Dear Hank & John - 461: Fun Facts to Combat the Horrors (w/ MB Ramirez!)

Episode Date: July 29, 2026

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 [e-mail] us for monthly livestreams at patreon.com/dearhankandjohnProduced for Hank and John Green by ComplexlySee Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

Hey, so something worth knowing is a benefit for the nonprofit organization that makes Crash Course and SciShow Complexly. It's September 16, 2026 in Los Angeles, California at the Wilshire Ebell Theater. Please join us. It's going to be incredible. Friends of Complexly like Mark Rober, Katie Max, Simone Yetch, and more will share inspiring talks about what makes them hopeful and join Hank Green on stage for fun, interactive discussions. Complexity's been creating free educational content. like SciShow and PBS Eons and Crash Course and Bizar Beast for nearly 15 years and 6 billion views. But this year, we've become a 501c3 nonprofit, and we're doing something worth knowing as an in-person event that benefits complexly and our impactful educational media.

It's the first ever complexly in-person event, and it's a fundraiser to support our mission of inspiring curiosity and lowering barriers to knowledge-building because curiosity builds understanding and understanding builds a better world. Tickets go on sale to the general public June 30th at something worth knowing.com. So come build a better world with us on September 16th and experience something worth knowing. You can get your ticket at complexly. info slash something. You're listening to a Complexly podcast. And welcome to Dear Hank and John.

Or as I like to think of it, Dear Hank and M.B. It's a podcast for 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, M.B., you're, oh, I have to do a dad joke. M.B., what do you call a dog that does science? A science dog? A lab. Oh, yeah, that's a dad joke. Also, Wimbledon? Wimbledon. I have to learn news about that today? No, no, no, no, don't We don't have to do news. We can, the news, I have, you're, you're confronting the news immediately that you have to do news about soccer.

But no, you don't because the news is actually. 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 Pangaea transports. viewers to a world shaped by the supercontinent Pangae, 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. 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 the Eons YouTube channel produced by Complexly. And select PBS television stations. and B, how has that been to make? 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 U.S. 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. Yeah. I mean, we hear about Pangaea. 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. That's the school. Pretty good evidence.

Yeah. And, but what you don't think about is, like, what are the implications of almost all of the land being globed up in one central place? And one of them that occurs to me, I don't. actually know if this is true is that the middle wouldn't get much water. It does not, dude. Oh, my God, it is dry and deserty 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 when we're looking at how it affects life on Earth.

Right. I mean, it seems, it would seem that these things move very slowly. But actually, 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? We can see that happening right now. Yeah, literally.

There's the African Rift Valley in East Africa is 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. We're forming a new ocean right now. Oh, my God. And it doesn't have a name yet, maybe? I don't know. The ocean, sure. I wonder if someone has named it yet. Somebody's trying. They're like, I'm the guy who figured this out. Name it after me is probably what's happening. Oh, boo. I, I, uh, are we going to be around to see that? Well, you could watch.

This is more of a human's question than it is a dear-hank and John question. It's a young's 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 over that, right? Like, if we know the 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. Panga Ultima, yeah. Future Pangea.

Go watch it on eons. Oh, okay. Well, you're not going to give away all your secrets here. It's going to be on YouTube. I need to drive that. It's crazy that I still do even now. I'm like, oh, my God, but it's going to be on real TV. Even though, of course, no one uses real TV.

I know. That's why everyone is like, but it's also on YouTube, right? Like, how do I actually see it, myself included? 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 the PBS app, which like you can download onto Roker or whatever. So right. Yeah, yeah, yeah, yeah. 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. That would be amazing. What a great family bonding moment. Yes. That's great. We need more things like that. The universe is too convenient.

So, yeah, it's a. 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. Yeah. Happy launch day.

Happy launch day, everybody. All right. We ask 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 M.B., were there islands around during Pangaea? Brandon, age eight, with support from his mom, age adult.

Each adult is fantastic. 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 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. 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, when we're talking about paleontology or the earth or nature, nothing's absolute. We're saying Pangaea, all the land is smushed together. We mean all of our modern continents are smushed together. There are still around the edge of that pangia, 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 freeway and an 18-wheeler, giant truck goes on the wrong lane, head on collision against my car. We're explaining this through death.

Well, but it's visceral. Yeah. Well, and how do I die? Did we bounce off of each other? No. Did my car go over the 18 wheeler? Not 18 wheelers like crush in the top of my car. I miraculously survive in this scenario.

Okay, great. I love that. You're fine. Yeah. Cool. My car took the impact to the, 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. Right. 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 that of lava, it's going to melt in the lava. And then those pieces of my Prius are going to float up because hot things rise. And that leads to volcanic island chains. Oh, wow. So you're still building island chains around Pangaea, but you mentioned Hawaii. Yeah. Yes, island chains are so,

because plate tectonics is still happening. That's what led to Pangaea, right? And then there's also going to be like the continental shelf islands, like just like there's a little bit of perturbations in the continental shelf and things are going to pop up. Yes. or there's like reef at holes or all that stuff. 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 going to 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 Pantha Lassa. Oh, it's like Pangea, but ocean.

but watery. 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, hot spots can still exist. Hot spot is what creates Hawaii. It literally is a spot 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 of that land. And so like Hawaii and these other hotspot islands is just really, really, really super tall volcanoes coming from the ocean floor. And so 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 Panga. It's called in accreted terrain. And this happens throughout all times. We have accreted.

Yes, yes, yes, yes. You can see like the smushed pieces. I do activity with my students where we take little pieces of Plato and like we're smushing them together and you can clearly see the yellow plateaus different than the purple plato. 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. And if they have different chemical signatures, they came from different lavas. Right. Or magmas, depending where they formed. And so they like ended up together in the same place,

even though they were not created in the same place. Yes, yes, because something, plate tectonics brought them together and smash them. But the other thing that I think is really cool. So you can see like the equivalent of a Hawaiian chain gets smushed into Pangea? Yes. Yes, yes, you can.

I know. Because 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 Pangaea's history. Yeah, Pangaea 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 Eons shows about. So the end of the Permian, you have Pangaea finally fully assembled. What's going on biologically in the Permian? Sorry. Yeah, so biologically in the permium, you have cool guys, like the ones on my shirt. Okay, so Demetrodons and weird, weird, but that guy, tictolic? Amphibian, yeah, tectolic actually was carboniferous, but you have a bunch of other tetrapods.

Okay. Yeah, I mean. So weird tetrapod amphibians. Yeah. So before dinosaurs. 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 pangia is going to 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 going to make it all the way to the center and so even just off of the coast what is going to 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 handle being dried out for a little bit its eggs can handle being dried out. 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. We don't say that anymore. Yeah. Interesting. 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. Yeah, we are descended from those kinds of things. Yes. Yes. We are one of those. The only lineage is still around. You look at a Dimetrodon and you think that's not, that's a dinosaur. But in fact. Because 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 lions, we would all get it right away. So I don't know that I would be like, what's this guy doing in here? It doesn't look like a lion or an elephant. It would spark your curiosity. Yes, it would do that. It's a giant sail on its back. Yeah.

What is it doing? How is it navigating the seas? Velasa, by the way, is the Greek word for sea. It comes from the literal personification and primeval spirit of the seas. She was born from the union of light and day. Oh, a goth girlie. No, wait, light and day. That's the opposite of a goth girlie.

Yeah, she's all sunshine and rainbows. Oh, God. Okay, so Pangea, lots going on. on is where we were. I just needed to get like into the into the biology of it to understand a little bit of what. So like that's a long time ago, but not so long ago that there's not there's not like vertebrates on land. Yeah, vertebrates are on land by this point. Plants are on land. You're getting to a point where it kind of looks like the world you know today, but instead of mammals being the big bads, dinosaurs are the big bads for most of panegia. Most of angia. Because again,

Pangeas, 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. Yeah. And kind of resets life on land, opening of the way for dinosaurs to become the big bands. And then dinosaurs outlast Pangea. Dinosaurs outlast Pangea, yes. Yeah.

Yeah. Pangea's ripping apart. And basically by the end of the Cretaceous, like when the asteroid hits, you, you've 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. So, okay. All right. We have a question from River that I want to get to also. It asks, Dear Hank and Michelle, I was just listening to an old episode of Dear Hank and John where you 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, Pangia 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.

What do you know about this, Hank? I know that Antarctica had not only, was it warm when it was part of Pangaea, but it was warm after that. 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. Yeah, yeah. And I love that you mentioned it was hot during Pangaea. It's been hot after Pangaea. It was hot before Pangaea. This person is very 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. Eons, Sonsus to Antarctica, please. But I have a colleague from when I used to work at the Natural History Museum of L.A. His name was Nate Smith, and he worked in our Dinosaur Institute. 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 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. 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't excavate. Like think about Pangaea. 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 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.

Yeah. Right. Yeah. That's interesting. So like not like the pieces didn't all go in the same direction. Some of them became much more accessible areas than underneath giant amounts of ice. Yeah, the glaciers are.

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, 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. 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 leave 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 of lava buried it until those little hills that you see, those are the peaks of what used to be really tall mountains. Oh, cool.

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. It's buried instead of underneath ice, it's buried underneath. Lamp. Yeah. Yeah. Yeah.

That's cool. That's cool. And there's no way to get down there. There's, and there's fossils down there, too. They'll probably messed up fossils. Yeah. Well, I mean, we have technically found fossils in lava because of the definition of a fossil is evidence of ancient life, right? It's not necessarily that has to be a bone or a part of the animal.

And in Washington, there is the float and bloat rhino. Have you heard of this? No. 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 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 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 over the eastern Washington. And you see the outline of this rhino that bloated and floated. It's upside down in lava rock in basalt, I believe it is. That is wild. It's so goofy. It was like, that's got to, because I'd look at that hole and be like, weird hole. But who decided that might be a rhino?

They reached out to the Burke Museum and actually the old Burke Museum, which is our local museum here in Seattle, 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 float and float rhino. Oh my God. So, yeah, technically you can find fossils in love. It's just not the yush. Not the yush. Kind of a bummer. It's awful, destructive, very hot, flowing rock.

I love lava except when it ruins all of my potential fossils. That is hard. Well, ice also is burying them. But, yeah, I mean, what percentage of... It's amazing how much we know, given how hard fossilization is. Yeah, becoming a fossil is really, really, really rare. Our fossil record, even the geologic record. wanted to be in the geologic record. How would I get there?

First, die. Okay, yeah, yeah, yeah. You need to end up somewhere. Then you got to 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 going to be hitting up against all those rocks. It's going to break you apart. Not great. Versus if you're on like a sandy beach with like very fine grain sand, the sand is not going to

break apart your body, it'll bury your body. Right. But I need like, there needs to be like water flowing to bury me. Yes, there needs to be water because that water is going to 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. Right, right. So like 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 a vinegar in it to wash it out. Yes. Or if you were a kid with water fountains at your school and they always look kind of crusty on the outside. 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. You know, I never really got that about fossils. That's a new way to understand it for me.

Yeah. It's not organic material that's left behind most of the time. knew that it was like somehow being converted into rock, but what the actual process of that is about like hard water deposition. 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 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. It's like if we wanted to design that process, we wouldn't be able to do it. We can. We wanted to be like, 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 it crystal this way. The fact that we even understand that that's happening is amazing to me. Yeah. I mean, 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. Yeah. And that's that these continents, which seem pretty dang stable, are moving around really pretty quick. 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, Vegner proposed continental drift. And that's why he was laughed out as 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. around, that's silly because you need to have a mechanism to explain them. And it wasn't until

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 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, yeah, the fact that our understanding of plate tectonics is so recent. Fundamental to like everything in geology.

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 is for sure. It's a theory in the same way that. like gravity is a theory. Gravity is a theory, but I'm not going to let go of my macha because it's going to spill all over me because I understand that it's going to fall, right? Yeah.

Yeah, these unifiers are so important. And yeah, and a lot of them are pretty recent. One of the ones I think about is that the fact that there are other galaxies is also, like the acceptance of the idea that there's more than one galaxy is also less than 100 years old. And it's like, okay. So, so like it makes sense that we're still, like, struggling with this reality. Like, the idea, 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, I guess as humanity, this is going to take us a little bit of time to get used to.

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 are still babies that are barely understanding that if we touch something it's going to have a consequence and an effect like I really don't think humans quite understand that. 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 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. So what's your favorite fun fact? I always have a fun fact that I'm working on. 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. It's fun to you. But I went with a fun little animal fact instead. Okay.

So immortal jellies. Have you heard of the immortal jellies? I have, yes. 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 teretopsis. Teripopsis. I'm going to say it very confidently in the genus tereptopsis. And 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. Yeah, sometimes we've ever said this out loud before. 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 life cycle. You have a larvae, which is planktonic. That means it's floating in the water. And then it settles down, becomes cessil, and turns into a pollock, which looks like a little plant, like a little stalk. And then that pollet blooms. And from there you get a swimming jelly, which is the mature form.

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 little bit of it.

has a physical injury. If it is, 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. Yeah. Yeah, no. It seems like it. Cellularly, it looks like they're just going, they're just like everything is basically starting from scratch, except it's not. It's starting from a living adult, which is very weird. Yeah, it takes the specialized cells and then just turns them back into stem cells, which I know there's a lot of research on. And so 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. Yeah, there is. That said, I was recently talking to a friend of mine who 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. So they don't have like the telomere problem that we have? 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. Well, I know that lobsters are kind of like this. They could just keep getting bigger forever. It seems like there's like hundreds years old, like a hundred year old lobster. Right. The only limit 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. Yeah. They're getting eaten. There's not, like it's not about. the cells themselves? Yeah.

Aging is a real mystery and we are not there. We've not figured it out. We are in the midst. It seems like the easy explanations have not turned out to be accurate, which is interesting. I mean, aren't the easy explanations like you get enough food and sleep? Because we're living a lot longer than previous humans. We are. We are.

Yeah. And also we see. to be aging less quickly. And there's all like, there's this, this is, here's, here's a fun fact. 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 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 that's not the

reason why this is happening. Whatever's causing it. 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. 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 huge part of it is better cardiovascular health. So it like it turns out that if your brain isn't getting good like 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. And it turns that that was very good for dementia. But it seems like there was also other stuff. There's just like people's lives are less intense. We imagine like modern life as being worse because of course we do. But it is not. It is better. And and thus, I love indoor plumbing. Oh man. Oh man. This is, 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 he tells the story of how his, when he went to visit his grandma growing up, she didn't have indoor plumbing and it was really unpleasant. Yeah, 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 go fill up the buckets from outside on the rancho 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. Yeah. Yeah, it's really fascinating to me. 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.

Now that it's not still a problem and that we aren't still working on it. And that that's great. And I think that we're making progress there. But all of this reminds me that this episode of Dear Hank and John is brought to you by Immortal Crabbs. Immortal crabs, maybe. 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. This episode is also brought to you by the idea that there are other galaxies. Oh, my God. Oh, no. This episode brought to you by Demetrodon. Not a mammal like reptile. Not a reptile like mammal.

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Lisa.com, promo code Dear Hank. This episode of Dear Hank and John is brought to you by Shopify. There are a lot of things that stand between I Have an Idea, and this is an idea that actually exists in the world, and people are buying things from me. And that is what Shopify makes easier. When you start with Shopify, the tools to design and launch and take payments, they're all there from day one.

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We have another question. It's from Rachel who asks Deer 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 topic, I feel like. 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? So 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 deorbit. But they also deorbit them intentionally so that they do the right thing and have all the right processes happen. And they don't crash in anything. But there are all these like old things that we set up in the 60s and 70s that are like 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 are completely 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. 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 so we've 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 that the sort of median time to a problem would be like a week. 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 a robot uprising 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. 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 exponentially increasing number of impacts. It wouldn't occur on the scale of like days or even months, but it would occur on the scale of years. It's not like the movie gravity where it all happens in like four hours.

But 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. 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 clutters of satellites. I'm less concerned about that. There's a lot of space. So if you're just moving through in one direction, the thing 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 concern. That would be a concern. But certainly like the International Space Station. How many satellites we need to watch sports TV or whatever. I mean,

the International Space Station is very big and it does get hit by these paintflex and, you know, things that are from other satellites. Oh, my God. Yeah. And 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. Wildhouse such a small little object when it gets enough speed. Yeah. It's an orbit like a paint flick. Yeah, paintflick won't go through the ISS.

But you can see the windows have like chips in them. Crazy. I don't want chips in my window when I'm up in space. 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. Ask 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?

first of all, they already provided a really great answer. And in order. First rocks, then water, then dinosaurs, mice, and monkeys. So good on you. Probably Stephanie, maybe Alex. Yeah, that's in order, exactly. Yeah. Like, wow. Okay. 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. Yeah, yeah, yeah. It was kind of today.

And speciation is such a, like, it seems like a very hard line. Like, I'm not a lion. We are different, very obviously. Right. But like, where's the transition point? Yeah, there's a lot of, 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, what are they called hominandals?

Neanderthals or homoenolid. Yeah, all the other hominids, right? And like if they can interbreed, 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. But this is super hard. Like there's sometimes you find like, you know, you don't find the whole dinosaur. You find teeth. You find pieces. You find 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 a goose and a duck look pretty similar. But but like a duck isn't a baby goose. But like how would you know that if you just had the bones? And you didn't even have all the bones. For the bones, we actually can tell that pretty easily. It's how the bones fuse together. 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 fuse 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 maybe like smaller fuse together versus larger fuse together.

That we're not totally there yet. That's fascinating because some animals look really different between males and females. 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 look like when it was in its like teenage versus fully mature phase. Right. So that like we don't totally know yet either. Because we like sometimes species have. 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 that the skull changes shape. Yeah. It's all kinds of stuff. Yeah. 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 Tyrannosaurus, 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. There's nobody like a T-Rex researcher for fights. Yeah. I regret it as soon as I said it. Yeah. People are very passionate and I respect that passion as long as we're nice.

Let's not talk about feathers at all. 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. Right. But are they actually? But they might just have different lifestyles.

Yeah. Yeah. So that's a thing. So species anyway, that's where in the weeds now, but speciation is super messy. Oh, that's right. The question, what's the last thing? Yeah. You would think that we would be able to tell this.

But it's 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 find themselves doing it less and less.

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

Where there were 18 different species that had evolved over the course of less than a million years, which is pretty quickly. Yeah. I think part of that is because they're on islands and islands are weird. Islands are very good at dividing up. Yeah. Yeah. Yeah. But 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.

Still happening. 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. That's cool.

When I said, you know, maybe it's kind of already happening. I was thinking about grower bears, which are a hybrid between grizzly and polar bears. Oh, no. In places where polar bears are where grizzly bears are moving into polar bears. bear ranges because it's getting warmer. They can interbreed and they do. And what does happen in speciation sometimes is two different species come together to make another species.

And so you could imagine this wouldn't necessarily happen with grower bears, but you could imagine a situation where it would, where that hybrid animal would have advantages over either of them in a specific niche. and so it would become its own species. And it feels very human impact for polar bears and grizzlies to have more habitat overlap than they once did. Cool. I mean, also, less fun answer, but probably the last thing to have currently evolved is some kind of bacteria, right? Definitely.

They're really small. It's called SARS-C-O-V-2. It's a virus. Oh, no. So, but that's less fun. So let's say that. Yeah, I'll tell you, 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. It's just really good at its job. But why are things evolving at all, right? Like, there's no pressure for them to evolve. There's no reason. Nothing is coming in and eating. eating them or move it. Yeah, they figured it out.

They figured out how to be a diatom. They're floating in the waves, unbothered. Just made of glass. Everybody's like, I don't want to eat that. All right, our final question, M.B., thank you for doing this. It's been so fun to just nerd out with you. We have a question from Abby who asks Dear Hank and Michelle. In episode 357 of Dear Hankajohn, 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. That's 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. That's crazy, dog. These sorts of brain problems, they're not problems. I mean, there are problems from my brain. But first of all, ow, 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 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 wormholeing whatever, says I'm getting somewhere instantly.

I want to go somewhere that's about 250 million light years away from Earth. Right. And I'm going to also have a very high-powered telescope. Very high-powered telescope. I've got all the science and tech. And I can see. It's binoculars even. So it's a three-dimensional view.

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

Yes, I would, that's the only way I can time travel right now. I feel like that's, we've got it. Because the, 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 that 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.

Yes, both biological and geological. There's actually a really amazing series of maps created by a paleogeographer called Christopher Scotasee. 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 forth, creating Pangea, splitting apart. We have actually a pretty decent amount of revolution and like resolution. and can see what the earth look like on like a world ride global basis, right? Part of that has to do with like paleo magnetism. 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 form during like, is this a piece of ocean because there's fish fossils in it? So we have a fairly decent understanding of what the continents have looked like over time based on, again, how little of time we've understood play tectonics and how much of the Earth we have and haven't mapped yet. Yeah, I highly recommend checking out the Scotasey. That's awesome. They are fabulous. Can I ask you a Hank Green question? Yeah.

What would, like what ecosystems do we not have as much of on Earth as we, as we, as we, maybe once had a bunch? Like, what do we currently, like, lacking, have a dearth of in comparison to other moments in history? Yeah. Reefs. 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, Rugo's 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. 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 we have glaciers right now, right? And so there's a certain amount of water on Earth. And that water is either. are 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 where it's been hotter and there's more sea, that sea is then covering the continents. And so instead of having deep ocean, 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 the Silurian, there's an ice age. And so all of these epicontinental seas, all that water gets sucked 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 of it. That is fascinating. So we are at this moment in the Earth's history. when we don't have this very productive ecosystem. It's just not there. Are there any places on Earth that are like that now? That is such a great question. Not to that scale. 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 to like very shallow seas. 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. Yeah, if you're going to look, M.B, 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. Life and Death on Pangea. 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 wait and go check it out. Congratulations on it. I'm so excited. Oh my gosh. Thank you. It was a pleasure. If you want to send us questions, the place to send them is Hank and John at gmail.com. 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 Halsrohoss and Hannah West. Our executive producer is Seth Radley. Our editorial assistant is Deboki Trockravardi. The music you're hanging now. And at the beginning of the podcast is by the great Gunnarola. And as they say in our hometown, don't forget to be awesome. I'm