Book Review – On Gaia, A Critical Investigation of the Relationship between Life and Earth by Toby Tyrrell

On Gaia coverThe Gaia hypothesis, put forth by James Lovelock in 1972, proposes that planet Earth is regulated by and for the life forms occurring on the planet.  The hypothesis suggests that life has somehow conspired in the regulation of the global environment so as to keep conditions comfortable. In some forms, the Gaia hypothesis suggests that the planet has a “consciousness.”

According to the author, Toby Tyrrell, a professor of Earth system science at the University of Southampton, England, the Gaia hypothesis makes three main assertions:

1. The environment is very well-suited to the organisms that inhabit it. As Tyrrell points out, this assertion is backwards, organisms adapt to the environment; the environment does not adapt to organisms.

2. The Earth’s atmosphere is a biological construct whose composition is far from expectations of (abiotic) chemical equilibrium.

3. The Earth has been a stable environment over time, despite variable external forcings.

Tyrrell also notes two competing hypotheses:

1. The Geologic hypothesis which holds that Earth’s environment is due mainly to geological forces and astronomical processes.

2. The Coevolutionary hypothesis which holds that “life and environment have both changed over time, and that changes in either have had effects on the other.”  The difference between this hypothesis and Gaia is that coevolution “is free of any connotations that, once life had evolved and started to influence climate, the planet was bound to remain habitable thereafter.”

Tyrrell has taken on a big job in a critical examination of the three Gaia assertions and the two alternate hypotheses.  The book is a tour de force that presents physical and philosophical evidence for and against the Gaia hypothesis, which, Tyrrell points out, has some similarities with Intelligent Design.   Fortunately, the book is written in plain language and each of the 10 chapters has introductory paragraphs dealing with what the chapter will cover and a concluding section providing a summary.  Many of the endnotes referenced within the chapters are interesting stories in themselves and provide amplifying evidence for the main points.

The book includes over 50 pages of end notes, suggested reading for each chapter, and 22 pages of references to the scientific literature.

Tyrrell ultimately concludes that “Gaia is a fascinating but a flawed hypothesis.  It is not a correct characterization of planetary maintenance and life’s role therein. Some of Lovelock’s claims…are seen to be dubious when probed more deeply.  Some of the key lines of argument advanced in support of Gaia are insecure, or else give support in equal measure to other hypotheses as well as to Gaia.  There is nothing that can be explained only by Gaia.”  The evidence shows that the Gaia hypothesis fails on assertions 1 and 3.

Tyrrell favors the coevolution hypothesis which, he says, “is fully compatible with what we know.”  “There are no natural phenomena that either Gaia or the geological hypothesis is uniquely able to explain.”  While I’m sad to see that geology can’t explain absolutely everything (I’m a geologist), I must agree with Tyrrell.

How he gets to his conclusions is a fascinating story illustrated by many interesting examples.  The book is well-written and easy to read.  Some of his perceptions may give you a different perspective on things.  I particularly like a sentence in Chapter Two: “Nature is a mixture of apparent cruelty and kindness, of economy and waste, of competition and cooperation.” (That’s so Dickensian: It was the best of times….)  It sets the tone of Tyrrell’s critical analysis.  Tyrrell’s story is very informative and the reader will learn many fascinating things along the way.

The book is published by Princeton University Press and available from Amazon and Barnes&Noble..

P.S. In an interview with MSNBC, on March 17, 2009, James Lovelock admitted that he had been a climate alarmist and had been “extrapolating too far.”


  1. I have observed that biology has played a major role to form the

    earth.infect earth itself is a single living organism like a tree.please

    observe the following explanation for this hypothesis. this hypothesis is

    like a Gaia hypothesis supported by some more evidences.

    1. Amino acid and Biological chemistry in chondrite meteorite.

    we have found amino acid and biological chemistry inside the

    chondrite meteorite. as i consider them seeds of planets. one planet is a

    result of one asteroid as one tree is a result of one seed. these amino

    acid and biological chemistry is a main property of any seed.

    2. bark as continent; if you will observe the continents can be fit in

    small globe like a puzzle game same bark can be fit in small gorth of same

    log of tree. — Bark &

    Continents TREE BARKS bark Earth & Tree Safeda

    3. core and crust; same as in log of tree. Core Crust

    4. plate tectonic; yes i agreed with PT but at the end biological process

    beneath the earth surface is responsible for the motion of plates. same PT

    is happening in the log of tree. Plate Tectonic 4. PLATE TECTONIC LINK

    5. subduction zone;same in log of tree. Subduction Zone

    6. HYDROCARBON a scientific ; this is a scientific evidence of my

    hypothesis.that earth itself is a single living organism and producing

    hydrocarbons like any all living organism. I believe crude oil has both

    deep and organic origin . fossil oil theory is not correct. we have

    observed hydrocarbons at almost whole universe including Titan. there is no

    solid reason that hydrocarbons at earth has been from fossils of past life

    and at rest universe with different method where no life has been observe


    More over i have solved the mystery that why sediments are signatures of

    presence of oil while has no involvement to produce it. this is the main

    logic of fossil oil theory. infect i have solved this mystery of

    petroleum. my theory is between the current biogenic and abiogenic

    theories. I believe oil has both deep and organic origin like a bark oil.

    Making Oil From Birch Bark

    7. presence of same minerals like iron,nickel,moly,crome,V,MN,

    etc at earth are also present in all living organism.this is very much

    common factor in all living organism inculding hydrocarbons.

    I have lot of these type of evidence and putting all together we can

    conclude it that earth itself is a living thing that has been grown from

    small asteroid.

    1. WOW, this comment may be a good example of something Alexander Pope wrote:”A little learning is a dangerous thing ;Drink deep, or taste not the Pierian spring :There shallow draughts intoxicate the brain,And drinking largely sobers us again.”

    2. Sorry, the Gaia hypothesis B.S. by any other name is still B.S. No one can ever polish that turd…

Comments are closed.