The Sixth Extinction: An Unnatural History – A Review

‘The Sixth Extinction’ by Elizabeth Kolbert is a Pulitzer Prize winning overview of past and present mass extinctions. Discover why many scientists believe that humans are causing a new era of mass extinction today.

When I was in Grade 6, I remember coming home to something new on TV. Now that we had cable, we could tune into stations from Buffalo, New York, just across the Canadian border.

The novelty was a children’s program called the ABC Afterschool Special. This was the much-anticipated, premier episode.

It was called The Last of the Curlews, and it won the Emmy for Children’s Programming that year. Hanna-Barbera, the same company that brought us Yogi Bear, produced the animated film. They based it on Canadian writer Fred Bodsworth’s 1954 novel.

Story of the Last Remaining Member of a Species

The Last of the Curlews tells the story of the last remaining male member of the Eskimo curlew bird species. He follows his annual migration from the Canadian arctic to Argentina and back, desperately hoping to find a mate along the way. 

I remember that after watching the show, one of the boys who lived across the street came over to talk to me on the porch, looking forlorn. A few years younger than me, he asked why people would hunt a species to extinction, and I didn’t have an answer for him.

Throughout Earth’s long history, there have been several mass extinctions. Paleontologists call the ones that stand out the Big Five. All of these took place before humans had arrived on the scene.

Movement to Call Our Time the Sixth Mass Extinction

There’s a growing movement to call the ever-increasing number of extinctions we’re experiencing in our time the Sixth Mass Extinction. The trend inspired The New Yorker science writer Elizabeth Kolbert to write her 2014 Pulitzer Prize winning book The Sixth Extinction: An Unnatural History.

The book’s thesis is that Humanity is a kind of invasive species that has been wiping out fellow species at an alarming rate almost since the dawn of our arrival. Our unequalled ability to adapt and use resources has enabled us to fan out worldwide and shape Nature to our own liking.

In doing so, we’ve exponentially increased our population, wiped out vast forests and shifted countless species from their native continents to others. Now, in our modern era, we extract energy resources from underground and burn them, altering the composition of our atmosphere.

Humans are Growing Like a Bad Weed

Kolbert makes an excellent case that humans are growing like a bad weed. She divides her book into two parts. The first part traces the extinction process of two animals we’ve already lost – the mastodon and a bird called the great awk, both of which humans hunted to extinction.

Along the way, while covering the history of these species, she introduces us to Georges Cuvier, Charles Darwin, Charles Lyell and other pioneering biologists. The author then moves into our modern era.

Her book tells a tragic tale. She warns us from the start that “If extinction is a morbid topic, mass extinction is, well, massively so.”

Last Mass Extinction Result of Asteroid Impact

We learn how father-and-son team Luis and Walter Alvarez began to realize that Earth’s last mass extinction resulted from an asteroid impact. They made this discovery while studying the formation of the Italian peninsula.

Geologists call the time span that led up to the asteroid strike the Cretaceous. So, they call Earth’s last mass extinction the Cretaceous-Tertiary mass extinction.

Elizabeth Kolbert is among those who call for today’s scientists to recognize a new period of mass extinction. They’re proposing that we call it the Anthropocene era since Humanity is now the dominant force shaping this sixth period of mass extinction.

Flow of Science Disrupted by Paradigm Shifts

During the chapter devoted to this proposal, the author introduces us to historian and philosopher of science Thomas Kuhn. Kuhn argued that the flow of scientific research is disrupted from time to time by anomalies that lead to paradigm shifts.

Kolbert shows that Kuhn’s model is remarkably consistent with the process by which the way scientists came to understand extinction over the last three centuries. At first, nobody thought there were species extinctions.

Then, more and more fossilized remains of creatures that no longer existed came to light. Eventually, paleontologists had no choice but to accept that many species existed in the distant past that are no longer here today.

Asteroid Impact Theory Encountered Staunch Resistance

The Alvarez theory of mass extinction due to an asteroid impact is the standard model today. At the time they published it, though, it encountered staunch resistance. 

Just as Kuhn described, established scientists dismissed or tried to explain away the evidence of the Cretaceous-Tertiary mass extinction. The notion that the cause of such an extinction came from outer space seemed far-fetched.

Today, we know that Team Alvarez was right. We even know the precise location of the crater in Mexico’s Yucatan Peninsula, where the asteroid slammed into our planet.

“Massively Morbid Tale”

Kolbert continues weaving her “massively morbid” tale, walking us through disasters that many of us now find all too familiar. We learn about ocean acidification, the decline of coral reefs and how the clear-cutting of the Amazon threatens biodiversity.

Most readers will be less familiar with how humans have transported other species far beyond the places where they arose. The author makes the analogy that it’s as if we’ve reversed the continental drift and all species live on one continent.

Having learned that I have some Neanderthal genes myself, I was fascinated by Kolbert’s history of their extinction. Their fate is uncertain, except that whenever modern humans cohabited the same territory as Neanderthals, before long, the Neanderthals vanished.

“Humans Remain Dependent of Earth’s Systems”

As she winds down her volume, Kolbert looks to the future, wondering where the Sixth Extinction will end. She points out that many believe that “having freed ourselves from the constraints of evolution, humans nevertheless remain dependent on the Earth’s biological and geochemical systems. By disrupting these systems… we’re putting our own survival in danger.”

Many people, including our readers, look beyond the proposed Anthropocene era in which we live. They believe that humans are called to evolve beyond our current period into a new age, known as the Ecozoic. 

In the coming Ecozoic era, they argue, humans will no longer pose a threat to Earth’s environment and instead live in harmony with it. Still, there are no guarantees.

Kolbert is a Gifted Storyteller

Kolbert is a gifted storyteller. This book is a valuable contribution to the new story Humanity needs to explain our place in Nature to one another. Public understanding of how mass extinctions have come about in the past is the best way to build awareness of future risks.

Still, I came away from the book feeling left hanging. Having walked us through so many past extinctions, you’d think the author might close with a clear moral to her story. 

 Instead, the concluding comments are brief and abrupt. There’s no final thoughts chapter or epilogue at the back of the book. Maybe Kolbert expects us to draw our own conclusions and make our own plans to make the Ecozoic a reality for future generations.

Make Ecozoic a Reality for Future Generations

Kolbert does offer these thoughts as part of the final chapter, which seem like an appropriate way to wrap up this review.

“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.”

We always have more learn if we dare to know.
The Sixth Extinction: An Unnatural History
Field Notes from a Catastrophe: Man, Nature and Climate Change

Origins: Cosmos, Earth and Mankind
The Canon: A Whirligig Tour of the Beautiful Basics of Science
Friendly People Ensured Human Survival


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