I have been promising/threatening for a while to cover degrowth, and thanks to a United States Society for Ecological Economics book club, now I will. In Less is More, economic anthropologist Jason Hickel identifies capitalism as the cause of our problems—the sort of criticism that makes many people really uncomfortable. Fortunately, he is an eloquent and charismatic spokesman who patiently but firmly walks you through the history of capitalism, exposes flaws of proposed fixes, and then lays out a litany of sensible solutions. It quickly confirms that sinking feeling most of us will have: that the economy is not working for us. What is perhaps eye-opening is that this is not by accident, but by design.

Less is More: How Degrowth Will Save the World, written by Jason Hickel, published by William Heinemann in December 2020 (hardback, 318 pages)

It helps, as Hickel quickly does, to clarify two things. First, he does not object to economic growth per se. Indeed, many of the world’s poorest countries need to grow further to meet basic human needs. The problem is growth for growth’s sake. In nature, growth is ubiquitous but normally follows a sigmoidal curve of some kind, eventually coming to a halt. Capitalism is different, which brings us to point two. People often confuse capitalism with markets and trade, but they pre-date capitalism by millennia. This is all textbook Marx, but, Hickel explains, markets and trade are organised around use-value: we trade for what is useful to us. Capitalism, on the other hand, is organised around exchange-value: goods are sold to make a profit, which is then reinvested to generate more profit. Growth is a structural imperative of capitalism: “It is a system that pulls ever-expanding quantities of nature and human labour into circuits of accumulation” (p. 40). The results are plain for all to see: environmental destruction and human immiseration benefitting a small minority.

In the first half of the book, Hickel prepares the reader by providing a history of capitalism. He starts in medieval Europe, where commoners violently revolted against feudalism, their success partially due to the bubonic plague killing so many people that labour became scarcer. For a while, a more egalitarian society developed but was soon crushed by economic elites violently enclosing the commons, especially in England, forcing people into wage labour. The profits thus reaped were reinvested overseas in the even more violent practices of colonialism and slavery. Once in motion, this self-reinforcing cycle has kept going for the last five centuries, taking us to neoliberalism today. Along the way, economists forgot about the natural world, blithely ignoring that infinite growth on a finite planet is a recipe for disaster.

I could dwell more on this fascinating history, but we have to keep moving, though not before highlighting one other aspect. Capitalism was enabled as much by a changing worldview for which Hickel blames thinkers such as Francis Bacon and René Descartes. Especially the latter’s dualism, which cast humans as apart from nature rather than a part of nature, removed any remaining sense of restraint. “Land became property. Living beings became things. Ecosystems became resources” (p. 70). This echoes Eileen Crist’s furious argument that language powerfully shapes our worldview. He returns to this in the final and possibly most challenging chapter. The animist views of our ancestors imbued our living world with spirit and agency; something Western religions and philosophies tried to stamp out, declaring it heretical or irrational. Now, think of animism what you will, but it usefully is characterised by a respect for the natural world and by cultural taboos on rampant extraction. We can draw lessons from this and Hickel contends that “we must learn to see ourselves once again as part of a broader community of living beings. If our approach to degrowth does not have this ethic at its heart, then we have missed the point” (p. 271).

“The fundamental flaw with [prominent technological and economic “solutions”] is that they refuse to question whether more growth is necessary.”

Hickel’s other task in this first part is to patiently pick over some prominent technological and economic “solutions” and expose their flaws. This includes the IPCC incorporating untested negative-emissions technology in most of its models, “green growth” solutions that are little more than corporations and governments greenwashing business-as-usual in sometimes inventive ways, and the lure of techno-fixes including risky geo-engineering proposals to tinker with our global climate. The fundamental flaw uniting them is that they refuse to question whether more growth is necessary. Hickel also disarms the claim that resource use and economic growth have decoupled and our economies are dematerialising. This confirms what I suspected about Andrew McAfee’s book More from Less: look at the global flow of materials and energy, and it is revealed for the accounting trick it is because you ignored outsourcing of industries. The Jevons paradox, the observation that efficiency gains somehow never translate into less resource use, is no paradox at all when hitched to the growth imperative: “technology is used not to do the same amount of stuff in less time, but rather to do more stuff in the same amount of time” (p. 153).

So what does this growth achieve? Hickel admits that, up to a certain point, economic growth is good, necessary even, but research shows it has rapidly diminishing returns after that. Numerous poor countries score higher on measures of human well-being than wealthy ones. Why? Turns out that investing in public goods and services (healthcare, housing, education, public transport, etc.) matters more to people’s everyday lives. Who would have thought?!

The second half of the book presents solutions. Hickel acknowledges Giorgos Kallis’s call for a culture of self-limitation but thinks on a bigger canvas. To stave off ecological collapse we need to limit growth by reorganising the economy. This is degrowth: “a planned downscaling of energy and resource use to bring the economy back into balance with the living world in a safe, just and equitable way” (p. 29). Is that not a recession? No, responds Hickel, recessions happen in a growth-dependent economy. Degrowth calls for “a different kind of economy altogether – an economy that doesn’t need growth in the first place” (p. 205), one organised around human needs rather than capital accumulation. What I feel is insufficiently emphasized here, and led to objections that I have seen more explicitly addressed in subsequent writing, is that degrowth is not forever either. It is a necessary course correction to a system in overshoot, a transitional phase towards a steady-state economy, or (in Hickel’s words) a post-capitalist world.

“[Hickel’s solutions] rely on both changing the (currently perverse) incentives inherent in the system and active government intervention and regulation.”

For Hickel, degrowth has two important components. The first one is obvious: reduce material and energy use to bring us back to within planetary boundaries (this refers to the framework of Johan Rockström and colleagues). How? We could end planned obsolescence, curb advertising, shift from ownership to “usership” (i.e. share things such as cars or power tools), address food waste, and scale down or eliminate ecologically destructive industries. The second component, vital to the success of the first, is to address economic inequality (the subject of his previous book). How? We could tax the ultra-wealthy more or cap income and wealth and redistribute the excess, eliminate tax havens, and renationalise public services. According to Hickel, there is enough money sloshing around the system to finance public services globally.

What about jobs? Hickel admits that “here’s where things get tricky” (p. 221) as decreasing production will eliminate jobs. He suggests retraining programmes, job guarantees, and especially a shorter working week. That last one already has a proven track record. People’s sense of happiness increases when they can finally reap the benefits of all those efficiency improvements we have achieved and spend time on more meaningful activities such as volunteering or caring for children and elderly relatives. Keep in mind, Hickel adds, that when the aim of goods and services is not to maximize profit, we could get by with less money. What ultimately matters is “welfare purchasing power”: what your money can buy you.

In short, his proposals rely on both changing the (currently perverse) incentives inherent in the system and active government intervention and regulation. Given that capitalism is the water in which we all swim, this will take a certain amount of deprogramming your mind. However, consider his suggestions and it is hard to disagree with his assessment that “In a growth-oriented system, the objective is not to satisfy human needs, but to avoid satisfying human needs” (p. 233). Capitalism has always artificially and often violently created scarcities of all kinds. Much here lines up with ideas in ecological economics and, if not quite the same, the two currents of thought seem close bedfellows to me.

“Of all the proposals I have come across, [degrowth] strikes me as the only sensible one, calling out the roots of the problem instead of meekly tinkering around the edges.”

Less is More resonated with me to an exceptional degree but did leave me with some questions and concerns. First is the how. I will give Hickel bonus points for going beyond mere exhortations to “do something”, providing an actionable roadmap, and admitting that none of this will be easy. The rich will be extremely hostile to the suggestion that governments play Robin Hood and redistribute their wealth to the poor, so how do you effect this when they exert undue influence on politics? Furthermore, I think even many “regular” people will have a hard time voluntarily abandoning certain ecologically destructive habits and activities. Entrenched cultural values and societal norms create a lot of inertia. Will introducing certain measures have unexpected consequences? How do you get nations to cooperate to achieve this vision globally? Hickel admits that he is no political strategist, adding only “that [it] will require a movement, as with every struggle for social and ecological justice in history” (p. 242). Given Walter Scheidel’s work that suggests that, historically, economic inequality has never died peacefully, I worry that this might well involve bloody violence. Simultaneously, past civil movements managed to enter the political arena, so what can we learn from their struggles?

My second concern is material (literally). Hickel urges that addressing climate change means transitioning away from fossil fuels towards renewable energy. Though he acknowledges that constructing the needed infrastructure has an immense material footprint and will require large amounts of mining, he omits that, once built, we have to maintain and replace machines as they wear out, requiring continuous material input. He briefly mentions the problem of declining ore grades but omits any mention of the hard limit of energy return on investment: at some point, we will face an endgame where it will take more energy to extract certain materials than they will generate. Even if we curb the worst excesses of capitalism and consumerism, we are still grinding our way through vast reserves of materials, including metals and minerals, that are not renewable on a human time scale, or not at all.

Hickel makes an incredibly compelling case for degrowth. Of all the proposals I have come across, it strikes me as the only sensible one, calling out the roots of the problem instead of meekly tinkering around the edges. This will not be the last book I will review on this intriguing topic. Less is More was published in 2020 so since will have been extensively analysed and criticized. The degrowth movement likely has responded to the points I raised above, and many others besides. And, with all due respect to Hickel, this movement is bigger than him. The Future Is Degrowth was already on my radar but I am particularly excited by the upcoming English translation (finally!) of the French book by the equally eloquent Timothée Parrique.

Less is More

Other recommended books mentioned in this review:

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If you have ever seen a diagram of a dinosaur skeleton in a book or scientific paper—white bones, black silhouette, I am looking at you—odds are that it was drawn by independent palaeontologist and palaeoartist Gregory S. Paul, or at the very least inspired by his work. As a consultant and illustrator-for-hire, he has been researching and drawing these diagrams for over 40 years, and The Princeton Field Guide to Dinosaurs brings together the largest such collection in print. I have previously reviewed his companion volumes on pterosaurs and extinct marine reptiles, which is coming at it somewhat the wrong way around. His tenure with Princeton University Press started back in 2010 with the first edition of this dinosaur guide, followed by the second edition in 2016, and the third edition in May 2024. High time, thus, to make up for that lack of review coverage. In the process, I will address the question of whether buyers of the second edition should upgrade.

The Princeton Field Guide to Dinosaurs, written by Gregory S. Paul, published by Princeton University Press in May 2024 (hardback, 384 pages)

If the idea of a field guide to extinct creatures sounds contradictory, think of them as illustrated guides for the palaeo-enthusiast. To recap, Princeton has thus far published guides to dinosaurs, pterosaurs, extinct marine reptiles, theropods (all by Paul), and prehistoric mammals (which features few skeletal reconstructions, though). A very welcome addition later this year will be a guide to Mesozoic plants, which are often neglected in palaeoart. All these books are large format hardbacks (216 × 279 mm) and make for an imposing set on your shelves. For his books, Paul has chosen a template and stuck with it: this third edition, like the previous ones and his other books, follows the same format, with many sections almost identically worded. As before, the book breaks down into an introduction to dinosaur biology (82 pages) and the species accounts (288 pages).

The introduction will set you up with everything you need to know, covering the history of research, a description of the Mesozoic world and its inhabitants, the era’s mass extinctions, a series of palaeogeographical maps, the steps involved in becoming a fossil, and the reverse steps to successfully excavate these. As before, Paul entertains some speculative zoology, imagining a spot of time travel for a dinosaur safari, and asking what might have happened had the asteroid missed and how we might interact with dinosaurs today. Most of the introduction is an extended primer on all aspects of dinosaur biology, including anatomy, appearance, locomotion, physiology, sensory biology, behaviour, reproduction, and the evolution and loss of flight.

One thing to note is that Paul does not provide citations to back up claims and includes only the briefest of recommended reading sections; this book aims to be neither textbook nor encyclopedia. Readers will want to keep in mind, as alluded to in previous reviews, that Paul has opinions and is not afraid to use them. Now, I think there is little here that will set you on the wrong foot; it is just that context as to how widely accepted his views are is not always present. Did an asteroid wipe out the dinosaurs? He thinks that extinction-by-asteroid, or even the combination of impact and Deccan volcanism, are problematic scenarios given everything else that survived. He settles for the not unreasonable conclusion that the mechanisms driving the K–Pg extinction “remain incompletely understood” (p. 28), which is more circumspect than you will typically encounter. He favours the presence of soft tissues such as lips—showing exposed teeth in palaeoart “may be an error as big as it is common” (p. 28)—which I would agree with, but equally confidently writes that birds have a poor sense of smell, to which I would object. A really interesting claim I have not seen elsewhere concerns the evolution of flight, or more accurately, its frequent loss early on. The conventional view that secondary loss was limited to birds proper “is critically flawed because the possibility that weak early fliers rarely if ever lost flight over the nearly 100 million years of the Late Jurassic and Cretaceous is not viable; it would have been happening all the time” (p. 66). He points to various anatomical features in non-fliers and thinks that “attempts to explain them as exaptations before the evolution of flight are at best speculative” (p. 66).

“[…] it is clear that a huge amount of work has gone into compiling all this information. Imbibing it all for days on end brings about a Gestalt shift in your perception of dinosaurs.”

The field guide section arranges taxa phylogenetically, though given that this is forever in flux, he has again “used a degree of personal choice and judgment to arrange the groups and species within the groups. Some of these placements reflect my considered opinion, while others are arbitrary choices between competing research results” (p. 76). Some 1700 species names are in circulation, but a substantial number of these are invalid, duplicated, or based on inadequate remains, so Paul limits himself to some 800 generally accepted ones that have sufficient fossil material behind them. Species are again described in telegram-style entries, listing size and weight estimates, known fossil remains, anatomy, geological age, location and geological formation of fossils, habitat, lifestyle, and other notes. This is the reference section of the book, collecting facts without a guiding narrative. Where sufficient material is available, he provides his signature drawings of skulls or (partial) skeletons, as well as the occasional life reconstruction. The few palaeoart pieces are, to my taste, still a mixed bag, though I liked some of these much better. There are no photos of fossils.

Having spent the last 13 days spelling out this book, it is clear that a huge amount of work has gone into compiling all this information. Imbibing it all for days on end brings about a Gestalt shift in your perception of dinosaurs. Any lingering notion of these as mythical monsters is swept away, replaced by a blossoming of biodiversity over millions of years, with evolution producing many and sometimes wild variations on themes. Some other impressions I came away with are just how many species are based on fragmentary fossils. Especially the skeletal diagrams, which make a point of showing only the bones we have, drive this point home. Very few illustrations are marked as composites. Related to this is the nomenclature: it is easy for each fossil discovery to get its own name, and the impression is of names serving more as specimen labels than representing distinct biological entities. This is how it is possible for Paul to write that several fossils assigned different names might represent different sexes or age groups of a single species. Species concepts are a notoriously tricky topic in biology, and applying them to fossils represents an additional challenge. Only a very small number of entries mention fossil evidence for behaviours, reinforcing that studying this is a speculative affair. Simultaneously, it is a testament to the hard work of generations of researchers that we have learned so much from such challenging material.

Given that I own the second edition, I compared the two in some detail for this review. The one-liner is that the third edition is not a drastically different book but is more of the same. Lest that sound negative: more is good. Increasing from 360 to 384 pages, the third edition has been expanded and revised throughout, the changes many and subtle. This, of course, sounds like the generic claim every publisher makes about new editions, but rather than regurgitating my changelog, which would be as riveting as reading the phone book, let me provide a select few examples.

“I compared [editions two and three] in some detail for this review. The one-liner is that the third edition is not a drastically different book but is more of the same. Lest that sound negative: more is good.”

The first part, in replicating the previous edition word for word, quickly reveals where Paul has inserted additional paragraphs or rewritten sections, discussing e.g. proposals for new top-level taxonomical arrangements such as Ornithoscelida, new details about the asteroid impact and the discovery of the site that seems to have recorded the last day of the dinosaurs, or the novel use of bone biomolecules to restore metabolic rates. In the field guide section, I noticed updates to size, mass, and age estimates throughout. Paul has introduced new divisions: prosauropods now holds baso-prosauropods and euprosauropods, while maniraptors and paravians have been eliminated in favour of a new group called airfoilans (one of the few examples of a semi-formal taxonomical proposal made here). There are well over 50 new species, e.g. Latenivenatrix mcmasterae (the current largest-known troodont), or the awesomely named ankylosaurid Minotaurasaurus ramachandrani (previously considered a juvenile of Tarchia kielanae). The alvarezsaurid Kol ghuva has been removed, while the lambeosaur Sahaliyania elunchunorum is now considered a juvenile of Amurosaurus (or Hypacrosaurus) riabinini. Some groups have been thoroughly reshuffled: a large number of species have been moved from baso-titanosaurids to lithostrotians, and from ankylosaurids to nodosaurids. There are new illustrations (a skeletal diagram of the euprosauropod Macrocollum itaquii) and expanded ones (the baso-tetanuran Cryolophosaurus ellioti has gone from a skull to a partial skeleton). You could even play “spot the difference”: the skeleton of the basotheropod Tawa hallae now features gastralia and a sclerotic ring, while the entry for the baso-eusauropod Spinophorosaurus nigerensis mentions that reconstructions showing tail spikes are incorrect. Looking at the second edition, this reads like a mental note to self, as he has removed the tail spike and tail tip that he previously drew.

Given that many readers might already possess an older version, should you spend the money to upgrade? If you are still rocking a copy of the first edition, what are you still doing here? But what about going from second to third? It all depends on your mileage with the second edition. For casual readers, this is going to be a personal choice dictated by, e.g. shelf space and liquidity. Unless you are a completist who must have every good dinosaur book, maybe you want to hold on to your money and check out the (*drumroll*) three-volume dinosaur encyclopedia that Princeton announced for later this year. If, however, the above changes sound meaningful and relevant to you, then you are in the market for the third edition. For palaeontologists or palaeoartists who regularly consult their current copy, the choice is straightforward: you need to upgrade. If you happen to be new to these books and are looking for a detailed reference work to as many dinosaurs as possible, or need scientifically sound illustrations, look no further. Paul’s drawings are a benchmark in the discipline, and this guide is a mouth-watering cornucopia of detailed skeletal diagrams.

I was going to conclude that, after three books, Paul has completed a remarkable trilogy of guides to all extinct Mesozoic reptiles and has shown laudable perseverance in updating the dinosaur guide not once, but twice, to keep it current. However, only six months later, Princeton published The Princeton Field Guide to Predatory Dinosaurs. What is this all about? Does it contain anything new? Is the dinosaur guide not as complete as it claims to be? Stay tuned for a follow-up review soon.

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

The Princeton Field Guide to Dinosaurs (3rd edition)

Other recommended books mentioned in this review:

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Having just reviewed the 2015 book On the Wing, I continue my brief two-part foray into the evolution of flight with Taking Flight by writer and conductor Lev Parikian. In a book that is full of wonder and humour, he marvels at the many different strategies for flying that have evolved in primarily insects and birds. However, the somewhat muddled explanations of flight mechanics and limited attention for other groups make for a somewhat uneven book.

Taking Flight: The Evolutionary Story of Life on the Wing, written by Lev Parikian, published by Elliott & Thompson in May 2023 (hardback, 282 pages)

Parikian is the author of five previous books on music and the natural world. His 2018 Why Do Birds Suddenly Disappear? told how, as a self-proclaimed lapsed birdwatcher, he refound his passion for it in his fifties. He has also contributed to the BTO anthology Red Sixty Seven, The Guardian‘s Country Diary column, and Bird Watching magazine, so knows a thing or two about birds. Now, in his sixth book, he delves into the story of the evolution of animal flight.

Flying creatures are so ubiquitous in our lives that it is easy to take the whole phenomenon for granted. The strongest impression this book leaves is that of Parikian seeking to re-enchant his readership, grabbing you by the scruff of the neck from the opening encounter with a blue tit to remind you that: “It flies. It. Flies.” (p. xiii). This sense of wonder infuses the book, whether it is flies capable of landing upside down on the ceiling—”we should, if we were properly curious and fascinated, be texting, ‘I BEHELD A MIRACLE’ to all our friends” (p. 59)—or awaiting the annual return of swifts to our skies—”as I roam the streets of south London, I’m a liability […] head up, staggering shambolically into bollards and bus shelters, ready to harangue random passers-by with a hoarse, deranged bark of ‘They’re here!’” (p. 199).

I will not deny that his enthusiasm is infectious and is helped along by a healthy dollop of humour and jokes. There are colourful descriptions of male stag beetles with massive mandibles whose ungainly flight says “We’re not really supposed to be doing this, but if you absolutely insist” (p. 50), or of pterosaurs whose fourth finger is “noticeably, weirdly, excessively long. A veritable überfinger. The kind of thing you’d use to get a ping-pong ball out from behind a radiator” (p. 111). There are pop-culture references, such as swifts whose “chief asset is speed. Speed and manoeuvrability. Speed, manoeuvrability and a fanatical devotion to the air” (p. 201). There is the occasional well-timed f-bomb, such as aforementioned flies landing upside down: “it seems weird and unnatural, a defiant ‘fuck you’ to everything we think we know about gravity” (p. 59). And I have yet to come across a more amusing explanation of the difference between taxonomical lumpers and splitters: “a ‘lumper’ would regard all Magnum ice-creams as the species ‘Magnum’, regardless of flavour; a splitter would deem the Double Raspberry Magnum and the Salted Caramel & Glazed Almond Magnum two separate species. Glad to have cleared that up for you” (p. 153). Admittedly, some of the jokes are a bit of a stretch. How did pterosaurs get airborne? “Perhaps they flung each other into the air with a primitive trebuchet” (p. 113). I guffawed my way through this book, but your mileage might vary, depending on how you like your popular science.

“The strongest impression this book leaves is that of Parikian seeking to re-enchant his readership, grabbing you by the scruff of the neck from the opening encounter with a blue tit to remind you that: It flies. It. Flies.“

Entertaining as Taking Flight is, I do have some criticism. First, the book feels somewhat uneven due to his choice to spend six chapters each on insects and birds (because they have the greatest diversity in morphology and flight styles), but only one each on pterosaurs and bats. As a consequence, many chapters are not strictly about the evolution of flight, but more about the diversity of flyers that evolution has given rise to. Chapters feature, for example, bee swarming and butterfly migration, or the adaptations that allow hummingbirds to hover and albatrosses to soar. He includes most of the theories on the evolution of flight covered in On the Wing and has read up on the literature, mentioning, for instance, the quadrupedal launching model for pterosaurs that Alexander left out. However, he omits other ideas, for instance, how flight in insects might have started simply by steering one’s fall (so-called directed aerial descent), as was reported for ants by Steven Yanoviak and colleagues.

Second are Parikian’s explanations of the biomechanics of flight. Rather than dedicating a chapter to the basics, he delves straight into the story of evolution, starting with the earliest insects, and drip-feeds you bits of information throughout the book. The opening Author’s Note admits he has come to this topic as an eager layman, but despite having consulted relevant literature, his explanations leave something to be desired. For example, he writes that lift is generated by leading-edge vortices increasing the speed of air flowing over the wing, which lowers air pressure, which increases lift. However, both Alexander and Gregory Paul point out that this is an incomplete and even misleading explanation. If I have understood these authors correctly, most, if not all, lift is generated by the downward orientation of the trailing edge (the back of the wing), which sends the airflow down and back. It is the downward component of this, and the vortices formed behind the trailing edge, that generate lift. Furthermore, even as Parikian defines certain terms, he uses others without explaining what they are, such as angle of attack and camber. Plus, he makes it sound as if camber is the same as a wing’s surface area, which it is not; it refers to the curvature of the wing, more specifically, the difference in curvature between the upper and undersides. Thus, when he explains that bees deal with the additional load of pollen by making their wing strokes deeper, I am not actually sure what that looks like. There are no diagrams included, which would have been helpful given the level at which this book is pitched. Unfortunately, I am left with the impression that, unless you are already familiar with the basics of animal flight, you might come away with a muddled understanding of it.

Overall, Taking Flight is a humorous look at the many different flyers and ways of flying that have evolved. Look out, for example, for the insane way in which dragonflies reverse. Parikian is unapologetically enthusiastic, and the book is all the more enjoyable for it. However, for a clearer and more factual explanation of how flight works, supplementary reading will be required, and Alexander’s 2015 book On the Wing remains relevant.

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

Taking Flight

Other recommended books mentioned in this review:

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Flight fascinates me for two reasons: one is pure envy at being earthbound, and the other because it is a fantastic example of convergent evolution, having evolved not once, but on four separate occasions. Last year I was sent Lev Parikian’s book Taking Flight and in finally reviewing that, I took the opportunity to also read David E. Alexander’s 2015 book On the Wing. A very accessible popular science book that tells the intriguing story of the evolution of flight, it helpfully assumes little background knowledge of either evolution or biomechanics. This, then, is the first of a two-part review of how life got airborne.

On the Wing: Insects, Pterosaurs, Birds, Bats and the Evolution of Animal Flight, written by David E. Alexander, published by Oxford University Press in November 2015 (hardback, 210 pages)

Alexander is (or was) a researcher at the Department of Ecology & Evolutionary Biology, The University of Kansas, investigating the biomechanics of flight and arthropod swimming behaviour. Previously, he wrote a 2002 monograph on the biomechanics of flight, and a 2009 popular book that explored the differences between flying animals and flying machines. I struggle to find any publications after 2015, and his academic staff page mentions he has retired. If so, he left on a high note.

On the Wing breaks down into two parts, discussing flying and flyers. The first three chapters discuss basics, wing anatomy, and wing mechanics. Alexander focuses on powered flight (i.e. flapping, though gliding is not entirely ignored) and discusses the anatomy of not just wings, but the sensory organs and nervous system that enable flight. The section on mechanics covers a whole bunch of physics (including lift, drag, thrust, and scale effects) and the biomechanics of both gliding and flapping. Admirably, he manages to clarify all this without presenting equations or getting lost in the aerodynamical weeds. Basically, he never forgets that his goal is not to give you a full treatment of the biology and physics of flight (which he already did in 2002) but to give you the relevant basics before turning to the question of how it all evolved.

The largest part of the book is devoted to the flyers: insects, birds, bats, and pterosaurs. This core of four chapters is introduced by one chapter on gliding and concluded by an interesting short chapter on the secondary loss of flight. Alexander discusses fossil evidence, family trees, physiological and sensory adaptations, and the history of different ideas on the evolution of flight in each of these groups.

“his goal is not to give you a full treatment of the biology and physics of flight […] but to give you the relevant basics before turning to the question of how it all evolved.”

The big picture looks something like this. Insects are in a class of their own: the period during which they evolved flight is lost in a large gap in the fossil record, they uniquely did not transform limbs into wings (though what their wings evolved from remains debated), and their small size and standard pattern of four wings means the biomechanics of insect flight differs markedly from the three larger vertebrate groups. For birds, the fossil record is fantastic and now extends well beyond the iconic bird ancestor Archaeopteryx, with especially Chinese fossil beds recently adding much to the story. The debate on whether flight started from the ground up or from the trees down increasingly favours the latter; Alexander prefers it because physics (i.e. gravity) works with you rather than against you. For both bats and pterosaurs early transitional fossils are missing, complicating the story. The consensus is that bats evolved from arboreal, gliding ancestors. Traditionally, the same was said to be true of pterosaurs, with scientists at some point considering—but ultimately abandoning—the idea that flight evolved from bipedal runners taking off from the ground. This is one of the few areas where the book is somewhat outdated: Alexander oddly does not mention Mike Habib and Jim Cunningham’s idea that pterosaurs could have launched themselves from a quadrupedal posture, using their forearms to catapult themselves into the air from a standing start. Mark Witton’s Pterosaurs, published two years earlier in 2013, reviewed the idea (originally published in a 2008 paper), but it seems Alexander missed it or did not read it in time before finishing his book.

Having outlined the book’s framework, three things stood out to me. First is the book’s clear structure, using headings and subheadings to divide chapters into bite-sized sections. Alexander writes factually, keeps rhetorical flourishes to a minimum, and includes some excellent explanations. Would it not be awesome to evolve propellers or use super-light materials for your wings? Sure, but that is just not how biology works, historical constraints are king: “my ancestry limits how much natural selection can change my lineage” (p. 22). Evolution makes do with the materials and structures an animal already possesses, and readily repurposes them. He cleverly cordons off in boxes explainers that are self-evident to biologists or engineers but are included here to benefit readers from outside those fields. For instance, how can complex structures evolve gradually? What is the Reynolds number? What is the right terminology for pterosaurs or immature insects? And there is a very insightful piece on convergences (similar structures that evolved independently) and homologies (similar structures inherited from a common ancestor). For functional biologists who want to understand why different animals work in similar ways, convergences are of interest while homologies have little explanatory power; for phylogeneticists making family trees, convergences are a source of noise that imply shared ancestry where there is none while homologies are their bread and butter.

“Alexander clarifies the relevance of phylogenetics. […] More than anyone I have read so far, he shows you the biological relevance of different evolutionary scenarios, most clearly illustrating this with bats.”

Second, Alexander clarifies the relevance of phylogenetics. Every family tree is a hypothesis, the best estimate of patterns of relationship and descent given your dataset. It is quite common that, having done all your complex analyses, you end up with multiple possible trees. More than anyone I have read so far, he shows you the biological relevance of different evolutionary scenarios, most clearly illustrating this with bats. Traditionally, these were split between megabats (family Pteropodidae which includes flying foxes and fruit bats) and microbats (everyone else) that both descended from a common flying ancestor. Then, in a 1989 paper, one group of researchers argued that, based on certain vision-related features, megabats were close relatives of primates and colugos (flying lemurs). If true, that meant flight in bats would have evolved twice independently. The deadlock was broken by molecular phylogenies analysing DNA that supported a single origin for bats. Those vision-related features thus evolved convergently in bats and primates; remember what I wrote above about convergences being the bane of phylogeneticists? However, the molecular analyses also broke up the traditional split, with some microbats more closely related to macrobats. Groups were reorganised and renamed to (ultimately) Yangochiroptera (Pteropodidae plus some former microbats) and Yinpterochiroptera (the remaining former microbats). Great, but that had other consequences in turn: Pteropodidae do not echolocate whereas all other bats do. So, was echolocation ancestral to all bats and lost secondarily in Pteropodidae? Or did it evolve independently in both groups in another case of convergent evolution? This matter remains unresolved for now.

Third, Alexander nicely illustrates the history of science, charting how theories have developed and changed over time. The history of thinking on Archaeopteryx is convoluted but interesting. When Danish artist Gerhard Heilmann in the 1920s pointed out we have no fossil evidence of a wishbone in Archaeopteryx and concluded that birds did not descend from dinosaurs, it sent researchers on a decades-long wild goose chase to locate the common ancestor of birds and dinosaurs further back in time. It was not until John Ostrom in the 1980s linked Archaeopteryx to small bipedal theropods, and we found better fossils including wishbones after all, that birds were welcomed back into the dinosaur clade. This, in turn, misdirected research on flight evolution for some time. If related to bipedal theropods, did flight evolve from the ground up from a running ancestor? Alexander puts it plainly: what researchers overlooked was that “Archaeopteryx wasn’t in the process of evolving flight, it was already a flyer […] Archaeopteryx is very important for unraveling the phylogenetic relationships of birds and their relatives [but] it may not tell us much about the beginnings of flight in birds” (p. 109).

Overall, On the Wing synthesizes research from diverse areas but remains accessible throughout, avoiding equations and very technical descriptions. Except for the recent developments on pterosaur take-off behaviour mentioned above, my limited background reading on the topic suggests the book still holds up well. I recommend it for those looking for an enjoyable, factual primer on the evolution of flight. Next up I review Lev Parikian’s recent Taking Flight, with an eye towards both his take on the subject and recent developments since publication of On the Wing.

On the Wing

Other recommended books mentioned in this review:

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Evolution is often characterised rather one-sidedly in terms of a struggle for existence, “red in tooth and claw”, and selfish genes. And yet, as evolutionary biologist Jonathan Silvertown shows here, cooperation in biology is both widespread and ancient. In his entertaining Dinner with Darwin which I reviewed way back in 2018, he briefly touched on food sharing in humans as one example of cooperation; in Selfish Genes to Social Beings, he gives the topic at large the book-length treatment it deserves. Silvertown here writes for a broad audience, explicitly including those without a formal background in biology. With nary an equation in sight, he relies on a potent combination of human-interest stories, wit, and ingenious metaphors to convince you that cooperation is an important component driving evolution.

Selfish Genes to Social Beings: A Cooperative History of Life, written by Jonathan Silvertown, published by Oxford University Press in April 2024 (hardback, 288 pages)

Cooperation initially flummoxed biologists, yet, Silvertown contends, a few straightforward conditions are sufficient for its appearance. I might just as well hit you over the head with his take-home messages now. Two conditions are required for cooperation to evolve. First, the benefits to the individuals involved have to outweigh the costs. Attentive biologists might immediately pipe up that that simple statement hides important technicalities, while others will undoubtedly exclaim: “Yes, but what about…?— bear with me, I will get to this. Second, there has to be a way for cheaters to be detected and excluded, or otherwise. the system will buckle under their exploitation.

Silvertown tackles his subject in 16 chapters that are divided over four parts, working his way down from groups to individuals, to cells, to genes. This approach has two advantages. First, it allows him to open the book with human interest stories that reel you in. Take the often-ignored aspect of trench warfare in World War I, particularly the numerous smaller skirmishes that saw infantry on both sides communicate and cooperate to minimise casualties in a live-and-let-live honour system. It was artillery and high command, both operating at a distance, that undermined these attempts and created the horrors for which this war is remembered. Or take the remarkable cooperation on , where the captain was democratically elected, the ship was owned by the whole crew, and plunder was shared^[1].

“A personal lightbulb moment was the insight that bacteria may be single-celled, but they are not solitary; there is a lot of communication happening.”

The second advantage of starting at the level of groups and individuals is that the examples speak to your everyday experience. It is relatively easy to imagine what sociality in insects, such as honeybees, or cooperative breeding in birds looks like. Somewhat less familiar are lichens, symbiotic organisms composed of a fungus and an algae or a cyanobacterium. I did not appreciate just how fascinating lichen biology is. Take the fact that this symbiosis has evolved numerous times independently and that different species are at different points along the continuum of becoming partially to fully integrated organisms. As the book progresses down to cells and genes, the subject matter becomes more complicated and abstract, but by then you will have internalized some of the logic. A personal lightbulb moment was the insight that bacteria may be single-celled, but they are not solitary; there is a lot of communication happening. Quorum sensing allows bacteria to check that a sufficient number of cooperators are present before secreting so-called public-good molecules. These include digestive enzymes (bacteria digest externally and absorb the resultant broth), or sticky substances that form a protective biofilm. Similarly fascinating are transposons, the mobile genetic elements that move around within and between individuals and species. They are cheaters that can disrupt cooperation between other genes, though many organisms have found ingenious ways to repurpose them. Insects, for example, “borrow” transposon enzymes to circulate their own antiviral molecules, tolerating transposons to receive protection from the even worse threat of viral infection. “It’s the original protection racket” (p. 183).

Those with a background in biology might notice some omissions. Silvertown weaves in a fair amount of history and biographical sketches. He features Lynn Margulis’s theory of endosymbiosis, but not the earlier work on symbiogenesis by Russian botanist Boris Kozo-Polyansky^[2]. Both offered an explanation for the origin of mitochondria and chloroplasts in terms of symbiosis between different single-celled organisms. Similarly, Silvertown includes J.B.S. Haldane, W.D. Hamilton, and genetical explanations for social behaviour in terms of kin selection and inclusive fitness, but he excludes George Price. Granted, his equation has wider applications, but Price dedicated much of his research to the evolution of altruism. Given the amount of ground Silvertown is trying to cover here, his decision to not give a full history of all players is defensible. Silvertown positions himself in the majority camp of evolutionary biologists who explain social behaviours in terms of benefits to self-interested individuals. He considers group selection a “siren call [that] has in the past led thinking onto intellectual rocks” (pp. 191-192) by arguing traits evolve for the good of the species. Though I have no objection to this viewpoint, it does not acknowledge that there is a debate around the levels of selection, nor explain why group selection is considered so contentious. Again, I imagine this will have been a matter of trying to contain how much ground is covered.

“Given that mitochondria and chloroplasts are hundreds of millions of years old, I always considered endosymbionts to be permanent fixtures once evolved. Not so.”

Silvertown’s writing is accessible, meaning this work is not a technical treatise but introduces theory through plentiful examples. Beyond explaining the logic behind the prisoner’s dilemma and Hamilton’s rule, he avoids equations and diagrams and instead relies on inventive metaphors. For example, given that mitochondria and chloroplasts are hundreds of millions of years old, I always considered endosymbionts to be permanent fixtures once evolved. Not so. The transfer of endosymbiont genes to the host’s genome can proceed so far that “endosymbionts themselves can be lost in this manner, leaving nothing but the grin of a Cheshire cat” (p. 71). When yeast cells float freely in suspension, cheats do well, “like a pickpocket in a crowded bar” (p. 114); when they form budding colonies where they are surrounded by clonal copies, kin selection favours cooperative behaviour, because here a cheat “prospers no better than a thief at a pickpocket’s convention” (p. 114). The metaphor of DNA as a blueprint or instruction manual is not correct given the prevalence of transposons; rather it is “part library and part zoo, with the unruly creatures of the menagerie constantly tearing into the pages, creating mutation and mayhem” (p. 177). The book’s concluding message about what this all means for how we should behave is similarly brief but to the point: we can choose to cooperate or cheat, but “just be warned, cheats rarely prosper or, to be exact, only prosper when rare” (p. 192).

That cooperation is an important component driving evolution is most clearly seen when it leads to the formation of a new kind of individual, dubbed a major transition in evolution by John Maynard-Smith and Eörs Szathmáry. Whether it is genes teaming up to form chromosomes, cells teaming up to form multicellular organisms, or individual insects teaming up to form eusocial colonies, this is a two-step process. First, a team is formed where cooperation is favoured through division of labour. Second, the team forms a new entity once its partners become so completely dependent on each other that they cannot reproduce alone. This process offers an answer to two paradoxes. First, if evolution is a gradual process that is not supposed to make large jumps, how do we explain the major discontinuities that we see? “The resolution […] lies in how teams of cooperators are formed and then transformed at major transitions” (p. 188), with new properties emerging that could not have been predicted from the parts. Second is the mistaken belief that evolution has an inherent tendency towards progress. “The appearance of progress is an illusion due to the fact that evolution has produced an accumulation of complexity” (p. 190). Where some have argued that increased complexity over time requires a new biological law, cooperation leading to major transitions offers an alternative explanation.

Selfish Genes to Social Beings is not intended as a formal treatment of cooperation in biology. However, for interested lay readers who are not afraid of a challenge, as well as for biologists coming in from other disciplines, this is a thought-provoking book that holds plenty of surprises.

1. ↑ Youtuber CGP Grey produced a brilliant two-part animated adaptation of the book The Invisible Hook back in 2021.

2. ↑ To his credit, Silvertown instead discusses the to-me unknown history of Paul Portier, who got so close to discovering endosymbiosis already in 1918.

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

Selfish Genes to Social Beings

Other recommended books mentioned in this review:

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I have written previously that deducing behaviour of extinct animals from fossils millions of years old might seem science fiction, but is very much science fact. That said, in his previous book, English palaeontologist David Hone pointed out that dinosaur behaviour is the one area where we see the greatest disconnect between what we know and what people think we know. His new book Uncovering Dinosaur Behavior is a sobering reality check for the lay reader, but I suspect that even palaeontologists might come away wondering whether there is anything we know for sure. Concise, well-structured, and beautifully illustrated by palaeoartist Gabriel Ugueto, this is a superb book that transcends “merely” being a good popular science work by also addressing professional palaeontologists.

Uncovering Dinosaur Behavior: What They Did and How We Know, written by David Hone, published by Princeton University Press in November 2024 (hardback, 232 pages)

Uncovering Dinosaur Behavior opens with a very clear mission statement: what the book is and is not about, who it is for, and even what its potential weak points are. Hone writes about dinosaur behaviour, yes, but this is more than a catalogue of studies showing that species X likely did behaviour Y. He is aiming for a more integrated work, explaining how we figured these things out and offering advice on how to resolve conflicting results and answer remaining questions. His target audience encompasses dinosaur enthusiasts, of course, but he is additionally aiming at both palaeontologists interested in animal behaviour and ethologists interested in dinosaurs. He is upfront about the potential weaknesses: in trying to serve several masters, he might please none. Furthermore, he unapologetically follows the biases of the existing literature that emphasizes the charismatic megafauna at the expense of a broader take on dinosaurs at large. Having explicitly laid his cards on the table, Hone follows through with a logically structured book.

Three introductory chapters cater to both palaeontologists and ethologists by providing primers on dinosaurs, the fossil record, and the study of animal behaviour. You will find both a helpful appendix briefly introducing all major dinosaur lineages, and an introduction to Niko Tinbergen’s four famous questions of why an animal behaves the way it does that became the foundation for ethology. One of the chapters introduces the basic biology that both determines and limits dinosaur behaviour; topics such as activity patterns (when during the day are you active?), habitat choice, physiology, posture, and locomotion. A final important concept is extant phylogenetic bracketing, that is, looking at the behaviour of the nearest living relatives of dinosaurs (birds, crocodilians, and reptiles more widely). This will help you determine how far back in time a certain behaviour likely evolved. Armed with all of the above, you should be better able to judge whether behaviours inferred for dinosaurs are theoretically possible, plausible, or even likely.

Hone here also lays out his challenge to fellow palaeontologists to produce more rigorous science, giving you a set of eleven guidelines that he published together with Chris Faulkes in a 2014 paper. He has observed several recurrent problems with how data is used, interpreted, and presented, leading to misrepresentation and over-extrapolation of behaviour far beyond what the data supports. His philosophy is to “always favor a degree of uncertainty or lack of confidence in a result, rather than embracing an interpretation confidently that may be wrong” (p. 35).

“[The] target audience encompasses dinosaur enthusiasts, of course, but he is additionally aiming at both palaeontologists interested in animal behaviour and ethologists interested in dinosaurs.”

The remainder of the book examines five broad categories of behaviours. Given what I just wrote about Hone’s attitude to the research field, I can now explain why I introduced this book as a sobering reality check. Take the frequently depicted idea that dinosaurs lived in groups, with a certain franchise making hay out of pack hunting. Now, many animals alive today live socially, and there are advantages to doing so, but how do you deduce this from fossils? The problem with bonebeds is that fossils found in groups did not necessarily live or even die together: the taphonomic history (what happened between death and burial) matters. But equally, many groups will have lost members individually: solitary fossils do not exclude social behaviour. Trackways can similarly not be taken at face value. Beyond the challenge of assigning them to species, determining if they were laid down together is challenging, and even if they were, many interpretations are possible beyond social behaviour.

Hone is similarly circumspect when it comes to signalling and reproduction. He highlights what we know and what remains unknown. For instance, dinosaurs likely used visual and auditory signals, and they laid eggs. But did they use touch, taste, or smell? How did they mate? How many eggs did a female typically lay? What amount of care did parents bestow on offspring before and after hatching? We have data and tentative hints for some species, but for many questions, we cannot go much beyond generalities. The situation is better for combat: many species sported implements that intuitively look like weapons, but how and on whom they used them is harder to determine. Studies have furthermore focused on a small number of species while ignoring many others. Feeding biology is the area that has the most robust support, bringing together many independent lines of evidence such as biomechanics, trace fossils, isotope data, tooth microwear analysis, stomach contents, and coprolites. Even here, though, such full pictures are only available for a handful of species.

Overall, interpreting dinosaur behaviour is “profoundly difficult” (p. 152) due to both the limitations of the fossil record and the diversity and plasticity we see in the behaviour of animals alive today. The problem he observes is that “much of the scientific literature tends toward a confidence in interpreting dinosaurian behaviors that probably should not be there [while failing] to recognize alternate possibilities and the inherent uncertainty of interpreting ancient behaviors” (p. 153). That sounds pretty damning but he also recognizes that the field has come a long way from early guesswork and extrapolations to more rigorous methods that take seriously the fact that dinosaurs were once real, living animals rather than mythical monsters.

“Hone’s work […] hit the sweet spot of the kind of depth I look for in my popular academic books: fairly technical, thought-provoking, never shirking the hard questions, and yet admirably brief”

Compared to the previously reviewed The Future of Dinosaurs, which had a somewhat haphazard ordering of its chapters, Uncovering Dinosaur Behavior benefits from an excellent and logical structure that flows very well. However, some noticeable typos did slip through again, despite the extensive proofreading. All chapters come with a helpful summary and an interesting case study; I thought the one on ankylosaurs and what their tail clubs were used for was particularly compelling. I also have to praise the fantastic illustrations by Ugueto. The colour plate section is mouthwatering eye candy, and there are numerous classy and useful black-and-white drawings and diagrams throughout the book. Some of the black-and-white photos of fossils are harder to decipher, and I would not have minded had some been included in the colour plate section.

Uncovering Dinosaur Behavior was published about a year after Michael J. Benton’s Dinosaur Behavior: An Illustrated Guide, meaning Princeton University Press now has two illustrated books on this topic. Which one do you choose? In my review, I highlighted that Benton’s is an introductory book for novices that starts from first principles. Hone’s work, though very accessible, is more advanced and, for me, hit the sweet spot of the kind of depth I look for in my popular academic books: fairly technical, thought-provoking, never shirking the hard questions, and yet admirably brief at 207 pages. One thing Hone does not do is introduce and explain the various techniques. He assumes that phrases such as isotope data, palynology, and finite element analysis mean something to you and do not require more than a brief definition. If you find your eyes glazing over at these terms, maybe start with Benton’s book. For everyone else, however, Uncovering Dinosaur Behavior is a superb book that should be your go-to reference for a thoughtful appraisal of what we know about dinosaur behaviour.

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

Uncovering Dinosaur Behavior

Other recommended books mentioned in this review:

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There are plenty of popular palaeontology books that tell you everything we know about dinosaurs and several excellent examples have been reviewed here in the past. For the 500th review on this blog, I take the road less travelled. In The Future of Dinosaurs, English palaeontologist David Hone flips the script by asking what we do not know about dinosaurs. I have been meaning to review this book since it was first published in 2022. With the recent publication of his latest popular book on dinosaur behaviour, I decided to make time and read up on Hone’s work. First up, an exploration of our ignorance that is as much a celebration of all we have learned and how we have learned it.

The Future of Dinosaurs: What We Don’t Know, What We Can, and What We’ll Never Know, written by David Hone, published in Europe by Hodder & Stoughton^[1] in March 2022 (hardback, 252 pages)

This book seemingly flows from Hone’s efforts at science communication. In speaking to the general public, he has noticed the sometimes large disconnect between what palaeontologists know and what people think they know. Thus was planted the seed for a Rumsfeldian^[2] book about what is unknown, what is knowable, and what is unknowable in palaeontology. Fifteen chapters run the gamut of topics and chart the cutting edge of our ignorance and our understanding. Given the large number of popular dinosaur books, it is a refreshing take on the genre that is chock-full of interesting insights.

Take some examples of unknowns. What is the total number of species that ever evolved and how many can we still expect to find? That is unknown, though if you plot discovery rate against time you expect a curve that will eventually level off. Where we are on that curve? Who knows! The rate at which we name new species each year shows no signs of slowing down yet. Did sauropods have multi-chambered stomachs like today’s large herbivores? That is unknown, as soft-tissue preservation of this kind is exceedingly rare. All we have for now is a spectacular fossil of the small theropod Scipionyx where the guts were infilled with sediment, resulting in a remarkable cast of an otherwise unremarkable digestive tract.

Many things are knowable though, with questions often being an absence-of-evidence problem that can be resolved with more fossils and more research. Anatomical features such as the frills of ceratopsians are usually bent and broken during the long journey through time, but detailed scans and computer analyses allow us to undo such distortion virtually. It is still early days for this technique, but we have the fossils, so with time, effort, and experience, our knowledge is likely to improve. Were dinosaurs sexually dimorphic? That is, did males and females differ noticeably in size or appearance? Since most species are only known from one or a few specimens, we just do not have the required sample sizes yet, and where we do, we have not found such differences. However, given the large diversity of dinosaurs, there are bound to have been sexually dimorphic species, so with more fossils this question is ultimately answerable.

“[The] disconnect between what palaeontologists know and what people think they know […] planted the seed for a Rumsfeldian book about what is unknown, what is knowable, and what is unknowable in palaeontology.”

The unknowables are some of the most fascinating and frustrating questions discussed here. Are tooth marks on bones the result of predation or scavenging? Predators readily did both and the two are near-indistinguishable. “This is annoyingly trite as a revelation about their behaviour” (p. 183), but the data simply do not allow for firmer conclusions. The small asterisk is that some questions are not strictly unknowable, but would require such unlikely fossils that, for all intents and purposes, we can consider them unknowable. Others require completely new types of evidence that we had not previously conceived of. For example, the colour of dinosaurs was considered unanswerable until recently. The discovery of ancient biomolecules such as melanosomes changed that somewhat, as their shape corresponds to colour. “It is as if you went to a paint store and each colour was in a uniquely shaped pot” (p. 151), is how Hone memorably describes it. But he quickly tones down the enthusiasm: only certain colours are melanosome-based and sampling them is destructive, so palaeontologists try and limit it to spot sampling. Our knowledge is thus far less certain and complete than artist reconstructions suggest.

Despite my enthusiasm for Hone’s three-pronged approach, I do have some criticism. First is that the order of chapters feels somewhat haphazard, with the book jumping around between different topics and levels of organisation. Some closely related topics are scattered over the book with e.g. chapters on habitat and ecology separated by seven chapters. Others feel out of order. Why start with a chapter on extinction when, by your own admission, anatomy (now chapter 7) is the fundamental topic on which everything else in palaeontology is built? I would have reorganised the chapters for a more logical structure. Second is that the writing is sometimes not the most graceful. Take the book’s subtitle: to me, it cries out for a third “know”; leaving it out of the middle clause is just jarring. There are examples of long, run-on sentences expressing several ideas that should have been separated. Other sentences are awkwardly constructed, or switch from passive to active voice midway, with my brain expecting one thing but Hone writing something else. Now, I do not want to over-egg this: big picture, they are all minor blemishes on what is otherwise an entertaining and engaging book.

Next to Hone’s stated running theme of the disconnect between the public’s perception of our knowledge and our actual knowledge, some other fascinating themes emerge. One example is the nature of the fossil record and how it can mislead through both a glut and a dearth of fossils. Bonebeds are often significant sources of information due to the large number of bones preserved, but if they resulted from abnormal circumstances such as catastrophic floods, droughts, or volcanic eruptions, how representative are such assemblages? They risk giving “a very misleading picture of what lived locally and in what kind of numbers” (p. 194). At the other extreme are the low odds of preserving the statistical outliers such as the largest or oldest individuals. Similarly, newly emerging species often occur in low numbers and limited geographic areas, so the age of a species should be considered a minimum estimate. The odds are very much stacked against the earliest, if not the first, representatives of a species entering the fossil record, surviving to the present day, and then being discovered rather than lost to erosion.

“[…] some other fascinating themes emerge. One example is the nature of the fossil record and how it can mislead through both a glut and a dearth of fossils.”

Another fascinating theme that emerges is the impact of the huge size range of dinosaurs on their biology and ecology. Dinosaurs never evolved to be rodent-size small; as Elsa Panciroli discussed, mammals occupied that ecological niche. Furthermore, independent of their adult size, dinosaurs hatched from eggs as small juveniles and had to go through sometimes gargantuan growth spurts. Hone points out that juveniles of sauropods and large theropods simply could not have been eating the same food and playing the same ecological role as the adults. Fellow palaeontologist Michael J. Benton recently highlighted research that suggested carnivores passed through a range of feeding modes as they grew up, sequentially occupying different ecological niches and effectively acting as different species on their way to adulthood. Similar shifts might have also happened to metabolism, Hone suggests. Adult sauropods were so large that their surface-to-volume ratio meant they did not need to actively generate body heat to keep warm (a condition known as gigantothermy). But the same could not have been true of small juveniles; seeing their growth rates they likely were endotherms, actively generating body heat. If true, this would be remarkable, as we know of no living species that so radically change their physiology growing up.

Despite some minor flaws, The Future of Dinosaurs is both a fascinating exploration of our ignorance and a celebration of how much we have learned from sometimes very challenging source material. By tracing the contours of where our knowledge ends, Hone gives you an insider’s look into the discipline—from its storied history to today’s cutting-edge technologies. It seems almost prophetic that he writes that behaviour is the subject where we see the greatest disconnect between what palaeontologists know and what the public thinks they know: he tackles this topic in his recently published Uncovering Dinosaur Behavior to which I will turn next.

1. ↑ Note that in the USA, this book was published by Princeton University Press with the title How Fast Did T. rex Run?: Unsolved Questions from the Frontiers of Dinosaur Science.

2. ↑ I am, of course, referring to United States Secretary of Defense Donald Rumsfeld’s briefing where he popularised the notion of known knowns, known unknowns, and unknown unknowns.

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

The Future of Dinosaurs

Other recommended books mentioned in this review:

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Until two weeks ago, Humboldt was one of several famous past scholars I only knew by name. Last month’s release of this short biography was the perfect opportunity to fill this knowledge gap, so I sat down to compare it with Andrea Wulf’s The Invention of Nature, which received widespread acclaim ten years ago. Historian Andreas W. Daum shows that good things come in small packages and delivers a factual, nuanced, and admirably concise biography. It also confirmed that reading two biographies back-to-back is a rewarding and instructive exercise. This, then, is the second of a two-part review of the long and remarkable life of Prussian naturalist, scholar, and explorer Alexander von Humboldt.

Alexander von Humboldt: A Concise Biography, written by Andreas W. Daum, published by Princeton University Press in January 2025 (hardback, 208 pages)

Straight off the bat, you can tell that this will be a different book. First is its size: at 208 pages and measuring some 13 × 21 cm, it is swallowed by The Invention of Nature. Second, though Wulf moved to Germany as a child and is thus equally comfortable parsing German sources, Daum is just that bit more qualified: he is a historian actively researching Humboldt’s biography. Currently based at the University at Buffalo, New York, he was born, raised, and educated in Germany. This book was originally published in German in 2019 by Verlag C.H.Beck, titled simply Alexander von Humboldt. The English translation is by Robert Savage, with Daum actively involved in revising and expanding it while directly translating quotations from German and French to retain their original meaning.

A more detailed comparison between the two biographies follows at the end as I first want to judge this book on its merits. Daum discusses Humboldt’s life in six chapters that (chiefly) cover his childhood and education, his work as a mining inspector and his early publications, his famous expedition through America, his twenty-year stay in Paris, his return to Berlin and journey to Russia, and his final two decades during which Kosmos became the focus of his life. A short interlude chapter reflects on his scientific approach, while the book ends with a chronology (3 pp.), a very useful narrative guide to sources and further reading (9 pp.), endnotes (13 pp.), and a selected bibliography (6 pp.). As mentioned in my previous review, biographies are more than statements of facts, with different writers emphasizing different aspects. Daum has a clear mission statement: to examine Humboldt’s life “through a refined biographical lens [that] avoids both mystification and vilification [and] to suggest a more nuanced interpretation, portraying a multifaceted Humboldt” (p. 3). Two aspects stood out to me.

First, throughout, Daum pushes back on previous portrayals of Humboldt. For example, after acknowledging Nicolaas A. Rupke’s fine analysis of previous biographies, Daum characterises the recent biographies by Wulf and Maren Meinhardt as “popular, heroic accounts” (p. 162) that tend to portray Humboldt as “a singular intellect way ahead of his time” (p. 2). He adds a clear barb at Wulf’s address by writing that Humboldt did not invent nature. He equally objects to linguist Mary Louise Pratt’s postcolonial critique of Humboldt as a gentleman colonizer who “saw non-European worlds primarily with ‘imperial eyes’” (p. 3). Though Daum agrees such criticism is “a necessary corrective to an idealized, glorifying image of the Prussian explorer” (p. 63), it needs to be combined with a fair assessment of his progressive sides. Portrayals of Humboldt as a second Columbus are similarly scorned as “simplistic tropes [that] reflect a colonial worldview” and simply are not true: “Humboldt was not venturing into unknown territory. Nowhere was he the ‘first’” (p. 55). This is true for both the American expedition and his later trip to Russia: naturalists in Estonia had already laid a scientific basis for Russia’s eastward expansion, and Humboldt was not the first researcher to travel here.

“Daum has a clear mission statement: to examine Humboldt’s life “through a refined biographical lens [that] avoids both mystification and vilification” (p. 3)”

More pushback comes when Daum distinguishes between Humboldtian science and Humboldt’s science. Humboldt’s call for systematic collection of geomagnetic and climatological data by networks of observatories, later pursued by both Russia and the UK, has been called an example of Humboldtian science by historian Susan Faye Cannon. Daum counters that this is a later archetype that “drew on Humboldt and his ideal of systematic measurements and quantification but jettisoned his emphasis on the aesthetic” (p. 124). Humboldt’s science, in contrast, was far more tentative, trying to balance empirical science with one’s subjective experience of nature. He did not have it all figured out before or after his American expedition. To suggest otherwise is “a retrospective projection that doesn’t do justice to his ongoing struggle to collect and generate knowledge” (p. 52). Finally, though Humboldt is venerated in South America and he welcomed declarations of independence, he played no role in them: “the label ‘father of Latin American independence’ is an […] ahistorical, heroizing trope” (p. 109).

Beyond criticism, the second aspect that stood out to me is Daum’s nuanced picture of Humboldt. Take, for example, his political stance, or lack thereof. Though Humboldt is remembered for his liberal values and criticism of colonialism and slavery, he feared bloody violence, such as seen during the French Revolution and favoured more gradual reforms. When Prussia took the fight to Napoleon and occupied Paris in 1814, his brother Wilhelm supported the German cause while Alexander refused to, “souring relations between the two” (p. 105). Humboldt helped prevent the Paris Museum of Natural History from being looted and drew criticism back in Germany when lobbying for stolen German artworks to stay in Paris. He supported and found patronage for French and German scientists alike and, by refusing to pick sides, easily moved in different social circles. When he later returned to Berlin with its increasingly conservative political climate that curbed freedom of expression, he swam against the tide by offering free public lectures that became incredibly popular.

Daum gives a similarly nuanced picture of Humboldt’s way of working. Hearing of his grand plans for the American expedition, his brother was already concerned he would overreach. Indeed, he habitually bit off more than he could chew, always had multiple manuscripts on the go, and left a legacy of unfinished projects. The American travel narrative, between various translations and abridgments, became “so fiendishly complicated […] it still has the power to drive experts, librarians, and readers to despair” (p. 99) and resembled “a construction site of knowledge” (p. 100). Kosmos, the magnum opus he laboured on for the last two decades of his life, was not necessarily a resounding success either, despite the high sales. Some contemporaries called it a challenging work, while others mentioned many readers put it down as it required too much prior knowledge. Ironically, the proliferation of simplified versions and explainers meant that Humboldt succeeded, sort of, in popularizing science, though it “had taken on a momentum that the author could no longer control” (p. 142). Daum’s characterisation of Kosmos as “more a synopsis of a mass of materials than a coherently argued synthesis” (p. 141) is exhibit A for his conclusion that Humboldt is remembered not for coming up with “a clearly defined theory that fundamentally changed scientific and social thinking“, but for leaving us with “myriad complex thoughts and incentives for further research” (p. 151).

“The book’s brevity is partially achieved by omitting all the biographical material on other people that Wulf included and partially by mentioning rather than describing events in lively detail.”

Given the number of people who will have read Wulf’s The Invention of Nature, a comparison is in order. My one-liner is that Daum’s book is less fluff, more facts. The book’s brevity is partially achieved by omitting all the biographical material on other people that Wulf included and partially by mentioning rather than describing events in lively detail. This is particularly noticeable when it comes to Humboldt’s expeditions. For example, where Wulf detailed his quest to find the Casiquiare river to establish whether the Orinoco and Amazon river basins were linked, Daum mentions this in a single sentence. In the process, he misses a beat as it is another good example of Humboldt not being “first”: Wulf mentions how local missionaries told him it had been figured out decades earlier. His travel partner in the Americas, Aimé Bonpland, is basically invisible, and there is virtually nothing about their working relationship or Humboldt’s later frustrations about his tardiness in writing up the botanical volumes beyond mention that “the less efficient” (p. 102) Bonpland was replaced by Carl Sigismund Kunth. And where Wulf cracked me up with her description of Humboldt’s audacious unscheduled detours in Russia, Daum merely mentions that he presented his hosts with a “fait accompli” (p. 122).

Now, before you conclude that Daum’s book contains less material than Wulf’s, let me stop you there. For all its brevity, there are numerous details here not mentioned by Wulf. Humboldt grew up speaking French. He had a half-brother, Heinrich von Holwede, who remains a complete enigma. He witnessed a solar eclipse while in today’s Venezuela. But beyond factoids, there are the aspects I highlighted above (the corrections to previous depictions of Humboldt, his political stance, his approach to work); there is attention for his lesser-known works; a more informed opinion on his sexuality; and many other things besides. In a mere 153 pages, Daum concisely offers a full yet nuanced picture of Humboldt’s life and work.

If you have already read The Invention of Nature, should you read this biography? Next to being a quick read, hopefully by now you are convinced Daum’s book is worth your time by offering a different perspective and much new information. If you have the bandwidth and inclination, I would even recommend you either reread Wulf’s book or, if you have not yet done so, read them together—I found the exercise both instructive and rewarding. If you insist on me recommending just one book, answer me this: do you read history books to be informed or to be entertained? In the former case, choose Daum for a more scholarly take; in the latter, choose Wulf for an entertaining book that indulges in digressions. I hasten to add that I am talking shades of grey here: Daum prioritising the facts does not mean his book is boring, just as Wulf prioritising storytelling does not mean her book is inaccurate.

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

Alexander von Humboldt

Other recommended books mentioned in this review:

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There are many famous scholars that I only know by name, so, lately, I have been developing a taste for science biographies. With the publication last month of Alexander von Humboldt: A Concise Biography, he was the next scholar to come onto my radar. However, I felt I could not do this subject justice without also considering Andrea Wulf’s highly-regarded 2015 biography The Invention of Nature, which won a slew of prizes and nominations. This, then, is the first of a two-part review of the long and remarkable life of Prussian naturalist, scholar, and explorer Alexander von Humboldt.

The Invention of Nature: The Adventures of Alexander Von Humboldt, the Lost Hero of Science, written by Andrea Wulf, published by John Murray in October 2015 (hardback, 473 pages)

You may well ask: why bother, why read two biographies? Is that not simply repetitive? I have several answers to these questions. The prosaic one is that I bought a copy some years ago, did not yet get around to reading it, and have heard good things about it. More importantly, however, is that the amount of scholarship on any topic or person is often dizzying (as is the case here) and taking any one person’s word as the final say is foolhardy. Yes, there will be inevitable repetition, but biographies are more than statements of facts. Each biographer will write for different audiences and approach their subject differently, accentuating some sides while downplaying others. People are complicated and multifaceted, so developing a fuller picture of someone is an iterative process. My thinking on this is hardly original. Science historian Nicolaas A. Rupke did just such a comparative exercise back in 2005, writing a “metabiography” that showed how the many different Humboldt biographies are products of their time that reveal as much about their writers as about their subject. In that light, consider the biographies I recommend below as starting points only!

Born in Prussia (today’s Germany did not yet exist), Alexander von Humboldt (1769—1859) was born to a wealthy family as the younger of two sons. Age 9 his father died, age 27 his mother. Liberated from their vision of a conventional career (he had trained as a mining inspector), and now in possession of a large inheritance, he pursued what he is best remembered for: a five-year exploration of the Americas (1799–1804). In true polymath fashion, he ranged across disciplines, collecting observations on, amongst others, zoology, botany, geography, history, agriculture, and politics. He spent two decades in Paris, turned his journey into influential books, including the hugely popular Views of Nature, and became an intellectual rock star. All the while he was supported by the Prussian king Wilhelm Friedrich III on a generous chamberlain’s pension, no strings attached; until of course there were and he was recalled to Berlin in 1827. Though his plans to explore the Himalayas never came to fruition, he remained ever-restless and, age 59, convinced tsar Nicholas I to finance a journey across Russia. Returning to Berlin with yet more ideas and observations, he continued writing and lecturing and, age 65, hit on the madcap idea to write a book, Kosmos, that would represent the whole material world. Taking a decade to complete, it became a bestseller. Realising he had yet more to say, it spawned four follow-up volumes^[1] that consumed the remainder of his life until his death age 89.

Above facts are remarkable enough, and Wulf follows a strategy of taking notable episodes from his life and elaborating on them in lively detail in this chunky, 473-page book. But, given that I just wrote that biographies are more than statements of facts, I want to highlight three noticeable aspects.

“His journey through Russia in old age was a revitalizing experience, especially once he defied the authorities by going off-piste in a well-told episode that had me pealing with laughter at his audacity.”

First is Humboldt’s character. Wulf does not have to psychoanalyse him as his contemporaries already did some of that. Correspondence between his brother Wilhelm and his brother’s wife Caroline explains Alexander’s unhappy childhood. The early loss of his father saw him search for a replacement in his private tutors while he felt incompetent compared to his precocious older brother. His mother was emotionally distant and though Wilhelm took care of her for 15 months when she fell terminally ill, neither brother chose to be there when she died or attend the funeral. All this meant Humboldt was haunted by feelings of insecurity his whole life. He was forever possessed of wanderlust, desiring strongly to travel and explore. His journey through Russia in old age was a revitalizing experience, especially once he defied the authorities by going off-piste in a well-told episode that had me pealing with laughter at his audacity. He was notoriously restless and talked at “race-horse speed” (p. 19, quoting Caroline), jumping from subject to subject. Both German poet Johann Wolfgang von Goethe and American President Thomas Jefferson wrote they learned more from talking to Humboldt for several hours than from reading books for several years. It does feel like he transitions from a young man dazzling his audience at salons with his eloquence to an old man lecturing them—the piano recital episode Wulf recounts is comically embarrassing. He generously supported other scholars, explorers, and artists but was hopeless with money—Caroline feared some took advantage of him. He never married, nor had romantic affairs with women, though he had plenty of suitors. Instead, he developed intense friendships with other men in serial fashion, declaring passionate feelings for them in his letters. Wulf adds that: “Humboldt never explicitly explained the nature of these male friendships but it’s likely that they remained platonic” (p. 83). Rather, he let off steam by venturing into nature and exerting himself physically: “nature, he declared, calmed the ‘wild urges of passions’” (p. 83).

The second noteworthy facet is Humboldt’s prescience. Wulf repeatedly argues he was visionary and far ahead of his time. This showed in his political views: he spoke out against slavery his whole life and was supportive of revolutions against oppressive regimes, though he ultimately tired of politics as many revolutions came to nought. It especially showed in his scientific ideas. His ascent of Mount Chimborazo in today’s Ecuador is credited with giving him the insight that everything in nature is connected, “conceiving a bold new vision […] that still influences the way that we understand the natural world” (p. 2). At a time when botany was all about taxonomy, he saw connections with climate and geography and grouped plants into vegetation zones, giving “western science a new lens through which to view the natural world” (p. 127). As Humboldt collated more data, plants to him “revealed a global force behind nature” (p. 128), whether indicating past human migrations or the movement of landmasses (prefiguring plate tectonics by more than a century). “No one had ever approached botany in this way” (p. 128). Observing Spanish colonial practices, he warned that deforestation and irrigation could affect the climate. Decades later, having visited Russia, he reiterated this and almost prophetically added a warning about “the ‘great masses of steam and gas’ produced in the industrial centres” (p. 213). Seeing the impacts of other forms of resource extraction, he connected the dots and warned that: “The action of humankind across the globe […] could affect future generations” (p. 58). And with that, Wulf concludes, “he unwittingly became the father of the environmental movement” (p. 58). As will become apparent in the next review, not everyone agrees with sweeping statements of this sort.

“Using a show-don’t-tell approach, Wulf does not merely tell us Humboldt was influential, she shows us how their diaries, letters, and books explicitly mentioned him.”

The third noteworthy facet is Humboldt’s influence. Eight out of the book’s 23 chapters discuss famous people he influenced, which break down into two distinct groups. The first group were close friends to the young Humboldt, such as Goethe, Simón Bolívar, and Jefferson (they only met in person for a few weeks and then corresponded for years). Thus, these chapters are as much about them as about Humboldt^[2]. While I can get behind her decision to detail these three, I struggled more with the second group. These people were younger than Humboldt and (except Charles Darwin) never met him, making these chapters mini-biographies of other people. Using a show-don’t-tell approach, Wulf does not merely tell us Humboldt was influential, she shows us how their diaries, letters, and books explicitly mentioned him, and how their personal libraries were stocked with his books. It is easily the most divisive aspect of the book. On the one hand, I felt it reiterated the theme of connectedness: just as his ideas were all about the connections in nature, Humboldt himself was deeply interconnected with others, influencing and being influenced by them. On the other hand, the end of the book started to feel like too many tangents. Humboldt’s death in chapter 20 is preceded by two chapters on Darwin’s Beagle expedition and Henry David Thoreau, and followed by another three on George Perkins Marsh, Ernst Haeckel, and John Muir. After finishing the book I had to remind myself I was reading a biography of Humboldt.

I furthermore want to give Wulf props for the endnotes. She opens with four pages of abbreviations to all the sources she has consulted: correspondence, letters, notebooks, and diaries held in library collections, plus Humboldt’s numerous books. This in turn allows her to then give you—ye gods!—82 pages of condensed endnotes. These meticulously document everything, often providing 5–10 endnotes per page of text. It evidences an impressive amount of background research and you would be hard-pressed to accuse her of making unsubstantiated claims.

Overall, despite its digressions, I found The Invention of Nature a hugely enjoyable book that gives a multifaceted portrait of Humboldt’s character, his ideas, and his impact. Wulf presents her in-depth research in a captivating narrative, and it is easy to see why the book received so many accolades. As the next review shows, some cast doubt on the claim that Humboldt was the inventor of nature, but Wulf convinces that this ever-restless polymath certainly was a force of nature. Acknowledging my opening gambit that we should not take any one biography as the final say on the matter, let us next fast forward ten years to Andreas W. Daum’s Alexander von Humboldt: A Concise Biography to see what he adds.

1. ? The first two volumes of Kosmos were intended for a general audience and saw many translations; the later three volumes were more specialist and less popular. Johns Hopkins University Press reissued the 1858–1859 English translations of volume 1 and volume 2 in 1997. A (rather lush) integral edition of all volumes with commentary is currently only available in German.

2. ? Interestingly, botanist Aimé Bonpland, his research partner on the American expedition, receives little attention from Wulf.

The Invention of Nature

Other recommended books mentioned in this review:

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As a bonus to conclude my (now) four-part review series on the history of taxonomy, I am looking back to Susannah Gibson’s 2015 Animal, Vegetable, Mineral? After dealing with biographies of Linnaeus and Buffon, and then Ragan’s Kingdoms, Empires, & Domains, her book was just crying out to be read next. Given that those three were all published in 2023 and 2024, I will leave a comparison for the end of this review and first judge this book on its merits. As it turns out, this is an easy and intriguing read that I ignored for far too long.

Animal, Vegetable, Mineral? How Eighteenth-Century Science Disrupted the Natural Order, written by Susannah Gibson, published by Oxford University Press in July 2015 (hardback, 215 pages)

Gibson is an affiliated scholar at the Department of History and Philosophy of Science, University of Cambridge. Though she keeps a low profile online, a little research shows that since this 2015 debut, she has written two more books, The Spirit of Inquiry (2019) and Bluestockings (2024), showing a continued engagement with (science) history.

Even as I acknowledge Ragan’s point that dividing the natural world into animals, vegetables (i.e. plants), and minerals was neither rooted in prehistory nor universal, it cannot be denied that for centuries it was a widely accepted division. The 18th century was a time of radical change, though, with e.g. the French Revolution and the Scottish Enlightenment causing political and societal upheaval, while colonialism and empire-building brought home a raft of organisms previously unknown to Europeans. All this caused people to question traditional ideas and beliefs, including scholars who re-examined those creatures that had always straddled the border between different kingdoms. Importantly, while science was advancing rapidly, “this greater abundance of knowledge did not always lead to agreement” (p. 166), so Gibson connects her examples to larger debates of the era.

Zoophytes, those creatures that mix traits of animals and plants, are an appropriate place to start. She is on the ball in not attributing the term to Aristotle (as Ragan was at pains to emphasize in Kingdoms, Empires, & Domains), even as he got the whole zoophyte ball rolling with his interest in polyps, corals, sponges, and other marine invertebrates. They were still being discussed in the 18th century when naturalist Abraham Trembley garnered attention with his description and study of freshwater polyps (distant relatives of jellyfish in the animal phylum Cnidaria). Next to its biology combining elements of animals and plants, it has the remarkable ability to completely regenerate and multiply when cut into pieces. Trembley’s work fed into the larger ongoing debate between materialism (all is matter and energy, and matter and energy is all) and vitalism (living beings possess a special spark, a vital force). It spurred such questions as: “Is cutting a polyp into two a separate act of creation?”, “Is the soul then split into two?”, and “Where is God in all this?”

“while science was advancing rapidly [in the 18th century], “this greater abundance of knowledge did not always lead to agreement” (p. 166), so Gibson connects her examples to larger debates of the era.”

Linnaeus used sexual reproduction as a basis for plant taxonomy and drew analogies between animals and plants, even as his critics pointed to plants reproducing without seeds. This work in turn fed into larger debates about reproduction, which saw preformationism pitted against epigenesis. The former held that God had created everything in one go such that future offspring were stacked inside each other like so many Matryoshka dolls; the latter held that life resulted from the gradual organisation of disorganised matter via the laws of physics and chemistry—no God required. Note that Gibson illustrates this with animal rather than plant examples, including the historical dispute between Albrecht von Haller and Caspar Friedrich Wolff on chicken eggs and the unbelievable work of Lazzaro Spallanzani who kitted out male frogs with tiny waterproof trousers (!) to test the idea of egg preformation.

Gibson has a knack for uncovering some of history’s whackier tales. The chapter on minerals, which includes our struggle to understand fossils, might not feature a link to larger philosophical debates but does come with two intriguing character stories. The history of William Smith’s first stratigraphical map of Britain that relied on fossils has been told before, but the amazing story of Johann Beringer who fell victim to an elaborate hoax as he was trying to understand fossils was completely new to me. Here, as elsewhere, Gibson is a sensitive historian. Even as she defends some scholars from modern accusations of gullibility, pointing out that their methods and logic were sound but their knowledge a product of its time, she subtly scolds others for not crediting the unnamed slaves, fishermen, or gardeners who helped them make the observations for which they are remembered.

My only real criticism is that I am not fully convinced by one important line of her argumentation. She repeatedly contends that new findings in science had serious ramifications for society at large: “anything that could be used to show that nature didn’t always echo religious orthodoxy was dangerous […] abstract scientific questions could have all-too-concrete consequences” (p. 177). All this academic chatter of border-straddling animals and plants might cause people to question the natural order of things! I think it is an intuitively appealing idea, but what is the evidence for it? Yes, she shows how Linnaeus’s ideas on plant reproduction were readily satirized, even as they offered an opportunity to discuss sex in polite company. However, what were the “bigger religious and social implications” (p. 78) of the interest in Trembley’s polyp research? And how did the discovery of the Venus fly-trap that seemed to defy the God-given category of plants cause people to question social stratification? Maybe I am being too literal-minded, but did people ever revolt, pitchfork in one hand and scientific paper in the other? Could you not just as well argue that the revolutionary spirit in society bled into science, or, equally likely, that the two influenced each other? To my taste, much is asserted here without providing clear examples, though I will gladly admit my ignorance of this historical period. Perhaps the answer lies in her conclusion that in dismantling the familiar concepts of animals, vegetables, and minerals, naturalists gave society “a focus for asking a set of much bigger questions” (p. 188).

“Reading Animal, Vegetable, Mineral? a decade after its publication, how does it hold up? Actually, rather splendidly.”

To wrap up, I promised a comparison with the previous three books. Reading Animal, Vegetable, Mineral? a decade after its publication, how does it hold up? Actually, rather splendidly. For Linnaeus, Gibson relies on Lisbet Koerner’s biography and by and large agrees with Broberg’s book, except in a few details. For example, where Gibson writes that Linnaeus’s ideas were welcomed in England, Broberg argued this took time and the initial reception was lukewarm; and where she mentions the outrage caused by his writing on plant sexuality, Broberg contended this has been exaggerated. Gibson is briefest on Buffon but nails the core difference with Linnaeus that Roberts highlighted in Every Living Thing: Linnaeus preached an artificial system while Buffon countered that nature did not yield to such strict classification.

Most interesting is the comparison to Ragan’s book. Though Gibson’s first chapter is effectively an appreciation of Aristotle, she compresses the next two millennia. I think this is justified: as Ragan has so painstakingly documented, in essence not much happened beyond repeatedly redefining the concept of zoophytes. Even Cuvier remarked that Aristotle “left very little to do for the centuries after him” (p. 15). Gibson thus focuses on 18th-century developments while her epilogue is a speed-run through 19th and 20th-century biology. In a mere 215 pages, her book is of course no match for Ragan’s encyclopedic overview, but that was never the intention. That said, Ragan did not mention fossils or the wider social context. Can this book be a starting point if Ragan’s book seems too intimidating at first? If you finish it fascinated by zoophytes and want to immerse yourself deeply in the history of that concept, then, certainly, yes. But, more than a mere prelude, Gibson’s work readily stands on its own two feet even a decade later, covering subjects and stories not encountered in these three later books. Animal, Vegetable, Mineral? is a whip-smart book that I ignored for far too long.

Animal, Vegetable, Mineral?

Other recommended books mentioned in this review:

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