One of the enduring questions about our planet is how it has remained continuously habitable over vast stretches of geological time despite the fact that its atmosphere and climate are potentially unstable. James Lovelock's Gaia hypothesis posits that life itself has intervened in the regulation of the planetary environment in order to keep it stable and favorable for life. First proposed in the 1970s, Lovelock's hypothesis remains highly controversial and continues to provoke fierce debate. On Gaia undertakes the first in-depth investigation of the arguments put forward by Lovelock and others--and concludes that the evidence doesn't stack up in support of Gaia.
Toby Tyrrell draws on the latest findings in fields as diverse as climate science, oceanography, atmospheric science, geology, ecology, and evolutionary biology. He takes readers to obscure corners of the natural world, from southern Africa where ancient rocks reveal that icebergs were once present near the equator, to mimics of cleaner fish on Indonesian reefs, to blind fish deep in Mexican caves. Tyrrell weaves these and many other intriguing observations into a comprehensive analysis of the major assertions and lines of argument underpinning Gaia, and finds that it is not a credible picture of how life and Earth interact.
On Gaia reflects on the scientific evidence indicating that life and environment mutually affect each other, and proposes that feedbacks on Earth do not provide robust protection against the environment becoming uninhabitable--or against poor stewardship by us.
Toby Tyrrell is professor of Earth system science at the National Oceanography Centre Southampton (University of Southampton).
"A handful of scientists have become crusaders for the Gaia hypothesis, while the rest have dismissed it without a second thought. Toby Tyrrell, on the other hand, is one of the very few scientists to have considered the evidence at length and in detail. In summarizing nearly forty years of arguments for and against the Gaia hypothesis, he has done a great service for anyone who is curious about Gaia, or about this fascinating planet that we all call home."--James Kirchner, University of California, Berkeley
"Toby Tyrrell unravels the various formulations of Gaia and explains how recent scientific developments bring the hypothesis into question. His criticisms are insightful, profound, and convincing, but fair. On Gaia is wonderfully informative and a pleasure to read."--Francisco J. Ayala, author of Am I a Monkey?: Six Big Questions about Evolution
"At last, a beautifully written and clear-eyed analysis of the interplay of life and the Earth system. On Gaia provides the understanding for moving forward in the quest for sustainability, and is essential reading if our planet is to remain habitable for humanity."--Thomas E. Lovejoy, George Mason University
"On Gaia makes a wonderful addition to the literature. It is scholarly, well-written, and well-reasoned."--Simon A. Levin, Princeton University
Table of Contents:
1. Gaia, the Grand Idea 1
2. Good Citizens or Selfish Genes? 14
3. Life at the Edge: Lessons from Extremophiles 47
4. Temperature Paces Life 67
5. Icehouse Earth 88
6. Given Enough Time . . . 113
7. Evolutionary Innovations and Environmental Change 130
8. A Stable or an Unstable World? 145
9. The Puzzle of Life's Long Persistence 171
10. Conclusions 199
Further Reading 273