The Sixth Extinction: An Unnatural History

One would have to have been living under a rock, or the most extreme kind of isolation, if one hasn???t encountered the dire news about the state of several of Earth???s species. Everyday it seems like one more species dies off, or comes even closer to extinction. Estimates vary, but scientists claim that as many as two hundred species go extinct every day, or roughly around three species per hour. There are also hundreds of undiscovered species that could be going extinct before they are discovered, because they die off before scientists can find them and give them a name. These species are also part of the ???three per hour??? count, which means that there are lifeforms out there???lifeforms that could exist nowhere else except this planet???that disappear before we even know they exist, before we even know what it is they do. There are interesting philosophical questions about whether or not trees really fall if there???s no one there to hear them, but if an undiscovered species goes extinct, other, bigger things are bound to follow, because that???s how Nature works: everything works together, and if something dies off, others suffer too???humanity included, though perhaps not directly, nor immediately.

Given how prevalent the message about extinction is, and how much information is out there, it can be hard to filter the sources to find a clear, understandable summation of what extinction is, how it works, what its effects are, and what causes it. One would think that the Internet could give one all the information one could possibly want about extinction, but so much of it is either inaccessible because of paywalls; is written in jargon the average reader does not understand; or is just badly-written, period. What???s needed is a text that discusses extinction with scientific accuracy, while doing so in layman???s language and a compelling journalistic style.

Elizabeth Kolbert???s The Sixth Extinction: An Unnatural History is precisely that book. At the end of the Prologue, Kolbert lays out what she tries to do with the book as a whole, and what she hopes readers will take away from it:

If extinction is a morbid topic, mass extinction is, well, massively so. It???s also a fascinating one. In the pages that follow, I try to convey both sides: the excitement of what???s being learned as well as the horror of it. My hope is that readers of this book will come away with an appreciation of the truly extraordinary moment in which we live.

Her use of the word ???extraordinary??? is interesting because the word is double-edged: both positive and negative, depending on the context. It???s not immediately clear to the reader whether or not Kolbert uses it positively or negatively, but as the reader progresses through the book, it becomes clear that Kolbert means it very negatively indeed.

The Sixth Extinction is divided into thirteen chapters, each one focused on a specific species deeply caught up in the extinction process. Some are already extinct: the great auk, the ammonite, and the Neanderthal are all gone, with nothing left of them except fossils or stuffed skins. Some species are still around, but their continued existence is balanced on a knife???s-edge: the Sumatran rhino, hundreds of amphibian species, and several bat species are all on the verge of dying out completely.

And then there???s us, Homo sapiens: ???one weedy species??? that has changed the world so extremely that we are, in and of ourselves, an extinction event similar to the Five Great Extinctions that came before: extinction events that nearly wiped out all life on Earth. We are the Sixth Extinction that gives Kolbert???s book its title.

Many readers have called Kolbert???s book ???heavy???, and this is very true, though perhaps not immediately. After all, her prose is very lucid and easy to understand, with very little jargon used???and when it is used, Kolbert takes the time to explain what the terms mean. Her narrative flow is also excellent: many nonfiction writers who don???t have a journalistic or creative writing background often have issues with their storytelling, but Kolbert???s strong journalistic background (she is a staff writer for The New Yorker) gives her the skills necessary to tell a compelling story without sacrificing the facts.

She also has a penchant for delivering bombshells to the reader in a manner that has the most impact???again, something I attribute to her journalistic background. Take, for example, this quote from the first chapter, ???The Sixth Extinction???:

Today, amphibians enjoy the dubious distinction of being the world???s most endangered class of animals; it???s been calculated that the group???s extinction rate could be as much as forty-five thousand times higher than the background rate.???There are all sorts of seemingly disparate reasons that species are disappearing. But trace the process far enough and inevitably you are led to the same culprit: ???one weedy species.???

This is where things start to get heavy. Beginning in this chapter, which describes the beginnings of Kolbert???s interest in the concept of extinction, the book explores the history of extinction as an idea, and how those ideas relate to how we think of extinction today. It is a story interwoven with the stories of palaeontology, evolution, and geology, as well as politics and religion. Some of the players in this story are old: Darwin, for instance, crops up quite frequently, as does Charles Lyell, whose ideas helped lead Darwin to the theory of evolution. Also mentioned is Georges Cuvier, whose concept of ???catastrophism??? was criticised by Lyell, whose own concept of ???uniformitarianism??? was meant to refute Cuvier???s own idea. In the years since Cuvier and Lyell and Darwin, other scientists have proven that the nature of extinction is caught somewhere between Cuvier???s catastrophism and Lyell???s uniformitarianism, with an extra dimension created by Darwin???s own theory of evolution.

Though the history of extinction is interesting, Kolbert puts greater emphasis on the present, on scientists who are out in the field, confronting the causes and effects of extinction day in and day out. There is Edgardo Griffith, a herpetologist who is spearheading an effort to save the Panamanian golden frog from habitat loss from the deadly chytrid fungus. There are the researchers on One Tree Island, way out in the Pacific, who are trying to understand what ocean acidification is doing to the world???s coral reefs. There is Dr. Terri Roth, who is leading an effort to save the critically-endangered Sumatran rhino by pursuing a captive breeding program for the species. And then there is Marlys Houk and her fellow researchers at the San Diego Zoo, where they maintain a ???frozen zoo??? of cell cultures drawn from recently-extinct or almost-extinct species: a last-ditch effort to save what could be???or already is???lost forever.

In every chapter, Kolbert points out that extinction and the things that cause it are natural processes: the world changes, mostly gradually, but sometimes nearly instantaneously (such as when there are massive natural disasters like earthquakes, storms, volcanic eruptions, or asteroid crashes). Species that cannot adapt die off, while those that can live on. However, what Kolbert emphasises, again and again, is that the current extinction event is unnatural???not because the processes are unnatural, but because of the rate at which they???re happening. Extinction naturally happens at a rate of thousands of years???slow enough that it is often measured in geologic time, in the gradual sedimentation and fossilisation (or not) of biological remains. Enormous catastrophes???like the massive Ordovician extinction that killed up to ninety percent of life on Earth, or the giant asteroid crash that wiped out the dinosaurs???can abruptly change life on Earth, but they???re very rare, with gaps of several million years between each catastrophe.

So: what???s changed? In the book???s last chapter Kolbert points out that what???s happening now is something very, very different:

What I???ve been trying to do is trace an extinction event???call it the Holocene extinction, or the Anthropocene extinction, or, if you prefer the sound of it, the Sixth Extinction???and to place this event in the broader context of life???s history. ??? What this history reveals, in its ups and its downs, is that life is extremely resilient but not infinitely so. There have been very long uneventful stretches and very, very occasionally ???revolutions on the surface of the earth.??????The current extinction has its own novel cause: not an asteroid or a massive volcanic eruption but ???one weedy species.??? As Walter Alvarez put it to me, ???We???re seeing right now that a mass extinction can be caused by human beings.???

This is why Kolbert???s book isn???t an easy read: the fact that, when all is said and done, it???s humans that are causing the current extinction event, and we???ve been causing it since our species first evolved the ability to create tools and communicate. Humans wiped out the megafauna; humans wiped out the Neanderthals; humans wiped out the dodo and the great auk; and humans are wiping out the Sumatran rhino and the Javanese tiger and many, many other species that have names, and many, many more that don???t. Kolbert ties it all together thusly:

When the world changes faster than species can adapt, many fall out. This is the case whether the agent drops from the sky in a fiery streak or drives to work in a Honda. To argue that the current extinction event could be averted if people just cared more and were willing to make more sacrifices is not wrong, exactly; still, it misses the point. It doesn???t much matter whether people care or don???t care. What matters is that people change the world.

Note how Kolbert states that it???s ???not wrong, exactly??? that people care, that people do whatever they can, however they can, to at least slow down the rate of change currently going on. It???s an idea some people hold: that if humanity can just slow down, or change its course entirely, things can go back to the way they were before this whole mess started. But that ???misses the point???, as Kolbert so bluntly, and eloquently, puts it. Whatever we do, for better or for worse, the change has already happened, and will continue happening because we are who we are: humans, Homo sapiens, specially evolved not just to move with change, but effect it. We cannot turn back the clock and regain what???s been lost; species have already gone extinct, and while we can still rescue (or try to rescue) those that haven???t, the world to which we return them has changed irrevocably. The Edenic idea of humanity ???living in harmony with nature??? never existed in reality, not since the moment one of our earliest ancestors figured out how to use sharpened sticks and group communication to bring down a mammoth.

And even when humans disappear from the Earth, whether because our current course causes our species to go extinct, or because our capacity for innovation allows us to outstrip that extinction, the Earth will not go back to the way it was before our species showed up and started changing things around. Kolbert concludes her book with this sobering message:

Right now, in the amazing moment that to us counts as the present, we are deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed. No other creature has ever managed this and it will, unfortunately, be our most enduring legacy.

Overall, The Sixth Extinction: An Unnatural History is a thought-provoking and intelligent read about what extinction is, and humanity???s role in the current wave of extinctions happening all around the world today. Kolbert combines historical research with investigative journalism and interviews of notable scientists and ecologists to tell the story of extinction: from the major events of the distant past to the ongoing Sixth Extinction caused by humanity. Humanity is a species unlike any other, one that acts as a force of change so great it can change the evolutionary course of all other species on this planet just by existing. In the far distant future, whether our species has gone extinct, or escaped any potential demise through our own ingenuity, we shall have left our mark upon the face of the Earth???and unfortunately, it is not going to be a pretty picture.