461: Fun Facts to Combat the Horrors (w/ MB Ramirez!)

Were there islands around during Pangea? Are there fossils under the ice in Antarctica? What is your favorite fun fact? What will happen to our satellites after humans are gone? What is the most recent species to have evolved? What ecosystems is Earth lacking now that it used to have in the past? …Hank and MB have answers! If you're in need of dubious advice, email us at [email protected] Join us for monthly livestreams at patreon.com/dearhankandjohn Produced for Hank and John Green by Complexly See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Hank Green?

  You're listening to a Complexly podcast.

• 0:09Hank Green?

  Hello and welcome to Dear Hank and John.

• 0:13Speaker 01

  Or as I like to think of it, Dear Hank and MB.

• 0:16Hank Green?

  It's a podcast where two brothers and sometimes two friends answer your questions, give you dubious advice and bring you all the week's news from both Mars and AFC Wimbledon. Hello, MB. Hello. You're a... Oh, I have to do a dad joke. MB, what do you call a dog that does science?

• 0:34Speaker 01

  A science dog?

• 0:36Hank Green?

  A lab.

• 0:38Speaker 01

  Oh, yeah, that's a dad joke. Also, Wimbledon?

• 0:45Hank Green?

  Wimbledon?

• 0:46Speaker 01

  I have to learn news about that today?

• 0:48Hank Green?

  No, no, no, don't worry. We don't have to do news. We could... The news... I have... You're confronting the news immediately that you have to do news about soccer. But no, you don't, because the news is actually...

• 1:01Speaker 01

  I thought that was tennis.

• 1:02Hank Green?

  Oh, it is also. The news is that there is a new six-episode PBS series, starting Wednesday, July 19th, 2026, set during the Permian period, hundreds of millions of years ago. Eons Life and Death on Pangea transports viewers to a world shaped by the supercontinent Pangea. Extreme climate shifts, ecosystems unlike anything that we have today. The series traces how Earth reached the brink of ecological collapse and how it ultimately recovered. It's streaming on all PBS platforms. This is very cool. It's... So if you've got whatever on the Roku or the PBS app or whatever, there's the... But it is also going to be on

• 1:42Hank Green?

  the Eons YouTube channel, produced by Complexly and select PBS television stations. MB, how has that been to make?

• 1:52Speaker 01

  Uh, I think more excitingly, how has it been to be able to tell everybody that it's coming? Because we started this like, what, two, three years ago at this point? And like, we're traveling all over the US and like, getting to visit all these cool sites. And I couldn't tell anybody. And now we get to be excited. So I'm really, really stoked that we're... It's time. It's time for everyone to see what we've been working on.

• 2:16Hank Green?

  Yeah. I mean, we hear about Pangea. We know that is a thing. We look at South America and Africa, and we think those two things could fit together. And then we find the same dinosaurs on both sides. And we're like, oh, my God, they did. They did fit together. There's other evidence. It's not just that. But that's the... That's the school... The school book version. Yeah. And, uh, but what you don't think about is like, what are the implications of almost all of the land being globbed up in one central place? And one of them that occurs to me, and I don't actually know if this is true, is that the middle wouldn't get much water.

• 2:51Speaker 01

  It does not, dude. Oh, my God. It is dry and desert-y and not a great place to live at all. And then the other implication is like, yeah, okay, all the land is together at once. But obviously, it's not like that anymore. So imagine the amount of volcanism and movement that it takes to move these plates apart. That's almost as, if not more significant, uh, when we're looking at how it affects life on Earth.

• 3:16Hank Green?

  Right. I mean, it seems, it would seem that these things move very slowly. But actually, that's... It's fast. The whole Atlantic Ocean had to appear. And it started as one little rift and then... Is that happening anywhere right now?

• 3:33Speaker 01

  We can see that happening right now. Yeah, literally. There's the African Rift Valley in East Africa. It's a divergent plate boundary. And so, you know, if you want some nice waterfront property, you could buy some land there, wait a couple million years, and you'll be set. So, you know, slow in human terms.

• 3:51Hank Green?

  We're forming a new ocean right now. Oh, my God.

• 3:53Speaker 01

  And it doesn't have a name yet, maybe? I don't know.

• 3:55Hank Green?

  The ocean. Sure.

• 3:56Speaker 01

  I wonder if someone has named it yet.

• 3:58Hank Green?

  Somebody's trying. They're like, "I'm the guy who figured this out. Name it after me," is probably what's happening. Uh, I... Are we gonna be around to see that?

• 4:11Speaker 01

  Uh, well, you could watch...

• 4:13Hank Green?

  This is more of a humans' question than it is a Dear Hank and John question.

• 4:16Speaker 01

  It's a Eons question. We did a whole episode about Pangea Ultima, which is, I mean, if we can rewind and see how the continents have been moving, and if we know what direction each of the plates are moving right now, you could just fast forward that, right? Like, if we know that East African Rift Valley is pulling apart, fast forward there, fast forward all other continents and plates, and you can see when theoretically, nothing else changing. Pangea Ultima, yeah.

• 4:41Hank Green?

  Future Pangea.

• 4:42Speaker 01

  Go watch it on Eons.

• 4:43Hank Green?

  Okay. Well, you're not gonna give away all your secrets here. It's gonna be on YouTube. It's crazy that I still do, even now. I'm like, oh, my God, but it's gonna be on Real TV, even though, of course, no one uses Real TV.

• 4:59Speaker 01

  I know. That's why everyone is like, but it's also on YouTube, right? Like, how do I actually see it, myself included?

• 5:05Hank Green?

  How do I figure out how to watch this at a time on a station? Or, or, I could watch it whenever I want to, download it and watch it on a plane.

• 5:14Speaker 01

  The PBS app, which like, you can download onto Roku or whatever. So...

• 5:18Hank Green?

  Right. Yeah, yeah, yeah, yeah.

• 5:19Speaker 01

  We're here for you. You don't need a TiVo. You don't need to go to your grandma's house, although you should go to your grandma's house and turn on Life and Death in Pangea. What a great family bonding moment. Yes.

• 5:32Hank Green?

  That's great.

• 5:32Speaker 01

  Actually.

• 5:33Hank Green?

  We need more things like that. The universe is too convenient. So, yeah, it's available to stream starting July 29th, which is very soon. I don't actually know when this episode comes out. It goes live on July 29th. It says so in the notes, so it's today.

• 5:50Speaker 01

  Yeah. Happy launch day.

• 5:53Hank Green?

  Happy launch day, everybody. All right. We asked people to send in questions that may be somewhat more suited to your skills than the traditional Dear Hank and John questions, and indeed, they did. And I want to start with an amazing question from Brendan, who asks, "Dear Hank and MB, were there islands around during Pangea?" Brendan, age eight, with support from his mom, age adult.

• 6:13Speaker 01

  Age adult is fantastic.

• 6:15Hank Green?

  It's a great question, because it does... It does... Well, here's two things. I don't actually know the answer to this question. You're the expert. So I will, I will provide you with two thoughts, though. One, islands come from somewhere. Like Hawaii, for example, is the result of a great deal of like, weird volcanism. That doesn't necessarily happen throughout all of the history of Earth. Like, that isn't a inevitability. It's a circumstance based on what the Earth is like right now. And then, two, everything's smushed up. So it seems a little bit like there wouldn't be islands. But my guess is that there must have been something.

• 6:51Speaker 01

  There's definitely islands, yes. And there's like, two ways we know this. And there's two different types of islands. So first of all, uh, when we're talking about paleontology or the Earth or nature, nothing's absolute. We're saying Pangea, all the land is smushed together. We mean all of our modern continents are smushed together. There are still around the edge of that Pangea, right? That is a plate. There are other plates coming up against it, and that leads to subduction. So the way that I like to explain subduction to my students is, I drive a Prius, of course, because I'm an environmental scientist. I have a tiny little car right here, driving on the freeway. And if I'm driving on the

• 7:31Speaker 01

  freeway and an 18-wheeler giant truck goes on the wrong lane, head-on collision against my car...

• 7:38Hank Green?

  We're explaining this through death.

• 7:41Speaker 01

  Well, but it's visceral.

• 7:43Hank Green?

  Yeah.

• 7:44Speaker 01

  Well, and how do I die? Did we bounce off of each other? Did like, my car go over the 18-wheeler? Not 18-wheelers, like, crushing the top of my car. I miraculously survive in this scenario. Actually, I'm fine.

• 7:57Hank Green?

  You're fine.

• 7:58Speaker 01

  Yeah.

• 7:58Hank Green?

  Cool.

• 7:58Speaker 01

  My car took the impact. This is Miracle Land. But car smushed underneath. So when we're thinking about the ocean plates, which is my Prius, versus the continental plates, which is the 18-wheeler, they're much thicker. And so the ocean, as it's smashing against the continent, goes underneath. But what's underneath the continent? You've got the basic kindergarten layers of the Earth, right? You've got the crust, you've got the mantle, you've got the core. And simplifying very much, the mantle is very hot and lava-like. And so if you're smushing my little Prius into a giant vat of lava, it's gonna melt in the lava. And then those pieces of my Prius are gonna float up because hot things rise. And that leads to volcanic island chains.

• 8:43Hank Green?

  Oh, wow.

• 8:44Speaker 01

  So you're still building island chains around Pangea, but you mentioned Hawaii.

• 8:50Hank Green?

  Yeah.

• 8:50Speaker 01

  Yes, island chains are still, because plate tectonics is still happening. That's what led to Pangea, right?

• 8:54Hank Green?

  Right. And then there's also gonna be like the continental shelf islands, like just like there's a little bit of perturbations in the continental shelf and things are gonna pop up, or there's like reef

• 9:02Speaker 01

  As sea levels rise and fall. Absolutely, yeah. I mean, like, again, thinking back to what leads to Pangea, it's plate tectonics and Pangea isn't just like, here's a moment in time, all the plates stopped, we're just gonna pause and like, it looks so cool. No, everything is still constantly being pushed against each other and pulled apart. But then also way off in the one ocean that exists, because we just have one land mass. And that ocean, by the way, does have a name. It's Panthalassa.

• 9:29Hank Green?

  Oh, it's like Pangea, but ocean, but watery.

• 9:32Speaker 01

  Yeah, I should have looked up what Lassa means. I don't know, but it's one Lassa, whatever a Lassa is. One of those. But yeah, like, hotspots can still exist. Hotspot is what creates Hawaii. It literally is a spot on, in the mantle that's extra hot. Thank you, very obvious. And because that spot in the mantle is extra hot, it's basically burning a hole through the crust above it. And the lava coming out of that hole then solidifies and makes islands. Right? Like, I think when we're kids, we imagine an island and we're like, oh, it's like this floating piece of land floating in the water. No, an island is just land that was underwater that is now so tall that we're seeing the tippy top

• 10:11Hank Green?

  Right.

• 10:11Speaker 01

  of that land. And so like Hawaii and these other hotspot islands is just really, really, really super tall volcanoes

• 10:19Hank Green?

  Yeah.

• 10:19Speaker 01

  coming from the ocean floor. And so the, the cool thing to think about with this is like, some of these islands, like the island chains, we actually do see eventually crashed onto Pangea. Uh, it's called an accretive terrain, and this happens throughout all time. Like, we have accretive, yes, yes, yes, yes. You can see, like, the smushed pieces. I do activity with my students where we take little pieces of Play-Doh. And like, we're smooshing them together and you can clearly see the yellow Play-Doh is different than the purple Play-Doh. And as a geologist, you can see like, this rock is a different type of rock than the other one, even if it was the same. Like, let's say they're both volcanic rocks. Let's say they're both the same type of volcanic rock, like basalt. You can look at the geochemistry of that rock and take the signature of it.

• 11:02Speaker 01

  And if they have different chemical signatures, they came from different lavas. Or magmas, depending where they formed.

• 11:08Hank Green?

  Ended up together in the same place, even though they were not created in the same place, or didn't form in the same place.

• 11:12Speaker 01

  Cause something, plate tectonics, brought them together and smashed them. But the other thing that I think is really cool.

• 11:18Hank Green?

  See like the equivalent of a Hawaiian chain gets smushed into Pangea?

• 11:23Speaker 01

  Yes, yes, yes, you can.

• 11:24Hank Green?

  Cause Pangea was active. It was like, it wasn't, it was a long time. And so there was like a lot of, a lot of different moments of Pangea's history.

• 11:31Speaker 01

  Yeah, Pangea existed for like over 150 million years. That's a really long time. Like, if you're thinking about when it first started coming together to when it finally fully ripped apart, it took basically all of the Mesozoic to completely rip apart. You start the Mesozoic, the end of the Permian, which is what the eon shows about. So the end of the Permian, you have Pangea finally fully assembled.

• 11:53Hank Green?

  What's going on biologically in the Permian? Sorry.

• 11:56Speaker 01

  Yeah, so biologically in the Permian, you have cool guys, like the ones on my shirt that I'm wearing.

• 12:01Hank Green?

  So dimetrodons and

• 12:02Speaker 01

  Yes.

• 12:03Hank Green?

  Weird, weird, but that guy, Tiktaalik?

• 12:08Speaker 01

  Amphibian, yeah. Tiktaalik actually was Carboniferous, but you have a bunch of other tetrapods.

• 12:14Hank Green?

  Okay.

• 12:14Speaker 01

  Yeah, I mean.

• 12:15Hank Green?

  Weird tetrapod amphibians.

• 12:17Speaker 01

  Yeah.

• 12:17Hank Green?

  So before dinosaurs.

• 12:19Speaker 01

  Before dinosaurs, yeah. Permian is before dinosaurs, but at this point, we do have reptiles. We've got the amniotic egg that has popped up and like revolutionizing life on land. Because you were just talking about, right, the center of Pangea is gonna be really dry. You're far away from the oceans. Any of that water that has been soaked up into the clouds, it's not gonna make it all the way to the center. And so even just off of the coast, what is gonna be able to survive? It has to be something, not like an amphibian, that needs to be tied to the water, but something like a reptile that can hand out, be, handle being dried out for a little bit. Its eggs can handle being dried out.

• 12:58Speaker 01

  Mammals, not around in the Permian yet, but we have things called synapsids, which are now called stem mammals. I think like, if you came up in earlier days, you might have heard them referred to as mammal-like reptiles.

• 13:10Hank Green?

  Right.

• 13:11Speaker 01

  We don't say that anymore.

• 13:12Hank Green?

  Yeah, interesting, yeah.

• 13:14Speaker 01

  Because mammal-like reptiles implies that they're more, that they are reptiles with mammal traits. But they're closer to being mammals with reptile traits.

• 13:23Hank Green?

  Yeah, we are descended from those kinds of things. Yeah.

• 13:26Speaker 01

  Yes, we are one of the only lineage still around.

• 13:28Hank Green?

  And you think, that's not, that's a dinosaur. But in fact.

• 13:31Speaker 01

  Cause they put it in the dinosaur tubes. Just, the propaganda has been so strong. If they kept putting him in with like the elephants and the, and the lions, we would all get it right away. So.

• 13:42Hank Green?

  I don't know that I would. I'd be like, what's this guy doing in here? He doesn't look like, he doesn't look like a lion or an elephant.

• 13:48Speaker 01

  It would spark your curiosity.

• 13:49Hank Green?

  Yes, it would do that. It's a giant sail on its back. Uh, what is, what is it doing? How is it navigating the seas? The Lassa, by the way, is the Greek word for sea. Uh, it comes from the, the literal personification and primeval, primeval spirit of the seas. It's great. She was born from the union of light and day.

• 14:13Speaker 01

  Oh, a Goth girlie. No, wait, light and day. That's the opposite of a Goth girlie.

• 14:17Hank Green?

  No, yeah, she's, she's all sunshine and rainbows. Yeah.

• 14:22Hank Green?

  Oh, God. Okay, so Pangea, lots going on, is where we were. I just needed to get like in, into the, into the, the biology of it to understand a little bit of it. So like, that's a long time ago, but not so long ago that there's not, there's not like vertebrates on land.

• 14:39Speaker 01

  There, yeah, vertebrates are on land by this point, plants are on land. You're getting to a point where it kinda looks like the world you know today, but instead of mammals being the big bads, dinosaurs are the big bads for most of Pangea. Cause again, Pangea is mostly through the Mesozoic. It's finally fully assembled in the Permian, and then you get that mass extinction bigger than the one that hits the dinosaurs.

• 15:02Hank Green?

  Yeah.

• 15:03Speaker 01

  And kind of resets life on land, opening up the way for dinosaurs to become the big bads.

• 15:09Hank Green?

  And then dinosaurs outlast Pangea.

• 15:12Speaker 01

  Dinosaurs outlast Pangea, yes.

• 15:16Hank Green?

  Yeah.

• 15:16Speaker 01

  Yeah, Pangea's ripping apart. And basically by the end of the Cretaceous, like when the asteroid hits, you've got multiple separate continents. They don't quite look like today's, but they look close enough that you'd maybe like what it looks like when I try to draw the continents on my whiteboard. Like, that's kind of what it actually looked like.

• 15:36Speaker 01

  Semi-accurate.

• 15:37Hank Green?

  All right. We have a question from River that I wanna get to also. It asks, Dear Hank and Michelle, I was just listening to an old episode of Dear Hank and John where y'all discussed Antarctica and how there is land underneath all that ice. And it suddenly occurred to me that continents used to be in different places, Pangea and all that, which means Antarctica wasn't necessarily always buried under ice, right? Like, a long time ago, Antarctica was more temperate. Did it have plants and animals and stuff? Are there fossils under the ice of Antarctica? What is hidden down their best river? Yeah.

• 16:09Speaker 01

  What do you know about this, Hank?

• 16:11Hank Green?

  I know that Antarctica had not, not only was it warm when it was part of Pangea, but it was warm after that. So, so there was a time when Antarctica was basically where it is now, that there was a lot of carbon dioxide in the atmosphere and that warmed the entire planet a lot. And we had a pretty temperate Antarctica, and it definitely has a bunch of fossils down there.

• 16:34Speaker 01

  Yeah, yeah. And I love that you mentioned it was hot during Pangea, it's been hot after Pangea, it was hot before Pangea. This person is very, uh, spot on with the fact that has not always had ice, right? The earth has not always looked the way it does today. Most of the times, well, so first of all, yes, there are fossils and we have found them. And finding fossils in Antarctica is wild. It's one of my dream excavations. Eon, send us to Antarctica, please. But I have a colleague from when I used to work at the Natural History Museum of LA. His name was Nate Smith, and he worked in our dinosaur institute.

• 17:12Speaker 01

  He was one of the researchers leading excavations in Antarctica, excavating Antarctic dinosaur fossils. And learning about the type of fieldwork they do out there, either Arctic and, and, and Antarctic is really intense because it's cold. It's hard to excavate when it's cold. And it's hard to excavate through ice. So you have to wait for really, really narrow windows of time when you could possibly go in and not freeze to death and be able to pull things out. And sometimes you have to wait multiple years because that window, there happens to be a storm where you just can't get down. So it's a very, very slow-going type of excavation.

• 17:54Speaker 01

  There's still a lot more down there that we haven't been able to excavate. But despite not being able to excavate everything that's there fossil-wise, we can still extrapolate pretty well based on other places where we can excavate, right? Like, think about Pangea. Antarctica was connected to Australia and South America at that time. Those pieces of land moved northward. They do not have ice on them anymore, and we can excavate those areas, right? We were talking about like Africa and South America and Antarctica have those same fossils. And so we can say, okay, well, if this was between these two areas and we're finding these fossils here, it makes sense that they would have passed through.

• 18:32Hank Green?

  Yeah.

• 18:33Speaker 01

  Right. Yeah, so.

• 18:34Hank Green?

  Interesting. So, so like, not like, the, the pieces didn't all go in the same direction. Some of them became much more accessible areas than

• 18:42Speaker 01

  Yeah, they, they scattered.

• 18:44Hank Green?

  Giant amounts of ice.

• 18:47Speaker 01

  Yeah, the glaciers are.

• 18:49Hank Green?

  If you, when you look at like a picture of what the landmass under Antarctica looks like, or what it would look like if all of the ice wasn't there, uh, it's, it's like, wow, that's a cool continent. That would be amazing to have that, just like doing something somewhere. But, you know, I guess I should also feel that way about all the existing continents, which are also very cool.

• 19:09Speaker 01

  Well, I mean, even on the continents we do access, like I live in Washington State, and the west side of Washington, we've got the Cascades, it's all full of mountains, beautiful. If you go on the east side, it's all flat and dry. But I lead field trips there. And so I tell my students, like, okay, what if I told you there actually are mountains in eastern Washington, but there was a volcano next to them that was erupting for 10 million years straight. And so layers and layers and layers and layers of lava buried it until those little hills that you see, those are the peaks of what used to be really tall mountains.

• 19:45Hank Green?

  Oh, cool.

• 19:46Speaker 01

  Popping up. So like, it's not just Antarctica where there's so much topography that we're not seeing. It's places like in our own backyards.

• 19:54Hank Green?

  It's buried, instead of underneath ice, it's buried underneath land.

• 19:59Speaker 01

  Yeah, yeah, yeah.

• 20:01Hank Green?

  Ah, that's cool. That's cool. And there's no way to get down there. There's, and there's fossils down there, too, though probably messed up fossils.

• 20:09Speaker 01

  Yeah, well, I mean, we have technically found fossils in lava, because of the definition of fossils, evidence of ancient life, right? It's not necessarily that has to be

• 20:17Hank Green?

  Like a bone.

• 20:18Speaker 01

  A bone, or a part of the animal. And in Washington, there is the float and bloat rhino. Have you heard of this?

• 20:26Hank Green?

  No.

• 20:27Speaker 01

  Oh, my God. Okay. So there was lava coming out of a volcano, and there was a rhino, because rhinos used to live in North America. We used to have a, a climate and ecosystem very similar to that of modern day Africa. And there was a rhino that died and fell into, or was washed into a lake. And when things die, they start to bloat as they're decomposing. And so like, we've seen this with dinosaurs, too. They will kind of flip upside down, and they're floating in the lake right before they finally sink. But while this rhino was in the floating position, lava came into the lake. The lake was really

• 21:06Speaker 01

  cold. And so the lava was semi-cooled by the time it hit the rhino. It hardened around the shape of the rhino, creating like a blow mold. And so like, the rhino inside did eventually decompose. It's gone now, but you can climb up into this cave in like northern Washington, I think it's northern, eastern Washington, and you see the outline of this rhino that bloat and floated, it's upside down, in, in, in lava rock in basalt, I believe it is.

• 21:35Hank Green?

  That's wild.

• 21:37Speaker 01

  It's so goofy.

• 21:39Hank Green?

  It was like, that's a, that's gotta, because I'd look at that hole and be like, weird hole. But who, who decided that might be a rhino?

• 21:47Speaker 01

  They, they reached out to the Burke Museum, and actually, the old Burke Museum, which is our local museum here in Seattle, uh, used to have, they made a cast, and they used to have a cast that you could like, play in, in the children's play section, inside the, the float and float rhino.

• 22:01Hank Green?

  Oh, my God.

• 22:01Speaker 01

  So, yeah, I got, technically, you can find fossils in lava, it's just not

• 22:06Hank Green?

  Right. Yeah.

• 22:07Speaker 01

  the usual.

• 22:09Hank Green?

  Not the usual, kind of a, kind of a bummer. It's all, it's awful destructive, very hot flowing rock.

• 22:15Speaker 01

  I love lava, except when it ruins all of my potential fossils. That is hard.

• 22:19Hank Green?

  Yeah. Well, ice also is burying them. And, uh, but yeah, I mean, what percentage of, it's amazing how much we know, given how hard fossilization is.

• 22:29Speaker 01

  Yeah, becoming a fossil is really, really, really rare. Our fossil record, even the geological record.

• 22:35Hank Green?

  If I wanted to be in the geologic record, how would I get there?

• 22:39Speaker 01

  First, die.

• 22:40Hank Green?

  Okay, yeah, yeah, yeah.

• 22:41Speaker 01

  You need to end up somewhere.

• 22:46Speaker 01

  Then you gotta end up somewhere where there is deposition. So you don't want to be in an erosional environment. Like, let's say you're at the edge of a rocky beach, your poor little corpse is gonna be hitting up against all those rocks, it's gonna break you apart, not great. Versus if you're on like a sandy beach, with like, very fine grain sand, the sand is not gonna break apart your body, it'll bury your body.

• 23:08Hank Green?

  Right. But I need like, there needs to be like, water flowing to bury, to bury me.

• 23:12Speaker 01

  Yes, there needs to be water, because that water is gonna then be flowing through your little corpse and your bones. And your bones have little holes in them, and then the water will evaporate out. But water is not just H2O, it's got all kinds of other little stuff in there that turns into minerals inside your body.

• 23:29Hank Green?

  Right, right. So like, part of the, are you saying part of the process of evaporation is what happens in my tea kettle? And then I have all that like mineral in there, and I have to put vinegar in it to wash it out?

• 23:38Speaker 01

  Yes. Or if you were a kid with water fountains at your school, and they always look kind of crusty on the outside. And part of that was probably children's spit. But the other part was all the hard water, right? All the minerals that were left behind, crusting the edge of that water fountain.

• 23:54Hank Green?

  You know, I never really got that about fossils. That's, that's a new way to understand it for me.

• 24:00Speaker 01

  Yeah, it's, it's not organic material that's left behind. Most of the time.

• 24:03Hank Green?

  I knew that it was like somehow being converted into rock. But what, the, the actual process of that is about like, hard water deposition.

• 24:12Speaker 01

  Yes, yes. Yeah, it's called permineralization. And it's actually just one of the ways that fossils can be made. But when people think of like a fossil, like a T-Rex skull, or like that bone, they're thinking of permineralization. And it is the water flowing through, and each of the minerals that is inside that water, again, as the hydrogen and oxygen evaporate away, replacing sometimes on a cellular level, whatever was inside your body. So it's not just like, a, a cast, like a jello mold, which can happen. But with permineralization, it's like you are 3D printing an exact replica with every single little hole for every single little blood vessel, still left behind.

• 24:53Hank Green?

  It's like, if we wanted to design that process, we wouldn't be able to do it.

• 24:58Speaker 01

  We can't, no.

• 24:59Hank Green?

  How do we create like, a perfect, like, fiber by fiber mold of a bone? And it's like, I have no idea. But it turns out, if you just like, run water through it with a bunch of minerals in the water, the minerals are like, I preferentially bind here, and I make a crystal this way. That's awesome.

• 25:15Speaker 01

  The fact that we even understand that that's happening is amazing to me.

• 25:20Hank Green?

  Yeah. I mean, the, the process of science, where we like, take tiny little clues, and we're like, there's, like, after all this time, hundreds of years later, there's only one way to explain this.

• 25:33Speaker 01

  Yeah.

• 25:33Hank Green?

  And, and that's, and that's that these continents, which seem pretty dang stable, are moving around really pretty quick.

• 25:41Speaker 01

  And that, the plate tectonics, the theory of plate tectonics, is not even, well, I guess now it's technically, it's a, no, it's not even 100 years old, because about 100 years ago, Wegener proposed continental drift. And that's why he was laughed out of society, because he said, these continents look like they fit together. What if they used to be together? And everyone said, no, man, how do you explain how they moved? You're saying they're floating around? That's silly, because you need to have a mechanism to explain them. And it wasn't till, uh, the 1940s or 50s, when we were doing the deep sea mapping, that we saw the actual underwater ridges, and like, put the whole story together. Even some of the professors that I studied with, when I was doing my geology undergrad degree, they had not been taught plate tectonics when they were in school, because it wasn't

• 26:25Speaker 01

  still fully accepted. Even though, as we said, all the evidence, you know, after a while, you, there's too much evidence, you can't say, it's not true, even if we don't fully understand how or why. And we're much closer to it now. But the, yeah, the fact that our understanding of plate tectonics is so recent.

• 26:44Hank Green?

  Fundamental to like, everything in geology.

• 26:49Speaker 01

  It, it's a unifier. It helps us put together all these ideas that otherwise wouldn't make sense. Right? And that's part of what lets us say, yeah, this, this is for sure. It's a theory, in the same way that like, gravity is a theory. Gravity's a theory, but I'm not gonna let go of my matcha, because it's gonna spill all over me, because I'm, I understand that it's gonna fall. Right? So.

• 27:08Hank Green?

  Yeah, the, these, these unifiers are so important. Uh, and, yeah, and, and a lot of them are pretty recent. One of the ones I think about is, is that the, the, the fact that there are other galaxies is also, like, the acceptance of the idea that we, that there's more than one galaxy.

• 27:27Speaker 01

  Yeah.

• 27:27Hank Green?

  Is, is also less than 100 years old. And it's like,

• 27:30Speaker 01

  Yeah.

• 27:30Hank Green?

  Okay. So, so like, it makes sense that we're still like, struggling with this reality. Like, the idea, the, the, the fact that the, you know, that, you know, not only are there hundreds of billions of stars in our galaxy, but there's hundreds of billions of galaxies, is like, okay, well, huh, I, I guess as humanity, this is gonna take us a little bit of time to get used to.

• 27:54Speaker 01

  Zooming out into like, deep space, in terms of like, spatial awareness, but also deep time, right? Like, the idea, or the understanding of extinction, really wasn't accepted until like, the mid to late 1800s. We haven't had that idea for very long either. And then what actually leads to extinction, and how quickly extinction can happen. Like, we're still babies that are barely understanding that if we touch something, it's gonna have a consequence and an effect. Like, I, I really don't think humans quite understand that.

• 28:25Hank Green?

  Yeah. Okay, this next one is from Anya, who asks, dear Hank and Michelle, what's your favorite fun fact to combat the horrors? Not a cent, not existential fun, like the earth will continue after humans are extinct, but something like river otters hold hands when they sleep, so they don't drift apart. I actually think that's ocean otters. Or Scotland's national animal is the unicorn. Uh, but, so what's your favorite fun fact? I always have a fun fact that I'm working on.

• 28:51Speaker 01

  Yeah, okay. I'm kind of sad they said nothing about like, the earth continuing after humans are extinct, because that's fun to me.

• 28:58Hank Green?

  It's fun to you.

• 28:58Speaker 01

  But I went with a fun little animal fact instead. So, immortal jellies. Have you heard of the immortal jellies?

• 29:06Hank Green?

  I have, yes.

• 29:07Speaker 01

  I had to do a little research to make sure I got the story right. But, there are jellies that we have found, that are in the genus Taroptopsis? Taroptops, I'm gonna say it very confidently, in the genus Taroptopsis.

• 29:21Speaker 01

  And

• 29:21Hank Green?

  That's how we defined pronunciations here on Eons. Eons is such a fun show because you guys are making up pronunciations all the time.

• 29:30Speaker 01

  Yeah.

• 29:30Hank Green?

  It's like, nobody's ever said this out loud before.

• 29:32Speaker 01

  Yeah, yeah, yeah. I mean, we try to be like, okay, what's the root word here? But sometimes we just got a shot in the dark. Anyway, this jelly is biologically immortal, so not immortal in that like, if you cut it in half and then throw it into the air, it'll regenerate. Although if you cut it in half and leave it in the water, it will regenerate. But biologically immortal in that it can keep on living as long as it's not eaten or some other external factor. And so this is how it works. A regular jelly lifecycle, you have a larva, which is planktonic. That means it's floating in the water. And then it settles down, becomes sessile and turns into a polyp, which looks like a little plant, like a little stalk. And then that polyp blooms. And from there you get a swimming jelly, which is the mature form.

• 30:17Speaker 01

  That's what we think of as a jellyfish. Eventually, the jelly goes to reproduce. And most jellies will then just die after they have released and provided for the next generation. But this jelly, after it reproduces, does not die. And what instead it can do is it reverts back to the polyp form. So it just becomes a little baby again and can continue living. And here's what's really wild about it. Like, if it was starving, or if it has a physical injury, if it is, uh, the tissues are like, not doing as well because it's aging, it'll just regenerate again. And it can do it, as far as we know, indefinitely.

• 31:00Hank Green?

  Yeah, yeah, no. It seems like it, cellularly, it looks like they're just going, they're, they're just in, like, everything is basically starting from scratch, except it's not. It's starting from a living adult, which is very weird.

• 31:13Speaker 01

  Yeah, it, it takes the specialized cells and then just turns them back into stem cells.

• 31:18Hank Green?

  Yeah.

• 31:19Speaker 01

  Which I know there's a lot of research on. And so there, there are scientists actively studying this jelly to try to figure out how it does it. I will say the one caveat, when I initially imagined this jelly, I was like, wow, this majestic thing in the ocean. I'm not saying it's not majestic, but I am saying it's about the size of your pinky nail or a little bit smaller. And I feel like there's probably some sort of biological limits on this immortality.

• 31:43Hank Green?

  Yeah, there is.

• 31:44Speaker 01

  That said, I, I was recently talking to a friend of mine who is, studies crabs. And he said that there's some talk in the crab community, there's like a debate about whether crabs are immortal because their DNA doesn't decay. So they're immortal in a different way, I mean, immortal, in a different way than the jellyfish. They don't age in the sense that like their DNA is breaking down.

• 32:09Hank Green?

  So they don't have like the telomere problem that we have?

• 32:12Speaker 01

  No, no, and I looked it up, like, crabs in captivity, like hermit crabs, have lived beyond 40 years. Whereas like a wild crab is like three years.

• 32:23Hank Green?

  Well, I know that lobsters are kind of like this. They could just keep getting bigger forever, it seems like.

• 32:27Speaker 01

  Yes, yes, yes.

• 32:28Hank Green?

  Hundreds of years old, like a hundred year old lobster.

• 32:30Speaker 01

  Right, the, the only limit on, on those right now, because their arthropods would be size, because there's not enough oxygen, right? So all the other limiting factors are not that it's the body itself. It's, they're getting eaten, there's not, like, it's not about the cells themselves.

• 32:45Hank Green?

  Yeah, aging is, is a, is a real mystery and we are not there. We've not figured it out. We are in the, in the midst. Uh, it seems like the easy explanations have not turned out to be accurate, uh, which is interesting.

• 33:03Speaker 01

  I mean, aren't the easy explanations like you get enough food and sleep? Because we're living a lot longer than previous humans.

• 33:11Hank Green?

  We are, we are, yeah, we're, a, a, and also we seem to be aging less quickly. And, and there's all like, there's this cra- this is, here's, here's a fun fact. Uh, the, the rate of dementia per person, per like age adjusted year, per like age adjusted person. So you can't just look at the rate of dementia because people are living much longer. But the, but if you look at, like, at people's age and how often an 80 year old gets dementia now versus every decade previously, the rate of dementia keeps going down. But we've not gotten better at treating dementia. We've gotten a little bit better at treating dementia. But we, but like not, like, that's not the reason why this is happening.

• 33:50Speaker 01

  Whatever's causing it.

• 33:53Hank Green?

  Yeah, we don't 100% know why this humongous success has occurred. And I did the math recently. And if this hadn't happened, it would have bankrupted our medical care system over and over again, multiple times.

• 34:08Speaker 01

  Oh, my God.

• 34:08Hank Green?

  So we don't know how it happened. But if the rates of dementia for an 80 year old today were the same as they were in 1950, our medical system would have been bankrupted like five different times. And we don't know how we did this. It's the best news and you've never heard it. Now, we know some things, it's probably, a, a huge part of it is better cardiovascular health. So it, like, it, it turns out that if your brain isn't getting good, like, flow, blood flow, then like, the rates of dementia go up a lot. So we weren't trying to fix dementia. We were trying to have people have better cardiovascular health. Uh, and it turns out that, that was very good for dementia. But it seems like there was also other stuff. There's just like, like people's lives are less intense.

• 34:52Hank Green?

  Uh, we imagine like modern life as being worse, because of course we do. But it is not, it is better and, and thus.

• 35:01Speaker 01

  I love indoor plumbing.

• 35:02Hank Green?

  Oh, man, oh, man, this is, I, I sit down at Thanksgiving, every Thanksgiving, my father-in-law's, the first thing he's thankful for, we do the thankful for thing, where you go around the table and he says, I'm thankful for indoor plumbing. And then he tells the story of how his, when he was, went to visit his grandma growing up, she didn't have indoor plumbing and it was really unpleasant.

• 35:22Speaker 01

  Yep, my mom still talks about how happy she is that we have running water in the house and like hot water, because she used to have to go fill up the buckets from outside on the ranch, like, to take a shower. Every day she's still grateful, so, yeah. It's, we're not that far off from not being this cozy and having a lemon foam matcha latte at my disposal.

• 35:42Hank Green?

  Yeah, yeah, I, it, it's, it's really fascinating to me that the, and it's been a really steady decline. It hasn't been like, one thing happened. It's just been a steady decline in the rate of dementia, which is great. Not that it's not still a problem and that we aren't still working on it and that, that, that's great, and I think that we're making progress there. But, uh, all of this reminds me that this episode of Dear Hank and John is brought to you by Immortal Crabs. Immortal crabs, maybe?

• 36:11Speaker 01

  They're not sharing their secrets. This episode also brought to you by Float and Bloat Rhinos. They're in a cave, just kidding, they are the cave.

• 36:22Hank Green?

  This episode is also brought to you by the idea that there are other galaxies. Oh, my God, oh, no.

• 36:29Speaker 01

  This episode brought to you by Dimetrodon. Not a mammal-like reptile, not a reptile-like mammal, a secret third thing, a synapsid.

• 36:40Hank Green?

  This episode of Dear Hank and John is brought to you by Wayfair. There are a number of objects in my home that I have been extraordinarily well-served by, maybe for 15 or 20 years. Like a pair of fake leather upholstered stools that I've had forever. But they've seen better days. They maybe need a little bit of a refresh. Good news, Wayfair helps you create a home that stands up to real life with quality products, great value, and trusted reviews. Wayfair verified products are hand vetted by product specialists using a 10-point quality inspection. You can use filters, customer photos, and more than 20 million verified five-star reviews to confidently find the right fit for your home. And now those stools that I had 15 or 20 years ago, I don't have those.

• 37:23Hank Green?

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• 37:43Speaker 02

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• 37:47Hank Green?

  This episode of Dear Hank and John is brought to you by Quince. I do very much like opening up my closet and finding an item that I know is going to be both comfortable and I'm just going to look good in it. It's going to go well with my khakis or my jeans or my third kind of pant? That I, I have like a, or, like a pair of orange pants. Just things that make getting dressed easier. And that's what Quince does best. Quince focuses on high-quality wardrobe staples made with premium materials like 100% Mongolian cashmere, organic cotton, and merino wool. And the styles are timeless and they're versatile. And they're designed to become dependable pieces that you reach for day after day. This morning, I put on this jacket that I'm currently wearing with just a white t-shirt. And I knew immediately, this is going to work.

• 38:31Hank Green?

  I went downstairs and Catherine was like, look at that nice jacket. Where'd that come from? You know where it came from? It came from Quince. Everything at Quince is priced 50 to 80% less than similar brands because they work directly with ethical factories and cut out the middleman. So you're paying for the quality, not the brand markup. Find your next fall favorites at Quince. Download the Quince app for app-exclusive offers or go to quince.com. Get free shipping on your order and 365-day returns, now available in Canada and the UK, too. And when Quince asks where you heard about them, let them know that it was Dear Hank and John. It's a good way to support the show. I feel like I should say it's Q U I N C E. I guess it's pretty easy to spell Quince. Quince.com. I feel tempted to make up a tagline for them, but that's not what they want me to do. I, I shouldn't do that.

• 39:21Hank Green?

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• 40:06Hank Green?

  a real meal and that's fine. And then I have one plate to clean. I don't have a bunch of pots and pans to clean though. Every week you will find over 100 nutrient dense menu items to choose from and new options like salmon burgers, shredded pork, collard greens and more. Plus add-ons you'll crave like pumpkin flavored cheesecake and protein shakes. 97% of users agree that Factor meals help them live a healthier life. So you can feel confident that you're doing something good for yourself with every meal. True story, right now I do not have any Factor meals in my fridge and I am hungry and I'm about to go inside and absolutely rummage for something and I'm sad about it. Some current Factor meals include chicken taco bowl with corn salsa and cilantro crema. This is making me so hungry.

• 40:52Hank Green?

  Onion portobello burger with potatoes and white cheddar. That's right, they can help you go vegetarian or eat less meat. You can also have golden corn and shrimp risotto with Brussels, cabbage and pepper medley. But I can't because I'm allergic to shrimp. Let's eat real. Head to factormeals.com/dearthank50off and use code DEARHANK50OFF to get 50% off and one free breakfast item per box for one year. While supplies last until October 31st, 2026. That's code DEARHANK50OFF at factormeals.com. Dear Hank, 50 off at factormeals.com. See the website for more details.

• 41:33Hank Green?

  We have another question. It's from Rachel who asks Dear Hank and Michelle. I recently heard the term satellite era for the first time and I liked that a lot until I started wondering about the end of the satellite era. If humans go extinct or lose a significant portion of our population in the next 100 years, what will happen to our thousands of satellites? I don't know if I should feel for them or hope that they come crashing down. In our satellite era, Rachel. This is a Hank, this is a Hank topic, I feel like.

• 42:01Speaker 01

  Absolutely, yeah. I mean, I have no answers to this other than I know we're making a lot of space junk and a lot of those satellites are already not something we're using, right? They're just, I mean, they are, why are they not crashing down Hank?

• 42:18Hank Green?

  So there's a couple of, there's a couple of things here. The more recent satellites that we send up actually are designed to have a much shorter lifespan and they are in lower orbit where there is more atmosphere still. So there's not a lot of atmosphere, but they still run into some atoms every once in a while and that slows them down and eventually they de-orbit and they crash down. So like a SpaceX satellite is not really even designed to be up in space for more than five, 10 years. And even naturally, if you did nothing, they would, they would de-orbit. But they also de-orbit them intentionally so that they do the right thing and have all, all the right processes happen as they, and they don't crash into anything. But there are all these like old things that we set up in the 60s and 70s that are like

• 43:00Hank Green?

  gigantic, like old Soviet rocket bodies that aren't even, they were never satellites. They're just orbiting because they were a part of the staging of getting something somewhere else. And so they're huge and they're weird and they're completely, there's no way to control them. There's no way to, they don't have like toe points. You can't even like hook something to them to pull on them. So it's very hard. There's companies now that are looking at trying to figure out how to get some of this stuff out of space. So those big objects are actually the big concerns. These old satellites that we sent up a long time ago, because if something crashes into them, suddenly they become many large objects and not just like many small objects, but many large objects. But we are very much in our satellite era.

• 43:44Hank Green?

  There are estimates that by the end of the decade, there could be tens of thousands of satellites in orbit. And that's crazy. What this means is that we need to actively, and we're currently doing this, actively do collision avoidance on all of these satellites, all of the time, doing maneuvers constantly. And so all these new satellites are designed to be able to move themselves. And, uh, and so we're got computers running all the time to make sure stuff doesn't run into itself. And there was a recent study done that if those computers stopped being able to access the satellites, it would be on average, the sort of median time to a problem would be

• 44:26Hank Green?

  like a week, like so maybe like as few as three days before there was a collision between two satellites. So we really need to make sure that we can continue to talk to them or program into future satellites, the ability to do it autonomously. Because there are like events you could imagine, a solar flare, some kind of, you know, hacking thing, like a cyber warfare thing, or just computers making a robot uprising. Like there was that time when, when like an airline suddenly couldn't fly its planes because of all of its software stopped working. So, you know, like things like that could happen. And, uh, and that would be really bad.

• 45:08Hank Green?

  Um, and then it, you know, one of the things, there's this thing called Kessler syndrome. The idea being if there's one impact that creates a bunch of debris and then that increases the number of impacts and you have like exponentially increasing number of impacts. Uh, it wouldn't occur on the, the scale of like days or even months, but it would occur on the scale of years. It's sort of, it's not like the movie Gravity where it all happens in like four hours. But you, you would get these increasingly cluttered orbits that would become less and less useful and you'd have to figure out other places to put the satellites.

• 45:41Speaker 01

  Right. So the problem is A, keeping the satellites from bumping into each other and blocking their own paths. But then B, if we want to leave our own orbit, not having a bunch of junk in the way and trapping ourselves underneath a clutter of satellites.

• 45:56Hank Green?

  I'm, I'm less concerned about that. If there's a lot of space. So if you're just moving through in one direction, the thing you're, you're really worried about is they're all on the same plane and they're moving all of the time very fast. But if you're just punching through, I feel like you can just punch through. They're probably not going to hit anything on the way out. I mean, maybe this is a, that would be a concern, but certainly like the International Space Station.

• 46:17Speaker 01

  How many satellites we need to watch sports TV or whatever.

• 46:23Hank Green?

  I mean, the International Space Station is very big and it does get hit by these paint flecks and, you know, things that are from other satellites.

• 46:34Speaker 01

  Oh my God.

• 46:35Hank Green?

  Yeah. And they're, because they can be going in like completely opposite orbits, they can be like moving very fast relative to each other. And so the ISS like has had multiple events where they start losing pressure and they have to like patch the hole, which is just so freaky to me.

• 46:55Speaker 01

  Wild how such a small, little object, when it gets enough speed.

• 47:00Hank Green?

  Yeah.

• 47:01Speaker 01

  It's in orbit like a paint flick.

• 47:04Hank Green?

  Yeah, paint flick won't, won't go through the ISS like, but they, you can like see the windows have like chips in them. Crazy.

• 47:11Speaker 01

  I don't want, I don't want chips in my window when I'm up in space.

• 47:14Hank Green?

  No, not when you're up in space. All right. I have another question. It's from Stephanie and Alex who asks Dear Hank and Michelle, today my four year old, I don't know which one of this it is. It might be Stephanie or Alex, probably just based on how people are being named right now, it's Alex. Asked me, humans were the first thing? And I explained that almost everything had come before us, rocks, water, plants, fish, dinosaurs, mice, monkeys. But the inevitable follow-up question was, humans were the last thing? And that seems pretty unlikely to me. Things are evolving all the time, but I couldn't provide a satisfactory answer to what was the most recently created thing or the last thing. So what was the last thing to evolve preschool and primates Stephanie and Alex?

• 48:00Speaker 01

  Uh, first of all, they already provided a really great answer and in order first rocks, then water, then plants, then dinosaurs, mice and monkeys. So good on you. Probably Stephanie, maybe Alex.

• 48:13Hank Green?

  Yeah, that's in order exactly.

• 48:16Speaker 01

  Yeah, like, wow, okay. Um, I feel like I have two answers to this because the first one's kind of unsatisfactory, which is that evolution is ongoing right now and it happens over very small changes over a very long time. So like, what is, I don't know, the last thing to evolve is currently evolving right now.

• 48:36Hank Green?

  Yeah, yeah, yeah. It was, it was kind of today, but and speciation is such a, like, it, it seems like a very hard line. Like, I'm not a lion. We are different, very obviously.

• 48:46Speaker 01

  Right. But like, where's the transition point?

• 48:50Hank Green?

  Yeah, there's a lot of, there, there's a lot of animals and humans are among them for whom the speciation has traditionally not been as hard a barrier as you might think. You know, you probably have some DNA from some non-human, uh,

• 49:04Speaker 01

  Yeah.

• 49:05Hank Green?

  What, what are they called? Hominids?

• 49:07Speaker 01

  Neanderthals or Homo, yeah, all the other hominids, right? And like, if they can interbreed, I like, I was initially taught that species means they can't. So those lines are all a little wick wacky. And then especially for paleontologists, we're traditionally, we're relying more on comparative anatomy. Now we're kind of double checking things with genetic sequencing. So now we have a little bit more of a hard line to determine what is a new species and maybe we'll be able to identify that more quickly. But there needs to be something external to make us think, let's check if this is a new species. We're not just like sampling everything.

• 49:42Hank Green?

  But this is super hard. Like, there, there's sometimes you find like, you know, you don't find the whole dinosaur. You find teeth, you find, find pieces, you find like, like a little thing. Is that a child? Is that a juvenile? Or is that the, like, a whole other species? That's like a, because sometimes, you know, like a goose and a duck look pretty similar. Uh, but, but like a duck isn't a baby goose, but like, how would you know that if you just had the bones?

• 50:06Speaker 01

  Yeah. Well, so for the bones, we actually can tell that pretty easily. It's how the bones fuse together. Um, like when you're a baby and you're born, your skull is not one solid piece of bone, right? Like soft squishy baby skulls and eventually fuses together into one solid piece. And so when we're looking at small bones, we look for, are these bones fused together? Which means they were part of a body that lasted a long enough time to fuse? Or are they still broken into multiple little pieces? So that is actually wildly something we can tell from the fossil record. Now, something that is harder is like sexual dimorphism, right? Like when, okay, they are fused together, but there's

• 50:46Speaker 01

  maybe like smaller fuse together versus larger fuse together. That we're not totally there yet.

• 50:52Hank Green?

  That's fascinating because some animals look really different between males and females.

• 50:58Speaker 01

  Or even like growth stages, like, okay, we can tell a baby triceratops from like an older triceratops, but there's different species that maybe are not different species and just what this one particular serotopsian looked like when it was in its like teenage versus fully mature phase, right? So that like, we don't totally know yet either.

• 51:20Hank Green?

  Because we, like, sometimes species have like these metamorphosis events where they just like suddenly look quite different. I mean, we kind of have this in puberty where it's like, suddenly we have like this metamorphosis that we go through where suddenly our bodies are different and like the skull changes shape and it's all kinds of stuff.

• 51:38Speaker 01

  Well, and then another thing that like leads or muddies the water is that different animals will sometimes at different stages in their life occupy different niches. So like, let's say, uh, tyrannosaurs, for example, like the teens, I think were more scavengers versus the adults more active hunters. There's been different studies on this. So don't come at me and dinosaur people, but if they're occupying different niches.

• 52:01Hank Green?

  Like a T-Rex researcher for fights.

• 52:04Speaker 01

  Yeah.

• 52:05Hank Green?

  I don't even know about T-Rex researchers.

• 52:07Speaker 01

  Yeah, people are very passionate and I respect that passion as long as we're nice.

• 52:14Hank Green?

  Let's not talk about feathers at all.

• 52:18Speaker 01

  But yeah, if you're occupying a different niche, then maybe you're living in different areas. And so you're only finding, let's say, what could be a teen that looks in one way in one area versus adult that lives in another area. And so initially you'd say, well, these are never found together, so they're not the same animal.

• 52:32Hank Green?

  Right.

• 52:33Speaker 01

  But are they actually?

• 52:34Hank Green?

  They might just have different lifestyles. Yeah.

• 52:36Speaker 01

  Yeah. So.

• 52:37Hank Green?

  So that's, that's a thing. So species, anyway, that's where in the weeds now, but speciation is super messy.

• 52:43Speaker 01

  Oh, that's right. The question, what's the last thing?

• 52:45Hank Green?

  Yeah. You would think that we would be able to tell this, but it's, it is hard to tell. And, you know, the, there's also all like the different circumstances under which a species becomes a new species. It's, it's like, you know, that thing gets separated by lifestyle, maybe like, maybe they're like finding like two, you know, common ancestor organisms that are quite similar. They like, one becomes a scavenger and one becomes a hunter, and then they start to evolve specifically for those lifestyles and that reinforces itself over time. And maybe they can still interbreed some, but they, they find themselves doing it less and less.

• 53:19Speaker 01

  Are there any evolutionary pressures causing these things to change? I feel like in the future, we're going to see a lot of speciation and evolution because of human pressures, right? Like.

• 53:30Hank Green?

  Oh, I think we're seeing it already. Yeah.

• 53:32Speaker 01

  Yeah, fair. Is, but like, is it a completely new species? I don't know. I mean, what you're talking about with like speciation makes me think of Darwin's finches, um, right? Where there were 18 different species that had evolved over the course of less than a million years, which is pretty quickly.

• 53:48Hank Green?

  Yeah.

• 53:49Speaker 01

  I think part of that is because they're on islands and islands are weird. There's a lot of weird pressures.

• 53:54Hank Green?

  Yeah, yeah.

• 53:55Speaker 01

  Yeah. But, um, I was reading that in 2025, so last year, researchers proposed that there's a new species of finches from those islands on the Galapagos.

• 54:06Hank Green?

  Still happening.

• 54:07Speaker 01

  Called, yes, still happening. It's called a woodpecker finch. I don't think it's been officially named a new species. They were just like, hey, we think this is new based on genetic sequencing. It also seems like it's filling a new niche. So maybe there's a 2025 birdie that is the last thing that we have recorded as being a new species to have evolved.

• 54:30Hank Green?

  That's cool. The, the, when I said, you know, maybe, maybe it's, it's kind of already happening. I was thinking about growler bears, which are the, a hybrid between grizzly and polar bears. Uh, so in, in places where, uh, polar bears are, or where grizzly bears are moving into polar bear ranges because it's getting warmer, they can interbreed and they do. And the, what, what does happen in speciation sometimes is two different species come together to make another species. Uh, and, and, uh, and so you could imagine, this wouldn't necessarily happen with growler bears, but you could imagine a situation where it would, where that, that hybrid animal would have advantages over either of them

• 55:15Hank Green?

  in a specific niche. And so it would become its own species and, and it feels very human impact for polar bears and grizzlies to have more habitat overlap than they once did.

• 55:26Speaker 01

  Cool. I mean, also, less fun answer, but probably the last thing to have currently evolved is some kind of bacteria, right? Like.

• 55:34Hank Green?

  Definitely.

• 55:36Speaker 01

  They're, they're really small.

• 55:37Hank Green?

  It's called SARS-CoV-2. It's a virus.

• 55:43Speaker 01

  So, but that's less fun. So let's say the bitch.

• 55:47Hank Green?

  Yeah, I'll tell you, uh, the bacterial evolution is wild, but also like, one of the crazy things about the fossil record of microbes is that a lot of them don't change that much. Like we have, like, we look at diatoms over hundreds of millions of years and it's like, well, that's the same diatom that we have now. Just really good at its job.

• 56:09Speaker 01

  At all, right? Like, yeah, there's no pressure for them to evolve. There's no reason. They're doing, nothing is coming in and eating them or moving like.

• 56:17Hank Green?

  They figured it out. They figured out how to be a diatom.

• 56:20Speaker 01

  They're, they're floating in the waves, unbothered.

• 56:23Hank Green?

  Just made of glass. Everybody's like, I don't want to eat that.

• 56:28Hank Green?

  All right. Our final question. MB, thank you for doing this. It's been so fun to just nerd out with you. We have a question from Abby, who's asks, Dear Hank and Michelle, in episode, uh, 357 of Dear Hank and John, you discuss that if space was full of air, we would hear the sun. Upon further investigation, I have learned that it would take about 14 years for the sound from the sun to reach Earth. Great. So we would see the sun as it was eight minutes ago, but hear it as it was 14 years ago. That's crazy, dog. Best, Abby. That's not a question, but that's a great fact.

• 57:06Speaker 01

  That's crazy, dog. That, these sorts of brain problems, they're not problems. I mean, they're problems for my brain. But first of all, ow, um, hurts to think about. Second of all, I love to think about this because when we're thinking about, okay, we're seeing things back in time, right? If the, if a star that's like 100 million light years away is dead, we won't know it because we're seeing it. So conversely, as a paleontologist, if I could teleport, I'm wormholing whatever, says I'm getting somewhere instantly. I want to go somewhere that's about 250 million light years away from Earth.

• 57:47Hank Green?

  Right.

• 57:48Speaker 01

  And that hat, and I'm going to also have a very high powered telescope.

• 57:51Hank Green?

  Very, very high powered telescope.

• 57:54Speaker 01

  Where, where, I've got all the science and tech.

• 57:57Hank Green?

  Yeah.

• 57:57Speaker 01

  And I can see.

• 57:58Hank Green?

  It's binoculars even. So it's, you're three dimensional.

• 58:01Speaker 01

  The best binoculars. Yeah, yeah, yeah. And I'm going to be bird watching. And by birds, I mean, the ancestors of birds. I'm going to be looking at all the dinosaurs. I'm looking at Pangea.

• 58:15Speaker 01

  Yes, I would. That's the only way I can time travel right now. I feel like that's.

• 58:20Hank Green?

  That's, we got it. Because Pangea, we don't have, we don't have like a, you can't imagine it being like a map the way that we have a map today. One, because it wasn't one thing and it was existed for a long time and changed shape over that time. But two, of course, we just don't have that level of resolution. But now, having talked to you a little bit, we have more resolution than I imagined we would have. I was kind of imagining it as like running a model backward and then what would we get? But we have all of this actual geological record of Pangea.

• 58:51Speaker 01

  Yes, both biological and geological. There's actually a really amazing series of maps created by a paleo geographer called Christopher Scotese. That's S C O T E S E, I believe. And we've been using his maps since I was an undergrad. He's been, he's dedicated his entire life to mapping out not just Pangea, but all of Earth's history, based on all of the knowledge that we have till now. And all of his maps are available for free online. He even has a really great video on YouTube, because he has a YouTube channel, where he just has the maps that we've created from the beginning of the planet Earth to modern day. And you can see the continents moving back and

• 59:32Speaker 01

  forth, creating Pangea, splitting apart. It's, we have actually a pretty decent amount of revolution and like resolution, and can see what the Earth looked like on, on like a worldwide global basis, right? Part of that has to do with like paleomagnetism. So if a lava is cooling, literally the Earth's magnetic field is like causing little magnetic minerals inside to be pointing certain ways. You can tell based on like, is this land covered by glaciers because it has rocks that formed during gla- like, is this a piece of ocean? Because there's fish fossils in it. So we, we have a fairly decent understanding of what the continents have

• 1:00:15Speaker 01

  looked like over time, based on, again, how lo- how little of time we've understood plate tectonics and how much of the Earth we have and haven't mapped yet. Yeah, I highly recommend checking out the Scotese. They are fabulous.

• 1:00:28Hank Green?

  Can I ask you a Hank Green question?

• 1:00:30Speaker 01

  Yeah.

• 1:00:31Hank Green?

  What would, like, what ecosystems do we not have as much of on Earth as we, as we maybe once had a bunch? Like, what are we currently like lacking, have a, have a dearth of in comparison to other moments in history?

• 1:00:47Speaker 01

  Yeah. Reefes. Right now, the coral reefs that we have are corals that have really only existed from the end of the Mesozoic onwards. I would like to go visit reefs with like Ruggos corals, for example, which are these little corals that look like ice cream cones. They are extinct now. They're like wild little like horns.

• 1:01:10Speaker 01

  The reefs before that, like the, during the Silurian, which is just after the Cambrian time, all of those reefs, like, there have been multiple different types of reefs that have existed throughout Earth's histories, but they haven't all been coral reefs. They've been reefs of different sorts of animals that have then gone extinct, and then a new type of animal comes to take them up. And like, yes, we have some reefs now, but there, we have glaciers right now, right? And so there's a certain amount of water on, on Earth, and that water is either all in the ocean, or some of it gets taken out of the ocean and it is in glaciers. So we don't have as many shallow oceans right now. We're getting back there because the glaciers are melting. But in periods

• 1:01:50Speaker 01

  where it's been hotter, and there's more sea, that sea is then covering the continents. And so instead of having

• 1:01:56Hank Green?

  It's like inland seas.

• 1:01:58Speaker 01

  You have epicontinental seas. Yeah, these shallow inland seas. And yes, there's life all over the ocean, but the majority of life is in, I believe it's called the photic zone, areas where the sun can still penetrate the water. And so if, like, here in the Pacific side of the, of North America, you have a very small continental shelf and then a quick drop off. And so there's only this tiny little, like nugget of space where these marine creatures are living, versus if sea level rises and it's covering the continents, you have way more space for all these reefs. And so a lot of these mass extinctions that happen, or at least some of them, like at the end of the Silurian, there's an ice age. And so all of these epicontinental seas, all that water gets sucked

• 1:02:43Speaker 01

  into the glaciers, those reefs are left high and dry, those animals go extinct. And since most of the life on land, or there is no life on land, most of life is in the water, and most of water life is in these seas, and most of these seas are gone, most of the life on Earth is gone during that extinction event.

• 1:03:01Hank Green?

  That is fascinating. So we are, we are at this moment in the Earth's history, and we don't have this very productive ecosystem. It's just not there. Are there any places on Earth that are like that now?

• 1:03:13Speaker 01

  That is such a great question. Not to that scale.

• 1:03:17Hank Green?

  Yeah, because all the seas that I'm thinking of are pretty deep places. They're like the Mediterranean. That's not, like, that, that's not what you should imagine. You should, like, we're talking like very shallow seas.

• 1:03:27Speaker 01

  Yeah, this is like Florida gets covered by rising sea levels, and all of Florida is now a big old reef, as it once was.

• 1:03:36Hank Green?

  Yeah. If you go and look. MB, thank you so much for sharing all of your understanding of our bizarre planet with us here on Dear Hank and John, and also on Eons, and also on the new show.

• 1:03:50Speaker 01

  Life and Death on Pangea.

• 1:03:52Hank Green?

  Life and Death on Pangea. It's starting now on the Eons channel. You can also watch it on pbs.org and all the PBS platforms, and also even on TV show At Your Grandmother's House. But don't, don't wait, and go check it out. Congratulations on it. I'm so excited.

• 1:04:07Speaker 01

  Oh, my gosh, thank you. It was a pleasure.

• 1:04:09Hank Green?

  If you want to send us questions, the place to send them is [email protected]. Thank you to Linus Obenhouse, who edited this episode. It was mixed by Andrew Smith. Our marketing specialist is Brooke Shotwell. It's produced by Rosiana Halsrohass and Hannah West. Our executive producer is Seth Radley. Our editorial assistant is Deboki Chakravarti. The music gearing now at the beginning of the podcast is by the great Gunarola. And as they say in our hometown, don't forget to be awesome.