Volcanoes of Life

really interested me. And that is the surprising and kind of counterintuitive link that has been proposed by many geologists now between life as we know it on Earth and the fires of mountain doom, specifically the most violent and scary of geologic processes like volcanic eruptions on the movement of tectonic plates. Yeah, this is a great topic to

get into. We kind of had a I guess a preamble to this's a couple episodes ago when we were talking about eggs and we talked about the volcano birds and the idea of a volcano being a seeming, you know, almost paradoxically to be something that can nourish life as

opposed to something that's just a purely destructive force. Oh. I didn't think about that comparison at all, but yeah, the way that the volcanic sand baby sits the egg for the for the megapode, so that it can just run off and do its own thing, raised by a volcano um. But so I thought a great place to start here might be with a brief reading from the Voluspa. It is a famous old Norse epic poem from the collection that is known as the Poetic Edda. Now this

is a this an anonymous work. The author is unknown, But the Voluspa tells the story of the Norse gods culminating in their destruction in the fiery doom of Ragnarok. And I'm just going to read a couple of quatrains here. In anger smites the warder of the Earth forth from

their homes. Must all men flee nine paces fair Air's the son of Jorgan, and slain by the serpent Fearless, he sinks, The sun turns black, Earth sinks in the sea, the hot stars down from heaven our world fierce grows the steam and the life feeding flame, until fire leaps high about Heaven itself. And one fun thing about this poem, it's a bit of Tolkien trivia. Robert, tell me if

you've heard this before. But the name of the wizard Gandalf that first appeared in in Tolkien's The Hobbit, and then of course is like the best character and Lord of the Rings. The name of Gandalf comes from the Voluspa. Tolkien actually borrowed the name from a section known as

the Tally of the Dwarves from this epic poem. Originally, he was going to apply it to the character in The Hobbit who became thorn oaken Shield, the leader of the Dwarf party, but then he decided later on that it made more sense to apply the name of Gandalf to the wizard, I think because Gandalf means something like magic staff elf, and I think he made the right choice, like Gandalf that makes more sense for the wizard than

for Thorin. But a cool thing that happens in this poem, it's sort of part of the Ragnarok myth, is that there is a rebirth that follows this fiery doom. You know, after the fire leaps high to heaven and the Kingdom of the Gods is destroyed, Earth is not just left in cinders. Instead, there is a renewal from the fire, and the author rights, now do I see the Earth a new rise, all green from the waves again, the cataracts fall, and the eagle flies and fish he catches

beneath the cliffs. So there's this great link between fiery cataclysm and rebirth and renewal of life in Norse mythology, and and of course there you know, these are symbolic elements. I'm not suggesting that they had some kind of scientific insight with this. It's it's just something you know that I think is taken as a metaphor largely about human life itself, but coincidentally it ends up kind of ringing

true with things we're finding out about geology and nature. Well, it's something you've see in a lot of different mythological cycles, right, I mean you see it in in in in Hindu mythology, you see it in uh various um American mythologies. Uh you know, thinking about Mezso and South America in particular, is this idea that things will rise, things will fall, Uh, that there will be cataclysm, that whole world will be destroyed, but new worlds will rise out of them and have

risen out of them before. Yeah, I was thinking about themes of fiery eruption and the greening of the Earth together or sort of a creator destroyer duality. One that came to my mind that that I thought you might know something about, because I know I've heard you talk about Hawaiian mythology before. Was the pale myth Yeah. Yeah, the Hawaiian goddess Pale is an interesting example a deity

of fire and volcanism. I was reading a book titled Pale Volcano Goddess of Hawaii by H. R. Low Nemo, and he points out that when Polynesian voyagers first arrived in Hawaii, they would have brought their gods with them. Now, now we don't know where in the Hawaiian islands. This would have specifically been which of the islands they would have landed on, and where and even when remains a topic of debate. I've seen dates ranging from three hundred seed to a thousand sea, and of course contact with

the Europeans didn't occur until seventeen seventy eight. But the newcomers would have arrived on sailing technology in keeping with that of the larger Polynesian expansion, as well as related cultural inventions such as gods and goddesses, all of which

would then evolve into distinctly Hawaiian models afterwards. Now, as we discussed in the show before, the Polynesians were some of the last true explorers of the inhuman regions of the Earth, and their saga, which is full of fascinating history, is is it's not unlike what we might expect of a space faring civilization with time and space sufficient enough to see the splintering and continued evolution of societies from region to region as they spread out across these far

flung habitable spaces. Now, Nemo points out that the first Hawaiians brought with them kane kind of lowa uh Ku loan, no gods known throughout the South Pacific. But they also brought with them what was apparently a minor fire deity named Pelee. And they didn't bring any volcano deities with them, but but she was this fire deity that seemed to pre exist, and she likely remained insignificant for a while there, at first, just another minor deity like she was previously.

But then eventually uh though the Hawaiian islands shook and the volcanic mountains, of which six are active today belch forth fire, magma, and ash, and this is what Nemo writes, quote, this minor deity was apparently transferred to the volcanoes and became the goddess Pele, who was destined to hold a powerful position in the Hawaiian antheon. The great volcanoes became her home, their power, her strength, their beauty and destruction,

her manifestation, and their unpredictability, her temperament. Now, Paley would not be the only god or goddess from a pantheon in the world that's associated with with specific volcanic activity. But I would imagine that that a volcano god takes on a very special significance when you are an island culture, So when you're like geographically bound very close amidst a vast ocean to that that ground forming and life giving volcano. Yeah.

Something to think about here is that we we see other gods, particularly um gods in the Greek and Roman cycle that are associated with with fire and also associated with volcanoes, but also associated with the forge, the forging of things. Um. We also see this in Lord of the Rings with with sarin Is. This is essentially a he Festus type character, right, But as we discussed previously on the show, in one of our armor episodes. Um, you certainly don't see metal work uh, occurring on the

Hawaiian islands. I mean, you don't see see iron. Therefore, the taking in the manipulation, they were using wood and fiber and shark tooth based technology and doing and using so excellently. But I wonder how much of it too has to do with the fact that that Pale would have been removed from that there would have been no human forge to overshadow the natural cycles of fire in

the earth, you know. And on top of that, here is the volcano itself, Here are the volcanoes and these volcanic islands, where where it's it's activity, it's it's it's geologic life is so obvious. Now. Nemo spends much of this book discussing the ways that Paley is viewed, and certainly drives home that that she's not a monolith. Traditions and ideas regarding Pale range from religious belief and cultural

identity to the abstract, the environmental, and even uh. There are these, um numerous examples of supernatural sightings in which one claims to have seen or believes to have seen a beautiful woman standing in the fire. But there certainly is this recurring theme of one who creates with volcanic fire and may also take back via the same power um of a quote traditional spiritual respect for the life

forms her creation supports. For instance, in the book, Nemo does bring up a specific example, uh talking with someone who lost uh some property due to a volcanic eruption, and they asked him, well, what, how did this change the way you think about Pelee? And they say, well, I do, it doesn't. Pelee gave this to me. She created the land and I was just using it, and now she has taken it back. Yeah. The Lord giveth

and the Lord taketh away. Yeah. Now the lord that people are usually talking about when they when they say that is the is the the god of of of Judeo Christian tradition, right, Uh, which brings up this question. Joe, you're more of an Old Testament kind of guy than I am. But so have you ever run across this argument that yahweh uh in Hebraic tradition may have started off as a volcano god. Yeah, I was reading a bit about this. Um. This seems like one of those

things that you it's kind of an interesting idea. You can't totally rule it out, but it seems highly speculative and based on kind of scanty evidence, So so I would say it's one of those things that is possible,

but probably not. I think it's mainly based on ideas about geography, like the idea that you know that Sinai Mount Sinai would have had some kind of volcanic element in the past, and then referring to specific passages in the Bible which described the Lord in terms that people say, well, maybe this could be describing a volcanic eruption or something, and it's one of those things that you can often

do with these geomethology. This actually, I guess would technically geomethology a geomethology inference, and so I'd say for this one, you know, it's not impossible, but it's kind of a reach. Yeah, I don't think i'd I'd run across it myself, but I saw mention of it, and one of the sources that was often there were often was often cited here was a book by Jack Miles title of God Biography, which is a popular work that seems to discuss this. So I looked it up and it's in reference to

Exodus forty eight. Uh, he writes, quote, nothing in nature looks like a cloud by day and a fire by night, except a volcano. The depth of the Lord God's compelling but contradictory power is well evoked by the extraordinary image of a volcano brought into a tent. Now speaking of volcanoes and gods and getting back to to Tolkien. Uh. Now, I've expressed in the show before that I love a good journal paper that that digs into some Tolkien that

tries to find the science of Middle Earth. We've talked about that previously with the Hobbit, you know, the how many meals does the Hobbit need a day? And Willy'll be able to march across the Earth? Uh. Also we got into the metallurgy of the One Ring. So I was like, well, somebody, somebody has to have considered Mount doom and um and you know, the geology of Middle Earth. And sure enough I found a paper titled the Geology of Middle Earth by William Anthony Swinton Sergeant, published in

the journal myth Lore in NI. Now, I know myth Lore doesn't have a resounding ring of geologic authority to it, but I looked up a Sergeant who lived five through two thousand two, and he was a professor of geology at the University of Saskatchewan. And he also apparently wrote a series of fantasy novels himself, The Perilous Quest for lion S. I looked it up. I have not read it, but I've noticed you can get at least the first

two books in the trilogy on kindle and paperbacks. Amazing. Okay, so he's the perfect person to right this, a fantasy novelist and and clear geek who was also a professor of geology. Yeah. Yeah, and uh he wasn't the first though, so he when when he dives into this, he ends up citing an earlier paper by Robert C. Reynolds titled the geo Morphology of Middle Earth, which is published in

The Swansea Geographer in nineteen seventy four. So basically, what Reynolds had done is he'd applied the concept of plate tectonics to the entire geography of Middle Earth, recognizing four different plates, the Erador played in the west, the Rovanian played in the north, and the Harad and more door plates in the south. And Sergeant then used this as his starting point kind of his bedrock, but updated it to reflect changes in plate tectonic theory between nineteen seventy

four in nine. Oh. Yeah, that's interesting because I would say at the time the Hobbit was written, plate tectonics was not yet an accepted scientific theory. Yeah. Yeah, it's easy to to overlook that, especially for those of us who who have grown up in the wake of that and you know, just encountered in our science books at a very early age. Yeah. It's one of those things that just feels like people must have known this for hundreds of years. But yeah, the widespread acceptance of plate

tectonics is fairly recent. Here's a quote from from that paper by Sergeant quote. Mount Doom is indeed one of four isolated volcanoes, each representing a hotspot at some distance from a plate margin, and all of them associated with evil doing dhal gouldar in Mirkwood or Thonk in Eisenard, and Arab or the Lonely Mountain. So he contended that Eisenard was a volcanic crater with central Orthanic itself carved via technology and magic from a column of solidified lava

thrust up from the vent in its last eruption. The Lonely Mountain, which is ever shrouded in gray and silent clouds, is another, and he argues that Smog's chamber is just a reshaped lava tube. But Mount Doom the underlines is the only volcano that seems to be truly active in the time of the Elbow and Frodo, and the only recorded seismic events in the books occur first when Gandalf cast down the ball Rog and then when Gallum falls into the fires of Mountain Doom with the one ring.

Uh So, Ultimately, he's as for a world in which all the major events are revolving around activities at a single active volcano, Middle Earth is is rather seismically calm, while still being quote geologically like our own world. Well, I gotta say, I do not know what natural processes could create that perfect rectangle of mountains around more door. That seems impossible to me. I always looked at that map and said, ah, that's just that doesn't look like

real Earth. You've gotta make the outline a little more jagged. I understand, surrounded by mountains, but come on, look at those corners. Uh. This is one of the things I really liked about about our Scott Baker's work where he his fantasy work takes place in this world of the Three Seas that is very much Middle or Earth that's been you know, transformed via these various philosophical ideas and a lot of you know, the Crusades interjected in there

and some other influences. But there is a more door like location in the books with a central fortress and then mountains surrounding it. But in in his books, this is essentially an impact crater created by this thing from space or beyond that has come to the Earth, and that is the central uh fortress in the middle of this uh, this this vast crater, and so the mountains encircling it are those that were cast up by that

impact A plus very plausible. I like it. So anyway, there's there's some just additional token to just really kick things off here. But um, again, I would say that that saron and certainly is getting more connected to those those gods such as have Hestas, uh Adronus and Volcanos. Uh. They are all smiths in the human sense, all creators through technology rather than through the nature. That seems to

be their key metaphor here. The volcano. Well to bring it back into the real world and look at this duality of you know, the same entity that might be both responsible for the creating sustaining of life, but then

also fiery destruction and and explosive calamity. I want to start by asking a question that we talked about on the show a good bit, and that question is, when you're looking at other planets, you stare out of the night sky and and you're trying to find examples of other planets that might be able to sustain life, what are the conditions you would check for. I think the

most obvious is liquid water, right absolutely. I mean water is the thing that, uh, more than just about anything else we just can't remove from the equation and get to life as we know it. Yeah, and that's one of the things we talked about when we discussed Brian Green's book The Until the End of Time. He has this great section where he connects the chemical properties of

water to its role in the evolution of life. You know, the great power of water as this polar molecule and as a solvent, as a sort of three dimensional canvas for the drafting of the structure of cells, allowing for energy to be processed and harnessed for replication. Uh. And of course all of these virtues depend on water being in its liquid state. Water and it's frozen or vapor state is not really useful for the evolution of life.

But in addition to just looking for the direct presence of liquid water, there are other conditions you might be able to look for that could, at least in theory, make a planet more hospitable to the origin, evolution and maintenance of life, at least in theory, And you might not expect it, but volcanic eruptions and the plate tectonics that volcanic eruptions might signal are another one of those conditions. So maybe we should take a break and then talk

about that when we get back. Than alright, we're back. So the idea we're discussing here is the idea that that the that just as pale is not merely at a stroyer, but is also a creator volcanoes and the underlying plate tectonics that they represent might also be key to life. Yeah, and so I want to talk about an article that I was reading by a researcher named

Craig O'Neill. So O'Neill is a director of the mcquarie Planetary Research Center, and he's an associate professor of geodynamics at mcquarie University, and he's done some direct research on on simulating the evolution of heating models, and you know, he thermodynamics within planets or geodynamics, And so he starts off by talking about how that you know, there are two things that make Earth unique in the Solar System.

You might think, because of the conversation we were just having a minute ago, that one of them is liquid water, but actually no, there are other objects in the Solar System that have liquid water. Sometimes people bring up the example of Mars. I think that's still an open question.

Of course, Mars doesn't have lakes or rivers. There's some indication that it may have transient liquid water here and there on occasion, such as in these features called recurring slope lineer though, I think I was reading a report that there is spectral analysis that has disputed the interpretation of these sort of dark spots that appear on slopes

as as actual water. I guess we don't know for sure what they are, but um, there are other examples that are more straightforward, like it is totally scientific consensus at this point that Jupiter's moon Europa has liquid water under its icy surface. It's got the shell of ice on the outside. Underneath that, it's got some motions. They're sloshing around, they're having a good time. Who knows what's happening there. But there is also possibly subsurface water on

Ganymede and on Enceladus. So the two features that O'Neill singles out that actually make Earth unique within the Solar System are that Earth has plate tectonics and that Earth has life. And the question that he's raising is whether

these two unique features are actually causally related. If it's not a coincidence that Earth's crust breaks apart into plates that shift around and move over its surface, that float on top of the mantle, uh, that sort of spread apart in in some places and then subduct and move down and get sucked back into the mantle and other places.

Does that process contribute to the creation and sustaining of life. Yeah, this is an interesting idea because it basically comes down to the question of of whether a geologically active planet is necessary for life, like if there's something there's something in this Uh, this continued geological life that makes biological life more possible, right, And I guess there are ways that a planet could be geologically active but not have

plate tectonics. Like I'm going to get to this in more detail and a bit, but there are models of planets where there are not plates on the surface, where the surface is basically just one single spherical hard crust sitting on top of the mantle, but it can still have volcanic eruptions that could in some ways regulate the heating of the planet and control its atmosphere in a way that that could sustain life according to some researchers. But but we'll get in more detail about that in

a minute. So we know that one of the prerequisites for the evolution and survival of life as we know it is liquid water. But why is it that Earth has maintained the conditions necessary for liquid water basically the entire time it's existed. Ever since we've had liquid water, there has been the ability for water to stay liquid. It's been long enough to allow life to continue evolving

the entire time Earth has existed. So how is it possible that Earth has been able to maintain these habitable conditions in an almost adaptive and almost kind of accommodating kind of way, right like, especially since the external conditions have changed, like the Sun has grown thirty percent brighter over the same period of time, so the heat inputs on Earth have gotten much greater, and yet still the

the atmospheric climate of Earth has stayed relatively stable. And O'Neill offers the answer that what's going on here to keep Earth relatively stable is it's is the profile of its geological activity. Primarily it's plate tectonics. So first of all, you've got the idea that when you have plate tectonics, you tend to create volcanoes at the edges of tectonic plates, and when volcanoes erupt, they release stuff from the earth. Stuff from the mantle comes up and is released up

into the atmosphere. Probably the most important things that get released here are carbon dioxide and water vapor. Now this this is a great point that we sometimes lose track off perhaps when we think about volcanic eruptions and they're more destructive aspects. The idea that uh that you could have and you do have examples of terrific volcanic eruption um blocking out the sun, essentially forming a kind of

nuclear winter type effect. Uh, sometimes on on the scale of an entire planet, right, I mean, so that that could be the case if particles get ejected up into the atmosphere, that that shield the Earth from the Sun's rays,

and that can create a cooling effect. But over the long term, what they're what they're releasing is greenhouse gases, which which even though there may be particles that block out sunlight and cool the Earth at a shorter term, on a longer term, they are the volcanoes are polluting the atmosphere with c O two and with water vapor that trap heat down in the atmosphere. So that works

to help keep the atmosphere warm. But then there are processes of plate tectonics that work in the opposite direction to uh, the natural process of plate tectonics. It not only releases these materials into the atmosphere, it also cycles the deep back into the belly of the Earth. Now

the question would be, well, why is that important? Well, obviously, if you just keep pouring more and more greenhouse gases like c O two into the atmosphere, the Earth could end up like Venus, you know, it could end up with so much trapped heat that the surface boils and there's no liquid water and thus no life. So how does Earth deal with the extra carbon dioxide that gets

released from volcanoes. Well. As the tectonic plates of Earth slide around on the surface, there are sites where those plates get sucked back under the crust and into the mantle. The Mariana Trench is one example of a location where the plates are gobbled up by the Earth. And as these plates get sucked in, they take substances with them. They take water, they take a carbonate or carbonic acid,

which is the mineral form of carbon dioxide. So the process is essentially taking c O two back out of the atmosphere and sucking it down deep into the air Earth. By the way, speaking of of Venus, um should should drive home that the Venus is apparently lacking in plate tectonics. Oh yes, and but for a long time, scientist didn't

think there would be any kind of volcanic activity. But according to a Reuter's report that came out just this month, scientists have identified thirty seven volcanic structures on Venus that appear to be recently active. Well I didn't know that, but that is an interesting indicator, and we can talk about more examples throughout the Solar System as we go on. That is totally possible to have volcanoes without having plate tectonics.

Though if you look at a map of volcanoes on Earth's surface, some volcanoes just appear at random, you know, they might be in the middle of a plate, just some mantle hot spot somewhere. But most of the Earth's volcanoes they line up right along those lines at the boundaries of plates. So, for example, the western coast of the America's the whole ring of fire, you know, around the edge of the Pacific Ocean plate is where a

ton of the Earth's volcanoes are. But there's another interesting feature of plate tectonics that that helps remove carbon dioxide from the atmosphere, and that is mountains. I had never thought about this before, but I read about this in a couple of articles in O'Neill's and another one I'm going to mention in just a minute. So the process

goes like this. As plates move around on the surface of the Earth, they're floating over the mantel, they smash into each other and they bunch up where they get smashed, so as they smash into each other over the millennia, they raise up the bedrock at their impact points, and one one plate pushes the other up, and as the rock is raised up, it forms mountain peaks of exposed mineral bedrock. And O'Neill points out that mountains are one

of Earth's major CEO two sinks. It's a place where CEO two from the atmosphere can be moved and stored in a stable form. Of course, another example that we could think about would be trees and plants. Remember that the flesh of a plant is made out of carbon compounds that are built out of c O two that gets sucked out of the atmosphere and fused into carbohydrates using the energy from the sun. This is what photosynthesis is. So as plants build their bodies, they suck c O

two out of the sky. But mountains also suck CO two out of the sky, but in a different way. They suck it out through weathering. So as rain pours down on the mountains, the c O two dissolved in the rain water mixes with the minerals that are exposed in the rocks of mountains. This forms new minerals, and then eventually those new minerals with the c O two locked inside, drained down the sides of the mountains and

end up in the oceans. So every time you see a mountain range, you think that is like, it's like a toilet for carbon dioxide. It's just like the Skies toilet. It is what that mountain is. Well, I don't know if that's the most romantic way to have to think of the mountains, but I think it's beautiful toilet of the okay, But still the point, the point is valid, yes,

And then there are other sinks as well. Also. C O two gets dissolved directly into the ocean water itself, so it's it's coming into the ocean in multiple ways. It gets absorbed directly from the atmosphere into the ocean, and it drains from the weathering of mountains and rocks down to the oceans and ends up in the ocean floor,

often in the form of limestone. But in both of these forms, the carbon dioxide that's locked up in the ocean eventually can get subducted, right because at these places where the plates meet, it gets sucked back down into the mantel. Now, this takes a really long time. The processes we're talking about take place over over geologic time,

not like on human civilization a line. So if you're getting your hopes up about the idea that, oh, you know, Earth has a natural thermostat, we we don't have to worry about climate change, Unfortunately, that's not how this works. The natural thermostat that's established by plate tectonics has helped keep the Earth within a temperature range where it can maintain an atmosphere and liquid water and at least some

life forms. But this temperature range that it maintains is number one, it's huge compared to the range that will support stable human civilization as it currently exists. Like human civilizations and cities and agriculture and the ecosystems we depend on are all much more fragile than the baseline of just maintaining an atmosphere, liquid water and some life and then of course, the other point is that this process

takes a really long time. So even even if it could help maintain in a much narrower range that we depend on, uh, it takes a long It takes you know, beyond human civilization levels of time to really reach equilibrium. But to just to sum up the process of how the thermostat actually works, I'm gonna quote directly from O'Neill. He says, quote, if the Earth gets too hot, high levels of rainfall and erosion start bringing c O two

levels down. If the Earth gets too cold and freezes over, the erosion mechanism stops, right, so it stops raining on the mountains and draining into the ocean. But vulcanism due to plate tik tonics continues pumping c O two into the atmosphere and the levels build up, eventually melting the ice caps. It was this mechanism that allowed Earth to recover from a global ice age in the neo Proterozoic

about six million years ago. Yeah, so again we're talking about processes that they are taking place at geologic scale and not a human lifetime scale. But then also on top of that, even if you were exceptionally long lived, do you are essentially immortal? These are not pleasant changes to go through, I would imagine, like in either direction,

and we're dealing with goth catastrophe here. Oh yeah, and these changes again, what we're talking about is how the Earth's plate tectonic thermostat if if this theory is correct, which it seems like it probably is. How the plate tectonic thermostat is able to maintain Earth as a habitable planet, So like it's still going to have liquid water, it's still going to have an atmosphere that's a very low baseline. You know that during this time they're going to be

mass extinctions there. You know, sea levels are going to be hugely rising and falling. Huge parts of continents get covered in ice, and then the ice retreats. So these are this is not like stuff that would be like, oh it's cold outside today. These are these are world changing variations. They just don't change to the point that Earth is no longer habitable like Venus or Mars. Does that make sense? Yes, Still, out of catastrophe comes life. And speaking of that, we're going to take a quick

ad break, but we'll be right back. Alright, We're back, all right. So we've been talking about theories in geology about how volcanoes and plate tectonics might be important for making the Earth habitable for life and maintaining its ability to host life over time. One of the things we were just talking about was the idea of plate tectonics

is a natural thermostat regulator for temperature on Earth. That it that allows the Earth to release and absorb greenhouse gases in a cyclical way that basically keeps the Earth from turning into Venus or Mars or some other uninhabitable

hell um. Now, there was another article I was reading that was in Quanta by the science writer Rebecca Boyle from June seen that mentioned a number of other theories that have connected plate tectonics and volcanoes two various life related plot processes on Earth and uh and I found this all really interesting, so I just wanted to explore a few of the things that she gets into in this article. One of them is the idea that plate tectonics might possibly have been important for the origin of

life itself. Now, this one is somewhat controversial because we don't know for sure when plate tectonics began on Earth. We we don't know how early it got started. There their various theories about that. But for example, Craig O'Neil, the author of the article I was just talking about before the Break, has been involved on research that posits that before the Earth had plate tectonics, it had a period of what was what is called a stagnant lid state,

where it didn't have plates sliding around. It had this sort of single hard shell floating on top of the mantle. But Boil's article points to research about how the subduction of plates on ocean floors actually creates conditions that are that are friendly to various types of extreme deep ocean life that we think of as being similar to, or possibly the direct analogs of the earliest life on Earth.

Uh to quote one section boil Rights quote. As the Pacific Plate is dragged down into Earth's mantle, it warms up and releases water trapped within the rock in a process called serpentine ization. The water bubbles out of the plate and transforms the physical properties of the upper mantle. This transformation allows methane and other compounds to percolate out of the mantle through hot springs on the otherwise frigid,

cold floor. And it's this type of chemical reaction that that on the ocean floor could possibly have given rise to the earliest chemical metabolism and jump started a chemical evolution of what would become cells and life as we know it. We don't know for sure, but it seems like one of the plausible origin theories for life on Earth. In other words, the sort of ancient chemistry labs that are are firing off random concoctions that that then end

up benefiting the emergence of life. Right now, there's another thing Boils article mentions that touches on an issue we've discussed on the show before, which is the Cambrian explosion. Apparently, plate tec tonics have also been implicated as a possible cause of the Cambrian explosion. Now, brief refresher on what's going on here. Remember we've talked about this fascinating paleontological mystery before roughly five hundred and forty million years ago.

There is a dramatic change in the fossil record before roughly forty million years ago, in a period that we know is the edi acron. Most of the life we have evidence of is very simple. It's soft bodied worm like creatures, sort of leaf shaped, multicellular fraunds. A lot of soft bodied organisms, many of which are not preserved very well. Um and there is not There doesn't seem to be a lot of diversity of body forms taking shape rapidly, but then over a period of time that

is geologically really sudden. There's this proliferation of animals with lots of different body types that have hard body parts that are preserved very well in fossils, so we have good records of them. This is when you get the trilobites, Anamala, Carus, Hallucigenia, Opabinia, all of your favorite monsters of the ocean primeval. This is the Cambrian explosion, And the question is what explains this apparently sudden acceleration of evolution and diversification of life

that happened about five and forty million years ago. Now, there are a lot of competing theories. Some I think some paleontologists say, well, maybe the rapidity of the Cambrian explosion is sort of overstated, maybe there's some bias in the fossil record, But I think it's generally agreed that, yeah, a lot of new animal forms really do show up pretty fast, and so other theories have to do with

like changes in the composition of the atmosphere. One that we've talked about on the show that was pretty interesting is that it was a reaction to the evolution of hunting and active predation. As a novel thing on planet Earth. There had not been hunting before, and suddenly as soon as organisms are hunting each other, there's just like this rapid race to find new ways that bodies can be But Boil's article points to research from that actually links

the Cambrian explosion to plate tectonic activity. So this is a paper by Ross Large at All published in Gondwana Research in and what's their theory, Well simplified, it goes sort of like this, plate tectonics smash continental plates together. So the plates are moving around and they smashed together, and at the places where they smashed together, it often raises up mountain ranges. And these mountain ranges at the borders of plates consists of exposed mineral bedrock that's heaved

up into the sky. We talked about this a bit earlier, and we we needed this a bit too in the gold episode where we talked about looking for gold in the ocean, and we talked just very briefly about why one pans for gold in mountain streams. Yes, Yes, a

very good point. Yeah. So the rock that gets lifted up as it smashes together at the edges of these plates, the mountains that get raised up can be hammered by the elements that exposes the underlying minerals to you know, the wind, but primarily the rain, and the rain drains chemical nutrients from the rocks down into the oceans, and this causes a proliferation of chemicals like phosphorous, copper, zinc, selenium, cobalt,

and stuff like that in the seas. These nutrients in the ocean then allow high biological productivity, the proliferation of life, intense competition, and so it's kind of like the some of the most important chemicals of life have been hidden by the gods uh in the deep earth and mountains. They're the Prometheus figure freeing those and releasing them into the ocean where they can become a part of life exactly, yes,

um and so boil rights quote. Maybe more surprisingly, Large and his colleagues also found that these elements were low in abundance during more recent periods, and that these periods coincided with mass extinctions. These nutrient poor periods happened when phosphorus and trace elements were being consumed by the earth faster than they could be replenished. Large said, so in times where the all of these very biologically useful elements like phosphorus and some of the other ones we mentioned

are getting sucked back down into the mantle. It's subduction areas faster than they're getting released from the from mountains and and other deep mineral sources. These are bad times for life on Earth. Suddenly, it's like life is not getting its vitamins. Boil's article also mentioned several other interesting theories I'm not going to go deep into detail about. One is that plate tectonics could be responsible for atmospheric

oxygen on Earth. There's basically a two step procedure here. Uh. First of all, plate tectonics create continents with rocks that don't react with oxygen in the atmosphere as easily as the iron rich early rocks of Earth did. And then after that, carbon dioxide gets released from rocks into the

air and the ocean. That feeds the growth of photosynthetic organisms like algae, which in turn produced oxygen as a waste product, sort of an oxygen two step, which, of course at the time was very bad for Earth because oxygen is a poison and it will kill you. But we evolved in the wake of that poison atmosphere and

here we are breathing it. And then another interesting idea. Uh. That article mentions is the work of Robert Stern, who is a geologist at the University of Texas, Dallas, who posits that because of plate tectonics, we have more opportunities for evolution on Earth than you might expect otherwise because the rearranging of continents and seas through plate tectonics drive

selection effects and the evolution of new species. Uh. Starn says, quote, you need isolation and competition for evolution to really get going. If there is no real change in the land sea area, there's no competitive drive and speciation. That's the plate tectonics pump.

Once you get life, you can really make it evolve fast by breaking up continents and continental shelves and moving them to different latitudes and recombining them, which I don't know if I had ever thought about it quite like that before, but you do kind of see this effect throughout history as continents drift around, they smash into each other, they separate from each other. You see different life forms kind of going their own way. Yeah, coming into contact

with each other for the first time. Um, you know, just changing the the scenarios that are driving evolution. Um. Yeah, that's that's fascinating. I've never really thought about it that way, but if you you could look at a planet with plate technomic tectonics as being like the ideal laboratory for um for for the for for evolution to take place in uh, it's it's kind of like it has an automatic shuffle mode in place. Yeah. I like that plate

tectonics puts biology on shuffle. That's so good. Otherwise you're just gonna listen to that one track over and over again, and you're just gonna listen to the first three. You know, you need to have it shuffled up every now and then so you'll you'll you'll you'll experience the album in a new order and suddenly you're gonna find new favorite tracks.

All right, I want to talk about one last thing before we finish up here, which is an article I was reading about the use of volcanoes and plate tectonics as a proxy for habit ability when searching for exo planets, because that makes sense based on everything we've said here. You know, in the same way that we would look for signs of water on another world as a potential as a potential sign that conditions could be right for life,

then perhaps looking for volcanoes makes sense as well. Yeah, so I was reading about this in a in a NASA press release that was covering a paper published an Astrobiology in TWI by Im Misra at All called transient sulfate aerosols is a signature of exoplanet vulcanism. I think these researchers were out of the University of Washington, and they're publishing a method for detecting volcanic activity on exo planets to figure out which ones might be good candidates

to host life. For all the reasons we've been talking about now, this began with students trying to find ways to detect plate tectonics on exo planets. Obviously, you can't resolve the surface of an exo planet with a telescope or look at it long enough to know if it's got continents that are moving around. Um. But the lead author Misra said in this press release quote, I came up with the idea of looking at explosive volcanic eruptions

as a proxy or stand in for plate tectonics. I've done some work modeling aerosols produced by volcanic eruptions for other projects, so I started looking into how we might detect an eruption and what it would tell us. Now, this is specifically focusing on explosive volcanic eruptions that tend to happen at the edges of tectonic plates. Again, I mentioned this earlier, but if you look at a map of tectonic plates, you'll notice that the boundaries match up

to lines of volcanoes on the surface of the Earth. Now, what is it about explosive eruptions in particular? We you know, we've all seen footage of volcanic eruptions that are not particularly explosive. They're basically kind of gentle lava flows, relatively gentle, you know, it's still a planet. And even during more you know, middle of the road volcanic eruptions, the gases and aerosols that get expelled from the Earth off intend to fall back to the surface pretty fast, at least

fast on a geological scale. But during these really highly explosive eruptions, gases and particles shot up from the volcano or often shot into the stratosphere where they can linger for months or years, and they affect what's called the transit transmission spectra of the planet. This is something that we can actually detect with telescopes at at a distance of you know, as far away as other stars and

their planets are. So, by looking at the frequency of light reflected by an exoplanet as it transits in front of its star between us and its star, you might be able to detect whether there are transient sulfate aerosols from explosive eruptions in the stratosphere, which in turn would be a good indicator, though not a guarantee, of plate

tectonics down on the surface. The authors of the study right quote, we propose that the detection of this transient signal would strongly suggest an so planet volcanic eruption if potential false positives such as dust storms or bowl eyed impacts can be ruled out. Furthermore, because scenarios exist in which O two can form a biotically in the absence of volcanic activity, detection of transient aerosols that can be linked with vulcanism along with detection of O two would

be a more robust biosignature than O two alone. Right. So this is another This is linking to another idea people have had that if you can look at an exoplanet and detect oxygen free oxygen in its atmosphere. That might be a sign of life in the atmosphere because you know, oxygen is often a byproduct of organisms, like photosynthetic organisms on Earth, but you know O two can be produced by other things. So they're saying, if you find that, and you find signs of volcanoes, this is

a good sign that this is a living planet. I mean, it sounds like a solid argument to me based on what we've seen here. And it's and the thing is, I mean, it's still vital information about the nature of a given world. So it's not like you'd be you know, you know, chasing after uh a wild hair here. This would be essential information either way, exactly. Now. On the other hand, we mentioned that volcanoes are not a sure sign of plate tectonics, and this brings me back to

something I wanted to talk about. That was also from Craig O'Neill, because O'Neill was writing about how you know, because of the assumed association between plate tectonics and life, some astronomers and astrobiologists are interested in looking for exoplanets with the potential for aliens and UH and they've tried to focus on places where plate tectonics seemed likely to exist, and one candidate that O'Neill points out was long thought

to be these planets called super Earth's their terrestrial rocky planets like Earth, like Mars, like Venus, but even bigger

than Earth. And O'Neill writes that it was once believed that the odds of finding plate tectonics on big planets like this was higher, but now it seems like that might not actually be true because computer simulations have shown that you can probably have very large rocky planets without plate tectonics and instead with a surface conforming to this thing I mentioned earlier called the stagnant lid model, which

sounds gross. Basically, it's where the interior of the planet is hot, it's cooling, it's releasing its heat, and the heat is released through volcanic eruptions. But the surface does not have moving plates, and so no recycling of water and CO two to the interior like we have in the subduction on Earth. Uh, no formation of mountains or

natural mineral sequestration like we have on Earth. It's just going to be kind of a big rocky planet with a hot interior that has volcanoes, but the volcanoes just sort of poke up occasionally out of its solid, spherical, rocky shell. And O'Neill and the co authors of his of his paper that this article was based on, we're addressing the question of how is it exactly that planets evolve over time, And they came to the idea that planets might start hot and turbulent and then far down

the road they end up cool and geologically inactive. And that quote. We found that the evolutionary track of planet takes depends not only on its size, but on how it starts. For example, two planets identical in every other way but with different starting temperatures may evolve down very different evolutionary paths. And so what they argue is that plate tectonics like we have on Earth might simply be a phase in the evolution of planets, sort of a

lacuna between two eras of stagnant lids. And it's possible Earth was once a stagnant lid planet with a single hard shell, and now we have plate tectonics, and may maybe one day we will not have plate tectonics anymore. So if this is the model that habitable worlds take you would you would end up having, assuming they lived long enough, some sort of highly evolved life form ruling

over a stagnant lid Earth. That's that's possible. Though there was another report I was reading that that complicates all this, because you know, as I was saying, this is still not a fully settled question. I was reading a report from Penn State News about a couple of Penn State researchers geoscientists there named Bradford Foley and Andrew Smile, who argued that no, in fact, they're findings show that you don't necessarily have to have plate tectonics to sustain life

on a planet. Given certain conditions, you can just have volcanoes basically keeping the planet roughly the right kind of temperature. Now, that wouldn't invalidate all the stuff we've said about the role that plate tectonics have played in the evolution of life on Earth. But it's still basically just an unsettled question. It seems to me whether or not plate tectonics are really necessary for the existence of life on a planet

or not. By the way, one cool thing I came across, I didn't get super deep into this but it's also hypotheses about what happened to Earth's early stagnant lid in order to turn Earth into a into a planet with with subducting plates, plates moving around, sliding under each other. And one theory is that was asteroid bombardment. So Earth up, yeah, exactly.

Earth may once have had this this solid shell on the outside where without moving plates, and then some kind of impact or series of impacts broke it all up and got things churning around, and ever since then we've had a crust in the form of moving plates instead

of one solid plate. And that that has a very kind of divine feel to it, right, like a stagnant world that is no longer advancing or creating anything new, and so now some force beyond them has to rain down destruction so that so that like new possibilities can

emerge our of this shattered stagnantally. Yeah, And and the one last thing I want to mention here is that O'Neill points to one of my favorite objects in the Solar System as an example of a of an object like a planet that can be geologically active and have volcanoes without having plate tectonics. And that example, of course is Jupiter's moon Io, the yellow hell of Galilee and Sulfur. You know, this was one of my favorites, and when we did the episode about Jupiter's moons and so iow

is Jupiter's innermost major moon. It's very geologically active, even more so than Earth. It's the most volcanic object in the Solar System. And this is a result of tidal forces that act on the guts of Io. It's gravitational man handling by Jupiter slashes the guts of this moon around and UH and its heat mostly escapes to the surface through what O'Neill calls heat pipes. These are volcanoes,

not through the movement of tectonic plates. So to come back to our our god analogy here, in this case, the god that is Jupiter is UH is too involved in the in the in the nature of the planet. It's like a um and micro managing oppressor UH as opposed to one that just periodically brings about destruction. Yeah, exactly, Jupiter, it will never leave you alone. And I think what Ion needs to do is to go down into the void and get the dim O organ to come up

and and kill Jupiter like he does in UH. In Oh, what's that play Prometheus Unbound? There you go. But anyway, so I don't know, I found this really interesting. I don't think I had ever looked this deeply into how entangled the geology of Earth um and specifically it's it's mineral geology, It's rocks are with the with the evolution of life on Earth. I think i'd always thought primarily

about like temperature and liquid water. Yeah, or i'd i'd probably focus more on sort of everyday human level things like the fact that, okay, that you know the soil near volcano is going to be rich and good for growing things, or that volcanic activity creates land that can eventually be become habitable that sort of thing. But this is a much much deeper dive into like the the truly geologic um level of the whole equation. Uh So, anyway, Yeah,

I think that does it for now. But but I hope you've enjoyed this journey into the volcano absolutely, And of course, as before when we discussed volcanoes on the show, we want to hear from you about your experience with volcanoes, life near volcanoes, visiting volcanoes, active and dormant, um, how

does this affect your interpretation of these amazing sites? And if you want to check out other episodes of Stuff to Blow your Mind, well you can find us wherever you find your podcasts and wherever that happens to be. Just make sure you rate, review and subscribe if you can. These are acts that really helped the show out in the long run. Before we wrap up, I've just got to say so, I don't forget. We need to get some mountains or the toilets of the atmosphere T shirts made. Oh,

I don't know if that is good. That would be a best seller. I don't know why not? Worst T shirt ever? Okay, anyway, huge thanks as always to our excellent audio producer Seth Nicholas Johnson. If you would like to get in touch with us with feedback on this episode or any other, just to say hi, or to suggest a topic for the future, whatever you want, you can email us at contact at stuff to Blow your Mind dot com. Stuff to Blow Your Mind's production of

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