Earth has a memory problem. Few rocks have survived from the first billion years of the planet’s history, when all kinds of important things happened, including—perhaps—the first stirrings of life. This amnesia has made it hard for researchers to piece together our origin story, and answer the really big questions like How did we get here? and Are we alone? But it hasn’t stopped them from trying. In a recent story for Quanta (which also got picked up by Wired), freelance journalist Rebecca Boyle reports on the latest efforts to settle these existential questions.
With her vivid prose, Boyle transports readers back in time to gaze upon the strange and alien early Earth. For decades, scientists have thought that our nascent planet was a blubbering ball of lava, pelted by a rain of asteroids that peaked during an event called the Late Heavy Bombardment and ended around 3.8 billion years ago. Until then, it seemed, Earth was not the kind of place where life would flicker into existence—and persevere. That’s why geologists dubbed this early eon the Hadean, after the hellish underworld of Greek mythology.
But, as Boyle explains, that story is coming under increasing scrutiny. Using ancient fossils and chemical traces trapped in the world’s oldest rocks, scientists are finding evidence of life as far back as they can look. Tiny crystals that survived from Earth’s infancy are also raising questions about whether the early Earth was really so inhospitable, and new studies on moon rocks are calling into question the very idea of the Late Heavy Bombardment. The answers researchers are uncovering not only help explain our own existence, but hint at whether life might be lurking in other corners of the cosmos too.
Here, Boyle tells Julia Rosen—a fellow freelancer and recovering geologist—how she tackled the oldest story in the world. (This interview has been edited for length and clarity.)
How did you come up with the idea for this story? Had you just been watching the literature and noticed a collection of studies on this topic?
Yeah. I wrote this really short story for The Atlantic probably a year and a half ago now, about one of the papers that was in this piece. It had a provocative claim in the abstract that said something like, “This shows that maybe the early Earth was not so Hadean.” That was, I thought, a pretty big extrapolation from a paper that was about Late Heavy Bombardment questions. One of the coauthors on that paper was Mark Harrison, who is really quotable and fun to talk to—and a really smart scientist—and he kind of enjoyed making that claim. In my story, I quote him saying something like, “we have developed this theory of the early Earth that’s no better than the creationists, because it’s not grounded in science.” People got upset with him. And that’s provocative language, but it’s actually true. We built this story based on evidence that we didn’t really understand. So that kind of piqued my interest and I started following the literature on this.
Throughout the next year, there was this flurry of papers on these fossils that started coming out from Greenland and Northern Canada and Australia and all these extreme places. And they all were kind of painting the same story, which was, anywhere that we look for life, the earliest that we can look for it, we’re finding its footprints. And that flies in the face of everything we’ve told ourselves about the early Earth for the last century, at least—that life could not have arisen until at least the end of the Late Heavy Bombardment, and that, surely, the early Earth was too horrible and hot and molten and dry to host anything. But now, that story is really changing. So, I sort of just watched the literature on this, and thought, there’s definitely a thread here.
I’m a geologist by training, and one of the challenges of writing about Earth science is that it’s usually about old, dead stuff. What’s your strategy for livening up geology and drawing readers into this material?
I don’t know if I have much of a strategy about that so much as that I just am fascinated by it. Part of the reason why I like covering space—which is really my primary beat—is because you feel so insignificant. And I don’t mean that in a way that’s meant to minimize human experience. But just, it’s an interesting perspective to see the scale of the universe, and how small we are in that scale.
“I like geology [because] it makes you realize how fleeting our experience is here. It helps me feel less anxiety maybe about my own life, because Earth has been here a really long time.”
I like geology for the same reason. It sort of makes you realize how fleeting our experience is here. It helps me feel less anxiety maybe about my own life, because Earth has been here a really long time. The universe has been here a really long time. And it’s sort of profound to me to think about that.
I like imagining what it would have looked like, what it would have felt like. One of my founding versions of this is ironic because now it’s very dated. But do you remember the Disney movie Fantasia?
There’s this whole scene where it shows the creation of the Earth and the Hadean eon. There are these volcanoes—I think The Rite of Spring is the song in the background—and the volcanoes are pumping out lava as the clarinets are playing. That’s kind of the earliest version I had of what Earth’s infancy would have looked like. And I loved that movie as a kid. I watched it over and over and over, and I was obsessed with that scene. That image has really stuck with me about this very dynamic place. The rocks are moving and they are very alive, and that’s sort of how I view those things. I don’t think of them as old and small and dead. I think of them as very much telling a story and having an experience. I guess I’m trying to conjure that.
It’s interesting that the large scale of geology is part of the allure for you. I noticed there was a lot going on with small things in this story too, like using tiny crystals to answer these big questions. Is that one of the things that attracts you to writing about Earth science?
Yeah, very much, and the same is true of particle physics, which is also one of my other subject areas. I always like the contrast between studying these huge massive problems in science—just the scale of the Earth or the size of the universe—by using these particles we can barely comprehend, let alone see. In physics, that’s things like quarks and neutrinos and things I like writing about because they are so hard to discern. And in geology, it’s things like zircons and inclusions and isotopes of argon or whatever. It’s a nice contrast between very large and very small.
Zircons and isotopes are things that your audience may be unfamiliar with. In the story, you have this nice way of telling the reader what they need to know about them and then moving on. Like, you describe zircons as “gems, which are often about the size of the period at the end of this sentence.” What’s your strategy for tackling those hairy, technical things without getting bogged down?
These are actually things I worry about a lot as a writer. I often will ask scientists, ad nauseam, “Is this an OK way to describe this?” or “Is this accurate? I know I have to hand wave some of these details, but is this, at its base level, a fine analogy?” Sometimes they’re like, “Hmmm, no, not really.” And I try to work with it. And sometimes they are like, “Yeah, that’s fine,” or “That makes sense, that’s how I would maybe describe it.”
I know that readers don’t care about what isotopes are, and they don’t care about zircons. Things that I find fascinating and romantic are super boring to people. So I try to give them some of that romanticism, but not make people’s eyes glaze over. I try to make it not inaccurate but as basic as I can while preserving the meaning.
People often advise writers to use human stories to write about this kind of research, but you didn’t do that here—and it worked wonderfully. Why did you choose the approach you did?
I guess I don’t write that many stories like that. I know that that’s probably a more effective way of storytelling and I know that’s very common. It can be beautifully done. I just don’t know that I’m that good at that sort of narrative storytelling—yet.
“I think if I had picked a single researcher to follow, it would have felt less about the Earth, which is what I wanted to write.”
And, it was more that this is an entire field, so it wouldn’t have seemed fair to me to pick somebody to focus on, even though that might have been an easier narrative thread. A lot of the papers in here are still really hotly debated. So I would have felt like I was playing sides, and I didn’t want to do that. And to me, it was also more that the Earth is the character here. I’m trying to tell its story, and to be neutral. I think if I had picked a single researcher to follow, it would have felt less about the Earth, which is what I wanted to write.
How did you think about developing that Earth character?
It was partly about convincing my editor, Michael Moyer, who is fantastic and a great editor. He saw what I wanted to do with it. We talked early on about how I was worried that it was almost going to be too much. You know, there’s so much science and there’s so much debate about this and that. I didn’t want it to be a thousand bullet points. Like, this paper said this and this paper said this. I felt like it was important to have some dynamism in the story. So making the Earth as this character, describing what it would have looked like—rocks being separated from each other and stuff like that—it felt like a way to make it more readable. And more writable, frankly. If that was the backbone of the story, it felt like I could sort of slot things in in a more natural way.
I wanted to talk about the structure. To me, it seemed like you were sort of marching backward through this traditional story of Earth’s history, dismantling it piece by piece, culminating in these questions about whether the Late Heavy Bombardment even happened. How did you decide on that way of structuring the story?
A lot of that ended up working out after my first main revision, in the second draft. I moved a lot around. This was very good advice from Michael about how to set up the quandary. You know, over the past year, all this stuff has come out that suggests that life is much older than we thought was possible, which is compelling by itself. But as it turns out, there’s a whole bunch of other evidence about what conditions were like on the early Earth that backs up those claims. So I felt like we needed to have a way to set up the story as we’ve known it—like my Fantasia version—before knocking it down with the most recent stuff.
By the time I get to the Late Heavy Bombardment stuff, it’s like, the very base level reason why we told even this Hadean Earth story in the first place is based on evidence for the LHB from moon rocks that are potentially biased. It’s possible that we didn’t sample as much of the moon as we thought, and we sampled the ejecta from pretty much one impact event—Mare Imbrium. It was sort of a nice way to be like, here’s the kicker: the story we’ve been told is wrong for x, y, and z reasons. But here’s the main reason why the entire thing might be flawed: because the LHB never happened—or if it did, it’s not what we thought.
In my experience, questions about the early Earth can be really contentious in the field. But in your story, it doesn’t come across that researchers are at each other’s throats. Did you encounter a lot of debate or were people professional about it?
I wish it was more the former than the latter! People were pretty polite. There are a couple people who like to kind of throw salvos—Harrison is one of them—and I actually didn’t quote him for this piece. But Bill Bottke has been a longtime proponent of the Late Heavy Bombardment idea. He’s sort of evolving his understanding of the theory to match evidence, which is what scientists do, right?
“The more I cover geophysics and planetary science and physics, the more I find that we are all trying to understand what the hell is going on here. Why are we here? How did we get here? … I like writing about geology because you can kind of go back through time to try to answer that question.”
No one, I felt, was being really intransigent or a jerk about it. Some people were more circumspect than others, but that was kind of fun to cover, in a way. It was like, the whole field is sort of realizing that this is evolving. Surely there are a couple of holdouts who are like, “This is wrong.” But it seems to me that, everyone I talked to for the story anyway—which was a lot of people, a lot of whom I didn’t even end up quoting—that, you know, we are all trying to figure this out. And the evidence has been changing very quickly, so it makes it pretty interesting science.
At the end of the piece, you explain the implications for extraterrestrial life. Why did you want to save this for the kicker rather than dangle it in front of people at the beginning?
To me, the part about extraterrestrial life elevates the whole story at the end to be about more than Earth. In the beginning, though, I wanted to focus on Earth’s history, and say, “Look at these beautiful rocks that tell us this amazing story!” I felt like throwing aliens in there would make people roll their eyes. It just doesn’t seem like it fits.
But also, to me, it’s a little bit more profound to think about how Earth is a weird planet. Earth has so much water. Earth has so much atmosphere. It has this huge moon that we can’t figure out how the moon got here, which is a whole other feature I did for Quanta last year. There’s no place like this at all that we can find. So I felt like it was important to center Earth in that first, before musing on what this could mean for someplace else.
I feel like stories like this really resonate with people because we have this strong desire to understand the origins of life. As someone who thinks about this a lot, why do you think that’s such a compelling thing for writers and readers?
I mean, this is my favorite thing to cover. The more I cover geophysics and planetary science and physics, the more I find that we are all trying to understand what the hell is going on here. Why are we here? How did we get here? What are the steps that led us to being here? And are we really that unique? I don’t think there’s a more profound question in human history than that. You know, are we alone and why are we here?
I like writing about geology because you can kind of go back through time to try to answer that question. The same is true with astronomy. Both of them are a form of time travel. You can see into the past by studying these things. And you can sort of see, maybe, into the future, because we have pretty good theories now for what will happen to Earth as the sun embiggens (which is now a word).
Yeah. Merriam-Webster just added that to the dictionary!
But yeah, it’s a very profound thing to think about. And nobody’s ever had the answer. I think it’s fun to cover the edges of that answer, which is where a lot of good science is happening right now in geology and physics, and in astrobiology. We’re kind of dancing around the edges of figuring that out, which I think is really cool.
It sounds like some of these questions we talked about earlier—how you bring this stuff to life and draw people in—really comes back to your own enthusiasm. Do you think that’s an important tool for science writers?
Totally! I’m very lucky to be in a position where I can write about things that I find are cool, which not everybody can do, and I recognize that and I appreciate that. But yeah, if you look for reasons to enjoy stories, then you will find them more interesting and they’ll be more fun to work with. And you might convince people along with you that they are cool and interesting.
I have a few friends—writers and scientists who are geology fans like me and armchair geologists—who find rocks really cool and exciting. But I will grant that most people do not. And so, I think by letting them see a little bit of my own excitement about it, people might pay more attention, and hopefully learn something.
Yeah, I didn’t realize until well into college that not everyone thinks rocks are awesome. I still don’t understand why!
I think people should be more excited about geology and planetary science. There are a lot of people who cover space and space exploration especially, especially now with SpaceX and Trump wanting to go back to the moon (maybe, kinda) and Mars. Mars is my main beat, so I’m not going to knock Mars. But I think a lot of journalists and a lot of outlets are kind of like, “Eh, geology, meh.” You know, they consider it boring. But it’s so interesting! It’s so compelling! And some of the people working on this stuff are super interesting, and the claims they are making are really profound in a way that I think more people should be excited about.
Julia Rosen is a freelance journalist based in Portland, Oregon. She writes about Earth and environmental science for outlets like Science, Nature, High Country News, and bioGraphic. Follow her at @ScienceJulia.