A good, solidly written book with no major flaws of composition, Snowball Earth tells the story of Paul Hoffman, an irascible geologist behind a new theory of the role played by geology and climate to kickstart the development of complex life on Earth. Geology is a discipline that describes “deep time,” filled ages so vast and processes often so slow that the whole of human history is but the blink of an eye. It is in many way the science that most intertwines the direct observation of the physical world and the resultant explanations that can be reasoned from those observations. Modern geology has been constructed on two centuries of serious observation, measurement, and recording of the rocks that make up the world around us, all over the planet. With every year that passes, our knowledge grows and is refined.
Most people who have at least a modest degree of science literacy have heard of the Cambrian Explosion. The term itself is in almost every way an erroneous representation of the millions of years that were required for multi-cellular life to emerge in the wild and bizarre forms found in the world-famous Burgess Shale of Canada. It is an explosion in a sense of geological time, perhaps, but still incomprehensibly vast on a human scale. What the Snowball Earth hypothesis suggests is that a planet-wide ice age 700 million years ago put such stresses on life that evolution, which had previously just been mucking about with small, simple creatures, began to drive a change whereby larger, multicellular entities had a survival advantage. This, it is suggested, drove the evolution of a complex array of multicellular creatures, a biological arms race which has yet to end. While seemingly a radical idea, the Snowball Earth hypothesis has a certain elegance about it. What we know, regardless of what we may believe about events three-quarters of a billion years ago is that something happened, and that the something in question changed life on earth from simple, largely uni-cellular creatures to animals of increasing complexity and diversity.
Walker’s narrative smoothly handles some of the complex and arcane technical issues of geology in such a way as to not overwhelm the non-technical reader, and also succinctly presents a compelling view of how science is built from hypothesis and testing. She also shows how personalities – not all of them warm and cuddly – can influence the ease or difficulty with which near ideas can enter the sphere of general knowledge and understanding.
The notion that a planet-wide ice age, the Snowball, led to the development of complex multi-cellular life, the Cambrian “explosion”, and eventually to dinosaurs, elephants, mice, and eventually a little species called homo sapiens is a fascinating and compelling one. As a tale both of personality and of science, Snowball Earth succeeds in being not only engaging, but fascinating. I would unhesitatingly recommend this book to anyone with a geological bent, or to people who simply want to understand one of the more interesting notions out there in geology at the moment.
Originally reviewed 22 February 2011.
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