This is the final part of my four-part review series on the Gaia hypothesis (see also part 1, part 2, and part 3), James Lovelock’s notion that the Earth is a giant self-regulating system that maintains conditions suitable for life on the planet. I selected this book as a counterpart to the hard-science analysis of Tyrrell’s On Gaia (also published in 2013) to take a step back and read about the wider reception of Lovelock’s ideas. As it turns out, professor of philosophy Michael Ruse additionally delves into the historical and philosophical precursors to the notion of Earth as a living planet. 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 Gaia Hypothesis: Science on a Pagan Planet, written by Michael Ruse, published by the University of Chicago Press in October 2013 (hardback, 251 pages)

The Gaia Hypothesis is part of Chicago’s science•culture series which contains books examining the intersection of the two and is the second book in this series that I review. Ruse opens the book with an introduction to the conception of the Gaia hypothesis, the cast of characters, and the basic premise of Lovelock’s ideas. Scientists initially did not take it seriously. When it became clear that Gaia was not going away, they rained down both scorn and well-deserved critique on it. The general public, on the other hand, lapped it up. Many people in Europe and the USA were abandoning traditional religion while a countercultural revolution was in full swing. “Earth as an organism was just the vision, just the metaphor, for which many individuals and groups were searching” (p. 37). Ruse sees a paradox here. How is it that scientists rejected a fellow scientist-inventor, while a predominantly progressive counterculture embraced the ideas of a man funded by the military and the industry?

To resolve this paradox, Ruse provides a historical analysis in chapters 3 to 6 that form the core of this book. It was also the section that I found challenging in places, but that will be because I have no background in classical philosophy and metaphysics. Given this, I am stepping onto some very thin ice here, and I apologise in advance to all philosophers reading this if I am about to butcher some of your favourite concepts. That said, here is my understanding of the relevant points being made.

Ruse starts with classic Greek philosophers such as Plato and Aristotle and their ideas on the nature of reality. They introduced different forms of teleology, which is the explanation of phenomena by arguing why—for what purpose or to what end—things happen in the world, rather than explaining what is causing them. Aristotle in particular had no hesitation in saying that the universe was striving towards the perfection of whatever godlike being had designed it. Furthermore, no distinction was made between body and soul. Next to the soul animating the body (hylomorphism), of relevance to the Gaia hypothesis is that this animatedness extended to all matter, something Ruse refers to as “world soul thinking” or hylozoism. This notion waxed and waned over the centuries and an important hallmark of the Scientific Revolution from the 16th century onwards was a gradual banishing of final causes. We moved towards a—to us—more familiar understanding in terms of mechanical metaphors, reductionism, and of matter as inert and without purpose. In particular, Ruse details the rise of mechanistic thinking and the expulsion of final causes in the two disciplines relevant to Gaia: geology and evolutionary biology.

“How is it that scientists rejected a fellow scientist-inventor, while a predominantly progressive counterculture embraced the ideas of a man funded by the military and the industry?”

Nevertheless, Plato’s philosophy and the notion of a world soul persisted. Seventeenth-century machine metaphors did not erase all other ways of thinking and it was not as if, moving forward, “everyone saw the physical world as nothing but blind matter in endless motion” (p. 57). Ruse traces a line through the German Romantic movement and American transcendentalism to the 19th-century rise of organicism, a school of thought in biology that erupted from intellectual hotbeds such as the universities of Harvard and Chicago. As defined here by Ruse, it stands in contrast to mechanism and argues that whole entities such as organisms are emergent properties that cannot be explained by considering their parts. “The organicists see an integrative aspect in nature that operates outside of or beyond selection. […] There is something wholesome about nature that the hard-line Darwinian misses” (p. 118). Interestingly, just last month Harvard University Press published The New Biology, co-authored by Ruse, in which he continues his thinking about mechanism and organicism. In the wider world, meanwhile, hylozoism lived on in a range of ideas from deep ecology and ecofeminism to more esoteric thinking that readily mixes religion and pseudoscience such as anthroposophy and New Age paganism.

An important piece in the puzzle is Lovelock himself. Ruse provides a piercing if fair character study in the last two chapters. He is fair by pointing out that Lovelock demonstrated “outstanding talents in his field” (p. 179) and his work with NASA showed “he did not break with traditional science; he simply did it better than anyone else” (p. 180). Ruse judges him to be “basically a very conventional scientist [who] was rightly elected to the Royal Society” (p. 181). However—and I am sure you can feel a “but” coming—this is no hagiography. His points confirm my suspicions that, frankly, Lovelock increasingly became a crank later in life. His response to criticism was “partly petulant” (p. 147), his attitude one of “cocky self-assurance [and] hubris” (p. 187). He was proud to be an independent scientist who dared, and could, think outside the box, and he felt disdain for academic institutes and the “self-imposed inquisition” (p. 147) of peer review. The bigger problem that Ruse highlights, in my opinion, is that “although he had spent much time in medical research, Lovelock was not a biologist, didn’t think like one, and wasn’t about to start now” (p. 155). Furthermore, lacking knowledge of classic philosophy, he was ignorant of the history of banishing teleology from evolutionary biology. He was “not a deep thinker [but] a tinkerer, an inventor, an instrument maker—and such people do think teleologically” (p. 187). Straying far outside his area of expertise and possessed of both ignorance and innocence, he “clearly had no idea of what he was embarking upon” (p. 186). What I found revealing is that even his most fervent disciples eventually reluctantly distanced themselves somewhat from him. Tim Lenton admits that “earlier on in my career […] I was more with Jim on my use of the Gaia banner” (p. 221), while Andrew Watson thinks that “the vision of the Earth as a single organism doesn’t quite work” (p. 222). Furthermore, in their book Revolutions That Made the Earth, they preferred the more neutral term Earth system science over Gaia, as the latter “is so closely tied to Lovelock that it is in a sense defined by his views” (p. viii therein).

“An important piece in the puzzle is Lovelock himself and Ruse provides a piercing if fair character study in the last two chapters.”

And then there was the company that Lovelock kept, with Ruse focusing on two people. First, there was the Nobel Prize–winning author William Golding who suggested the term Gaia. An enthusiastic confidant to Lovelock before Lynn Margulis, he used to be deeply involved with anthroposophy and the Steiner movement and was thus receptive to Lovelock’s idea of Earth as a living being. Ruse beautifully summarizes his contribution thus: “The idea was Lovelock’s, but the facilitator was Golding” (p. 183). Second, there was Lynn Margulis, the headstrong scientist who finally had won acclaim with her hypothesis of endosymbiosis but then went off the rails by seeing symbiosis everywhere. She was on a crusade against neo-Darwinism and concocted ever-stranger ideas. Though she continued to support Lovelock’s cause throughout her life, they only co-published an initial batch of papers. After this, they gradually drifted apart as Lovelock could not get her to understand the theoretical aspects of his ideas.

How do all of the above strands help resolve the paradox of how Gaia was received? In a nutshell, public reception was positive because Gaia resonated with the spirit of the times and Lovelock was affable in his interactions, resulting in little scrutiny of either him or his ideas. The scientific reception was more hostile for several reasons. Lovelock neither could nor wanted to rid his idea of its implicit teleology. Gaia was furthermore found wanting. Having given it a fair hearing, “Gaia didn’t do what professional scientists expect of a good, new, fruitful hypothesis” (p. 202). Especially James Kirchner’s criticism—”always blunt […] never less than courteous” (p. 158)—is insightful. He called out Lovelock for his loose definitions and questioned if the idea was actually testable or was creeping into pseudoscientific territory. Predictably, Lovelock thought this criticism unfair. Gaia also entered the room when science was beleaguered by forces within and without. Ruse clarifies that this goes far beyond the debate on levels of selection that I highlighted in my review of On Gaia. Finally, the enthusiastic and uncritical public reception made scientists wary. To put it mildly, Gaia “obviously did and still does on balance appeal more to those challenging conventional norms” (p. 200). Like Tyrrell, Ruse concludes that “despite general agreement that Gaia had pushed thinking in some important directions, by around 2000 the Gaia hypothesis […] had lost momentum” (p. 220).

“What I found revealing is that even [Lovelock’s] most fervent disciples eventually reluctantly distanced themselves somewhat from him.”

Ruse tries to put a brave face on it when finishing the book: “no more talk of failure. Lovelock and Margulis were big people with a big vision. Whether science likes it or not, the vision lives on” (p. 224). To me, that belies the critical and piercing analysis in this book. The Gaia Hypothesis provides tremendous context but who is it for? The book is split between Ruse’s stomping ground of history and philosophy, and a more accessible dissection of the characters and careers of Lovelock and Margulis. I think the book is reasonably balanced, though it does lean towards the former so will appeal more to an intellectual audience. On a personal note, this book marks Ruse as a scholar of interest to me. I know of his many other books but this is the first Ruse I have read. I will certainly seek out more.

And thus we have arrived at the end of the Gaia quartet. Reading Lovelock’s books raised many red flags, even if I could appreciate the grandeur of his vision. On Gaia delivered a very satisfying overview of how Gaia is not supported by the data. And The Gaia Hypothesis helped to put it all into a larger context. Having reviewed these four books, where do I now stand on the Gaia hypothesis? In The Ages of Gaia, Lovelock mentioned how Erwin Schrödinger’s 1944 book What Is Life? was at the time criticized by a prominent scientist as mostly wrong, though Lovelock still praised Schrödinger “for having set us thinking in a productive way” (p. 24 therein). Ironically, I think this perfectly summarises what I think about Gaia: mostly wrong, though stimulating much interesting new research.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Gaia Hypothesis

Other recommended books mentioned in this review:

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The scientist, environmentalist, and futurist James Lovelock is probably best remembered for the Gaia hypothesis: the notion that the Earth is a giant self-regulating system that maintains conditions suitable for life on the planet. It has gained a certain respectability in academic circles over the decades, but how justified is this? In my previous reviews of Lovelock’s original 1979 book Gaia: A New Look at Life on Earth and the 1995 follow-up The Ages of Gaia, I was critical of various assumptions and claims expressed therein. At the same time, I am aware that other, more knowledgeable people have worked on this idea for years, so what do I know? In On Gaia, Earth system scientist Toby Tyrrell gives a thorough and dispassionate overview of the scientific evidence and whether it supports Gaia. This, then, is the third of a four-part review series that explores the Gaia hypothesis in greater detail (see also part 1, part 2, and part 4).

On Gaia: A Critical Investigation of the Relationship between Life and Earth, written by Toby Tyrrell, published by Princeton University Press in July 2013 (hardback, 311 pages)

Given the holistic, top-down nature of the Gaia hypothesis, any critique of it will have to cover a lot of ground and straddle many disciplines. Tyrrell tackles this challenge in several ways. The book is well structured with good use of numbered sections to keep information organised while relegating digressions and technical details to a fascinating collection of sometimes long endnotes. Furthermore, the book is self-contained and you do not strictly need to read Lovelock’s work. I did so as I felt it is incumbent on me to be well-informed, plus I wanted to be able to judge for myself how fair Tyrrell’s critique is. Lastly, by going back to first principles, On Gaia is a terrific primer on palaeoclimatology and Earth system science.

Additional challenges in evaluating Gaia are that Lovelock both modified the idea with time and was not very clear in his definitions. Rather, it appears as “a collection of several related hypotheses, often couched in rather vague terms” (p. 4). Even so, the different formulations have three assertions in common: 1) the environment is hospitable to life (i.e. its biosphere), 2) life can change the environment, and 3) the environment has been constant through time. Evaluating these claims is at the heart of this book and takes up five of the ten chapters. Tyrrell furthermore compares Gaia to two alternative explanations dubbed the geological and coevolutionary hypotheses. The former says that Earth’s environment is primarily shaped by geological forces (this was the default paradigm when Lovelock formulated his hypothesis). The latter only says that life and the planet influence each other but remains neutral on whether the outcome will be favourable for life or not. It is credited here to Stephen Schneider and Randi Londer who, in their 1984 book, borrowed the term coevolution from population biology and applied it to the interaction between climate and biosphere, and this idea is alive and well.

Before delving into the meat of the book, Tyrrell discusses the question of mechanism. How could something like Gaia evolve? Part of this is a history lesson as Lovelock unwittingly chose a bad moment to introduce Gaia. Just as evolutionary biologists were embroiled in fierce arguments against group selection, in steps Lovelock with an idea even more radical than natural selection acting on the level of groups of organisms: how about the whole planet? Tyrrell outlines why it was, and still is, considered unlikely by evolutionary biologists: it would require cooperation amongst very distantly related organisms which is simply not what we observe in the real world. There are admittedly limited circumstances where natural selection leads to regulation of local environments and Lovelock made a lot out of them. However, both Gaia-as-physiological-homeostasis and Gaia-as-superorganism work as crude analogies but, Tyrrell explains in some detail, “any suggestion of a deeper resemblance is very misleading” (p. 30). Similarly, though Lovelock’s Daisyworld model showed that planetary regulation could theoretically emerge from individual actions, it is not a realistic description of how the climate and biosphere interact. This material, covered in chapter two, flagged up many points of criticism I had not even considered. Shame on me, but also, how terribly interesting.

“Evaluating Gaia is complicated because Lovelock modified the idea with time and was vague in his definitions. Even so, three assertions crop up repeatedly and the core of the book compares them with the data.”

The core of the book compares the three abovementioned assertions with the data. Lovelock’s first assertion is that the environment is well-suited to life. As I suspected, he gets the arrow of causation backwards: adaptation to one’s environment via natural selection is a sufficient explanation, even if it can give “the impression that all environments have been made to be uncannily well suited to their inhabitants” (p. 202). Moreover, this is not even always true. Lovelock has suggested that Gaia likes to keep the planet cool. Tyrrell fleshes this out in two further chapters by looking at the biological effects of temperature. Biological processes proceed faster at higher temperatures and do so not in a linear but in an exponential fashion. Though there are exceptions (this is biology after all), the overall tendency is for physiological rates, biomass, and biodiversity to increase with higher temperatures. Furthermore, after considering a range of factors, Tyrrell makes the point that ice ages are unfavourable: the planet is simply too cold for life to thrive.

The evidence for Lovelock’s third assertion, that the environment has been held constant by Gaia, also crumbles under the weight of the evidence against it. This is a chapter that showcases the marvellous array of proxies that palaeoclimatologists have developed. By cross-referencing multiple such indirect lines of evidence (e.g. ice cores, lake sediments, microfossils, tree rings, and many others) they have reconstructed an increasingly detailed picture of Earth’s past climate. Tyrrell here considers evidence from stratigraphy, ocean chemistry and acidity, temperature, greenhouse gases, and erratic climatic episodes such as Snowball Earth and more recent ice ages to convincingly show that our planet’s climate has been anything but constant.

Only Lovelock’s second assertion, that life can influence the planetary environment, is supported by the data. Tyrrell makes no bones of it either: “The evidence […] is sparkingly clear” (p. 127). He explores in more detail two factors that are under biological control: the composition of Earth’s atmosphere and the nitrogen-to-phosphorus ratio in seawater. Indeed, the fact that Earth’s atmosphere is far from chemical equilibrium and contains short-lived gases such as oxygen and methane was one of Lovelock’s original observations that sent him down this path.

” Tyrrell pulls no punches in his conclusion […] Many of Lovelock’s claims are not supported once carefully evaluated and there is nothing that can be explained exclusively by the Gaia hypothesis.”

The above is but a brief summary of some of the key arguments that Tyrrell makes. There are various other interesting points I have not touched on here and the whole book, including its extensive endnotes, deserves close reading. Tyrrell pulls no punches in his conclusion: “in my view Gaia is a fascinating but a flawed hypothesis [and] a dead end” (pp. 208–209). Many of Lovelock’s claims are not supported once carefully evaluated and there is nothing that can be explained exclusively by the Gaia hypothesis. Circling back to the other two hypotheses, the geological one also has its flaws. Instead, the data support the coevolutionary hypothesis: life and the planet influence each other, though not always to life’s benefit.

On a side note, maybe we just got lucky. Though I am not a fan of such explanations because they are by definition beyond the purview of scientific enquiry, chapter 9 brings in the weak anthropic principle: the fact that we are here as observers asking these questions means that life by definition must have survived up to this point in time. In other words, we might just have gotten lucky. How lucky? Unfortunately, our sample size of known habitable worlds in the universe is one, so we lack the data to quantify the odds. This chapter to me was the weakest in the book and it felt like Tyrrell was stepping outside of his comfort zone to dabble in philosophy^[1]. The most satisfying thing Tyrrell has to say about this is that it likely was a combination: “crude regulatory mechanisms on Earth increased the chances of continued survival from vanishingly small to just very small, but […] luck also played a part” (p. 191).

Tyrrell’s book-length argumentation and evaluation to arrive at his conclusion is, in my opinion, calm, reasoned, fair, and still relevant despite the book now being ten years old. He focuses on the facts and I would even say that he gives Lovelock a pass in some places, pointing out how many palaeoclimatological findings were made after Lovelock first published his ideas. Though true, what irks me is not that Lovelock was initially mistaken, we all are at times, but that he never recanted nor acknowledged the growing body of evidence against his idea. Instead, he doubled down on his assertions, as evidenced by the prefaces to the 2000 reissues of both Gaia and The Ages of Gaia, while the 2016 preface to Gaia does not mention Tyrrell’s book.

“Tyrrell’s book-length argumentation and evaluation to arrive at his conclusion is, in my opinion, calm, reasoned, fair, and still relevant despite the book now being ten years old.”

You might wonder if it matters whether the Gaia hypothesis is right or wrong (Lovelock certainly did not think so). In closing the book, Tyrrell argues that, in the face of anthropogenic climate change, having a true picture of how the Earth system functions has never been more important. The risk of the Gaia hypothesis is that it fosters complacency: “confidence in Earth’s natural resilience is emotionally comforting, but is most likely to be misplaced and could be dangerously deceiving” (p. 214). Importantly, “there is no Gaian safety net to come to the rescue if we mismanage it” (p. 218). That is a sentiment I can very much find myself in.

In conclusion, On Gaia has confirmed my suspicions while pointing out many other flaws I had not even considered yet. Even so, Tyrrell praises Lovelock for his originality and breadth of vision, recognizing that “his audacious concept has helped to stimulate many new ideas about the Earth, and to champion a holistic approach to studying it” (p. 209). I found this a phenomenally interesting book and highly recommend it. Though he builds on previous edited collections such as Scientists on Gaia and Scientists Debate Gaia, Tyrrell has done readers a tremendous service in writing such a focused and in-depth review of the Gaia hypothesis and presenting it in such an accessible manner.

But wait, the preface to The Ages of Gaia also mentioned how environmentalist Jonathon Porritt in 1994 expressed his opinion that the idea of Gaia is too important to be the sole domain of “finicky scientists” (p. xvi therein). For the last instalment of this four-part review series, I will take a step back from the hard science and turn to Michael Ruse’s The Gaia Hypothesis for a wider appreciation of Lovelock’s ideas.

1. ↑ After publication of this review, the author kindly linked me to subsequent papers by himself and others that further explore the role of chance in the long habitability of our planet.

On Gaia

Other recommended books mentioned in this review:

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