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In the 1970s, chemist James Lovelock and microbiologist Lynn Margulis put forth a bold theory: The Earth is a giant living organism.
When a mammal is hot, it sweats to cool itself off. If you nick your skin with a knife, the skin will scab and heal. Lovelock and Margulis argued that our planet has similar processes of self-regulation, which arguably, make it seem like the Earth itself is alive.
The idea wasn’t unprecedented in human history. “The fundamental concept of a living world is ancient,” says Ferris Jabr, a science journalist and author of the upcoming book Becoming Earth: How Our Planet Came to Life. The book explores all the ways life has shaped our physical world and, in doing so, inevitably revisits the question “Is the Earth alive?”
Lovelock and Margulis called the idea “the Gaia Hypothesis” — named after the ancient Greek goddess of the Earth. It was openly mocked by many in mainstream Western science. “For many decades, the Gaia hypothesis was considered kind of this fringe sort of woo-woo idea,” Jabr says. “Because for biologists,” Jabr says, life is a specific thing. “It is typically thought of as an organism that is a product of Darwinian evolution by natural selection. And Earth as a planet does not meet those criteria.”
It didn’t help that the original articulation of Gaia granted Earth a certain degree of sentience. The hypothesis argued “all of the living organisms on Earth are collaborating to deliberately create a climate that is suitable for life,” as Jabr says. But yet, this idea has persisted, for a few reasons. Scientists have never been able to precisely define what life is. So, it’s been hard to dismiss Gaia completely.
The Gaia hypothesis has also evolved over the years. Later iterations deemphasized that life was “collaborating” to transform the Earth, Jabr explains. Which still leaves a lot to be explored: Certainly living things don’t need to be thought of as conscious, or have agency, to be considered alive. Consider the clam, which lacks a central nervous system.
Jabr found in the years since Gaia was first introduced, scientists have uncovered more connections between biology, ecology, and geology, which make the boundaries between these disciplines appear even more fuzzy. The Amazon rainforest essentially “summons” its own rain, as Jabr explains in his book. They learned how life is involved in the process that generated the continents. Life plays a role in regulating Earth’s temperature. They’ve learned that just about everywhere you look on Earth, you find life influencing the physical properties of our planet.
In reporting his book, Jabr comes to the conclusion that not only is the Earth indeed a living creature, but thinking about it in such a way might help inspire action in dealing with the climate crisis.
Brian Resnick spoke to Jabr for an episode of Unexplainable, Vox’s podcast that explores scientific mysteries, unanswered questions, and all the things we learn by diving into the unknown. You can listen to the full conversation here. This interview has been edited for length and clarity.
Brian Resnick
Do you think the Earth is alive?
Ferris Jabr
I do. I think Earth is alive. We can think of Earth as a genuine living entity, in a meaningful sense, and in a scientific sense. There are four parts to the argument that substantiate that statement.
Brian Resnick
What’s the first?
Ferris Jabr
Life isn’t just on Earth. It literally came out of Earth. It is literally part of Earth. It is Earth. All of the matter that we refer to as life is Earth animated — that’s how I come to think about it. If you accept that, then at a bare minimum, you have to accept as a scientific fact that the surface of the planet is genuinely alive, because it is matter that has become animated.
Brian Resnick
Earth animated? What do you mean by that?
Ferris Jabr
Every single living organism is literally made of Earth. All of its constituent elements and components are parts of the planet. We all come from the planet. We all return to the planet. It’s just a big cycle. And so life, the biological matter on the planet, is literally the matter of the planet, animated. It is living matter.
Imagine a vast beach and sandcastles and other sculptures spontaneously emerge from the sand. 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.
Brian Resnick
So, the physical components of Earth are the material of life. And so distinguishing these two — Earth and life — seems silly because they comprise each other?
Ferris Jabr
The more you think about this, the more the boundaries dissolve.
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.
Brian Resnick
So all life contains Earth, and Earth contains life?
Ferris Jabr
There are components of the Earth that are not alive in any way. The center of the planet, it’s all molten rock and there might be some solid metal in the core.
But think about a redwood tree: It is mostly dead wood in terms of its volume and mass. It is mostly nonliving tissue. And then a little bit of tissue that is laced with living cells. So, you know, most complex multicellular living entities are a jumble of the animate and inanimate. Earth is not unusual in that way.
Brian Resnick
What is part two of your argument?
Ferris Jabr
All these organisms [on Earth], they give Earth a kind of anatomy and physiology. Life dramatically increases the planet’s capacity to absorb, store, and transform energy, to exchange gases, and to perform complex chemical reactions.
Brian Resnick
What’s a good example of this?
Ferris Jabr
You can think of all of the photosynthetic life on the planet acting in concert. It’s not that they’re deliberately collaborating to do something, but they’re all doing their own thing at the same time.
NASA has made these amazing videos and animations and they’ve literally called them “Earth breathing,” because you can see how the levels of carbon dioxide and oxygen in the atmosphere fluctuate with the seasons. The amount of vegetation that rings the continents, especially in the Northern Hemisphere, in the mid-latitudes, it changes dramatically with the seasons. It has a sinuous rhythm. It looks like a pulse or like breathing.
Brian Resnick
So, are you saying something like all of the algae or plankton in the ocean are generating this together? … Is that kind of like how all of the cells in my lungs are working together to exchange gases? Or is that not quite the right way to think about it?
Ferris Jabr
I think we have to be careful with making too direct a comparison. You as an organism are a product of evolution by natural selection. Your structure, your anatomy is something that was written into your genome. That’s not how the Earth system formed.
Brian Resnick
I’m realizing a key to this conversation is what you just corrected me on. When we’re discussing this notion about the “Earth being alive,” we’re not suggesting it’s not alive in the same way you and I are. But there’s these equivalent processes that look very similar to the way my body maintains homeostasis, for example. It’s not like the Earth is exchanging gases and doing metabolism-like things in the way I’ve been evolved to. It’s not achieving homeostasis the way you or I do. But yet it is doing something that seems analogous. Is that the kind of thing that you’re arguing here, overall?
Ferris Jabr
Absolutely.
When we’re looking at the planet, we see life-like qualities, things that resemble the characteristics of the organism, which is the most familiar life form to us. But it is not exactly the same. It is still genuinely alive, in my opinion, but is not exactly an organism.
Life is a phenomenon that occurs at multiple scales. The way I think of it is that it’s not identical at all of those scales, but it rhymes and there are analogies between each of those scales.
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. The tissues that those cells form are alive. The leaf as a whole is a living tissue. The tree we consider an organism that is 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. And there are analogous processes that happen at each. But they’re not exactly the same.
Brian Resnick
What is the next plank of your argument?
Ferris Jabr
Life is also an engine of planetary evolution. 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.
Organisms and their environments continually co-evolve. Each is profoundly changing the other.
This reciprocal transformation 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 environments. These are not default features of the planet. Life has created them over time.
Brian Resnick
What is the most stunning example of how life has actually changed the planet?
Ferris Jabr
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 toward the blue part of the spectrum.
The entire chemistry of the planet changed. I mean, you suddenly had an oxygen-rich environment, whereas before it was an oxygen-poor environment. That changes absolutely everything.
Brian Resnick
Okay, so to get back to what you were saying before, it’s not that Earth evolves in the same way that organisms evolve. But it evolves with a different mechanism, is that right?
Ferris Jabr
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.
But there are analogous processes by which changes are passed down from generation to generation that are not genetically encoded.
If we think about a bunch of large mammals, they’re transforming their landscape by walking through it with their immense hefts. They’re tearing down vegetation. They’re digging in, uprooting things. They’re changing the landscape.
Those changes persist. And so their descendants now are evolving in a new environment changed by their predecessors. 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.
Brian Resnick
If a fundamental part of life is that it changes the world in which it exists, how are we different for accelerating the climate crisis? Because you look at the history of the Earth and you say, well, life has powerfully changed it. Who’s to say what we’re doing is necessarily not a natural process?
Ferris Jabr
It’s simultaneously humbling and empowering to recognize ourselves as simply the latest chapter in this long evolutionary saga of life changing the planet. It is a basic property of life to change its environment, and we’re not an exception to that.
But I do think there’s a major distinction between what our species has done and what has happened before in terms of the combined scale and speed and the variety of our changes to the planet. I don’t think there’s any species or creature before us that has changed the planet on such a large scale so quickly and in so many different ways simultaneously.
We have radically altered the atmosphere, the oceans, and the continents. We’ve done it in a couple of centuries. That’s a huge part of the reason for why the crisis we’re going through right now is a crisis. It has so much to do with the scale and the speed of it.
Brian Resnick
What’s part four of your argument?
Ferris Jabr
This co-evolution, on the whole, has amplified the planet’s capacity for self-regulation and enhanced Earth’s resilience. Earth has remained alive for, you know, around 4 billion years, despite repeated catastrophes of unfathomable scale, unlike anything that we have ever experienced in human history. We have to account for that resilience, for that incredible persistence through time.
It is not a deliberate thing. You know, it is not a conscious or collaborative thing. It is simply an inevitable physical process, just as evolution by natural selection is an inevitable physical process.
Even in the mass extinctions in Earth’s history, life recedes to its most fundamental and most resilient forms: microbes. And then life sprouts from there.
Brian Resnick
Are you sure you’re right about all this? Is the scientific community coming around to accept this notion that Earth is indeed alive?
Ferris Jabr
I mean, this book is my personal synthesis, an argument. You know, this is my viewpoint. This is how I have come to see the Earth. There are scientists who agree with me, but I would not say that this is the consensus of modern mainstream science. I think the statement that Earth is alive remains quite controversial and provocative. However, everything else we’ve been talking about, the co-evolution of life and environment, the fact that life has profoundly changed the planet. These are all well-accepted points.
Brian Resnick
Which part are you most likely wrong about? Or which part do you feel like has the most room for doubt?
Ferris Jabr
We do not have a precise, universally accepted definition of life. We haven’t explained it on the most fundamental level. Like 100 years from now, will we have a fundamental explanation for life that we’re missing right now? And if we do, will that make thinking of planets as alive defunct? And so, I think open-mindedness is fundamental to any scientific thinking or scientific process. And we have to be open to the idea that a century from now, or even sooner, all of this will be wrong.
And that’s part of what I find thrilling: We don’t have all of the answers yet. Right? These are incredibly challenging ideas and concepts that we are still working out. If we had figured it out, then we wouldn’t be talking about the Gaia hypothesis anymore. The Gaia would have been officially dead a long time ago. But I think the reason that it remains relevant and continues to be debated means that we just haven’t figured it out yet.
Brian Resnick
Why is it useful to think of the Earth as alive?
Ferris Jabr
There’s a massive difference between thinking of ourselves as living creatures that simply reside on a planet, that simply inhabit a planet, versus being a component of a much larger living entity. When we properly understand our role within the living Earth system, I think the moral urgency of the climate crisis really comes into focus.
All of a sudden it’s not just that, oh, the bad humans have harmed the environment and we need to do something about it. It’s that each of us is literally Earth animated, and we are one part of this much larger, living entity. It’s a realization that everything that we are all doing moment to moment, day to day, is affecting this larger living entity in some way.
Brian Resnick
So, the simple point that you’re making is that we are Earth, and don’t self-harm.
Ferris Jabr
Right, exactly.
