive?
4:16
Speaker 1: Okay, all right, well, so it'll take me an hour
4:18
Speaker 1: or so to give you that answer. But let's start
4:20
Speaker 1: with reiterating that there are probably more than thirteen hundred species.
4:24
Speaker 1: In fact, it's under Kingdom Animalia. There's something like thirty
4:28
Speaker 1: phylum and tartar grade they're their own phylum whoam and
4:32
Speaker 1: so there's a lot of them, right, But usually you're like,
4:35
Speaker 1: tartar grades do blah blah blah, as though there's just
4:37
Speaker 1: one species, but there's a lot more than just one species.
4:41
Speaker 2: And the fact that they're so high up in this
4:43
Speaker 2: tree of life. I mean, it's not just like bile'll
4:45
Speaker 2: just like to organize things because they don't really understand them.
4:48
Speaker 2: It tells us something about.
4:50
Speaker 1: Like wait, wait, wait, let's listen to the particles episode
4:53
Speaker 1: and you're like, I don't know how we categorize these things,
4:56
Speaker 1: so anyway, little hypocritical.
4:57
Speaker 2: But no, seriously, I think when particle physics is feeling
5:00
Speaker 2: is when it's just doing taxonomy. If we're just doing botany,
5:04
Speaker 2: then we don't really understand anything. It's when we're doing philosophy,
5:08
Speaker 2: when we're linking things together, we understand how they work underneath.
5:11
Speaker 2: That's when I think we're really making progress. But what
5:13
Speaker 2: I want to ask you.
5:15
Speaker 1: I think we need both. We'll move on.
5:16
Speaker 2: But what I want to ask you is how we
5:18
Speaker 2: should interpret where people have put tartar grades in this
5:21
Speaker 2: tree of life. The fact that they're so high up,
5:23
Speaker 2: does that mean that they're really their own kind of thing.
5:26
Speaker 2: They're so different from everything else, or they have their
5:28
Speaker 2: own weird history or both.
5:30
Speaker 1: Let's go with both, and let's talk about why they're
5:32
Speaker 1: so unique awesome. All right, So, first of all, these
5:35
Speaker 1: are tiny little guys. They're multi cellular. They got lots
5:37
Speaker 1: of cells. Big ones are about a millimeter long, so
5:40
Speaker 1: about the size of a period. They have this hard
5:43
Speaker 1: outer cuticle, and because it's hard, that doesn't grow with them,
5:47
Speaker 1: so they have to molt the way like nematodes, and
5:50
Speaker 1: some insects will mold the way snakes shed. Because snakes
5:53
Speaker 1: are awesome. What's get snakes in there? You probably don't
5:55
Speaker 1: even like snakes, do you, Daniel?
5:58
Speaker 2: You probably don't like like that's an outrageous thing, like,
6:01
Speaker 2: oh yeah, snakes, rats and cockroaches. You don't like any
6:04
Speaker 2: of that, doa Daniel?
6:07
Speaker 1: Do you not like those things? Daniel?
6:08
Speaker 2: Well, I mean I wouldn't want to like snuggle up
6:10
Speaker 2: with them. You know. It's not like if I see
6:12
Speaker 2: a bunch of the my bed, I go ooh cozy.
6:15
Speaker 2: You know. They're not in the same category as like
6:17
Speaker 2: kittens and bunnies for sure.
6:19
Speaker 1: All Right, all right, I won't disagree with that, but
6:21
Speaker 1: I have seen some snugly rats. But anyway, okay, heart
6:23
Speaker 1: outer cuticles. Sometimes when they lose that cuticle, that is
6:26
Speaker 1: when they release the contents of their bowels that they've
6:29
Speaker 1: been holding onto for a while. That's also sometimes they'll
6:31
Speaker 1: release their eggs into that cuticle when they mold, and
6:34
Speaker 1: then the eggs sort of have this like protective little
6:36
Speaker 1: case that they're in for a while, and then when
6:38
Speaker 1: they hatch, they have to find like the holes in
6:39
Speaker 1: the cuticle to get back out.
6:41
Speaker 2: All right, So these things are really small. You're saying
6:43
Speaker 2: a millimeter is the biggest one. Can I see something
6:46
Speaker 2: with my naked eye that's just a millimeter? So like
6:48
Speaker 2: tartar greates, you could actually, like if you squint see
6:50
Speaker 2: one of these things.
6:51
Speaker 1: So it's about the size of like a period on
6:53
Speaker 1: a printed out sheet of paper, and so like you know,
6:56
Speaker 1: maybe you could see some like flailing limbs, but like
7:00
Speaker 1: if you had a dissecting scope you could see them better.
7:03
Speaker 1: But again, a millimeter is about the size of like
7:05
Speaker 1: some of the bigger ones, and so a lot of
7:07
Speaker 1: them are even smaller, and so you'd be better off
7:09
Speaker 1: with like a compound microscope.
7:11
Speaker 2: And does everything that has this hard out or shell
7:14
Speaker 2: have to molt when it grows? Or are there some
7:16
Speaker 2: critters out there that can like gradually expand, Because like
7:19
Speaker 2: our skeleton gradually expands as we grow, why can't you
7:22
Speaker 2: gradually expand your exoskeleton as you grow? Or is that
7:26
Speaker 2: a totally naive biology question.
7:28
Speaker 1: Our skeletons are inside of us, and so they can
7:31
Speaker 1: like expand as our squishy outer parts sort of like
7:33
Speaker 1: accommodying that. But I think that if you have a
7:37
Speaker 1: particular kind of cuticle that's like super hard that doesn't
7:40
Speaker 1: tend to grow and expand, I think you do usually
7:42
Speaker 1: need to lose those all right?
7:44
Speaker 2: And so do all of these things look roughly the
7:46
Speaker 2: same even though some of them are a little bigger
7:47
Speaker 2: and some of them are smaller. Do they all roughly
7:50
Speaker 2: look like the same critter? Like an individual non trained
7:53
Speaker 2: biologist tell them apart by eye?
7:55
Speaker 1: They do have some definite characteristics that help you tell
7:58
Speaker 1: them apart. So my question for you is, I think
8:01
Speaker 1: when most people think of tartar grades, there is an
8:03
Speaker 1: animated video that they saw. Is something coming to mind
8:06
Speaker 1: for you? Or have you not seen this video?
8:08
Speaker 2: No? I definitely have a mental image of a tartar grade.
8:11
Speaker 2: I think the phrase water bear has also influenced me.
8:14
Speaker 2: So I'm imagining something that looks a little like a
8:16
Speaker 2: fat caterpillar, but with sort of claws and then a
8:20
Speaker 2: weird face with like a tube sticking out the front
8:23
Speaker 2: of it. So it's a little like a possum or something.
8:25
Speaker 2: I'm not sure exactly animal. It looks like maybe like
8:28
Speaker 2: a microscopic water possum.
8:30
Speaker 1: Oh, I love possums. Okay, So there's this like famous
8:33
Speaker 1: video where they're pink and they've got that like almost
8:36
Speaker 1: a toilet paper roll on top of their face, and
8:39
Speaker 1: it kind of like goes into the face and out
8:41
Speaker 1: of the face over and over again as the tartar
8:43
Speaker 1: grades eight little legs furiously have it swimmed through this water.
8:47
Speaker 1: So I was listening to ologies and Allie Ward was
8:50
Speaker 1: interviewing doctor Paul Bartel's and he was lamenting that that
8:53
Speaker 1: is like not what they look like at all, what.
8:57
Speaker 2: Popular science has led us astray.
8:58
Speaker 1: Kelly, really, hold on, I know, I know, it's amazing. Okay,
9:02
Speaker 1: So first of all, that toilet paper roll, nos thing
9:05
Speaker 1: does not go out and in and out and in
9:07
Speaker 1: and out and in That was a mistake because someone
9:10
Speaker 1: took a special kind of microscopic picture. They used a
9:13
Speaker 1: scanning electron microscope, and the way the sample was prepared,
9:17
Speaker 1: one of the tartar grades had that thing sticking out
9:20
Speaker 1: like it usually does, and one of them, because of
9:22
Speaker 1: how it was prepared, it just kind of got like
9:24
Speaker 1: sucked into the face. But I don't think that usually happens,
9:27
Speaker 1: and so the nose thing isn't going in and out
9:29
Speaker 1: and in and out and in and out. I think someone
9:30
Speaker 1: just saw both of those photos and were like, oh,
9:32
Speaker 1: it must alternate between these two states as opposed to
9:35
Speaker 1: like the preparation process just kind of messes up specimens sometimes.
9:40
Speaker 2: Wow, it's like they saw two frames and just animated
9:43
Speaker 2: the interstitial. That's crazy.
9:45
Speaker 1: And then the other thing is they don't swim. They
9:48
Speaker 1: are what's called benthic, so they walk around on like
9:50
Speaker 1: the floor of things, or like they crawl up vegetation,
9:53
Speaker 1: but they're not swimming. They're crawling along. And that video
9:58
Speaker 1: that most of us are, you know perhaps right now.
10:00
Speaker 1: It has eight legs that are all like in front
10:02
Speaker 1: of it. It's like a bear, but all of its
10:04
Speaker 1: legs have been multiplied by two but what really happens
10:08
Speaker 1: is it has six legs and like the usual configuration,
10:11
Speaker 1: and then another two that go like straight out from.
10:13
Speaker 2: Its butt butt legs.
10:15
Speaker 1: Butt legs, Yeah, how can we get So those butt
10:20
Speaker 1: legs hold on to stuff so that they like don't
10:23
Speaker 1: get washed away with the current or something. And some
10:25
Speaker 1: have claws and some don't have claws, and they're not
10:27
Speaker 1: usually pink. A lot of them are clear or white,
10:30
Speaker 1: or if they've got color, a lot of times it's
10:32
Speaker 1: because they are clear, but you can see like the
10:34
Speaker 1: algae they ate, so they look green, or you can
10:37
Speaker 1: see their poop so they look brown. And so some
10:40
Speaker 1: of them do have some colors, but they're not even
10:42
Speaker 1: though they're moss piglets, they're not pink. Hmm.
10:45
Speaker 2: I see so clear, like they're invisible, like you can
10:48
Speaker 2: see through them. They're like transparent.
10:50
Speaker 1: If they are starved, some of them probably are transparent.
10:55
Speaker 1: But if they've eaten anything, you can see their digestive
10:57
Speaker 1: tract because they've got like green in it.
11:00
Speaker 2: Wow, that's crazy. So like little tartar gray children when
11:03
Speaker 2: they've been sneaking cookies from the cookie jar, it's not
11:06
Speaker 2: a question the parents are like I see.
11:07
Speaker 1: That cookie exactly. Yes.
11:09
Speaker 2: Wow, what's the evolutionary advantage to being transparent? Is it
11:13
Speaker 2: like a form of camouflage or is it just totally incidental?
11:16
Speaker 1: Everyone don't know. My first guess would be that it
11:18
Speaker 1: does help with camouflage if like a predator just kind
11:21
Speaker 1: of sees through you. But then the other thing is that,
11:24
Speaker 1: like creating pigmentation, is often a process that requires some energy,
11:28
Speaker 1: and so maybe being clear is just easier than creating pigmentation.
11:32
Speaker 1: But if you're in an aquatic environment, probably being clear
11:34
Speaker 1: is a good way to hide and blend into stuff.
11:36
Speaker 2: Wow. All right, so we have totally the wrong mental
11:39
Speaker 2: image of a tartar grade, but it is still kind
11:42
Speaker 2: of cute. Yeah, and it does have those fat little
11:44
Speaker 2: legs and a toilet paper snout. But we're setting the
11:47
Speaker 2: record straight here today.
11:48
Speaker 1: Well, they don't all have the toilet paper snout. Again.
11:50
Speaker 1: There's over thirteen hundred species. Some of them look like
11:52
Speaker 1: you little salamanders, but instead of a tail, they've got like,
11:55
Speaker 1: you know, the two butt legs. There's some variability in
11:58
Speaker 1: how they look, but they do have that. Like general,
12:00
Speaker 1: there's also tons of variability and where you find them.
12:03
Speaker 1: Some are in lakes, some are in oceans, and some
12:06
Speaker 1: are living in like when there's a little bit of
12:08
Speaker 1: water on lichens or moss, they live in that like
12:10
Speaker 1: little water film. And there's some that you find in
12:13
Speaker 1: like roof gutters. They're essentially anywhere where there is enough
12:16
Speaker 1: water to keep them from like desiccating, or are there
12:19
Speaker 1: in environments that dry out sometimes and then water comes back,
12:24
Speaker 1: and this is what they're so well known for. They
12:26
Speaker 1: have a bunch of different strategies for surviving that dry
12:29
Speaker 1: out period.
12:30
Speaker 2: If you find them in large bodies of water. How
12:32
Speaker 2: come you never find like mega tartar grades, you know,
12:36
Speaker 2: like there are sharks and then there used to be
12:37
Speaker 2: like huge sharks. Was there ever a tartar grade that
12:40
Speaker 2: was like a meter long or like a one hundred
12:43
Speaker 2: meter long or is that the next Michael Bay movie
12:45
Speaker 2: we're looking forward to.
12:47
Speaker 1: There have been I believe a couple fossil tartar grades
12:50
Speaker 1: that have been found, and I don't think we've ever
12:52
Speaker 1: found a mega big one. So yeah, pass that idea
12:55
Speaker 1: onto Michael Bay. I think it's a winner because there
12:57
Speaker 1: are some that are carnivores and include there are some
13:00
Speaker 1: that will eat other TURTI grades, So I think that
13:03
Speaker 1: would make a great movie.
13:04
Speaker 2: Exactly. You thought they were cute and fuzzy until you
13:06
Speaker 2: saw the big one come for you. Okay, but what
13:12
Speaker 2: limits them from growing? Like why aren't there bigger ones?
13:15
Speaker 2: Is there something about their geometry which doesn't scale up?
13:18
Speaker 2: Or is an ecological thing like they can't eat enough
13:21
Speaker 2: food to get that big? Or is there something which
13:24
Speaker 2: will eat them if they get too big? Or do
13:26
Speaker 2: we not know?
13:26
Speaker 1: I don't think we know. Amazing, amazing that we don't know.
13:30
Speaker 2: Amazing how many things biologists don't understand.
13:33
Speaker 1: I feel like that's a theme of the physics talks.
13:35
Speaker 1: But all right, fair, fair, all right, okay man, it's
13:40
Speaker 1: a battle between California and Virginia and physics and biology today.
13:43
Speaker 1: I appreciate when you and I are both anti chemistry
13:46
Speaker 1: and we're on the same team, but because today we're
13:49
Speaker 1: doing battle, all right, So let's start with their abilities
13:53
Speaker 1: to survive desiccation, which means like drying out.
13:56
Speaker 2: So this is something you hear about a lot in
13:57
Speaker 2: popular science. Are you going to ruin this for us also?
14:00
Speaker 2: Or is this something they really can do?
14:02
Speaker 1: They really can, well, not all of them, So again,
14:06
Speaker 1: many many species the ones that tend to live in
14:09
Speaker 1: like mosses and lichens and roof gutters, like places that
14:11
Speaker 1: are wet sometimes but dry other times. They're able to
14:15
Speaker 1: form this stage known as a ton state, where they
14:17
Speaker 1: essentially it's like almost go dormant. Some of them describe
14:20
Speaker 1: it as like it's near death. So they're able to
14:22
Speaker 1: like go into this like super resistant form. And when
14:24
Speaker 1: they're in this super resistant form, this is when scientists
14:27
Speaker 1: have done all manner of horrible things to them, like
14:29
Speaker 1: dip them in liquid nitrogen, shoot them out of guns
14:33
Speaker 1: just to see like how much can they handle when
14:35
Speaker 1: they're in this state.
14:36
Speaker 2: So this is what they're famous for. When it's not
14:38
Speaker 2: like a nice and cozy and damp time to be
14:41
Speaker 2: a Tarta grade, you like convert into this like weird
14:43
Speaker 2: long lasting state where you're basically immortal, and then you
14:46
Speaker 2: can just like unfurl and be a Tarta grade again
14:48
Speaker 2: later it's like time traveling to the future.
14:51
Speaker 1: So immortal, no, when they go into this state, they
14:54
Speaker 1: can survive for like years, maybe decades. But so one
14:57
Speaker 1: thing you might have heard is they can stay in
14:59
Speaker 1: this stage for hun ndreds of years. Actually that seems
15:02
Speaker 1: to be possibly a misreading of a study. So there
15:04
Speaker 1: was like a museum specimen where we knew when it
15:06
Speaker 1: was collected, and one hundred years later it got taken
15:09
Speaker 1: out of like some drawer and they found some tartar
15:11
Speaker 1: grades and they added some water, and it looked like
15:15
Speaker 1: part of an arm kind of moved a little. This
15:17
Speaker 1: was written in Italians, either Italian or French in some
15:20
Speaker 1: Romance language, and so it was like an arm moved
15:23
Speaker 1: a little, but then nothing else.
15:25
Speaker 2: Well, you know, in Italian hand gestures are super duper important,
15:28
Speaker 2: So maybe that was interpreted as communication, you know, that's right.
15:32
Speaker 1: It could be. As a biologist, I've had to look
15:37
Speaker 1: at a lot of specimens where like, oops, the ethanol
15:39
Speaker 1: dried out, and now this animal's totally dried, and I'm
15:41
Speaker 1: going to try to like get it back in its
15:43
Speaker 1: normal shape by adding like water or more ethanol. And
15:46
Speaker 1: when that happens, they often like move in response to
15:49
Speaker 1: the rehydrating And it's not that they're alive, that's just
15:52
Speaker 1: the molecules responding to the presence of water. And if
15:56
Speaker 1: it did do a like hello, guys, hand gesture, it
15:58
Speaker 1: died right afterwards. Maybe it's impressive, but probably it's just
16:02
Speaker 1: an artifact of it, like rehydrating.
16:04
Speaker 2: That could you poured water on a dried up belief,
16:05
Speaker 2: it would change its shape also, and you might interpret
16:08
Speaker 2: that its motion, but it's definitely not alive.
16:10
Speaker 1: Yes, exactly, and so that's a possible scenario. But there
16:13
Speaker 1: has been a specimen collected from Antarctica where it was
16:17
Speaker 1: two Tarta grades that had entered this dormant state and
16:19
Speaker 1: an egg that hadn't hatched yet, and the specimen was
16:22
Speaker 1: put in cold storage at life think negative twenty for
16:25
Speaker 1: thirty years and then removed and they came out of
16:28
Speaker 1: their ton state, became adults. One of them croaked, but
16:32
Speaker 1: the egg hatched, and then the two individuals who were
16:35
Speaker 1: still alive went on to like reproduce I think more
16:38
Speaker 1: than once even, and so they were like definitely alive,
16:41
Speaker 1: like not maybe waved at you and then croaked, like
16:44
Speaker 1: they're definitely alive, so decades.
16:47
Speaker 2: Now the adult. That's really impressive, right to freeze an
16:49
Speaker 2: adult and have it then reanimate and survive. That's amazing.
16:53
Speaker 2: Eggs are a different story, right, because like human eggs,
16:55
Speaker 2: you can freeze. That's not such a big deal. But
16:58
Speaker 2: why is that I've never really understood. Like I thought,
17:01
Speaker 2: if you freeze any cell, the water inside of it
17:04
Speaker 2: expands and bursts the cell membranes. And that's why it's
17:06
Speaker 2: like hard to freeze a cow and then like reanimate it.
17:09
Speaker 2: Why is it possible to do for eggs or sperm
17:12
Speaker 2: or stuff like that. Why doesn't that same physics supply?
17:15
Speaker 1: Yeah, so I am not an expert on cryopreservation, but
17:17
Speaker 1: I think that it has something to do when you're
17:20
Speaker 1: freezing human eggs, If you freeze them really fast, the
17:26
Speaker 1: cells don't lice the same way. This is part of why,
17:28
Speaker 1: like if you get meat, you don't want to like
17:30
Speaker 1: slowly freeze it and then defrost and do that over
17:33
Speaker 1: and over again because the cells lice and the meat
17:34
Speaker 1: taste less good. I think something about freezing them really quick,
17:38
Speaker 1: but I don't know why it is that they can
17:40
Speaker 1: come back after that.
17:41
Speaker 2: Yeah, because even human embryos can do that, right, even
17:44
Speaker 2: fertilized eggs. It's sort of amazing.
17:46
Speaker 1: It is. We should have a whole episode on cryopreservation.
17:48
Speaker 2: Yes, let's do it right, but it's definitely not something
17:51
Speaker 2: you can do to like a human adult, right, Yeah,
17:54
Speaker 2: at least not yet. If people are working on that, right,
17:57
Speaker 2: preserving the brains of old baseball players for the future.
18:02
Speaker 2: All Right, so you're telling us that this is real,
18:04
Speaker 2: that tartar grades really can't go into this crazy state
18:07
Speaker 2: and then survive insanely long exposure to really difficult conditions
18:13
Speaker 2: and then be alive again and reproduce and be happy.
18:16
Speaker 2: What's going on during that state? Like are they alive
18:19
Speaker 2: or are things paused? Like is there some metabolism happening? Like,
18:22
Speaker 2: what's going on?
18:23
Speaker 1: I'm going to tell you the answer to that, Daniel
18:26
Speaker 1: after the break. Okay, So you wanted to know what
18:44
Speaker 1: happens when the tartar grades go into this like semi
18:47
Speaker 1: dormant state. So first of all, they like kind of
18:49
Speaker 1: squish up into a ball, and so they like pull
18:52
Speaker 1: their heads in that they pull their legs in, and
18:54
Speaker 1: they like expel and they lose almost all their water.
18:58
Speaker 1: By the end, they have something like two to three
18:59
Speaker 1: percent of the water they started with. Just to be clear,
19:02
Speaker 1: that would kill humans. Like we're like, what seventy percent
19:05
Speaker 1: water or something. If we went down to three percent,
19:07
Speaker 1: we'd be gonners. We'd be gunners way before then. So
19:09
Speaker 1: as they lose that water, they start producing something called trehlos,
19:15
Speaker 1: which is a sugar, and it ends up forming kind
19:17
Speaker 1: of like a glass like structure that holds everything together
19:21
Speaker 1: and gives it like structural integrity. And this has long
19:24
Speaker 1: been the explanation for why tartar grades are able to
19:28
Speaker 1: survive such incredible conditions, including the explanation you gave five
19:32
Speaker 1: years ago on Daniel and Jorge Explained the Universe. When
19:35
Speaker 1: I listened to that episode.
19:36
Speaker 2: Oh all right, doing some research.
19:38
Speaker 1: Yeah, yeah, well, you know, I needed something to listen
19:41
Speaker 1: to while I was walking around the other day. But so,
19:43
Speaker 1: here's the thing though about trehelos. Lots of tartar grade species.
19:47
Speaker 1: Some of them make trehelos when they go into this
19:50
Speaker 1: ton state. Some of them make quantities so small that
19:54
Speaker 1: we're not actually sure that it can do the function
19:58
Speaker 1: of making this glass structure that protects organism. And some
20:01
Speaker 1: of them don't appear to even have the equipment at
20:04
Speaker 1: all to make trehillos, which suggests maybe it's part of
20:09
Speaker 1: the picture for some species. But that's not like an
20:11
Speaker 1: across the board answer for how tartar grades are able
20:13
Speaker 1: to do this, So it's complicated, and they make a
20:16
Speaker 1: bunch of other proteins So cryptobiosis is a term. It
20:19
Speaker 1: means hidden life, and so it's another way for describing
20:22
Speaker 1: this ton state. And I found a line in a
20:25
Speaker 1: twenty seventeen paper that said, mechanisms that protect tartar grade
20:28
Speaker 1: cells during cryptobiosis are still poorly understood or completely unknown.
20:33
Speaker 2: Ooh, that sounds like a fair description of all biology
20:36
Speaker 2: and physics.
20:37
Speaker 1: And physics and you guys only have like six questions
20:40
Speaker 1: you need to answer. Get to work on that, guys.
20:47
Speaker 2: And that's my favorite thing about the universe, that it's
20:49
Speaker 2: poorly understood or completely unknown, because otherwise it would be boring, right, I.
20:54
Speaker 1: Feel the same way about biology, dude.
20:57
Speaker 2: All right, So some of these guys have the these
21:00
Speaker 2: weird glass like proteins called trehillosies, which maybe provide some
21:04
Speaker 2: internal scaffolding that like support the cell when it's all
21:08
Speaker 2: dried out. But some of them don't even have it,
21:10
Speaker 2: but they can still do this ton state weird survive
21:13
Speaker 2: for everything.
21:14
Speaker 1: Yeah, right, and so we don't really know what's happening there.
21:17
Speaker 1: We felt like we had a handle on it, and
21:18
Speaker 1: then we were like, oh, wait, some of these don't
21:20
Speaker 1: make that at all. So I don't know. Back to
21:22
Speaker 1: the drawing board.
21:22
Speaker 2: Do you think that means that other target grades have
21:24
Speaker 2: different strategies or that this glass like structure has no
21:28
Speaker 2: connection to their ability to survive.
21:31
Speaker 1: I bet it's both. So it could depend a lot
21:34
Speaker 1: on the ecology of the animal. So some animals that
21:38
Speaker 1: are in these environments with no water for longer might
21:41
Speaker 1: need sort of more extreme solutions to this problem. And
21:44
Speaker 1: so it could be something about like what kind of
21:46
Speaker 1: environment you tend to be in, Whereas if, like I
21:48
Speaker 1: don't know, maybe you're at the edge of a lake
21:51
Speaker 1: and you know, every once in a while you find
21:53
Speaker 1: yourself dry for five minutes, you can just kind of
21:55
Speaker 1: like get through that. And so it might depend on
21:57
Speaker 1: your ecology how frequently you encounter these weird situation, or
22:00
Speaker 1: it could be different solutions entirely. I don't think we
22:03
Speaker 1: know yet, all right, And then I.
22:04
Speaker 2: Have a basic biology question, which is, like, in biology,
22:07
Speaker 2: how do you answer the question this is how they're
22:10
Speaker 2: doing it, or that's how they're doing it. Do you
22:12
Speaker 2: have to develop an alternative where you're like knocked out
22:14
Speaker 2: that capability and show that like, if they don't have
22:16
Speaker 2: this protein, then they can no longer do this thing.
22:19
Speaker 2: And that's how we know. Because biology is such a huge,
22:21
Speaker 2: complicated roup Goldberg machine. How can you point to any
22:23
Speaker 2: one bit and say this is the essential bit.
22:26
Speaker 1: Yeah, so it's super complicated. So sometimes you can say, like,
22:30
Speaker 1: you know, if trehelos is produced by a gene or something,
22:35
Speaker 1: you could go in and turn that gene off and
22:37
Speaker 1: then put the tartar grade through a drying cycle and
22:41
Speaker 1: see how it does and measure like, Okay, definitely it
22:43
Speaker 1: didn't make trehelos anymore and it died.
22:46
Speaker 2: But even then, maybe trehelos is just a precursor to
22:48
Speaker 2: something else which is actually doing the crucial function. Right.
22:52
Speaker 2: I mean, there's just such a complicated series of events.
22:54
Speaker 2: It seems to me hard to ever point to one
22:56
Speaker 2: and say this is the explanation. Do you think it's
22:58
Speaker 2: just that we always want to simple explanation and there
23:02
Speaker 2: really aren't any, or that sometimes there really are simple
23:04
Speaker 2: explanations and we can find them.
23:06
Speaker 1: There are probably rarely simple explanations, but I think that's
23:10
Speaker 1: pretty rare. Like when we did the human genome project,
23:13
Speaker 1: I think we expected we would like immediately understand the
23:16
Speaker 1: cause of cancer and a bunch of other diseases because
23:18
Speaker 1: now we have the whole genome and it's going to
23:20
Speaker 1: be super easy. But no, it depends on like how
23:22
Speaker 1: the genome is expressed, lots of complicated extra bits, and
23:26
Speaker 1: you know, like for the Trehelos example, if you knocked
23:28
Speaker 1: out trechlos and the tartar grades died, maybe it's because
23:31
Speaker 1: Trehlos does something else earlier, like even when it's not
23:34
Speaker 1: in desiccation mode and you've killed it in some way
23:36
Speaker 1: that has nothing to do with desiccation. So ideally you
23:39
Speaker 1: try to address the question from a bunch of different
23:42
Speaker 1: angles and see what the picture you put together tells you.
23:46
Speaker 1: But usually the answer is like it involves five thousand
23:49
Speaker 1: different genes that are all upregulated and different in and
23:52
Speaker 1: you know some of them are cell signaling genes. It's
23:55
Speaker 1: almost never like the answer is X. But you know,
23:58
Speaker 1: you guys have complicated answers to Sometimes.
24:01
Speaker 2: Yeah, we do, absolutely, And sometimes you look at a
24:03
Speaker 2: big complicated system and there is no simple story that
24:06
Speaker 2: you can tell or model that you can use to
24:09
Speaker 2: understand it. But sometimes you can, right like ten to
24:12
Speaker 2: the twenty nine little molecules can all fly through the
24:15
Speaker 2: air together following F equals M. It's a very simple
24:18
Speaker 2: story about a lot of complicated things that are all
24:20
Speaker 2: happening in concert, and somehow simplicity emerges. So I was
24:25
Speaker 2: sort of wondering how often that happens in biology, that
24:28
Speaker 2: you can pull one strand of a story and say
24:30
Speaker 2: this is the role this is playing, or if it's
24:33
Speaker 2: always just a huge courus.
24:35
Speaker 1: Yeah, no, it never happens that it's one string, Like
24:39
Speaker 1: I like to joke that an ecology, like, you know,
24:41
Speaker 1: the only quote unquote theory that we have is it depends.
24:47
Speaker 2: See that's my problem with biology exactly.
24:50
Speaker 1: But you know, if you don't try to figure out
24:52
Speaker 1: all the things it depends on, then you never cure
24:54
Speaker 1: cancer or you know, you never save the endangered animals
24:57
Speaker 1: or whatever. So you know, you got to dig in anyway, know.
25:00
Speaker 2: Exactly biology has no clear answers, but the questions are
25:03
Speaker 2: super duper important and interesting and so they're worth going after.
25:06
Speaker 1: Anyway, I appreciate the effort you're making to understand my perspective.
25:10
Speaker 1: You're doing a great job. You're doing a great job,
25:12
Speaker 1: all right, So I forgot to answer a question that
25:15
Speaker 1: you had earlier, which was like, what is happening to
25:17
Speaker 1: metabolism and stuff when they're in this tot and the
25:19
Speaker 1: answer is it depends. Right, This might be pretty straightforward,
25:27
Speaker 1: all right, tell me. They reduce their metabolism, they reduce
25:30
Speaker 1: their oxygen use, and it's almost like they're frozen in time.
25:33
Speaker 1: So they're not doing a lot of biological stuff when
25:36
Speaker 1: they're in this desiccated state.
25:37
Speaker 2: But to me, there's a difference between actually frozen like
25:40
Speaker 2: there's no motion and very slow like are they alive?
25:44
Speaker 2: Is there some consumption of energy? Are they going to
25:47
Speaker 2: run out of energy at some point or is it
25:50
Speaker 2: really just paused.
25:52
Speaker 1: I think it's got to be the case that there's
25:54
Speaker 1: still some consumption of energy, so one otherwise you'd expect
25:56
Speaker 1: that they could like live forever, and so I think
25:58
Speaker 1: at some point they kind of run out their stores.
26:00
Speaker 1: But of course during that time they're also like accumulating
26:03
Speaker 1: radiation damage and other sorts of problems of just being alive.
26:07
Speaker 1: They're amp in it down, but I don't think it's
26:08
Speaker 1: completely zero.
26:10
Speaker 2: Yeah, amazing, Yeah.
26:11
Speaker 1: And so because they're resistant to things like desiccation. Actually,
26:15
Speaker 1: I wish I knew the history of the first time
26:16
Speaker 1: somebody was like, let's throw these guys in liquid nitrogen.
26:20
Speaker 1: Doesn't seem super nice, but they've got this sort of
26:23
Speaker 1: reputation for being super environmentally resistant. We've exposed them to
26:28
Speaker 1: pressures of seven and a half gigapasscals, which is equivalent
26:31
Speaker 1: to being one hundred and eighty kilometers below the surface
26:33
Speaker 1: of the Earth, and this is an environment that I
26:36
Speaker 1: just can't imagine you would expect that selection would be
26:39
Speaker 1: preparing these organisms for it, because it just doesn't come up.
26:43
Speaker 1: But they mostly did. Okay, at six hours, they were alive.
26:45
Speaker 1: And so here's the thing. You'll hear like a list
26:47
Speaker 1: of like they can survive seven point five giga pass
26:50
Speaker 1: scales of pressure, blah blah blah. They can survive seven
26:53
Speaker 1: point five gigapascals of pressure for six hours.
26:56
Speaker 2: That's pretty good, though six hours is a long time,
26:59
Speaker 2: Like we're talking the same like a hydraulic press. You know, yes,
27:02
Speaker 2: this is serious stuff.
27:03
Speaker 1: No, that's a good point. Like so every once in
27:05
Speaker 1: a while, though, you'll see like a YouTube headline that's
27:07
Speaker 1: like they're immortal. This is incredible. You're right, it's incredible.
27:10
Speaker 1: They can survive this, but they can't survive it for long.
27:14
Speaker 1: If they're exposed to it for twenty four hours, they've
27:16
Speaker 1: kicked the bucket, all right.
27:17
Speaker 2: And I can understand why evolution wouldn't need them to
27:19
Speaker 2: be able to survive one hundred kilometers underground for a
27:22
Speaker 2: thousand years. But it's not that hard to imagine why
27:25
Speaker 2: it would be useful to survive high pressure briefly, right,
27:28
Speaker 2: you can imagine some high pressure situation comet impact, dinosaur
27:34
Speaker 2: steps on you. I don't know, right, these things do happen.
27:37
Speaker 2: I suppose evolution can select for them. No, you're looking
27:40
Speaker 2: skeptical over there.
27:41
Speaker 1: So if you are a tartar grade living in the
27:43
Speaker 1: Marianna's Trench, and I don't know if we have tartar
27:46
Speaker 1: grades in the Marianna's Trench, then you would have experienced
27:49
Speaker 1: selection for being able to handle extreme pressures. But I
27:53
Speaker 1: don't know if like a once in many millions of years,
27:58
Speaker 1: commet would still be exerting selection pressure now for seven
28:02
Speaker 1: point five gigapas skials of pressure.
28:04
Speaker 2: Well, if we had like lots of pianos dropping out
28:06
Speaker 2: of buildings on people's heads the way I always thought
28:09
Speaker 2: we were going to have when I was a kid,
28:10
Speaker 2: I thought that was like a feature of adult life,
28:12
Speaker 2: you know, quicksand pianos and anvils, dropping on people. Wow,
28:15
Speaker 2: that was happening more often than you would expect evolution
28:17
Speaker 2: to somehow select humans to be able to survive you know,
28:20
Speaker 2: anvils and pianos and stuff like that, so you know
28:23
Speaker 2: there must be some biological equivalent to an bills and pianos.
28:26
Speaker 1: First of all, I think Looney Tunes gave you a
28:27
Speaker 1: distorted view of adulthood.
28:29
Speaker 2: But fair, fair, I feel like.
28:31
Speaker 1: The strategy could just be like you have eye spots
28:34
Speaker 1: that detect a shadow overhead, and when that happens, your
28:38
Speaker 1: brain is just like piano move and you get out
28:40
Speaker 1: of the way. That seems like an easier path for
28:42
Speaker 1: selection to take than being able to withstand a piano
28:45
Speaker 1: dropping on your head.
28:46
Speaker 2: Also, it probably takes a while to get into this
28:48
Speaker 2: ton state, so it's not like target grade is swimming
28:50
Speaker 2: along sees a comet coming down and then like switches
28:53
Speaker 2: into ton state like a superhero. This is like already
28:56
Speaker 2: happens to be in this state and then survives the impact, right.
29:00
Speaker 1: Yep, yes, exactly, Okay, they can get into it, like
29:02
Speaker 1: I think a couple hours pretty quick, but not like immediately,
29:05
Speaker 1: not like snap in your fingers. It takes some work.
29:07
Speaker 2: A couple hours. Isn't great for our superhero movie plot.
29:09
Speaker 1: Yeah, that's true. But you know, if Michael Bay contacts us,
29:12
Speaker 1: we can like change some biology stuff. Like, as we've
29:15
Speaker 1: talked about in the past, what's important is your consistent
29:18
Speaker 1: so you know, we will consistently change their biology. Another
29:22
Speaker 1: incredible stressor they've been able to survive is a bunch
29:26
Speaker 1: of different kinds of radiation at levels that certainly would
29:29
Speaker 1: have killed people. Amazing, and we think that we know
29:33
Speaker 1: partly how they do this one. So tartar grades produce
29:38
Speaker 1: a class of proteins called intrinsically disordered proteins. And you're like,
29:42
Speaker 1: why are you making me hear that multi syllabic phrase
29:45
Speaker 1: that is, in.
29:46
Speaker 2: Fact exactly what was going through my mind.
29:47
Speaker 1: Yes, I know, I've gotten to know you pretty well.
29:49
Speaker 1: But so the fact that they're disordered and like kind
29:52
Speaker 1: of all over the place is important. And so if
29:54
Speaker 1: you think of this like blobby thing, this blobby protein
29:58
Speaker 1: is attracted to DNA, so your genetic material that codes
30:03
Speaker 1: for everything else, and it binds to the DNA like electrostatically.
30:07
Speaker 1: And because it's sort of like this blobby all over thing,
30:10
Speaker 1: and you know, I wish the listeners could see the
30:12
Speaker 1: beautiful things I'm doing with my arms right now.
30:14
Speaker 2: You're basically Italian right now.
30:16
Speaker 1: I was just gonna say that, Yeah, you beat me
30:18
Speaker 1: to it. And so this blobby thing is able to
30:21
Speaker 1: just kind of like fall over the DNA like a coat,
30:24
Speaker 1: and then it appears to provide like a physical barrier
30:27
Speaker 1: to the radiation and protect the DNA from breaking. And
30:30
Speaker 1: in fact, they were able to get bacteria by like
30:34
Speaker 1: moving some genes around to produce these proteins, and then
30:37
Speaker 1: they mix them in to human cells, and these proteins
30:41
Speaker 1: bound to human DNA. And when you blasted the human
30:45
Speaker 1: DNA with radiation, they were protected by these disordered, blobby
30:51
Speaker 1: kinds of proteins that were like coats for the DNA,
30:54
Speaker 1: radiation shielding for the DNA.
30:55
Speaker 2: Oh my god, this is our superhero origin story. Bitten
30:58
Speaker 2: by a radioactive chartic D, Kelly gained that critter's ability
31:03
Speaker 2: to withstand radiation.
31:05
Speaker 1: It's gonna be amazing coming it's fall.
31:09
Speaker 2: Tart to Kelly. So let's reminder of listeners exactly what
31:13
Speaker 2: radiation is and how it damages to sell because we're
31:16
Speaker 2: talking about X rays and ultraviolet light and gamma radiation.
31:19
Speaker 2: Those all sound like very different things, but they're all
31:21
Speaker 2: just photons. Talking about very high energy photons, photons like
31:25
Speaker 2: the ones emitted by your lamp or your screen or
31:28
Speaker 2: by the sun, just higher energy, so they like penetrate deeper.
31:32
Speaker 2: And the problem, of course, is that when these things
31:34
Speaker 2: penetrate into your cells, they can like blast open delicate
31:37
Speaker 2: stuff like your DNA, and that's how you get cancer, right,
31:41
Speaker 2: Or also sometimes that's how your kids end up being
31:43
Speaker 2: like amazing cross country runners even though you have no
31:46
Speaker 2: athletic skills yourself. Hypothetically speaking, right, mutations are sometimes good
31:51
Speaker 2: and sometimes bad. You never know, But it's like going
31:53
Speaker 2: into computer code and just like randomly changing a few
31:56
Speaker 2: things and hoping that it gets better. Yeah, sometimes it
31:58
Speaker 2: gets worse, And so that's what we're protecting against, right,
32:01
Speaker 2: that's right.
32:01
Speaker 1: And the study that I was reading it was looking
32:03
Speaker 1: at breaks in the DNA. So DNA is like a
32:06
Speaker 1: double stranded helix. It's almost like you took a ladder
32:08
Speaker 1: and that sort of twisted it so that it's like
32:11
Speaker 1: a spiral staircase, and they're looking at do you get
32:14
Speaker 1: one break in the ladder or two breaks in the ladder.
32:17
Speaker 1: So does one of the like long poles break or
32:19
Speaker 1: both of them, And so they were able to find
32:21
Speaker 1: that you get fewer breaks overall when you have this
32:24
Speaker 1: like radiation coat protecting it.
32:27
Speaker 2: So why don't we all have this radiation coat. Is
32:29
Speaker 2: it like good to be susceptible to radiation because then
32:32
Speaker 2: you get these mutations? Or is this radiation coat like
32:35
Speaker 2: expensive in some other way that's usually not worth it.
32:38
Speaker 1: I think it'll probably surprise some people to learn that
32:41
Speaker 1: usually when you get blasted with radiation, you get like cancer,
32:43
Speaker 1: but not superpowers. You probably generally want to avoid it.
32:48
Speaker 1: But to be clear, we don't actually know the answer
32:50
Speaker 1: to this because we don't understand the system very well.
32:52
Speaker 1: But one hypothesis that I read about was that, you know,
32:55
Speaker 1: probably we don't all have these because if you've got
32:58
Speaker 1: something that's like a coat for your DNA, you know,
33:01
Speaker 1: like the way your DNA replicates is like stuff comes
33:04
Speaker 1: in and opens up the double strand, and like there's
33:06
Speaker 1: machinery that starts replicating stuff, and if you've got like
33:09
Speaker 1: a big coat covering it, you can't do that stuff
33:11
Speaker 1: and like gets in the way, And so it might
33:13
Speaker 1: be nice to protect you during a period where you're
33:15
Speaker 1: not doing a lot of replicating your DNA because you're
33:18
Speaker 1: just kind of hanging out waiting for the awful situation
33:20
Speaker 1: you find yourself into. Pass.
33:22
Speaker 2: So it's sort of like you're locking down your DNA,
33:24
Speaker 2: but then you can't really use it. It's like when
33:25
Speaker 2: you freeze your credit and then you can't like open
33:27
Speaker 2: a new bank account because you've protecting yourself against yourself.
33:31
Speaker 1: That's right. You shouldn't have sent your Social Security number
33:33
Speaker 1: to that person over email. Kelly from the past anyway.
33:38
Speaker 1: So they're surprisingly radiation resistant. Let's talk about what happens
33:42
Speaker 1: when you dip them in liquid nitrogen or expose them
33:45
Speaker 1: to the vacuum of space next. All right, we're back.
34:04
Speaker 1: We've talked about how tartar grades are amazingly resistant to
34:08
Speaker 1: high pressures, amazingly resistant to radiation, although not completely resistant.
34:13
Speaker 1: You can kill them eventually, but they're impressively resistant. Also, weirdly,
34:17
Speaker 1: we've been very interested in exposing them to temperature extremes,
34:20
Speaker 1: and so, Daniel, I have a question for you. There's
34:22
Speaker 1: this commonly made claim that you can expose tartar grades
34:27
Speaker 1: to very close to absolute zero and they survive cool
34:32
Speaker 1: This was from a paper in the nineteen fifties in
34:35
Speaker 1: a language I don't speak, and I couldn't find the original.
34:40
Speaker 1: How long have we been able to create temperatures close
34:43
Speaker 1: to absolute zero? Has it been since the nineteen fifties?
34:46
Speaker 2: So the history is that colder, earlier than you might expect.
34:50
Speaker 2: Like Faraday, Michael Faraday, who did so much amazing work
34:54
Speaker 2: on electromagnetism, he got stuffed down like negative one hundred
34:57
Speaker 2: and thirty s, so that's one hundred and forty degrees
34:59
Speaker 2: above app flue zero. That was in eighteen forty five.
35:02
Speaker 2: And then a guy named Doer after which the Doers
35:05
Speaker 2: are named liquified hydrogen down to twenty one kelvin in
35:09
Speaker 2: eighteen ninety eight. Right, So this is already just twenty
35:12
Speaker 2: degrees above absolute zero in the eighteen hundreds, and then
35:16
Speaker 2: it was just ten years later we got down to
35:19
Speaker 2: four degrees kelvin when the Nobel Prize in nineteen thirteen
35:22
Speaker 2: for that one.
35:23
Speaker 1: Oh wow.
35:23
Speaker 2: And the current record, the closest we've ever gotten is
35:26
Speaker 2: one hundred pico kelvins. That's zero point zer zero zero
35:30
Speaker 2: zers or zero zerzero zero one kelvin. And there's an
35:34
Speaker 2: instrument on the International Space Station that's going to try
35:37
Speaker 2: to get to one pico kelvin is called the cold
35:40
Speaker 2: Atom Lab.
35:41
Speaker 1: All right, okay, so definitely by the nineteen fifties you
35:44
Speaker 1: could be testing how tartar grades survived too close to
35:48
Speaker 1: absolute zero? And Daniel, what is absolute zero? I believe
35:51
Speaker 1: that's the temperature at which molecular stuff just stops and
35:54
Speaker 1: everything's frozen in place. Is that right?
35:55
Speaker 2: Absolute zero is a theoretical limit we've never achieved and
35:59
Speaker 2: don't know if it's act actually possible. And essentially the
36:02
Speaker 2: argument is when things get colder, velocities internally slow down.
36:06
Speaker 2: It's a model of temperature that says things are hot
36:09
Speaker 2: because the stuff inside it is moving fast or wiggling
36:12
Speaker 2: a lot. And so what happens when things get colder,
36:14
Speaker 2: They move slower, They wiggle less. Okay, make them colder,
36:17
Speaker 2: all right, they wiggle less. Is there a point at
36:19
Speaker 2: which all wiggling stops? And so sort of the way
36:23
Speaker 2: like when you learn calculus in high school, you could
36:25
Speaker 2: never actually approach infinity. You like approach it and see
36:27
Speaker 2: what the tendencies are. In that same way, we estimate
36:30
Speaker 2: that absolute zero might be the place where everything stops.
36:34
Speaker 2: But that's extrapolating, and it's all kind of classical physics
36:37
Speaker 2: and quantum mechanics says you could never actually get there
36:39
Speaker 2: because there's a minimum energy to all the fields in
36:42
Speaker 2: the universe, so everything has to be buzzing because if
36:45
Speaker 2: anything was ever completely motionless, they would have no uncertainty,
36:50
Speaker 2: and there's a minimum uncertainty to the fabric of the universe.
36:52
Speaker 2: So we don't know if anything can ever get to
36:54
Speaker 2: absolute zero, if it's a real thing or not. But
36:57
Speaker 2: we've gotten pretty close.
36:58
Speaker 1: Okay, and grades were able to handle it for at
37:01
Speaker 1: least a little while, even though I couldn't find the
37:03
Speaker 1: original paper.
37:04
Speaker 2: Wow, So how cold did they get these heartigrades?
37:06
Speaker 1: So the paper that I was able to find both
37:09
Speaker 1: because it was online and in my native language. They
37:12
Speaker 1: dipped them in liquid nitrogen, So that's negative one hundred
37:15
Speaker 1: and ninety six degrees celsius. Pretty cold, super cold, and
37:19
Speaker 1: ninety percent of them survived.
37:22
Speaker 2: Wow.
37:22
Speaker 1: Yeah, it was for fifteen minutes.
37:24
Speaker 2: I don't think many Californians would survive at that temperature
37:27
Speaker 2: for that.
37:27
Speaker 1: Long, you know, even though Virginians are a hardier bunch
37:30
Speaker 1: than you all Californians, I don't think we could have
37:33
Speaker 1: survived that either.
37:33
Speaker 2: That's because you have to wrap your heart in so
37:35
Speaker 2: many layers of protection that it's not available during normal use. See,
37:39
Speaker 2: that's why Californians are friendlier.
37:41
Speaker 1: That doesn't make sense. No, no, no, no, no, that's
37:44
Speaker 1: not how this works, all right. But one point that
37:47
Speaker 1: I want to make here is that some of the
37:49
Speaker 1: Tartar grades that were not in the Ton state also survived,
37:54
Speaker 1: and that was also true during the radiation experiments too.
37:58
Speaker 2: Oh wow, and.
37:59
Speaker 1: That makes us like those disordered proteins that we were
38:03
Speaker 1: talking about, maybe they help, but maybe that's not the
38:05
Speaker 1: whole picture, because you wouldn't expect the active, untunned individuals
38:12
Speaker 1: to be surviving if those proteins were the whole picture,
38:14
Speaker 1: because they're not making a bunch of those when they're
38:16
Speaker 1: not in the Ton state. So everything's complicated. Okay, But
38:21
Speaker 1: now let's get to the juicy stuff. Space. Some scientists
38:25
Speaker 1: have wanted to figure out if Tarte grades can survive
38:28
Speaker 1: the super extreme environment of space. So first we sent
38:32
Speaker 1: them up into spacecraft and expose them to microgravity and
38:35
Speaker 1: some space radiation. But they were still like in this
38:37
Speaker 1: temperature controlled container thing. They did pretty well. In response
38:41
Speaker 1: to microgravity. Like, whereas humans are bones and our muscles
38:44
Speaker 1: fall apart in the ton state, they're just kind of
38:47
Speaker 1: chillin And.
38:47
Speaker 2: Let's remind ourselves what is the extreme environment of space?
38:51
Speaker 2: What's difficult about space? So this high radiation because we
38:53
Speaker 2: don't have the magnetic field of Earth to bend those
38:55
Speaker 2: particles away, and we don't have the atmosphere to shield us.
38:58
Speaker 2: Then there's microgravity that's not so extreme. But then there
39:01
Speaker 2: could also be low temperatures if you're out in space,
39:04
Speaker 2: low pressure, and then of course no oxygen.
39:07
Speaker 1: Yes, And so this first experiment was replicating the microgravity problem,
39:12
Speaker 1: but they weren't exposed to the vacuum of space, they
39:14
Speaker 1: weren't experiencing full radiation, and they were in low Earth orbit,
39:18
Speaker 1: so they were still protected by the magnetosphere, and they
39:21
Speaker 1: weren't experiencing the kind of temperatures extremes you usually experience
39:24
Speaker 1: in space. Okay, So another experiment or a set of
39:27
Speaker 1: experiments amped things up. They put them in a container
39:30
Speaker 1: that had holes in it, and then they had a
39:33
Speaker 1: variety of UV filters on top of the different containers.
39:36
Speaker 1: So some of the tartar grades were exposed to the
39:39
Speaker 1: vacuum of space well, having their temperature controlled but not
39:43
Speaker 1: being exposed to UV radiation. And then others experienced various
39:47
Speaker 1: kinds of UV radiation well being exposed to the vacuum
39:50
Speaker 1: of space while still having their temperatures controlled in a
39:52
Speaker 1: nice way. Does that all make sense? Vacuum of space
39:56
Speaker 1: they rocked at which, to be clear, it would kill people, right.
40:01
Speaker 1: The three Soviet cosmonauts who were exposed to the vacuum
40:04
Speaker 1: of space did not survive the experience, and that's pretty
40:08
Speaker 1: much what you should expect for the rest of us too.
40:10
Speaker 2: The thing that first kills you there is what is
40:11
Speaker 2: it the low pressure that like, your eyeballs are boiling
40:14
Speaker 2: and your blood is boiling because you're used to being
40:16
Speaker 2: squeezed in by all the air.
40:18
Speaker 1: I think what killed them in particular is that the
40:20
Speaker 1: nitrogen boiled out of their blood and it happened in
40:22
Speaker 1: their brains and they had a bunch of brain hemorrhaging.
40:25
Speaker 2: That does not sound good, no, And.
40:27
Speaker 1: So TARTA grades don't have the same circulatory system, the
40:30
Speaker 1: internal goo that keeps these little guys going. It's not
40:33
Speaker 1: the same system as ours. So you might not have
40:34
Speaker 1: to worry about nitrogen bubbles, but also they've gotten like
40:37
Speaker 1: a bunch of the water out already, and so you're
40:39
Speaker 1: probably not going to have like stuff that could bubble out.
40:42
Speaker 1: So they did great in the vacuum of space, but
40:45
Speaker 1: as soon as you opened those filters so that you
40:47
Speaker 1: reradiation could get them too, they started dying in droves.
40:50
Speaker 1: Like I think, oh, really, maybe four of the like
40:54
Speaker 1: sixty survived that exposure, and that wasn't fair, like a
40:58
Speaker 1: whole lifetime. I think it was. Like one of the
41:00
Speaker 1: things that frustrates me about papers that are published in
41:02
Speaker 1: really high impact journals is that they give you a
41:04
Speaker 1: short page limit and so important details get left out.
41:08
Speaker 1: And I couldn't figure out how long they were exposed,
41:10
Speaker 1: but it couldn't have been more than ten days, because
41:13
Speaker 1: that's how long the entire mission lasted.
41:15
Speaker 2: Said, we heard earlier that they can survive UV radiation
41:18
Speaker 2: on its own, and we heard just now that they
41:20
Speaker 2: can survive the vacuum of space. But you're saying that
41:22
Speaker 2: you combine them, then that snuffs them out, so they
41:25
Speaker 2: can't survive the combination.
41:27
Speaker 1: So here's the problem. All these studies that we've been
41:29
Speaker 1: talking about, yeah, all looking at different species of tartar grades.
41:33
Speaker 1: So because a tartar grade could survive some high radiation
41:37
Speaker 1: doesn't mean that the next species that you expose it
41:39
Speaker 1: to could survive. And also, not all of these studies
41:43
Speaker 1: have the exact same experimental design, so it could be
41:46
Speaker 1: that a bunch of the tartar grades that were exposed
41:47
Speaker 1: to radiation were exposed to it for like five minutes,
41:49
Speaker 1: but when you're exposed to it for ten days, then
41:52
Speaker 1: you start dying. And so you know, when you hear
41:56
Speaker 1: someone like rattling off a list of all the extreme
41:58
Speaker 1: stuff that tartar grades can do, so some species can
42:01
Speaker 1: do some of those things for some lengths of time,
42:04
Speaker 1: but it's not like all of them can do all
42:06
Speaker 1: of those amazing things indefinitely.
42:07
Speaker 2: So that's like saying, oh, polar bears can swim in
42:10
Speaker 2: cold water and grizzly bears can run really fast, and
42:13
Speaker 2: doesn't mean that they can do.
42:14
Speaker 1: Both, yes, exactly, or that they could do both like forever.
42:17
Speaker 1: Like eventually, the polar bear is going to need to
42:19
Speaker 1: find land and stop swimming. So the space people don't
42:21
Speaker 1: invite me to their parties. The tartar grade people aren't
42:23
Speaker 1: going to invite me to their parties anyway, It's all right,
42:25
Speaker 1: I'm a downer.
42:26
Speaker 2: Physicists will always invite you to their parties, killing because
42:29
Speaker 2: we don't have any.
42:30
Speaker 1: Oh, oh, that's probably not true. Maybe, So here is
42:37
Speaker 1: the question everybody's been dying to know the answer to.
42:40
Speaker 1: In twenty nineteen, the Bearasheet Lunar Lander crashed on the Moon.
42:45
Speaker 1: It contained tartar grades, although the government officials who approved
42:49
Speaker 1: that launch did not know that because the company that
42:52
Speaker 1: had bought space on the lander did not disclose that
42:55
Speaker 1: they were sending biological specimens, which they are supposed to do.
42:59
Speaker 2: And why were they sending biological specimens? Was this some
43:02
Speaker 2: can tartar grades survive experiment? Or were they hoping to
43:05
Speaker 2: populate the Moon?
43:06
Speaker 1: I hope that it was a can tartar grade survive experiment,
43:09
Speaker 1: and also like that probably would have been a pretty
43:11
Speaker 1: cool pr move for their mission to be able to
43:15
Speaker 1: be like, oh, tartar grades in space, they really can
43:17
Speaker 1: survive everything. But for whatever reason, they decided to not
43:20
Speaker 1: disclose that it was happening, and I was not able
43:23
Speaker 1: to figure out what species they sent. I spent a
43:26
Speaker 1: long time asking. I asked Blue Sky. Nobody knew and
43:30
Speaker 1: if you know, let me know. But so part of
43:32
Speaker 1: figuring out whether or not they can survive involves knowing
43:35
Speaker 1: the tolerances for that species in particular, right, But I
43:38
Speaker 1: don't know what species it is.
43:40
Speaker 2: So the answer is it depends.
43:42
Speaker 1: Well, we were talking about biology, so of course the
43:45
Speaker 1: answer is it depends. Biology. Doesn't disappoint but I think
43:48
Speaker 1: probably not. And here's why. All right, So, first somebody
43:52
Speaker 1: decided to stick tartar grades in bullets and then shoot
43:56
Speaker 1: them at sandbags to try to figure out if they
43:58
Speaker 1: could survive the impact and the subsequent shock wave that
44:01
Speaker 1: would have been experienced when the lander crashed into the moon.
44:05
Speaker 2: This was an experiment done in response to the crash,
44:07
Speaker 2: like just to answer this question, not an independently motivated experiment.
44:11
Speaker 1: That's exactly right. Wow, it doesn't say that in the paper,
44:14
Speaker 1: but I found an interview with the authors it sounds
44:16
Speaker 1: like that's true. And so there's a sentence in the
44:18
Speaker 1: paper that says, accordingly, we have fired tartar grades at
44:22
Speaker 1: high speed in a gun onto sand targets, subjecting them
44:25
Speaker 1: to impact shocks and evaluating their survival. Actually, this paper
44:28
Speaker 1: was all about if something hit the Earth and dislodged
44:32
Speaker 1: Earth that had tartar grades. Could the tartar grade survive
44:35
Speaker 1: base and survive so that they could land on the
44:38
Speaker 1: Moon or Mars or populated. So it was a study
44:40
Speaker 1: about pants spermia on the possibility of the tartar grades
44:43
Speaker 1: becoming you know, interplanetary before the rest of us. I
44:46
Speaker 1: found an interview where the author said, probably they wouldn't
44:51
Speaker 1: have survived because of the shockwave. So it seems unlikely
44:55
Speaker 1: that they survived. But let's go ahead and assume that
44:59
Speaker 1: maybe they got lucky and they survived the initial shockwave, because.
45:02
Speaker 2: We don't know the speed of the descent of the lander, right,
45:05
Speaker 2: it depends on when it failed. If it fails just
45:07
Speaker 2: before it hits the surface, it's going to be a
45:08
Speaker 2: pretty gentle crash. If it fails really far away, then
45:11
Speaker 2: it's going to plummet towards the surface. But the Moon's
45:14
Speaker 2: gravity is still not very strong, so it's not going
45:17
Speaker 2: to be going that fast, right, But still it depends.
45:20
Speaker 1: This paper that I read had a bunch of different
45:22
Speaker 1: impact speeds and shockwaves that they looked at, and I
45:25
Speaker 1: looked on the internet to figure out what we think
45:27
Speaker 1: the impact speed was of the bearsheet lander and based
45:31
Speaker 1: on their table, I think it's possible it survived. But
45:34
Speaker 1: then in an interview with the authors they said, no, no, no,
45:37
Speaker 1: the shockwave, it wouldn't have survived. But then I found
45:40
Speaker 1: another paper that was like, no, it might have survived
45:42
Speaker 1: based on the info and the table. So you know,
45:44
Speaker 1: it depends.
45:45
Speaker 2: Were any of these papers written by anonymous authors from
45:47
Speaker 2: the Moon?
45:48
Speaker 1: Oh, I don't know. Yeah, the TARTI grades achieved sentience.
45:52
Speaker 1: I think we have to worry about them sending like
45:54
Speaker 1: moon rocks down at us as punishment for all the
45:56
Speaker 1: things that we've done to them in the lab.
45:58
Speaker 2: All right, so you think it's unlikely they survey the
46:00
Speaker 2: impact on the Moon once they're on the Moon, say
46:03
Speaker 2: they happen to survivor if you do, then what did
46:05
Speaker 2: they have to put up with?
46:06
Speaker 1: So now they've got to worry about radiation. So the
46:08
Speaker 1: Moon doesn't have a strong planet wide magnetosphere like Earth
46:12
Speaker 1: does or a thick atmosphere, so they'd be exposed to
46:15
Speaker 1: all of the space radiation. And as we saw in
46:17
Speaker 1: those earlier studies, base radiation, solar radiation is bad for them,
46:21
Speaker 1: so that would kill them if they were exposed to it.
46:24
Speaker 1: But let's say, well, what if maybe when they crashed,
46:28
Speaker 1: the little container that was holding them ended up burying
46:31
Speaker 1: itself under the regolith, and so now the regolith is
46:33
Speaker 1: protecting them from radiation. Creative, let's imagine that. Okay, so
46:37
Speaker 1: now you've got to deal with temperature. We know they
46:40
Speaker 1: can handle really cold temperatures. The moon at night has
46:44
Speaker 1: about a two week period where it's negative one hundred
46:46
Speaker 1: and thirty three celsius, which is negative two hundred and
46:49
Speaker 1: eight fahrenheit. That's at the equator. We know that they
46:53
Speaker 1: survived negative one hundred and ninety six celsius, which is
46:55
Speaker 1: more than that, but for fifteen minutes, So we don't
46:58
Speaker 1: know if they could survive the law long polar nights,
47:01
Speaker 1: which are the equivalent of two weeks on Earth. But
47:04
Speaker 1: I think the bigger problem is one temperature swings back
47:08
Speaker 1: and forth between extreme heat and extreme cold, but two
47:10
Speaker 1: the fact that the moon does get really hot, so
47:12
Speaker 1: without that atmosphere, things just heat up a lot. So
47:16
Speaker 1: without an atmosphere, things get really hot and really cold.
47:19
Speaker 1: There's nothing to sort of dampen the temperature swings. And
47:21
Speaker 1: as we saw previously, tartar grades don't do great at
47:25
Speaker 1: really high temperatures. They do pretty well with cold temperatures,
47:28
Speaker 1: but with hot temperatures they can't survive for super long.
47:30
Speaker 1: But let's imagine, Hey, we said that they're underneath the regolith.
47:34
Speaker 1: They're protected from radiation. Underneath the regolith, you're also to
47:37
Speaker 1: some extent protected from temperature extremes. So maybe they're still
47:41
Speaker 1: alive there. But now you've got a problem with water.
47:45
Speaker 1: So in order to come out of their ton state,
47:48
Speaker 1: they need to be hydrated, and the lunar regolith is
47:52
Speaker 1: as wet as cement, so not super wet. So say
47:56
Speaker 1: it got hit by a comet that was bringing water, Well,
48:00
Speaker 1: I think that impact and the like heating up that
48:03
Speaker 1: happens when the comet hits the surface could kill the
48:05
Speaker 1: tartar grades. But also if you get water, you're only
48:08
Speaker 1: going to get it temporarily and then it's going to
48:10
Speaker 1: like be lost to the vacuum of space. So I
48:12
Speaker 1: don't see them getting out of their ton state. And
48:14
Speaker 1: then the final big problem is food. If they did
48:17
Speaker 1: get out of their Ton state, they don't have anything
48:20
Speaker 1: to eat, Like, I don't know what species this is.
48:22
Speaker 1: If this is the carnivorous ones and there was enough
48:24
Speaker 1: of a size variability, maybe the big ones could eat
48:27
Speaker 1: the little ones, but eventually you're gonna run out of it.
48:30
Speaker 1: So I don't see the tartar grades permanently settling the Moon.
48:34
Speaker 2: So it's unlikely that the tartar grades are like water,
48:37
Speaker 2: bearing around, being cute and bouncing around the surface of
48:40
Speaker 2: the Moon, living happily. But it's possible that some of
48:43
Speaker 2: them are in the ton state, survive the impact, are
48:46
Speaker 2: buried in the regolith and don't need water or food
48:49
Speaker 2: because they're just basically paused for a long time, but
48:53
Speaker 2: maybe not forever.
48:54
Speaker 1: I feel like that is a very low probability scenario,
48:57
Speaker 1: but it depends. I don't know that I can rule
49:00
Speaker 1: it out entirely. Maybe they're still in their ton state.
49:02
Speaker 1: We'll find them. I mean, we know that they can't
49:04
Speaker 1: be in that state for forever, and it's already been
49:06
Speaker 1: like five years, so I'm not super hopeful.
49:09
Speaker 2: Sorry, But if a huge impactor slams into the Earth
49:12
Speaker 2: and like completely demolishes it so there's no record of
49:15
Speaker 2: life left on Earth, there could still be on the
49:19
Speaker 2: Moon some basically like frozen proof that there was once
49:23
Speaker 2: life on Earth. So that aliens visiting in the deep
49:26
Speaker 2: future could be like, oh, look, there was something here once.
49:29
Speaker 1: Maybe, or those incredible temperature swings have killed them and
49:34
Speaker 1: the bacteria that live in their guts have consumed them
49:36
Speaker 1: and they've become liquid munch because biologies grows.
49:39
Speaker 2: Also, all right, well, I guess we're just gonna have
49:41
Speaker 2: to wait millions of years for a huge impact and
49:43
Speaker 2: alien arrival to find out the answer to that one.
49:46
Speaker 1: Ah, and people say I'm the negative one.
49:49
Speaker 2: All right, well, thank you Tim for your really fun question.
49:51
Speaker 2: I think Kelly had a lot of fun digging into
49:54
Speaker 2: the research on tartar grades.
49:56
Speaker 1: I did. It distracted me while I was sick and
49:58
Speaker 1: couldn't get out of bed, So thank you for this
50:00
Speaker 1: wonderful question. I had a blast.
50:02
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50:04
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50:09
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50:11
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