The Great Extinctions: What Causes Them and How They Shape Life - Hardcover

MacLeod, Norman

Hardcover

ISBN 10: 1770851879 ISBN 13: 9781770851870

Publisher: Firefly Books, 2013

Synopsis

A fascinating history of species extinctions, their causes and the looming "sixth extinction".

It is the central issue for this generation. Respected journals and popular publications worldwide pose the question, call the warning: "Are we in the middle of a sixth mass extinction?" (Science), "Multitude of species face climate threat" (The New York Times), "The sixth great extinction: a silent extermination" (National Geographic).

Of the 1-3 billion species estimated to have appeared during Earth's history, only 12.5 million exist today. Geologists know that species extinction is as natural a process as species evolution. They also know that the rate of extinction in the geological past has not been constant. On at least five occasions in Earth's history, extinction intensities have spiked well above the normal level.

For over a century, geologists have tried to conclusively identify and understand the processes responsible for the complex, fluctuating history of species extinction through the millennia. This has become even more important over the last decade as human populations and technology may now rival sea-level change, volcanic eruptions and asteroid impacts as an extinction mechanism. Will there be a sixth Extinction? When? What will cause it?

The Great Extinctions explores the history of this search, its subjects, its controversies, its current conclusions, and their implications for our efforts to preserve Earth's biodiversity. It explains what extinction is, what causes it and whether it is preventable, and by comparing past geological extinction events, it aims to predict what will happen in the future.

Author Norman MacLeod covers this compelling topic in a concise, easy-to-read style with illustrations and diagrams throughout. He examines a controversial subject with universal implications, which will fascinate a wide readership with interests in geology, prehistory, the environment, endangered species, conservation, wildlife, biodiversity, climate change, zoology, botany, invasive species and more. The Great Extinctions is an essential choice for an informed contemporary readership.

About this title

About the Author

Norman MacLeod is Keeper of Palaeontology at the Natural History Museum, London. He studies the origin and maintenance of form in fossil and modern organisms using mathematical models of shape variation. He also creates new mathematical tools for studying plant and animal form and develops systems for automating the identification of species.

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Introduction

For the past 30 years a significant proportion of the scientific community has been obsessed with the idea of extinctions, especially the extinction of the 'dinosaurs' at or close to the boundary between the Cretaceous and Palaeogene intervals of Earth history. This interest pre-dates the current concern with the 'sixth' extinction, a hypothetical event that may occur in the future and which takes its name from the 'Big Five' ancient (mass) extinction events of the fossil record. The reasons for this and the sustained level of interest in extinction related topics are many and varied. But they share a common source. The concept of extinction elicits a deep emotional reaction in most people today, in no small way because we all share an intuitive concern about transformations being wrought in our increasingly unnatural environment. When we see declines taking place in landscapes, animals and plants at the local, regional and even global scales we cannot help experience the sense of foreboding that comes from drawing obvious parallels between the status of our own species and the fates of other, far more ancient, species that 'ruled the Earth' in the distant past.

Much has been written about extinction. Many treatments of this topic end up claiming that the problem of understanding extinctions in general or particular extinction events has been solved (e.g. Raup 1991, Ward 1995, Alvarez 1997). In reality, the scientific community is far from having a detailed understanding of the enigma that is extinction, as attested to by the simple fact that 'extinction debates' constitute one of the longest-running scientific controversies in living memory. If a consensus regarding what 'killed' the dinosaurs, the ammonites, and their kin has been achieved (see Alvarez et al., 1980, Schulte et al., 2010), why do so many professional palaeontologists -- especially those who know the extinction record best -- stand outside it (e.g. see Archibald et al., 2010)? Given the current state of knowledge about extinction as a phenomenon, what inferences for the contemporary and future management of our planet can, or should, we draw? What type of cataclysm does it take to extinguish 50, or 60, or 75, or 90 percent of all species on the land and in the sea, as has happened repeatedly in the Earth's distant past? What causes the sort of changes in the environment that drive extinction rates to these astonishing levels and over what timescales? Perhaps most importantly, how does a planet recover from devastations of such magnitude?

I have undertaken and published extinction research using the fossil record as my primary source of data for most of my professional career. I and my colleagues have grown up (literally) with this research programme, this scientific debate, this public controversy. Like all participants in any human activity, I have a particular point of view that I believe conforms to the most reasonable interpretation of the greatest proportion of evidence currently to hand. I disagree with explanations offered by some of my colleagues and some of them disagree with me. Such is the character of healthy scientific debate. But my goal in this book is not to simply present the case for my own point-of-view by citing the evidence in its favour and ignoring contrary observations. Rather, it is to present the data extinction researchers of all persuasions work with as fairly as I can, mentioning all the nuances, caveats and assumptions that often get left out of presentations for a popular audience. Once this evidence has been presented it will be up to you, the reader, to come to your own conclusions about extinctions, what has happened in the past, and what might occur in the future. No doubt my own biases will creep in from time to time. This is inevitable. I pledge here to make a diligent effort to identify instances in which I am offering a personal opinion or interpretation. More than this though, I hope to convey some inkling of the excitement, the novelty, the frustration and the sense of grandeur that accompanies the study of one of natures most common processes, but also one of its deepest mysteries.

It has been said that the secret to a long life is to have a chronic incurable disease and to keep treating it. By the same token, the secret to a productive life in science is to have a chronic insoluble problem and to keep working on it. By this measure I and my extinction-studies colleagues on all sides of the interpretational fence have been very fortunate indeed.

Edition details

• Publisher: Firefly Books
• Publication date: 2013
• ISBN 10: 1770851879
• ISBN 13: 9781770851870
• Binding: Hardcover
• Language: English
• Edition number: 1
• Number of pages: 208