When Life Nearly Died: The Greatest Mass Extinction of All Time [Hardcover]

Subsequently, it is refreshing and reassuring to actually find a piece of text actually concerned with a mass extinction that appears to have had the most decimating effect on metazoan life ever detailed in the Phanerozoic, the Permo-Triassic extinction. Well it’s about time, but why the wait?

Benton addresses this reason adequately from the start of the book, giving a clear account of how generations of earth scientists have been shoe-horned into adapting a prose of thinking instigated by Charles Lyell. This involved believing that there has always been a regular consistency in the history of the Earth, that no processes can be involved that are not immediately observable on a day to day basis, i.e. ‘the present is the key to the past’. To suggest mass-extinctions, momentous periods of volcanic activity and occasional asteroid impacts would result in being allocated to the ‘crackpot wing’. Therefore, the acceptance that mass-extinctions have occurred is a very recent acceptance in the field of Earth Sciences, none more so that the Permo-Triassic extinction.

As a geology student, I was always taught the transition in faunas and floras over the Permo-Triassic boundary was a long, gradual affair, caused by the simple event of the cohesion of continents to form Pangaea, resulting in a significant loss in habitat and mass extinction in the marine environment. Simple as that. On land? That was a certain ‘grey area’, to say the least.

Appreciatively, this issue is resolved at long last. This book brings together a compendium of valid, relevant information. This includes analytical studies of exposed stratigraphy across the Permo-Triassic boundary in China, Greenland and Russia that has given a wonderful opportunity to analyse the concurrent sedimentology and evident palaeontology. Also involved is a wide range of intricate isotope and radiometric work. The result is fascinating. Something truly devastating did actually occur approximately 251 million years ago and like a classic case of bad luck it appears to have happened three times concurrently.

I thoroughly recommend this book to any individual who may have an interest in the Earth Sciences, whether layman or academic. The text is smooth and reads well, Benton clearly has the ability to transfer information in a clear and concise fashion that ultimately proves to be addictive reading. I consider this book to be a benchmark in Earth Sciences literature in that it acts as an effective summary at this present moment in time (at going to press!) on what is actually known about the Permo-Triassic extinction. It’s a great piece of work and it’s a joy to read.

Sharply criticising Darwin's contemporaries and successors for clinging too resolutely to the notion that Nature's forces merely creep along, Benton notes the persistence of one theme. The "uniformitarians", he says, blinded scholars to the evidence - evidence that suggested life could end suddenly. Charles Lyell, one of Charles Darwin's inspirations, argued that what is seen today typifies the entire, and lengthy, history of our world. Slow, gradual change on today's surface is but the most recent example of the panorama of millions of years. Sudden change, "catastrophism", promoted by Baron Cuvier in France, was false. In life, Darwin's evolution by natural selection reflected the gradualist theme.

Benton dismisses Lyell and his adherents as overcommitted to gradualism. He contends they shut their eyes to contrary evidence. He admits the data was less than readily apparent, but argues some questions should have been raised long before now. New research, sometimes in places already once observed, finally brought reassessment. The Ural Mountains in Russia offered the first clues. Roderick Murchison toured there in the 1840s, naming the "Permian System" of rocks. Wars and revolutions interrupted the surveys and geologists and paleontologists peered at new ground. The Great Karoo of South Africa, China and other sites provided new information. A gradually emerging picture revealed a massive die-off 251 million years ago. What had happened?

After a long introduction of chapters recounting the researchers and their findings around the planet, Benton dismisses the notion of a bolide impact. This idea, fostered by the discovery that the Dinosaur Era had likely been concluded by the impact of a 10 kilometre asteroid, wasn't matched by the evidence. While the Permian Extinction may have been accompanied by darkened skies and deluges of rain, the real killer was something else. The dinosaur extinction wasn't typified by massive intrusions of poisonous gases, but the Permian was another matter. Benton surmises that 251 million years ago a series of volcanic fissures spewed immense waves of lava over the land near the North Pole. This area, now known as Siberia, is still covered by the remnants of the outburst. With the lava came noxious gas, mostly carbon dioxide and sulfur dioxide. These "greenhouse" gases warmed the seas, releasing life-killing methane. The catastrophe may have killed off up to 96% of all living things.

This is not simply an arcane analysis of events in the ancient past. It's a book that should gain a wide readership, since the events of all those millions of years ago have implications for today. Benton notes the sediments at the bottom of our seas contain a build-up of methane equalling or exceeding that of the Permian. Today's human-spurred global warming may be leading to the same scenario. Extinction, Benton reminds us, isn't limited to dinosaurs or other ancient life. It is clear that we must learn how these mechanisms work to make rational decisions about our dealings with the biosphere. [stephen a. haines - Ottawa, Canada]