Is Earth alive?
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You've probably been to a book club before, right? Or maybe you've heard about them and consciously stayed away because there are a lot of rules. You have to show up. Someone picks a book. You have to read the book. Then you have to talk about the book.

It's a lot, but we've come up with what we think is a better system. One of us picks a book, we tell you exactly why we picked it, and then we just call up the author and talk to them about it. No frills, no guilt, simple. So for the first edition of the Unexplainable Book Club, here's our science editor, Brian Resnick.

The book I chose is Becoming Earth. It's the debut nonfiction book from a science journalist named Ferris Jaber. I've admired his work for years, and his book grapples with a question I have also been fascinated with. Can we think of the Earth itself as a living entity?

It's probably one of the most ancient beliefs that we know of in human culture. And there are so many different religions and cultures and mythologies around the world that have written or spoken about the world, the planet, Earth being alive in some sense.

One of the most famous versions of this idea, at least in modern Western spaces, is called the Gaia Hypothesis. It was developed in the 1960s and 70s. A couple of scientists, one was named James Lovelock, the other Lynn Margulis, they basically said, "Look how interconnected everything on Earth is. The water cycle, volcanoes, the ocean, the atmosphere, they all play into one another."

So, these scientists suggested that all of this added up to a self-sustaining system. Earth didn't just have life on it, it was alive.

The Guy Hypothesis was roundly criticized. It was even ridiculed. And for many decades, the Guy Hypothesis was considered kind of this fringe sort of woo-woo idea that wasn't completely ludicrous, but it certainly wasn't rigorous science. And many scientists remain very opposed to the idea that an ecosystem could be considered alive or that a planet could be considered alive.

To this day, biologists don't have a perfect definition of life.

But still, Gaia did not fit in with the conventional ideas that were out there. What a living thing is, is quite a specific thing. And it is typically thought of as an organism that is a product of Darwinian evolution by natural selection. And, you know, reproduction, genetic inheritance, natural selection, these are all fundamental properties of life. They're defining qualities of life. And Earth, as a planet, does not meet those criteria.

But now, some scientists are reconsidering that stance. So, Ferris, he looked through a lot of this new research for his book, Becoming Earth, and he's come to his own answer on the question, is Earth alive? My answer is yes, Earth is alive. And I think there are kind of four parts to the argument that substantiate that statement. So, this is Unexplainable. I'm Brian Resnick, and today on the show, is the Earth alive? ♪

Ferris Jaber is going to present his four-part argument for saying yes, and also his argument for why this whole discussion matters. Okay, let's start. What's point one in your argument for is Earth alive?

So, the first huge revelation for me was to stop thinking about life as simply inhabiting Earth or residing on the planet and to realize that life is a literal extension of the planet. And so the way I like to think about this is if you imagine a vast beach and you imagine that all of these sandcastles and other sculptures emerge from the sand, they

They are still made of sand, right? They're not suddenly divorced from the beach just because they've arisen from the beach. Those castles and sculptures are still literally the beach. And I think it's the same with life and earth. Life isn't just on earth. It literally came out of earth. It is literally part of earth. It is earth. Wow. So, okay. This first bit of argument, kind of a mind blown. The material of life is earth. And so like...

Distinguishing these two seems silly because they obviously comprise each other. Exactly, exactly. Every layer of the planet that we've been able to access, we find life there. And in the deepest mines that we have dug, we continue to find microbes and sometimes even more complex organisms like nematodes, these tiny worm-like creatures.

The more you think about this, the more the boundaries dissolve. We cannot separate life and environment or earth and life categorically from each other. They're too connected to be separated that way. But aren't there parts of the earth that just

don't have life in them? There are components of the Earth that are not alive in any way. So, like, if we got to the center of the planet, we don't actually know, but presumably it's all molten rock and there might be, like, some solid metal in the core. But that's true of all complex living entities. We are part mineral and largely water.

Water and minerals are not alive. That's inert matter. Think about a redwood tree. It is mostly dead wood.

In terms of its volume and mass, it is mostly non-living tissue. And then a little bit of tissue that is laced with living cells, you know, here and there. So, you know, most complex multicellular living entities are a jumble of the animate inanimate. So Earth is not unusual in that way. Okay, so that's part one of your argument. Earth is alive because all life is part of the Earth. And even though...

some parts of it are minerals or water that's true for most organisms. What's part two? What's the next part of your argument? So number two, as an extension of that, is that what we call life, all these organisms, they give Earth a kind of anatomy and physiology to continue the analogies to organisms. And the way to think about this is that

Scientists have shown, they've calculated, that life dramatically increases the planet's capacity to absorb, store, and transform energy, to exchange gases, and to perform complex chemical reactions. Earth is covered on both the oceans and the land with photosynthetic organisms that are literally channeling energy from the sun all the time and converting it into other forms. You know, that's an amazing planet-wide phenomenon.

complex chemical process that is happening every single second that we're talking right now. So, you know, Mars and Venus, they're not capable of doing this. So are you saying something like all of the algae or plankton in the ocean, you know, it does gas exchange. It generates oxygen. Yeah.

takes in carbon, all that stuff. Is that kind of like how all of the cells in my lungs and body are playing that game? Is that the comparison here, or is that not quite the right way to think about it? I think we have to be careful with making too direct of a comparison there, only because...

You as an organism are a product of evolution by natural selection. And so your structure, your anatomy is something that was written into your genome. That's not how the Earth system formed. But there are still some analogies. You know, like NASA has made these amazing videos and animations and they've called them "Watching Earth Breathe."

because you can see how the levels of carbon dioxide and oxygen in the atmosphere fluctuate with the seasons. And it's a sinuous rhythm. It looks like a pulse or like breathing. It is a planetary rhythm. Like up and down, like comes in and out. Exactly, exactly. So, you know, there are these genuine planetary scale rhythms that emerge from the collective activities and processes of life.

I'm realizing a key to this conversation is when we're thinking about the Earth as alive, it's not alive in the same way you and I are. But there's these equivalent processes that look very similar to life where you say, "Okay, it's not exchanging gases and doing metabolism-like things in the way I am."

But yet it is doing something that seems analogous. Absolutely. I think you've hit upon a really important point, which is that life is a phenomenon that occurs at multiple scales. For many people, life and organism mean exactly the same thing, but they should not be synonymous. Organism is one form, one scale at which this phenomenon we call life happens, but it happens at multiple scales.

And the way I think of it is that it's not identical at all of those scales, but it rhymes at each of those scales. There are analogies between each of those scales.

So I like to think of a leaf on a tree in a forest on a planet. There's no disagreement whatsoever within science that the cells that compose that leaf are alive, right? The tissues that those cells form are alive. The leaf as a whole is a living tissue. The tree we consider also alive. We consider each of those layers to be alive. There's no debate or controversy about that.

Once we go above the scale of the organism, this is where the debate begins. Can we think of the forest, the ecosystem, as alive as well? And then one more level higher, can we think of the planet as alive? My argument is yes, that each of those levels, each of those scales is equally alive, but not identical.

So I'm becoming fairly convinced of your argument, and we've only done the first two points, so congrats. Thanks. But I feel like for completionist's sake, we should go through the last two. But first, let's take a little break.

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So, Ferris Jaber, author of Becoming Earth, you told us that one of the main reasons that scientists haven't liked Gaia hypothesis is that it doesn't fit the conventional definition of what life might be, that it's this self-sustaining system that also evolves. But you also argue that there are ways that the Earth does fit that definition. And we've done two parts of your argument. We're on part three. So what is part three?

Okay, so part three is that in addition to life being an extension of the planet and being an anatomy of the planet, life is also an engine of planetary evolution. And so this is the idea that the planet evolves over time dramatically. It is not exactly the same as standard Darwinian evolution through natural selection, but it is very much a type of evolution. It is dramatically

change over time. And organisms and their environments continually co-evolve. Each is profoundly changing the other. And over the past several billion years, this co-evolution has

is responsible for many of the planet's defining features, for our breathable atmosphere, our blue sky, our bountiful oceans, our fertile soils. This is all because of life and because of the way that life has changed the planetary environment. These are not default features of the planet that were there from the very beginning. Life has created them over time. Okay, so you're kind of saying two things here. You're saying that the Earth evolves, right?

But also that life is what is making it evolve or change. So what do you think is the most interesting example of how life has changed the earth?

I think the most radical, profound, single change by life is the oxygenation of Earth, which began with cyanobacteria many billions of years ago and continued with the advent, in a sense, of land plants. In the beginning, Earth had essentially no free oxygen in its atmosphere, and the sky was probably a hazy orange.

And when cyanobacteria began to oxygenate the atmosphere through the innovation of photosynthesis, the sky probably started shifting towards the blue part of the spectrum. And the entire chemistry of the planet changed. I mean, you suddenly had an oxygen-rich environment, whereas before it was an oxygen-poor environment. And so that changes absolutely everything. I mean, almost everything that, you know, makes Earth Earth is because of life.

And kind of like what we were talking about before, Earth evolves, not in the way that life on the scale of you and I or rabbit or snake evolves, but it clearly does evolve. It does change. It responds to differing conditions, and it's clearly changing because of this collective force of life. Exactly. And another important point to get across is that

Evolutionary biologists will say a planet cannot evolve because it doesn't have a cohesive genome. There's no genetic inheritance going on. There's no sexual reproduction going on. And that's fundamental to evolution. But there are analogous processes by which changes are passed down from generation to generation that are not genetically encoded. So you're not saying that the Earth is

Reproducing. That would be quite a cataclysm, I think. But can you help me understand what you mean when you say that it's passing down changes in a way that looks like evolution? So if we think about, on a smaller scale, a bunch of large mammals transforming their landscape, they're walking through this landscape with their immense hefts, they're tearing down vegetation, they're digging and uprooting things.

they're carving tunnels or whatever they might be doing. They're changing the landscape. Those changes persist, and so their descendants now are evolving in a new environment changed by their predecessors. So these environmental changes are not themselves genetically encoded, but they are being passed from generation to generation, and they are inevitably influencing the evolution that follows. That is the basic mechanism of coevolution of life and environment.

And I think it requires a substantial update to modern evolutionary theory. It's not, nobody's arguing against

natural selection or Darwinian evolution. Darwin was not wrong, but there's more than just natural selection happening. And in fact, a lot of scientists have argued for a long time of what they call the extended evolutionary synthesis of moving beyond just natural selection as kind of the crown jewel of evolutionary theory and recognizing that there are other processes happening at the same time. Okay, I think I got it. So the third argument here is the Earth evolves.

It doesn't evolve in the same way a more typical organism evolves. But if we expand our idea of what evolution is, it does check the box. So what's part four of your argument? So the fourth part is that this coevolution is

on the whole, has amplified the planet's capacity for self-regulation and enhanced Earth's resilience. So like we were talking about before, Earth has remained alive for, you know, around four billion years despite repeated catastrophes of unfathomable scale, unlike anything that we have ever experienced in human history.

And we have to account for that resilience. And I think we've seen that over and over again, where even in the mass extinctions in Earth's history, life recedes to its most fundamental and most resilient forms, which is microbial life, and then it re-sprouts from there. Okay, so I do get the point about mass extinctions that after one of them, life re-emerges after a while.

But is it just life, or does the physical Earth itself also have ways to heal? I think one of the most powerful examples is what's known as the planetary thermostat.

we see that Earth has a capacity to regulate its climate to some extent. And so the way the planetary thermostat works is that carbon dioxide from the atmosphere is continually dissolving into the ocean and it fuels photosynthetic plankton there.

And when these plankton poop or they die or they sink to the seafloor, they take that carbon with them. It settles on the seafloor. It accumulates in layers of muck. And that muck is eventually compressed into stone and traps that carbon for many millions of years. At the same time, volcanoes are spewing out carbon dioxide, which combines with water vapor in the atmosphere. And it makes rain naturally acidic.

And so therefore rain eats away at rock when it falls on the planet's surface. It's a process called weathering. In addition, life is enhancing this weathering process. Plants, microbes, and fungi are eating away at the planet's crust. Now, if Earth enters a torrential hot house state where the climate is extremely hot, as a part of that, rainfall becomes more intense and frequent.

And weathering happens more quickly than usual. So you get a flood of minerals going to the ocean that's nourishing more life. It's removing carbon from the atmosphere faster than volcanoes can replenish it. And over hundreds of thousands to millions of years, this feedback loop cools Earth.

Conversely, if Earth enters a snowball state, you know, an extreme freeze and ice smothers the sea and land, the water cycle basically stops. It stalls. And so the productivity of plankton under ocean life drops, carbon dioxide builds up in the atmosphere, and that eventually warms the planet.

So that is the planetary thermostat. And although it can technically operate abiotically, life has been intimately entangled with it for at least 3.5 billion years, maybe more than 4 billion years. And it enhances this thermostat. It amplifies its power. Okay, just to recap here. The first argument is that all life on Earth is Earth. So it's hard to distinguish the two.

Two is that there's a lot of things on Earth. The structures of it kind of rhymes with the organism. It seems to be breathing in a way. Three is that the Earth has its own version of evolution. It's not reproducing, but it is passing down changes. And four, the Earth has these mechanisms to heal itself and to sustain itself as a place for life. So...

Why does it matter to understand the Earth in this manner, in the Earth as somewhere on this continuum of alive? Or is it kind of just a parlor game in, I don't know, do people meet in parlors? No. Or is it some sort of just intellectual candy for people to think about? Or does it really matter to think about the Earth in this lifelike framework? Yeah.

I think it's hugely important. I think there's a massive difference between thinking of ourselves as living creatures that simply reside on a planet versus being a component of a much larger living entity. It's the difference between thinking about simply harming the environment that we inhabit through our actions versus severely imbalancing this massive living entity of which we are a part. And I think that is so crucial to understand that distinction right now.

Because we are finally reckoning with, you know, grappling with what our species has done to this living entity that we call Earth. And, you know, when we properly understand our role within the living Earth system, I think the moral urgency of the climate crisis really comes into focus.

Each of us is literally Earth animated, and we are one part of this much larger living entity. And literally everything that we are all doing moment to moment, day to day, is affecting this larger living entity in some way. And, you know, there's always these discussions of like, oh, is it about the individual choices and actions versus like collective political action or government level action? But it's

Clearly both, right? Isn't that part of what this is showing us is that it's all about the connections between the tiny and the planetary, between the individual and the collective? I think I got a simple point from what you just said in that

We are Earth. Don't self-harm. Right, exactly. And I think one of the phrases that has become an anthem recently is we are Earth defending itself. Right. I've heard that in climate discussions a lot. And I feel that is that is not just metaphorically true anymore. That is literally true when you think of the Earth this way. Ferris Jaber is the author of Becoming Earth, How Our Planet Came to Life. His book will be out in June.

This episode was produced by Brian Resnick and by me, Bird Pinkerton. It was edited by Jorge Just. Meredith Hodnot runs the show. Noam Hassenfeld did the music. Christian Ayala did the mix and sound design. Melissa Hirsch did our fact-checking. And Manning Nguyen is the fact that pigeons are doves. And now, some news from our host, Noam. Yeah, so this was the first episode of our book club episode.

But it's also the last episode with Brian on our team. He's moving on to new and exciting things. Brian will always be a part of the show. His ideas shape the way we all think about science and how we approach making episodes of the show. So he's basically the DNA of the show. Yeah, and...

To kind of showcase that, we wanted to send Brian off by playing a moment from the pilot we made before this show was even a show. We were trying to explain to people what Unexplainable was going to be about. And we just had this whole conversation about the mysteries of dark matter, how unknowable it was, and what it felt like to stare into the unknown like that. And Brian said this.

The only thing I can think about is the feeling that makes me feel is, have you ever hiked the Grand Canyon, like to the bottom? Not all the way to the bottom, no. So you get to the Grand Canyon, it looks enormous. You're at the rim. It looks like this like oil painting, like it's so huge. But then as you start to descend into it and get towards the bottom,

it only starts to look bigger. Like you realize that like little details that you saw at the top are actually huge, like craggy rock faces that descend hundreds and hundreds of feet. And you just feel so small. And I love these moments of like realizing the questions are so profound and so big. You know, there's a sense of optimism in a question, right? Like it makes you feel like we can know the answer to them. We can fill in a little bit more of the hole of our ignorance.

The whole Unexplainable team has been exploring the grand, mysterious canyon of science with Brian since the beginning of the show. And we'll keep exploring it without him. But we're going to miss Brian a lot. Thanks for everything, Brian. If you want to tell us how much you love Brian, or if you have thoughts about Earth being alive, or ideas for the show, email us with your thoughts or questions. We are at unexplainable at fox.com.

This podcast and all of Vox is free in part because of gifts from our readers and listeners. So you can also go to vox.com slash give to give today or support the show by leaving us a review. Unexplainable is part of the Vox Media Podcast Network. And we will be back next week.