The Sixth Extinction.

My annual column on players I got wrong is up for Insiders.

I was feeling okay until I read Elizabeth Kolbert’s The Sixth Extinction: An Unnatural History, winner of the most recent Pulitzer Prize for Non-fiction, an unbelievably well-written and thorough accounting of the history of mass extinctions with a particular emphasis on the current one that is the first to be caused by another species – us.

The various scientists who work on the history of life on earth and of the planet itself agree that we’ve seen five mass extinction events since life first began, including the one we all learned about in school, the massive impact of a foreign body on earth that ended the Cretaceous period, killing all non-avian dinosaurs and three of every four species extant on the planet at that time. That wasn’t even the most damaging to life on earth – the end Permian event wiped out over 90% of extant species – and other extinction events had differing causes, including widespread glaciation or gradual oceanic acidification. But these events did occur, along with numerous smaller extinction events, which is why the current biosphere looks like it does, with our species the dominant one … and causing the current mass extinction event, which could lead to the loss of half of the biodiversity on the planet by the end of the century.

Kolbert has a lot of what could be some very dry paleontological and geological research on the history of mass extinction events, but instead weaves them into numerous narratives around specific species that we’ve lost or are trying to protect. She flashes backward into historical research to discuss long-vanished species like graptolites, which were wiped out in the ice age that ended the Ordovician period roughly 444 million years ago, or to discuss the various natural environmental phenomena that caused previous mass extinction events. In many of these chapters, she traveled to conservation sites, to zoos, or to natural habitats to follow scientists attempting to stave off extinctions or learn the causes of population losses. She travels to Panama to witness the desperate attempts to save various golden frog populations from the chytrid fungus, which eats away at amphibians’ skin, and to a cave in upstate New York where the native bat population was decimated by “white nose syndrome,” caused by another fungus called Pseudogymnoascus (formerly geomyces) destructans that thrives in the cold temperatures the bats favor.

By the end of the book, Kolbert has devoted a chapter to each of the major effects of human development on the biosphere that are now factors in the ongoing mass extinction event, including climate change, ocean acidification, habitat destruction, geographic fragmentation, spreading invasive species, and hunting/poaching. It’s utterly horrifying, not least because there’s so little we can do at this point: Our very existence, and our (temporary) supremacy atop the evolutionary pyramid, has led to numerous extinctions, from our hunting the great auks out of existence to deforestation that has wiped out numerous bird and amphibian species. Global warming is a dire threat to marine life in particular, and ocean acidification, climate change’s “equally evil twin,” is killing the world’s coral reefs. We’re bringing pathogens to ecosystems where the native species haven’t evolved any resistance, and bringing invasive plant, insect, and reptile species to environments where they lack natural predators. We suck.

Of course, we are also the only species in the history of the planet to actually care about stopping extinctions, although our efforts tend to focus on single species and to come very late, rather than trying to stop massive factors like climate change that threaten thousands of species simultaneously. Kolbert can’t even muster a high note on which to end the book, not that she should sugar-coat the truth, and concludes with the open question of what consequences these environmental catastrophes and the consequential loss of biodiversity might have for us.

Kolbert goes into the suspected causes of the mass extinctions, four of which are more or less tied to the current event. The end Permian “impact” event makes for a fascinating story because the hypothesis is so recent (first proposed in 1980) and was so widely derided at the time, including a famous New York Times editorial from 1985 titled “Miscasting the Dinosaur’s Horoscope,” which concluded with the line, “Astronomers should leave to astrologers the task of seeking the cause of earthly events in the stars.” While it’s the one kind of mass extinction event cause we’re not currently putting in play ourselves, it makes for a compelling side story as Kolbert explains both the discovery of the evidence that backs it up and the scientific establishment’s resistance to the idea when it was first proposed.


  1. I’ve always wondered if the reason we don’t find signs of intelligent life elsewhere is because once life becomes complex enough to use natural resources, it eventually destroys itself and the environment.