Part Two: Humanity's Final Chapter / Lyle Lewis
Why humanity will soon vanish
This is part two—the latter half—of my interview with Lyle Lewis, former endangered species biologist and author of Racing to Extinction: Why Humanity Will Soon Vanish.
In the first half of our discussion, we discussed his decades long career working under the US Department of the Interior, and the various bureaucratic hurdles that stood in the way of protecting and preserving endangered species in the various roles he served there.
In the second half, Lewis makes the compelling case that humankind has reached the end of the road. With human-caused climate disruption being felt more and more intimately and intensely across the planet, relentless resource extraction and ecological disintegration reaching unprecedented levels, what has been called the Sixth Mass Extinction Event is reaching its logical conclusion. And while we may be reaching the most perilous phase of this drawn out process, with all of its calamitous horrors to witness and experience, our species has been precipitating this extinction event far longer than we may be willing to recognize.
Lewis contends the Sixth Mass Extinction Event didn’t begin with the Industrial Revolution, or the dawn of complex hierarchal social systems thousands of years ago, but instead, about 2.5 million years ago with the development of certain anatomical and cognitive functions unique to our species.
As he examines in Racing to Extinction, previous mass extinctions on Earth transpired over a relatively long (on a human timescale) period. Like with the dinosaurs, their eventual extinction may have been initially caused by a catastrophic asteroidal impact, but their eventual demise took many thousands of years to play out. And for very novel reasons, the mass extinction event we are in now is transpiring in the inverse, with the cascading collapse of ecological systems and die-offs ramping up in scale and severity over time.
To read the full interview transcript, visit the episode webpage.
The transcript of our interview was edited for clarity and length.
Patrick Farnsworth
But in general, you're really just trying to present your understanding of what Homo sapiens are. And one thing that really stuck with me is I tended to think about the Sixth Mass Extinction Event and human extinction, potentially, as being something that is a more—depending on how you want to look at it, depending on who you talk to, some would say that, well, it really started when carbon emissions really kicked up with the industrial revolution. So a few hundred years ago, that's really when the Anthropocene began. That's really when human beings began to really change the climate and the ecologies on the planet so thoroughly that we can call it the Anthropocene, or a Sixth Mass Extinction Event. Some could say you can go back further to the initial colonization of the Americas by the Europeans.
There are different points at which people can begin to look at when this started. But you go back really far, actually. You actually almost go to—I wouldn't say the beginning. [I'll] just ask you, how are you trying to reframe our understanding of when the Sixth Mass Extinction Event began? When did that really begin, in your view?
Lyle Lewis
That question is the most fascinating thing I've learned as a result of writing my book. Because when I started writing my book, I thought the Sixth Mass Extinction started with the megafaunal extinctions of Australia and the Americas and Europe, and at the time, I thought that was 20,000 to 30,000 years ago. But by the time I'd done the research on my book, and by the time my book was published, I felt certain that the Sixth Mass Extinction started probably 250,000 years ago, which was about the time Homo sapiens became a species.
But in the year and a half since my book was published, I have come to the conclusion that the Sixth Mass Extinction started between 2.5 and 3 million years ago. I'm actually kind of rewriting the first chapter in my book on the history, because I've learned a lot of new information, and also just have time to think about how it all kind of fits together. And it's really kind of a fascinating story.
We're now reaching the conclusion of the Sixth Mass Extinction. It's been going on for so long, but a lot of it is just in the way we look at time. For most people, Genghis Khan is ancient history, and the beginning of Christianity is ancient history. And so people have a lot of difficulty moving back beyond what most humanity considers ancient history. It's kind of like a jigsaw puzzle more than anything else because you've got paleontologists, archeologists, evolutionary ecologists trying to put this together, but many of the pieces are missing and will always be missing. To put it all to together requires extrapolation, imagination, curiosity, experience, and a lot of persistence to try to figure out what's going on.
I've actually found it really enjoyable to try to kind of piece together the process. And then in the process, I've also uncovered some additional information that makes me certain that we've just overlooked some very obvious things in formulating when the Sixth Mass Extinction started. And I mentioned it in my book, bipedalism and the evolution of our shoulder and our ability to both make tools and throw was what precipitated the Sixth Mass Extinction.
For millions of years, we were very much tied to forests and forest canopies, because just like all other species, we need food, water, and shelter, and when we first branched off from the great apes, trees and forests provided that shelter that we needed to escape big predators at night and other dangerous situations. Forests were our security. But then, as we evolved, we gradually started moving into dry land habitats as a result of our ability to use caves, rock shelters, and cliff overhangs, and that was a huge step in moving into habitats that had never seen a hominin before.
The things that happened in Australia and the Americas and Europe was that humans all of a sudden appeared in places where they had never been before, and precipitated—it is fairly well documented—megafaunal extinctions. [Megafaunal extinctions] happened in Africa in the same way, but it happened over such a long period of time that no one really has put it together. We went from forested habitats into dry land habitats at the same time that, about 5 million years ago, Africa became more [arid] and drier. And so the forests were shrinking, and savanna habitat grasslands were increasing. The species that evolved in those habitats had never seen a hominin before, and all of a sudden, we were an invasive species in a habitat in Africa and Asia, the same way there that we were in Australia, the Americas, and Europe. And as a result, there's well documented extinction paradigms for Madagascar and New Zealand and Hawai'i— what happens when humans enter into the equation and the extinctions that occurred, but also the types of extinctions that occurred.
Megafaunal animals disappeared, but they aren't the only ones. Giant tortoises were probably the first animals that bit the bullet as a result of the Sixth Mass Extinction. There were giant tortoises in both Africa and Asia 2.5 million years ago, and that's about when they disappeared. And all it took was humans finding their nests, raiding the eggs. They're such a long-lived species. But also we could throw, so finding small infant turtles and cracking their carapaces over rocks for the meat was probably something that happened around the time of Australopithecus afarensis, probably before the genus Homo was even there. And so that whole lineage has been precipitating the Sixth Mass Extinction. The ground nesting birds probably took a huge hit.
And just the connotation of caveman. Everybody thinks of ancient humans—the really ancient humans—as cavemen, and nobody thinks about what the consequences of humans moving out of forests into caves are, but as someone who did a lot of bat research and monitoring and over the years, one of the things that most affects cave ecosystems is humans moving in. And a lot of the things that we did to protect bat populations was to gate caves and mines to keep people out of them. Well, in Africa and Asia, humans were moving into those caves. And cave ecosystems on their own—there are some caves that have as many as 75 unique species living in a cave, and many of those species were wiped out as a result of humans moving into cave ecosystems millions of years ago.
And just the connotation of caveman—people don't put it together, and biologists don't put it together, that there is a cause and effect of us moving into new habitats. We displace other critters. We either cause their extinction or the numbers are greatly reduced. But it transcends the caves into dry land habitats in general, like ground nesting birds and the tortoises we've already mentioned, and all kinds of species impossible to document, that have disappeared millions of years ago.
Farnsworth
Yeah, there are a few things that I wanted to bring up regarding this. I think that, again, in the larger span of Earth's history, we're a blink of an eye as a species [since] our appearance on this planet over the many thousand of years that we've existed. I guess what I wanted to bring up was really a question of whether you think that this is an intrinsic characteristic of human beings: that we cause extinctions or species loss—that we cause ecological disruption wherever we arrive.
There were a few passages in your books that I wanted to raise some questions about. I'm not denying those things that you described just now, going back into deep history, but I'm curious if there are certain particular societies or cultural forms that exist where human beings have recognized their impacts in some form or another and have found some way to exist in some sort of ecological capacity that is not disruptive.
For example, there's this point in your book where you're talking about logging, and really, what you're talking about is European-descendant settlers moving west across North America and arriving on the West Coast and finding just these incredibly beautiful old-growth forests, and even marveling at how large these trees are and just how diverse the ecologies are, and then immediately beginning to log them, almost completely, where [now] there are very few old-growth trees left in North America, and in the world, really. And when you talked about that point, you were describing this as a human thing, that human beings, when there's a lot, they take a lot—and I don't remember the exact phrasing—and when there's a little, they take the rest or take it all.
Now I don't deny that that's a part of human beings, but I guess what I want to just raise there was that people have been living in North America for many thousands of years, and those old-growth forests are also hundreds if not thousands of years old as well, and they weren't destroyed. So there obviously are examples of human beings living in, say, North America or in other parts of the world where they just did not destroy at least all the ecology, or they understood the importance of maintaining that ecological diversity, and those forests in particular.
So I just wanted to ask this question to you, just as a way of understanding how you understand what is intrinsic to what human beings do, versus what, I think, is almost a cultural or a particular iteration of human beings that I think we are products of. Because we exist as part of this culture that is the same one that has been destroying the forests and the wetlands and the prairies, and have just done this enormous ecological destruction over just the past few hundred years alone. So I just wanted to understand what your understanding of that was.
Lewis
That's one of the controversies I found, especially on social media. People want to believe that our ancestors were good. And I think what it does is that it ignores deep time. Because if you look at North America, people make the case that for 10,000 years, people lived here in "harmony" with the environment. But we're a species, and to begin with, 10,000 years is almost meaningless.
When I go back into evolutionary history and try to reconstruct what happened like in Africa or Asia, and paleontologists and other people are going, well, between about 1.4 million years ago, give or take 100,000 years, these megafauna disappeared, and probably as a result of hominins. Well, that's a 200,000-year window—a 200,000-year window in North America. If somebody lived without destroying the environment for 10,000 years—or there's evidence that in Australia, maybe 20,000 years—it's so insignificant. And when you look at what our species is doing across the planet, anything good that was happening was being washed out somewhere else. If you look at our species and the planet as a whole, we're just a destructive species and always have been.
And that's the part that's actually hard for me. It's not really human's fault. We're a product of evolution. We are who we are.
I hope you found the section on leopards in the history part interesting. It was a behavioral evolutionary advantage to be sociopathic, steal, and drive other critters out and burn them out of areas. Sociopathy is just part of our evolutionary makeup.
I suspect there's always been a minority of people that can see what was happening and, and just like me, watching what's happening is almost like watching a slow-motion fatal car wreck. Humanity is just going over a cliff, and there's nothing I can do to stop it, no matter how hard I try.
But I often wonder, of the indigenous people 10,000 years ago, if there was one or two of them that could see that what they were doing was resulting in the extinction of mastodons and mammoths and giant buffalo and all those other things. And yet, the rest of their tribe killed them all.
And I have no question they were much more in-tune with the environment than we will ever be because they lived in it 24/7. They knew what was there, and yet they killed them all anyway. And so I suspect there's always been just a small segment of our species that could see what was happening and was probably always chagrined by what was happening. And just because there's 8 billion people in the world now, there's more of those people, but they're always a small minority and have no real effect.
Farnsworth
We can have a whole discussion about that particular subject. But the fact of the matter is, is that we are here now, and this is what has happened. And so I want to talk about where we are right now.
Actually, I just want to repeat this point, which is that you make an important point in the book. We tend to think of evolution—we say there was a mistake, but that implies that evolution is like God. That God designed us, and then there was some mistake that was made by someone who made us, or whatever it was. But evolution is not a thinking, feeling, conscious being making things. It's just a process, and we are part of that process. And just like any other species, we have a trajectory, and we could survive or not. And that's just the way it goes for every living being on the planet. I think we tend to anthropomorphize processes, even—not just animals and not just living systems, but actual processes. It's kind of fascinating how we tend to project ourselves onto so many things.
And I think it actually does—I don't know if it's a relieving [thing] or what it does for us psychologically and emotionally to recognize that it is not a mistake, that it just is. I think that actually—speaking to just how we deal with the facts of what we're living through currently, as we're alive right now—somehow recognizing this isn't a mistake actually does, on some level, alleviate some of the burden or the weight that comes with that.
Lewis
Yeah, because we use human exceptionalism in two completely different ways. For most people, human exceptionalism is we're going to live forever, and humanity is the greatest thing that's ever existed on the planet, and we're the most successful species that has ever lived, etc. But the flip side of that is we're the most destructive species that's ever lived on the planet; we're terrible; we're just the worst thing that's ever happened—we can't disappear soon enough.
But both of those discount all the things that happened that precipitated our species, our genus, our behaviors. And just like the section on leopards, we were formed as a result of our interaction with other creatures, with other plants, with other animals. We didn't do it all on our own. And so understanding that we're a product of our environment, we're a product of the planet, is really important in coming to grips with, we're just another species that is playing itself out on this grand stage of life on Earth.
Farnsworth
Yeah, well, I want to talk about, as we reach the last part of this interview—again, just thank you for everything you've gone over so far. And in a way, I don't know how to talk about this subject without just recognizing that people who are maybe coming to this subject are feeling what they're feeling. It's important to understand that it is a process, and that there are communities of people—and I think you're part of that—providing the information.
But I think that there's just this sense that coming to this information and addressing this subject and issue is a very difficult thing. Every time there's an article about how bad things are, or there's a book that comes out, there's always a final paragraph or chapter that says, but it could be better, and this is how. There's always that. And I've heard from other writers that often it's the editors or the publishers that want to put that in because they feel like it's going to affect the sales of the book, or it's going to somehow affect the publication in some way that's negative. It's often, I think, a kind of fatal flaw.
But I do want to just address the point that you make near the end of the book. I'm wary of predictions because I don't think they're actually very helpful, but I don't think you're exactly providing a prediction as much. But you are looking at the trends, you're recognizing what's currently happening and where we are today, and you do provide something of a timeline here. I'm curious what your process was in writing the book, and how you came to that. Because, for me, if I were in your position, I would be kind of waffling a bit. I would be like, well, should I even be saying a year or a time, or putting some sort of timeline here?
I'm curious how you came to, for lack of a better term, a prediction, as far as when you expect extinction for the human species. Because it's such a final and difficult thing to come to, I'm just curious how you came to that.
Lewis
And that's an excellent question because my final draft didn't have one, and it was a publishing expert who encouraged me to put a prediction in, even though I didn't want one.
Farnsworth
Interesting.
Lewis
And so I made it as waffly as I could with the over-under of 2055. And despite that, I tried to make the point that it really doesn't matter whether we disappear in 10 years or 30 years or 50 years or a century. It's going to be soon, from an evolutionary standpoint.
I see all these people bad-mouthing Paul Ehrlich because his predictions back in 1970 were wrong. Anybody who makes a prediction, if it doesn't come to fruition exactly when they say, then they're discredited, and it just evolves into this big furor. But it's kind of like predicting your own death, that I'm going to live 20 years. Does it really matter whether you lived an extra 10 years or not?
I think it would be a miracle for humanity to be able to survive this century. Miracles happen. But from an evolutionary standpoint, is it significant that we say we lived 150 years more years? It's not significant. It's not even a blip on the radar. There are a zillion different scenarios for how collapse is playing out, and we're seeing it happening.
But there are also biological thresholds that any species has, and we have those same biological thresholds as any other species. Right now, the chemical toxins in the environment, the microplastics—everybody is building up microplastics in their body. It's everywhere.
Climate change gets all of the publicity, but some of the other things we're doing seem, to me, a much more sure thing than climate change. Maybe we come up with some miracle geoengineering thing that divorces us from—it doesn't matter. The microplastics that are accumulating in our body, at some point in time, there's going to be a threshold through which we can't survive. The chemical toxins like PFAS, the forever chemicals.
There's just so many different things we're doing that amplify the effects of each other that it's virtually impossible for us to survive all the things that are happening.
Farnsworth
Yeah, I think the plastics—and it's not just microplastics. We're also talking about nanoplastics. We're talking about things that breach the blood-brain barrier.
In the last second to last chapter of the book, there are various sections of various things that are on the table as far as what's causing the extinction of human life, and of other life too. Because I don't think that any of these things you're describing is just for humans. Plastic pollution is obviously affecting other species profoundly. Profoundly. The composition of the ocean, seemingly, has changed, from my understanding, due to plastic pollution and other sorts of things that are changing the chemical structure of much of the ocean.
So it's just an incredible—at the very end [of the book]—compilation of different cascading things that are all interconnected. And again, climate change does take up a lot of that, because—I don't know why exactly. I guess it's something that maybe we feel like we can potentially find solutions to. But again, but that isn't really happening.
So it's pretty astounding when you really kind of put it all together, and you realize that all of these things are rather complex and interplaying with one another.
I think the final question I would have is—I read some interesting reviews of your work, for people that really liked the book, even, and they say, well, extinction is just so final; how can you possibly say there isn't even a chance that there will be pockets of humanity? Yes, maybe billions of people will die off in the next century. But, what about some remote groups of people existing in some place, somewhere, and continuing to exist and survive into the future?
Do you feel that having that sort of finality of an extinction impedes the kind of warnings that you're presenting in your book? Or do you think that that is just a fair and accurate way of describing the trajectory that we're on as a species?
Lewis
Oh, I think it's a fair and accurate trajectory.
There are two things that are occurring that preclude our survival, even in small pockets, to begin with. If you look at how we have survived for millions of years, like all animals, we rely on water. And for most of our existence, the most important habitats for our survival were biodiverse, shallow aquatic environments. Whether they're fresh water or salt water, that's that's how humans survive.
The people like to think of us and romanticize humans as hunter-gatherers, but we are mostly gathers. We're physiologically tied to water, just like almost all mammals are, and maybe more so than most mammals. So from just an energetic standpoint, our ability to gather eggs or maybe trap amphibians and fish and all of those things surrounding aquatic environments was critical.
There are no more seriously degraded environments on the planet than shallow aquatic environments. They could no longer support humanity. They just can't.
The other thing—the three premises of evolution is, first, to survive, and if you can survive, then a species wants to reproduce, and if this species reproduces successfully, then they want to grow. We've been able to overcome the force of gravity, but we're absolutely helpless against those premises of evolution, of survival, reproduction, and growth. We just cannot overcome those things.
And so, say a small group of people survived. They would do the exact same thing that humans have done for—maybe they would extend our longevity on the planet for a couple of thousand years, but they would do the same thing. The planet's environmental baseline, the status of the planet now, is so degraded. They would survive, reproduce, and grow, but we've never learned anything from history. When it comes to survive, reproduce and grow, the only thing we learn from history is that we don't learn from history.
And so, between the evolutionary processes, our ability to forget history almost immediately, and the degradation of shallow aquatic habitats, there's no way that we can prevent our extinction.
Farnsworth
Well, I just wanted to address what were a few points that that stuck in my mind reading the book, but also reading what other people had to say. And again, there were some positive takes [from people] that still had a few questions that they didn't know how to resolve.
I find it interesting to read the reviews, just to see how people are generally responding to something. And some people just didn't seem to really understand the picture that you were painting for them. And that's just them. That's just, I think, their shortcomings.
But anyway, Lyle, this is one of those subjects where I keep on revisiting because this is really why I started the podcast, in great part. Again, I think your book is really the kind of book that I was really looking for, and where you stand with your career, and what you've done in your life, and just your perspective is, I think, wholly unique within the space of people who are talking about this.
I loved how you wrote the book, and just how direct it is. It's uncompromising. It's not cruel. It's not intended to make people feel any particular way. This is the way it is. And I just really appreciate you writing the book and for coming on the podcast today, and I really just have been looking forward to meeting you and asking you some questions.
So Lyle, thank you so much for the time.
Lewis
Well, thank you for having me. It's been a fun conversation.
Lyle Lewis is a former endangered species biologist with the US Department of Interior. He is the founder of the Western Bat Working Group and Southwestern Carnivore Committee and has received numerous awards for bat, carnivore, and natural area conservation. His career and love of the outdoors has taken him to many of the wildest backcountry places in North America. In 2024, Lewis published Racing to Extinction: Why Humanity Will Soon Vanish, which provides new insights into factors triggering the current mass extinction event and examines conventional wisdom regarding human intelligence.