Sixth Extinction (book review)

Well, calling this a review is a bit strong.  But as GG teaches Historical Geology to undergraduates (yes, it seems illogical, but somebody has to do it), The Sixth Extinction by Elizabeth Kolbert merits GG’s attention.

The obvious and main message is that humanity is engaged in eradicating species at a rate comparable to the previous 5 great extinctions.  As such, this is not particularly new ground to either biologists or earth scientists.  What makes this book stand out is that it is not a polemic and it provides a nicely nuanced view not only of what is happening now but what has happened in the geologic past.  This book covers one of the main themes of the class GG teaches and so there is a lot GG hopes is familiar to those from his class.

Modern popular science books are mainly written by science writers and not scientists (it was not ever so, but as scientists descend further into the condensed science-speak of the professional literature, it is that much harder to reemerge and write with clarity and wit for those not in tune with lyrics made of acronyms and polysyllabic nonsense).  At one point, such writings were rather passive (in the literary sense): the author would not be present in the text.  But that has mainly fallen by the wayside, and now the science writer is present.  While this is gratifying in that passive voice is far less common, at times such writing feels smug and self-congratulatory.  Such books make GG wince and, well, yes, grumpy.  The success of a science writer is, oddly enough, less in learning what scientists have learned but in finding ways of sharing that with interested readers uncomfortable confronting scientific journals themselves; thus the evident pleasure some writers take in showing that they have figured things out is, well, out of place.

This book walks that line carefully and, to GG’s eye, successfully.  While Kolbert does have us travel along with her in seeing vanishing frogs or tumbling down the side of the Andes, these feel more like introductions than conclusions and she does step aside to allow the science of extinctions to come through.  And you have to applaud any popular book that brazenly includes a few equations and x-y scatter plots.

And that history of extinctions is well done, avoiding the numerous traps out there for the lazy science writer.  That extinction itself is a relatively recent concept comes through early in the book. The author manages to capture the way that the hypothesis of a meteorite impact at the end of the Cretaceous came to be, and how that hypothesis was attacked and yet overcame initial skepticism to be the best accepted hypothesis today.  Kolbert also shows how that led to an initial burst of enthusiasm for extraterrestrial impacts that turned out to be a false lead (such as the Nemesis concept of periodic extinctions, which showed why you want to be careful with a Fourier analysis of a fossil record); it seems the major extinctions might all be quite different.  This is a nice touch: too often popular science books focus on our current state of knowledge without recognizing the false leads and errors of the past that well could still color our present perceptions.  She doesn’t duck the culturally uncomfortable inference that early inhabitants of the Americas, Australia, and various Oceania areas were responsible for many extinctions at the close of the Pleistocene.  We as a species were dangerous when all we had was fire and stone-age tools; imagine our capabilities now. All of these events are tied in to the various ways modern humanity is pressuring species towards extinction, through hunting, competition for forage, reduction of range, by introducing predation and sickness by transporting organisms, by acidifying the ocean, by accelerating changes in climate.  

It is of course a rather depressing vista overall, but the voyage is entertaining.

There is not a lot to really quibble with; despite dealing with some controversial and challenging material, it doesn’t feel that the reader is being fed a line of hooey, nor does it seem that the author got sidetracked into a curious but ultimately futile sideshow (such as the Younger Dryas impact hypothesis).  There are some more hopeful things out there: focusing on the barren nature of a locally acidic part of the ocean may not be nearly the harbinger of doom that this book makes it out to be.  And recent work suggesting that the Paleocene-Eocene thermal maximum might have cranked up in a few years might indicate that there is some hope that even our rapid warming today might not be nearly as fatal as many have feared.  But these are minor quibbles and, realistically, they may turn out to be more misleading than encouraging.

In many ways this would make a better textbook than most historical geology textbooks (which mainly drown important points in a sea of trivia).  It eloquently connects the ancient world that many students find irrelevant to modern concerns; it shows how scientific endeavor works at many different stages of the process.  And it is a good read, which almost no textbook can claim to be (though GG does like Cowen’s History of Life as a text you can read and learn from at once). Its main challenge as a text is its wandering back and forth through time. This is a great suggestion though to students as a sort of auxiliary text.

In sum, this is more than a diatribe about modern civilization wiping out species; it is a great introduction to the events of the distant past that have shaped life on Earth and the means by which we learn of such events.  It is readable and engaging without being too cloyingly personal.  By all means, get a copy and read it.


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