what is gaia hypothesis

Who was James Lovelock, what is Gaia theory, and why does it matter today?

Science Who was James Lovelock, what is Gaia theory, and why does it matter today?

Australian climate scientist Andy Pitman only met James Lovelock once at a conference and remembers a "classic elderly, charming Englishman", but it's an image that belies nothing short of a revolutionary influence.

For someone like Professor Pitman, who studies the interaction of climate and vegetation, it's obvious that living things play a key role in regulating Earth's climate.

"If it wasn't for life, we would have cooked long ago, because life sucks the carbon dioxide out of the atmosphere into the land," says Professor Pitman, of the University of New South Wales.

But when Professor Lovelock first went public with his idea that the   Earth was a giant organism that could regulate itself (including its climate) by using feedback between biological life and the rest of the planet, it was seen as rather radical.

"It was just so out there. It wasn't taken very seriously by many," Professor Pitman says.

But that was back in the 1970s — and today, even though many of Professor Lovelock's ideas remain controversial, his Gaia theory underpins a whole field of research called Earth systems science .

"I cannot overstate how profoundly transformative his contribution was," Professor Pitman says

"There are many people who think he has had more impact on our understanding of the Earth than any other singular scientist through the 20th century."

Life on Mars

Professor Lovelock, who died last week on his 103rd birthday , has been described as the "ultimate polymath" and a "connoisseur of nature" for whom "intuition and feeling" were just as important as science and data.

"My role has been to bring separated things and ideas together and make the whole more than the sum of the parts," he once told The Guardian .

It all started back in the 1960s when Professor Lovelock, while working for NASA, designed an instrument to measure the chemical composition of Mars's atmosphere.

After comparing his measurements with those taken from Earth's atmosphere, he concluded there could be no life on the Red Planet.

Professor Lovelock argued the Martian atmosphere did not contain the signature balance of gases including oxygen, which is a sign of life on our planet.

"He basically was able to demonstrate without sending robots to Mars that there was no life there," Professor Pitman says.

The findings changed the way we understand Earth's atmosphere and its relationship to the rest of the planet.

In 1987, Professor Lovelock and colleagues proposed that phytoplankton in the ocean helps regulate the climate by giving off a gas, especially when it is sunny, which helps form clouds that shade the Earth, and bring rain that helps forests grow.

While scientists still debate how these cycles work , it was complex planet-scale interactions like this — involving biology as well as physics and chemistry, and the recycling of nutrients — that were key to Professor Lovelock's thinking.

Professor Pitman likens the feedback processes central to Gaia theory to what happens in our bodies to regulate temperature — we sweat when we're hot and shiver when we're cold.

He says Professor Lovelock's writings were "essential reading" for his own PhD back in the 1980s, and a vast amount of what we understand today is the result and direct consequence of such work.

Like minds with a planetary perspective

The idea of using the name Gaia — the Greek goddess who personifies the Earth — originally came from a chat with novelist William Golding of Lord of the Flies fame. And a Pentagon consultant by the name of Dian Hitchcock also appears on an early scientific paper of Professor Lovelock's.

But his key long-term intellectual collaborator was the evolutionary theorist, microbiologist and fellow maverick Lynn Margulis, who overturned our understanding of how life on Earth evolved.

Professor Margulis also had a planetary perspective on things, says Bruce Clarke, of the Texas Tech University, who is a co-author of Writing Gaia, a new book that analyses 300 letters exchanged between professors Margulis and Lovelock between 1970 and 2007.

"She understood life as a global or planetary phenomenon," Professor Clarke says.

That's not surprising given that Professor Margulis was once married to cosmologist Carl Sagan, who knew Professor Lovelock, and suggested his wife connect with him.

"Lynn believed Gaia is run by the microbes," Professor Clarke says.

As well as collaborating on ideas, professors Lovelock and Margulis (who died in 2011) supported each other, in justifying their opposition to mainstream ideas, he adds.

And during the '70s and '80s it was them against scientists like Richard Dawkins, who was reducing life to a "molecular gene-centred vision" that made living organisms all "lumbering gene robots" at the mercy of their environment.

"For the longest time, Richard Dawkins was their mutual nemesis."

Gaia myths and climate prophecies

The fact that Gaia had mystical or spiritual connotations that resonated with many in the New-Age movement undermined Professor Lovelock's ideas in the eyes of some scientists.

So he spent a lot of time explaining that Gaia was not some kind of benevolent Earth mother, but it would take care of itself first, even if that wasn't great for humans.

As his collaborator Professor Margulis said: "Gaia is a tough bitch."

Professor Lovelock is also well known for warning of the dire consequences of human activity pushing Gaia to the limit.

At the age of 86 he published a book called The Revenge of Gaia, which predicted destructive extreme weather from climate change would be the norm by 2020.

He even thought the COVID pandemic might be "a Gaian negative feedback mechanism to reduce human pressure on the Earth system".

At the same time, he argued humans were part of Gaia, and needed to use their consciousness to "give her a hand" to stave off the worst of climate change.

Professor Lovelock shocked many environmentalist fans, for example, by advocating the use of nuclear energy and then geoengineering as solutions to global warming.

His recipe for human salvation also included human retreat to megacities and artificial intelligence controlling the climate.

A free thinker

Whatever you think of James Lovelock, he will be remembered for being a truly independent scientist, which, Professor Pitman says, is "a very rare" thing in this day and age.

"He was a free thinker who thought outside the box … and had hard core scientific credentials."

Professor Lovelock was elected a Fellow of the Royal Society not long after his first paper on Gaia was published, and has received many other honours.

And it seems he was able to be so independent because he funded his own work, with the help of the income from no less than 40 patents from inventions he had created over the decades.

These included the electron capture detector, which ended up detecting ozone-depleting chemicals.

Professor Lovelock's protégé, Tim Lenton, a professor of climate change and Earth systems science at the University of Exeter, believes his mentor's ideas on the interconnectedness of Earth's systems will help humans build a more sustainable future.

"He will go down in history as the person who changed our view of our place on Earth," Professor Lenton says.

"We need Jim's way of thinking now more than ever, if we are to get out of a climate and ecological crisis of our own making."

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• Published: 18 December 2003

Gaia: The living Earth

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Imagine a science-based civilization far distant in the Galaxy that had built an interferometer of such resolving power that it could analyse the chemical composition of our atmosphere. Simply from this analysis, they could confidently conclude that Earth, alone among the planets of the Solar System, had a carbon-based life and an industrial civilization. They would have seen methane and oxygen coexisting in the upper atmosphere, and their chemists would have known that these gases are continually consumed and replaced. The odds of this happening by chance inorganic chemistry are very long indeed. Such persistent deep atmospheric disequilibrium reveals the low entropy characteristic of life. They would conclude that ours was a live planet — and the presence of CFCs in the atmosphere would suggest an industry unwise enough to have allowed their escape.

As part of NASA's planetary exploration team in 1965, thoughts such as these led me to propose atmospheric analysis for detecting life on Mars. I also wondered what could be keeping Earth's chemically unstable atmosphere constant and so appropriate for life, and what kept the climate tolerable despite a 30% increase in solar luminosity since the Earth formed. Together, these thoughts led me to the hypothesis that living organisms regulate the atmosphere in their own interest, and the novelist William Golding suggested Gaia as its name. Although the concept of a live Earth is ancient, Newton was the first scientist to compare the Earth to an animal or a vegetable. Hutton, Huxley and Vernadsky expressed similar views but, lacking quantitative evidence, these earlier ideas remained anecdotal. In 1925 Alfred Lotka conjectured that it would be easier to model the evolution of organisms and their material environment coupled as a single entity than either of them separately. Gaia had its origins in these earlier thoughts, from the evidence gathered by the biogeochemists Alfred Redfield and Evelyn Hutchinson and from the mind-wrenching top-down view provided by NASA.

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Gaia theory: is it science yet?

Honorary Senior Associate, Faculty of Science, The University of Melbourne

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Ian Enting does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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James Lovelock’s “ Gaia hypothesis ” has challenged conventional thinking about the nature of the earth as an integrated system. Gaia proposes that the earth acts like a living organism — that life is part of a self-regulating system, manipulating the physical and chemical environment to maintain the planet as a suitable home for life itself. Lovelock has developed this idea in a series of books, from “Gaia: A new look at life on earth” (1979) through to “Revenge of Gaia” (2006) and “The Vanishing Face of Gaia” (2009). He argues that as changes in the physical earth system occur, living systems respond so as to mitigate such changes.

How can a planet be alive?

In claiming that Gaia is “lifelike”, Lovelock notes the difficulty of defining life. He points out that a biological emphasis on (potential for) reproduction would, for example, exclude postmenopausal women. On the other hand, a physical emphasis on entropy reduction would include refrigerators. This leads Lovelock to emphasise physiological self-regulation as the defining characteristic of life-like systems - networks of interacting processes serve to regulate each other to preserve the functioning of the organism

In discussing the concept of Gaia, Lovelock now distinguishes:

Gaia hypothesis : the original version — the Earth’s organisms regulate the physical and chemical components of the earth system so as to maintain the planet as an optimal habitat for life.

Gaia theory : the revision in response to critics — the combined physical, chemical and biological components of the earth system regulate the planet so as to maintain it as a habitat for life.

Various analyses have tried to distinguish between “weak” and “strong” Gaia, with weak Gaia differing little from conventional earth system science.

But isn’t Gaia for hippies?

The name Gaia has been widely used as a metaphor, as well co-opted for a large amount of pseudo-scientific baggage. This does not invalidate any underlying science any more than the majority of physics is invalidated by similar appropriation of terms such as “relativity”, “crystals”, “force fields” etc.

After stripping away such baggage, one has to confront the question: is what Lovelock is saying science and mysticism? While Lovelock has used the term “geophysiology” to avoid some of the mystical associations, he notes that all that has been achieved is that the term geophysiology now carries the same suspicion as the name Gaia.

The confrontation between Gaian theory and “conventional” science is largely focused on a few key words: “Gaia is like a living organism … whose goal is to maintain the planet in state fit for life”.

A powerful argument against the Gaia hypothesis is the assertion (such as that made by Richard Dawkins in The Extended Phenotype ) that Gaia cannot arise from Darwinian evolution of life — the planet as a whole is not a unit of selection.

Dawkins can be answered by an anthropic argument (wherein observations of the physical universe must be compatible with the existence of the conscious life that observes it):

The emergence of Gaian self-regulation through the course of evolution is allegedly extremely improbable.

Nevertheless, the long-term survival of life on a planet without Gaian self-regulation may well be even more improbable.

Therefore, intelligent observers are most likely to find themselves on a planet with Gaian self-regulation.

Personally, I find this sort of argument unsatisfying. However, similar arguments seem to be needed to “explain” the physical universe — it is a very precise combination of physical constants that allows the existence of atoms heavier than hydrogen and helium. Anyway, if Gaian self-regulation has arisen by chance, one would still want to know how it works.

For me, one of the most intriguing possibilities is some form of “innate Gaia” — rather than being highly improbable, some degree of Gaian self-regulation is inevitable.

Writing in Nature Tim Lenton has proposed that if:

• the physical system is stable, and
• the biological system has self-increasing growth, and
• there is a physical optimum for growth

then the steady state will be whichever side of the optimum leads to negative feedbacks, thus enhancing the stability of the physical system. The “optimal for life” in the original Gaia hypothesis is replaced by “mutually enhanced stability of the physical and biological systems”.

A theory with gaps is still a theory

While Thomas Henry Huxley famously talked of “the slaying of a beautiful hypothesis by an ugly fact” such discrepancies can also mean that the “ugly facts” are being misinterpreted.

For example, the gap in Wegener’s account of continental drift was that the continents aren’t ploughing through the crust — they are being carried by the crust. The gap in Darwin’s argument 150 years ago was the implicit assumption of blending of characteristics, so that new traits would be diluted. Mendel’s experiments showed that this is not so. Working out the details has been the work of subsequent generations of population geneticists.

Returning to Dawkins’ argument as quoted above, the hidden assumption that may represent a weak point is the assumption of a single level of selection.

In Revenge of Gaia , Lovelock quotes William Hamilton: “Just as the observations of Copernicus needed a Newton to explain them, we need another Newton to explain how Darwinian evolution leads to a habitable planet.” This echoes Alfred Wegener: “The Newton of [continental] drift has not yet appeared. His absence need cause no anxiety.”

To summarise: gaps and discrepancies in a theory imply a case for serious further study, not necessarily a reason to panic and immediately abandon any consideration of the idea.

What does Gaia mean for humankind?

In his recent books, Lovelock argues that humanity is like an army with over-extended supply lines — there is no option but to retreat (allowing Gaia to recover). Depending on humanity’s choices the retreat could be comparable to the British from Dunkirk or Napoleon from Moscow. We can take control of population ourselves, or see it plummet as Gaia kills us off.

My interpretation of what Lovelock is proposing as the potential relation between Gaia and humanity is the 20th century concept of “Mutually Assured Destruction” rather than “revenge”.

These concerns seem to be based on Lovelock’s expectation of a third climate state. The last 500,000 years show an alternation between quasi-stable warm and cold states, flipping on a 100,000 year cycle.

Lovelock (using simple modelling described in Vanishing Face of Gaia) proposes that higher CO₂ will lead to a third, hotter, quasi-stable state. The proposed causal chain is: warming from more CO₂ → more stable oceans, less circulation → less nutrients at surface, so less algal production → less pumping of CO₂ into deep oceans → more CO₂ remains in the atmosphere, locking in the warming.

But is there real evidence for a “third climate state”? Apart from the general principle that once self-regulation of a system fails, the failure can be very abrupt, are the arguments really Gaian?

So does it work?

An “ideal” summary would answer the question: “Is Lovelock right? Does the Gaia concept describe how the earth works?” I hope you won’t be too disappointed if I fail to commit to an answer. Indeed the whole process of preparing my talk and then editing it for The Conversation would have been less fun if I had been working from a preconceived view.

At times Lovelock seems to equate “Gaia” with “earth system science” by asking “would you have bought The Vanishing Face of Earth System Science?” A more substantive question is to ask: “is the (strong) Gaia concept established science?”, to which the answer is “not yet, and maybe it never will be”.

We come back to the statement that for Gaia “we need another Newton…”. Would a complete theory be a matter of filling in the gaps, as 150 years of accumulating evidence has “filled in the details” in Darwinian evolution? Or would the survival of Gaian theory mean morphing into something different, in the way that continental drift morphed into plate tectonics?

My best guess is that if “strong” Gaian theory survives (with or without the name Gaia) it will be through some such similar transformation. The “innate Gaia” implied by negative feedbacks being an “automatic” consequence of an interaction between expanding life and a dissipative physical system may well be part of such a re-synthesis.

Assessing Lovelock’s role as a “key thinker” raises the question of whether, regardless of its validity, the Gaia hypothesis has had a positive influence on the development of earth system science. (Lovelock’s other contributions to science through instrumentation have been invaluable). If, as I do not, one equates Gaia to current earth system science then the question largely disappears — the implication is that the rest of science has caught up with Lovelock.

My view is that even though “strong Gaia” and probably “innate Gaia” currently lie beyond the boundaries of established science, Lovelock’s role in pushing the boundaries of thinking about the earth system has spurred the thinking of many in the emerging earth system science community. This is a valuable legacy, regardless of the ultimate fate of his ideas.

This article is based on a lecture delivered in April 2009 as part of The University of Melbourne series of public lectures on Key Thinkers.

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The Gaia Hypothesis: Fact, Theory, and Wishful Thinking

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Organisms can greatly affect their environments, and the feedback coupling between organisms and their environments can shape the evolution of both. Beyond these generally accepted facts, the Gaia hypothesis advances three central propositions: (1) that biologically mediated feedbacks contribute to environmental homeostasis, (2) that they make the environment more suitable for life, and (3) that such feedbacks should arise by Darwinian natural selection. These three propositions do not fare well under close scrutiny. (1) Biologically mediated feedbacks are not intrinsically homeostatic. Many of the biological mechanisms that affect global climate are destabilizing, and it is likely that the net effect of biological feedbacks will be to amplify, not dampen, global warming. (2) Nor do biologically mediated feedbacks necessarily enhance the environment, although it will often appear as if this were the case, simply because natural selection will favor organisms that do well in their environments – which means doing wellunder the conditions that they and their co-occurring species have created. (3) Finally, Gaian feedbacks can evolve by natural selection, but so can anti-Gaian feedbacks. Daisyworld models evolve Gaian feedback because they assume that any trait that improves the environment will also give a reproductive advantage to its carriers (over other organisms that share the same environment). In the real world, by contrast, natural selection favors any trait that gives its carriers a reproductive advantage over its non-carriers, whether it improves or degrades the environment (and thereby benefits or hinders its carriers and non-carriers alike). Thus Gaian and anti-Gaian feedbacks are both likely to evolve.

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Kirchner, J.W. The Gaia Hypothesis: Fact, Theory, and Wishful Thinking. Climatic Change 52 , 391–408 (2002). https://doi.org/10.1023/A:1014237331082

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Issue Date : March 2002

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The Gaia Hypothesis

Science on a pagan planet.

Michael Ruse

272 pages | 15 halftones, 5 line drawings | 5 1/2 x 8 1/2 | © 2013

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Earth Sciences: General Earth Sciences

History of Science

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“[Ruse’s] treatment is thought-provoking and original, as you would expect from this perceptive, irrepressible philosopher of biology.”

New Scientist

“Fascinating. . . . The book is full of empathetic, insightful, and often very funny portraits of Margulis, Lovelock, and a community of other figures associated with Gaia and its histories. It is also a wonderfully lively and readable narrative.”

Carla Nappi | New Books in Science, Technology, and Society

"Explores the philosophical and historical bases of Gaia’s principle, beginning with Plato and taking readers up to the present with modern ecology and evolutionary biology. . . . There are few people writing today more qualified than Ruse to take on this job. He has the history and philosophical skills to tackle the literature across millennia, and his three-decade immersion in evolution allows him to read critically from complicated sources. Best of all, he still knows how to write in a way that makes philosophy and science fun."

Quarterly Review of Biology

"Anyone interested in the Gaia hypothesis--its history, its philosophical underpinnings and the scientific controversy over it in the mid-twentieth-century--will find this book an exceptionally interesting read."

Paul Thompson | Studies in History and Philosophy of Biological and Biomedical Sciences

"Fascinating. . . . A refreshing reminder of just how much the scientific enterprise is a social phenomenon, both in its inner workings and in how it is affected by the broader social milieu."

Massimo Pigliucci, City University of New York | Ethics and the Environment

"Written with Ruse’s usual flair and attention to the relevant evidence (that he shows is itself rich and varied), this book is scholarly and illuminating, on the one hand, and a thoroughly enjoyable read, on the other."

Lynn Hankinson Nelson, University of Washington | Soundings: An Interdisciplinary Journal

"Original, well researched, timely, and well written. . . . In short, The Gaia Hypothesis is highly recommended reading."

Arthur C. Peterson, University College London | European Society for the Study of Science and Theology

“An intellectually rigorous if sometimes challenging book,  The Gaia Hypothesis  gives a very satisfying overview of why Lovelock got the reception he did and, for me, marks Ruse as a notable writer to keep an eye on.”

The Inquisitive Biologist

“Entertaining and highly readable. . . . The value of Ruse’s book is in how he captures the wider importance of the debate triggered by the Gaia hypothesis. Like all good philosophers, he makes the reader think about how we think.”

Tim Lenton, University of Exeter | BioScience

“Few philosophers have blended the history and philosophy of science more successfully than Michael Ruse. And no contemporary scholar has played a more active role in establishing and maintaining the boundaries of science. In this riveting examination of the Gaia hypothesis—that is, the claim that Earth is a living planet—Ruse even-handedly applies his expertise to dissecting a controversial case where science, pseudoscience, and religion all came into play.”

Ronald L. Numbers, University of Wisconsin—Madison

“Written with Michael Ruse’s trademark combination of storytelling verve and philosophical insight, this book offers a fascinating history of the appealing but scientifically heretical idea that the earth is in some sense alive. Ruse not only recounts the successes and failures of this intriguing notion, but along the way poses searching questions about the nature of science and its popular reception.”

Peter Harrison, author of The Fall of Man and the Foundations of Science

“Michael Ruse has a habit of tackling big ideas in the history and philosophy of science, and there is hardly any idea bigger than the Gaia hypothesis. Ruse situates James Lovelock and Lynn Margulis’s theory of Earth as a living, self-regulating organism within several contexts, ranging from their personal biographies to the long history of mechanism and organicism in the life sciences. The trek through the past helps make sense of both the immense popularity of Gaia among the lay public and the hostility it faced from professional scientists, as Ruse contends that they are both part of the same process.”

Michael D. Gordin, author of The Pseudoscience Wars

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One of the most unpredicted outcomes of the space program was the Gaia hypothesis, the theory the biosphere itself works to regulate the temperature and chemical content of the Earth’s atmosphere. According to Gaia theory, life is a planetary-wide phenomenon that alters the environment on a planetary scale.

Table of Planetary Atmospheres, after Lovelock, The Ages of Gaia .

When the Earth was formed billions of years ago, the atmosphere was almost entirely made out of carbon dioxide, just like Mars and Venus. But with the emergence of blue-green bacteria and photosynthesis, carbon dioxide became a life-giving food. In the alchemy of Earth’s primordial oceans, the living metabolism of bacteria transmuted carbon dioxide and other elements into an expanding tapestry of life. The metabolic activity of the first bacteria started to give birth to a planetary-wide physiology. These first blue-green bacteria removed carbon from the atmosphere, which cooled down the planet, and gave off oxygen as a waste product. But around two billion years ago, the process gave rise to a planetary crisis—an “oxygen holocaust”—when too much oxygen had accumulated. Oxygen itself was highly toxic to the first bacteria. [1] This planetary-wide crisis provided a window of opportunity, however, when a new type of blue-green bacteria finally learned to synthesize oxygen into life-energy. Over immense periods of time, the biosphere transformed the atmosphere into its present composition. The atmosphere so composed was an atmosphere friendly to life, both in terms of its content and its stable, hospitable temperature.

While other planetary scientists had supported a “Goldilocks theory”—assuming that the temperature and atmospheric composition of the Earth had been “just right” for the emergence of life by chance—Lovelock showed that life itself had altered the planetary environment. Lovelock proposed that “the evolution of the species and the evolution of their environment are tightly coupled together as a single and inseparable process,” [2] a claim that was supported by his colleague, the microbiologist Lynn Margulis. Moreover, Lovelock and Margulis claimed that Gaia was a testable, scientific hypothesis.

During the past 4.5 billion years, solar luminosity has increased by at least 10–30%. [3] But the Gaian superorganism has successfully maintained a steady temperature through its metabolic processes. When critics complained that Lovelock’s theory smacked of teleology or design, he created a simple computer model called Daisyworld. Daisyworld contains two types of daisies, white and black, that naturally live in a certain temperature range and absorb different levels of heat. If the temperature is low on Daisyworld, the black daisies flourish because they absorb more heat. This causes the planet to warm up. If the temperature is high on Daisyworld, the white daisies flourish and reflect heat back off into space. Even if the luminosity of Daisyworld’s sun increases substantially, Daisyworld itself maintains a constant temperature—until the environmental conditions caused by the solar warming become just too extreme for the biota to regulate. Lovelock had proven that life can act like a planetary thermostat, and more complex models with twenty shades of daisies produced the same result. [4]

In addition to holding the temperature constant by reducing carbon dioxide, life has regulated the amount of oxygen in the atmosphere. Right now oxygen makes up 21% of the atmosphere, a level that must have remained constant for over 300 million years. If the concentration of oxygen was just a few points higher, devastating forest fires would engulf the planet. But if the oxygen level was a few points lower, animal life would perish.

As biologist Lynn Margulis points out, “life does not exist on Earth’s surface so much as it is Earth’s surface. . . . Earth is no more a planet-sized chunk of rock inhabited with life than your body is a skeleton infested with cells.” [5] Gaia’s radical challenge to traditional Darwinian biology is that life influences the environment. For Darwin, life was essentially passive, a process that was forced to adapt to a specific environment. Gaia theory shows that life and environment evolve as a single, coevolutionary process. On Earth, all life is an embodiment of the planetary environment, but the planetary environment is also product of life. Gaia theory and the new biology embodies the circular, metabolic logic of life. The universe brings forth life and mind—but life and mind work to shape the universe. Life and environment are folded back on themselves in a self-referential, evolutionary spiral. Gaia is not a single organism, but a superorganism. Like the single organisms of which it is comprised, it is self-regulating and autopoietic. Like my own body composed of many individual cells, Gaia has its own metabolism. As we breathe and exhale, we participate in the life-breath of the entire biosphere. Gaia theory is strongly supported by complexity science, which shows how complex systems with feedback loops spontaneously self-organize and develop metabolic patterns. From the Gaian perspective, our own lives are totally inseparable from the life of the larger planet.

[1] For a discussion of the oxygen holocaust, see chapter six in Margulis and Sagan, Microcosmos: Four Billion Years of Microbial Evolution (Berkeley: University of California Press, 1997) .

[2] James Lovelock, The Ages of Gaia (New York: W. W. Norton, 1988), 18. As he writes, “Through Gaia theory I now see the system of the material Earth and the living organisms on it, evolving so that self-regulation is an emergent property. In such a system active feedback processes operate automatically and solar energy sustains comfortable conditions for life. The conditions are only constant in the short term and evolve in synchrony with the changing needs of the biota as it evolves. Life and its environment are so closely couple that evolution concerns Gaia, not the organisms or the environment taken separately” (19–20).

[3] M. Newman, “Evolution of the Solar Constant,” in C. Ponnamperuma and Lynn Margulis, editors, Limits to Life (Dordrecht: D. Reidel, 1980) . See also Lawrence Joseph, Gaia: The Growth of an Idea (New York: St. Martin’s Press, 1990), 121–25.

[4] See Lovelock, The Ages of Gaia, chapter 3.

[5] Margulis and Sagan, What is Life? (New York: Simon and Schuster, 1999), 28.

Reprinted from chapter 11 of  Restoring the Soul of the World: Our Living Bond with Nature’s Intelligence by David Fideler. Copyright © 2014 by David Fideler. All rights reserved. May not be reproduced in any form without the written permission of the author.

“Viewed from the distance of the moon, the astonishing thing about the earth, catching the breath, is that it is alive. The photographs show the dry, pounded surface of the moon in the foreground, dead as an old bone. Aloft, floating free beneath the moist, gleaming membrane of the bright blue sky, is the rising earth, the only exuberant thing in this part of the cosmos. If you could look long enough, you would see the swirling of the great drifts of white cloud, covering and uncovering the half-hidden masses of land. If you had been looking a very long, geologic time, you could have seen the continents themselves in motion, drifting apart on their crustal plates, held aloft by the fire beneath. It has the organized, self-contained look of a live creature, full of information, marvelously skilled in handling the sun.” — Lewis Thomas, The Lives of a Cell

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