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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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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2024 was a year in which I managed to read and review 38 books. What follows is my personal top 5 of the most impactful, most beautiful, and most thought-provoking books I read this year.

1. Jay Matternes: Paleoartist and Wildlife Painter

I instantly fell in love with Jay Matternes’s palaeoart when I encountered it in Visions of Lost Worlds. Science historian Richard Milner spent eight years on this fully authorised career retrospective by Abbeville Press, and it is full of mesmerising palaeo- and wildlife art by an underrecognized master of the genre. Read more…

2. Every Living Thing: The Great and Deadly Race to Know All Life

I read this book as part of a still-ongoing review series. Author Jason Roberts writes an epic history of taxonomy across three centuries that charts the lives, works, and legacy of Linnaeus and Buffon. Published by Riverrun, it quickly became a personal favourite for introducing me to a new intellectual hero. Read more…

3. Eat, Poop, Die: How Animals Make Our World

What a killer title. I was stoked the moment Profile Books announced this one. Fun, fascinating, and always with one eye firmly on the facts, conservation biologist and marine ecologist Joe Roman shows how animals shape ecosystems through their everyday activities. Read more…

4. Playing Possum: How Animals Understand Death

Princeton University Press published this translation from the Spanish original by philosopher Susana Monsó where she provides an exceedingly interesting take on how animals understand death. Playing Possum manages to be both accessible to a general audience and relevant to specialists by showing why comparative thanatology still has a whole lot of growing up to do. Read more…

5. Why Animals Talk: The New Science of Animal Communication

Zoologist Arik Kershenbaum joins Viking Books to deliver Why Animals Talk: a highly stimulating and thought-provoking exercise in decentering the human experience and trying to understand animals on their terms. Read more…

In the category “also-ran”, honorary mention goes to Free Agents: How Evolution Gave Us Free Will and Alfie & Me: What Owls Know, What Humans Believe. I would have loved to include these deeply impressive books as well, except that they were technically published in 2023. If you are looking for more recommendations, do check out my earlier top 5s or browse the archive which lists all reviews.

Finally, some announcements. First, I realise the total number of books read this year is the lowest it has ever been. It is not that I am losing interest, but simply that the same processes of intensification I mentioned last year are still in effect. I am spending more time with each book, taking more notes, doing more background research, drawing on more accumulated knowledge, and writing longer reviews. Second, I intend to continue doing more two- and three-parters and go back to relevant earlier books when touching on certain topics. I hope readers are enjoying the digressions into yesteryear’s books. Once I am finally in control of my to-be-read pile, I hope to feature the occasional classic from decades ago that I keep coming across and have since acquired. Third, you might have noticed that I have abandoned certain social media platforms: their business tactics and management were becoming insufferable. I am really enjoying the crowd on Mastodon, so find me there or sign up here to get email notifications of every new review. I have also opened a Ko-fi account and would like to once again thank the readers who made some very generous donations there: you know who you are. Lastly, I would love to have your feedback! This blog has been running for over seven years now and I am only a few posts away from review #500. I am doing a fair amount of maintenance on older reviews, cleaning up broken links and streamlining the layout I have settled on. I have toyed with ideas such as audio versions of reviews, author interviews, or a newsletter. What would you like to see more or less of?

Of all the insects that have a PR problem, cockroaches must rank very high. That, however, did not stop German entomologist, journalist, and filmmaker Frank Nischk from spending a year-long internship studying them. In this book, he regales the reader with stories of his time in the lab and the field studying first cockroaches and later crickets. A light and breezy read despite the serious undercurrent of biodiversity decline, Of Cockroaches and Crickets turned out to be an entertaining read.

Of Cockroaches and Crickets: Learning to Love Creatures That Skitter and Jump, written by Frank Nischk, published by Greystone Books in March 2023 (hardback, 214 pages)

This book was originally published in German in 2020 as Die fabelhafte Welt der fiesen Tiere by Ludwig Buchverlag and has been translated into English by Jane Billinghurst who frequently works with Greystone Books. Carl Safina contributes a short foreword that cracked me up and immediately set the tone. The book is effectively a memoir of Nischk’s early years studying for his undergraduate and doctorate degrees in the mid-nineties, told in 18 short chapters in two parts. His subsequent career pivot to documentary filmmaking only receives passing mention.

Given Nischk’s concern about biodiversity decline, and his desire to communicate to a broad audience why insects are fascinating and important, there is an irony to his undergraduate internship. He spent a year in the lab of Martin Dambach studying the aggregation behaviour of the German cockroach, Blattella germanica. By day, large groups of them bed down on their own excrement, likely attracted by pheromones released by the faeces. The irony? Nischk’s internship was funded by biotechnology giant Bayer which was hoping to isolate the chemicals responsible for putting the cockroaches in sleep mode to develop a pheromone-based cockroach trap: “the exterminator’s holy grail” (p. 25).

For his subsequent doctoral studies, Nischk got his conservation priorities in order. Staying with Dambach, he turned to crickets and spent time in Ecuador recording their songs. Next to discovering species new to science, this is his entry into the fascinating field of soundscape ecology or ecoacoustics. A small cadre of ecologists has been recording soundscapes of natural habitats. Bernie Krause (not mentioned here) is one particularly well-known example. By comparing recordings made years or decades apart they have shown how natural soundscapes are changing and often disappearing due to human encroachment. Others are hoping to train software to analyze recordings and identify species by their calls. If scaled up, the dream is to have passive acoustic monitoring stations in biodiversity hotspots around the globe.

“For his subsequent doctoral studies, Nischk […] spent time in Ecuador recording [cricket] songs. Next to discovering species new to science, this is his entry into the fascinating field of soundscape ecology.”

This backbone of his research is livened up with personal anecdotes and interesting asides. A friend’s call about a wasp infestation in her kitchen drawer is an excuse to introduce the 18th-century French entomologist Jean-Henri Fabre who was one of the first European naturalists to systematically collect and study butterflies, beetles, and wasps. Getting stung by a bullet ant in the rainforest of Ecuador leads to an aside about the late entomologist Justin O. Schmidt, the man who got stung for science (and wrote a fine book about it too). Tracking down a particularly loud cricket in Ecuador is the starting point for an unusual case where entomologists helped to defuse international political tensions between the USA and Cuba (this story has a surprising twist that I will not spoil here). A botched attempt to eradicate cockroaches that escape his experimental setup backfires most spectacularly, while fieldwork in the tropics is always fodder for amusing cultural misunderstandings and sober reflections. There is a nice mix here that never dwells on any one topic too long and makes for a book that is hard to put down.

The third and final part is, perhaps surprisingly, comparatively the weakest of the book. In four chapters Nischk muses on the biodiversity crisis, particularly the still poorly understood decline of insects, and discusses examples of individuals and organisations who are creating and protecting wildlife habitat. Probably most interesting are the little-known grassroots initiatives in Ecuador that are undertaken by villagers and farmers turning to ecotourism. But is this really the answer? Or does it merely perpetuate the idea that nature can only be protected if it has monetary value? You will not find a critical or comprehensive analysis of wildlife conservation here. There is also an odd focus on projects in the USA, e.g. the High Line in New York, the Xerces Society, Joan Maloof’s Old-Growth Forest Network, and the Yellowstone to Yukon Conservation Initiative. I wonder if this was added for the English translation. There is no mention of e.g. the European Natura 2000 network of protected areas or E.O. Wilson’s bold call to protect half the planet, and only passing mention of the German environmental organisation NABU or the practice of rewilding. Putting aside such nitpicking, none of this takes away from his genuine concern about the ongoing loss of biodiversity nor from his conclusion that the key to protecting species is protecting their habitat.

Overall, Of Cockroaches and Crickets is an amusing and light read that I devoured in a day. Nischk offers a nicely balanced blend of interesting natural history, amusing personal stories, and captivating scientific research. Whether it is flies, wasps, or rats, we need more books that celebrate those species we all too readily dismiss as pests.

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

Of Cockroaches and Crickets

Other recommended books mentioned in this review:

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2023 was a year in which I managed to read and review only 42 books. Yes, there were some really big books, but mostly this has been a year of intensification: reviews are becoming longer and I am taking many more notes while preparing them. A course correction seems in order as I would like to increase that number next year. Another development you might have noticed was several double-reviews, triptychs, and even a quartet. Increasingly often I find that new titles complement earlier books that I have on my shelves, unread. I am keen to learn more, dig deeper, and in the process hopefully provide useful context, so I plan to continue this habit next year.

What follows is my personal top 5 of the most impactful, most beautiful, and most thought-provoking books I read during 2023.

1. Radical by Nature: The Revolutionary Life of Alfred Russel Wallace

Princeton University Press published some smashing science biographies this year, several of which I still need to get around to, but Radical by Nature was hands down my favourite book of the year. Evolutionary biologist James T. Costa has written an in-depth, tremendously enjoyable, and updated biography that draws on intimate details gleaned from the Wallace Correspondence Project. As I have long wanted to read more about Alfred Russel Wallace, it marked the start of a three-part review. Read more…

2. Blue Machine: How the Ocean Shapes Our World

Oceanographer Helen Czerski’s new book, published by Transworld’s non-fiction imprint Torva, has been lauded by the press and it is not hard to see why. An engrossing odyssey into oceanography that oozes lyricism in places, Blue Machine is a captivating book about the liquid engine powering our planet. Read more…

3. The Age of Mammals: Nature, Development, & Paleontology in the Long Nineteenth Century

The University of Pittsburgh Press seems to have had a major shake-up of its biology roster as a large number of fascinating titles flowed from the press this year. Chief amongst them was science historian Chris Manias’s book The Age of Mammals. Admittedly a more obscure and academic topic, this wide-ranging and serious intellectual history shows that you cannot understand the history of palaeontology without considering mammals. Read more…

4. The Value of a Whale: On the Illusions of Green Capitalism

Published last year by Manchester University Press, and part of an expanding list of highly critical books, researcher and analyst Adrienne Buller’s The Value of a Whale is a shocking and necessary corrective to the green capitalist solutions being peddled to address climate change. Read more…

5. Crossings: How Road Ecology Is Shaping the Future of Our Planet

When I learned that environmental journalist Ben Goldfarb had just written a new book, I knew this was going to be good. Published by W.W. Norton during their centenary year, Crossings is a globetrotting, wide-ranging, and eye-opening reportage on the impacts of roads and how ecologists are trying to mitigate them. Read more…

If you are looking for more recommendations, do check out my earlier top 5s. Or browse the archive which lists all reviews where, newly added this year, you will notice separate subject archives and a cover gallery.

As the invisible glue that holds the world together, microbes might well be some of the most underappreciated life forms on our planet. While the previous review of The Curious World of Bacteria dealt with “the who” by discussing fifty noteworthy bacteria, Invisible Friends deals with “the what and how” by discussing the many beneficial and vital roles microbes play in our lives. This is an enthusiastic and hopeful romp through microbiology that encourages readers to rethink their relationship with nature and see themselves as embedded in it. Keep your critical thinking caps at hand though, as the book gets starry-eyed in places.

Invisible Friends: How Microbes Shape our Lives and the World around Us, written by Jake M. Robinson, published by Pelagic Publishing in March 2023 (hardback, 290 pages)

Microbial ecologist Jake M. Robinson is a man on a mission: to challenge our negative perception of microbes and to encourage people to rethink their place in nature by showing how, when it comes down to it, microbes run the show. As used here, microbes encompass not just bacteria but also fungi, algae, viruses, archaea, and protozoa. I expected coverage of the microbiome, and Robinson indeed discusses the ecosystem of invisible organisms that live in and on us. One chapter in particular delves into the microbiota-gut-brain axis, i.e. how our diet affects our gut flora, how our gut flora communicates with our brains, and how this whole ensemble influences our physical and mental health. Now, this topic has already been thoroughly explored by other popular science writers, notably Ed Yong. Fortunately, Robinson considers many other topics and does so in a chatty and conversational tone. Some ideas I previously encountered in Planet of Microbes, but much of it was both novel and eye-opening.

Let me give you some examples of topics I thoroughly enjoyed. I was familiar with one formulation of the hygiene hypothesis: the idea that we have weakened our immune system through the constant indoor use of household cleaners and disinfectants. An interview with immunologist Graham Rook discusses how this hypothesis morphed over time and why he thinks it does not stack up. He instead proposes that our indoor environments are lacking the so-called “old friends” found outdoors that humans evolved in symbiosis with. In their absence, opportunistic bacteria can more easily overwhelm us. Meanwhile, growing up without sufficient exposure to outdoor environments does not properly train our immune system, leading to an increased risk of allergies or even autoimmune diseases as an adult. Another intriguing idea is that microbes impact our behaviour and decisions. Robinson has argued in print that our microbiome might influence our decisions to spend time in certain environments favourable to these microbes, while some of our impulsive behaviours could be driven by “our microbial puppet masters” (p. 98). Or what about the prospects of forensic microbiology? Microbes left behind at a crime scene could be linked to specific places and people, potentially identifying perpetrators, or revealing the cause of death. He admits more research is needed to ground truth these methods, but I would argue that the field of forensic entomology offers a noteworthy precedent, while two forensic botanists have previously written about their use of microscopic plant remains to solve crimes.

“Robinson considers many […] topics and does so in a chatty and conversational tone. Some ideas I previously encountered […] but much of it was both novel and eye-opening.”

However, other topics fall into the “sure, but” category where I find Robinson is not critical enough and becomes optimistic to the point of being starry-eyed. He is enthusiastic about the idea of getting people outdoors and in contact with health-promoting microbes through e.g. community gardens. Sure, I do not want to downplay the benefits, but he does not mention that urban agriculture has been criticized for in practice not producing much food and being a boutique hobby for well-off urbanites. (For instance, this 2019 article in Anthropocene Magazine reporting on a case study in New York City, and this 2016 Vox article highlighting findings from a report by the Center for a Livable Future at Johns Hopkins University.)

Robinson furthermore visits a farm practising regenerative agriculture which puts soil health, and thus soil microbes, above all else. Sure, conventional agriculture does much environmental harm in the name of feeding people, but he glosses over important details. George Monbiot’s book Regenesis critically asked whether this kind of farming has comparable yields and highlighted there is little land left that we can still bring under cultivation. He also does not challenge the farmer who claims to grow “delicious chemical-free vegetables” and use “all-natural matter, soil and compost” (p. 127). This is surprising; as a microbiologist, Robinson understands that food is nothing but (bio)chemistry. I am sure this farmer means he avoids synthetic pesticides, but this kind of sloppy language has the appeal-to-nature fallacy written all over it. One notable gaffe is that Robinson supports the idea that modern food is less nutritious by claiming (p. 126) that today’s apples contain 26 times less iron than those in 1940—only to then in an endnote (p. 252) immediately add that he could not verify this claim. Next to this idea having been questioned (see also this paywalled New Scientist article), throwing in unverified claims is just bad science writing—the risk of readers missing that asterisk and the book perpetuating potential misinformation is high. No need to add to the noise already out there.

Fortunately, this seems to be an isolated incident. Robinson thinks more critically when discussing bio-integrated design, i.e. the use of microbes in architecture. Could algae be used to create buildings that can purify the air? Possibly—others have highlighted these miraculous plants—but “ideally, we should be focusing on reducing the pollution at the source” (p. 156). Many design firms hype the idea of e.g. making bricks out of fungi, but Robinson does not comment on whether such solutions can be scaled up beyond prototypes. Plus, if you mention biodegradable buildings, why overlook traditional practices such as mud or wattle and daub?

“[…] here is someone of boundless enthusiasm constantly throwing out new ideas. Not all of these will necessarily stick, but, arguably, we need creative minds to inspire new directions in research.”

Somewhere on page 165, Robinson jokes about churning out conference posters with new research ideas in the hopes of attracting a rich benefactor. I think this explains some of my criticism: here is someone of boundless enthusiasm constantly throwing out new ideas. Not all of these will necessarily stick, but, arguably, we need creative minds to inspire new directions in research.

Finally, it is worth mentioning Robinson has a progressive outlook. He discusses issues around social equity: poor people and minorities frequently have less easy access to healthy, biodiverse environments. He highlights where indigenous cultures have held ideas that modern science is now verifying and is especially keen to draw lessons from their holistic worldviews that see humans as an integrated part of nature. Research on the microbiome and its link to human health and well-being resonates with such ideas. His last chapter considers how we can rekindle our relationship with nature through e.g. mindful outdoor activities such as forest bathing—while being exposed to a healthy dose of outdoor microbes.

Overall then, Invisible Friends is interesting, optimistic, and hopeful, but also speculative in places. Does it succeed in making you reconsider your place in nature? Sure, but readers are advised to keep their critical thinking caps on.

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

Invisible Friends

Other recommended books mentioned in this review:

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For many people, parasites top the list of nature’s most unwanted creatures. For biologists, however, they offer a window into the ecology and evolution of their hosts, while a full understanding of an ecosystem needs to take its parasite fauna into account. Parasites: The Inside Story offers an engrossing and well-illustrated introduction to some of these processes. However, the brevity of the chapters and the input from three authors does turn this into a bit of a medley that might leave readers wanting more.

Parasites: The Inside Story, written by Scott Lyell Gardner, Judy Diamond, and Gabor R Rácz, published by Princeton University Press in January 2023 (hardback, 205 pages)

This book has resulted from a collaboration between three authors. Curator of parasites Scott L. Gardner and parasitologist Gabor Rácz both work at the H. W. Manter Laboratory of Parasitology at the University of Nebraska State Museum where Judy Diamond is a professor and curator. Between them, they have written thirteen short chapters divided over three parts and serve up a parasitical potpourri of interesting studies and findings. Fortunately, they avoid going for the low-hanging fruit of presenting stories to gross you out.

In the first part, they discuss the human burden of various nasty diseases, including a chapter on the discovery and treatment of river blindness. But this book is not a compendium of unpleasant human infections. Equally interesting is what parasites can reveal about for example past human migrations, such as the peopling of the Americas during the last ice age. It is widely accepted that humans migrated across the Bering Land Bridge from Asia into North America. But could some people separately have crossed the Pacific by boat and landed in South America? The authors here mention that genetic analysis of parasites recovered from coprolites (fossilized faeces) shows different parasite communities in different places. Some of these include cold-sensitive hookworms, which would support the idea that not all settlers in the Americas arrived via the frozen northern route.

“[The authors] serve up a parasitical potpourri of interesting studies and findings. Fortunately, they avoid going for the low-hanging fruit of presenting stories to gross you out.”

Humans are not the only victims; parasites are found all over the tree of life and some of the most fascinating and well-written chapters follow in the second part. I never thought I would write these words, but I have a renewed respect for tapeworms. Generally, biologists think that parasites and hosts evolve in lockstep in a process of co-evolution, but studies on the tapeworms of seabirds reveal a far deeper evolutionary history, stretching back in time some 300 million years. “Like old wine in new bottles, the parasites were vastly older than their seabird hosts” (p. 50). These parasite ancestors might have lived in ancient fish, marine reptiles, or pterosaurs. Meanwhile, when whales returned to the sea, it seems their parasites did not come along during this evolutionary transition. None of their current parasites has a recent common ancestor found in land mammals. I simply have never really given much thought to the intersection of parasitology and phylogenetics, but the authors have piqued my interest. The other fun side of parasites is the direct manipulation of host behaviour, frequently in an attempt to be passed on to the next host in their lifecycle. From slugs whose eyestalks puff up and pulsate—something birds find irresistible—after infection with the fluke Leucochloridium variae to ants who turn “into a nightly automaton” (p. 67) and climb up grass stalks at night^[1] waiting to be eaten by deer after infection with the fluke Dicrocoelium dendriticum—these stories are guaranteed to be a hit at your next dinner party.

The last part of the book, which focuses on research done by parasitologists today, often in remote locations, continues the theme of avoiding simple war stories and instead presenting fascinating science. Next to parasites influencing animal behaviour, the reverse is also true, and animal ecology and behaviour intersect with parasitology. For example, pocket gophers and grasshopper mice in the Nebraska Sandhills ecosystem do not share parasites despite sharing the same burrows. However, in South America, the burrow-sharing tuco-tucos (a rodent) and pink fairy armadillos do. Understanding why requires detailed knowledge of the ecology of the hosts and parasites involved, but it seems that the former example resembles one of “next door neighbours with different job schedules” (p. 101). Of course, given their close relationship, hosts and parasites co-evolve, engaged in an endless arms race in which each gain achieved by the parasite invites a countermove from the host. I appreciated, though, how the authors earlier on point out that “host-parasite relationships are less a victory between contestants than a compromise in which both parties meet their survival needs to some degree” (p. 43). Consider, also, that parasites face double the evolutionary challenge as their success depends not just on their own adaptations but also those of the host. “Choose a host on its way to extinction, and that could be the end of the parasite. The ability to switch hosts is a great insurance policy against ending up with a dud for a host” (p. 11). Admittedly, host switching is not without risks and challenges, but some of the abovementioned examples reveal that certain parasites have succeeded.

“I never thought I would write these words, but I have a renewed respect for tapeworms.”

These three parts are generously padded out with extra material, setting an example for the kind of attention I wish more publishers would lavish on popular academic titles. Most chapters contain a full-page illustration of the lifecycle of a particular parasite drawn by graphic artist Brenda Lee. Add to this 16 unpaginated plates containing 29 colour photos, an 18-page illustrated appendix to the parasites mentioned in the text (consider it a parasite bestiary), a 13-page glossary, and a 32-page bibliography, altogether making up just under half of the book. And herein lies perhaps the book’s greatest weakness: it really is quite short. With three authors writing thirteen chapters in only 118 pages, and chapters being 6–11 pages each, they are spreading their material thin. There are really interesting ideas covered here but the book goes off in so many directions at once that it risks losing coherence a bit and I would have loved to see certain topics expanded more. The matter of authorship is also unclear. There are noticeable stylistic differences between some chapters, but who wrote what chapter, or whether they were all co-written by everyone is not mentioned. Finally, the text does not refer you to the plates, nor does it insert references to the generous bibliography. You will have to do some searching if you want to follow up on the studies described in the text.

Parasites: The Inside Story is thus a very readable, interesting, and well-presented introduction to the often overlooked evolutionary and ecological aspects of host-parasite interactions. As an introduction to parasitology, this will likely whet your appetite, though be warned that it might leave you hungry for more.

1. ↑ This is very reminiscent of, but not to be confused with, the zombie ants that climb to a high point, clamp down, and die after infection with Ophiocordyceps fungi.

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

Parasites

Other recommended books mentioned in this review:

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If you had asked me last week how animals and plants will respond to climate change, I probably would have told you that they are expected to move towards the poles, shifting their home ranges as temperatures rise. This is indeed one possible response, but the challenges and opportunities for organisms are far more diverse and unpredictable. Biologist Thor Hanson has previously written much-praised books on feathers, seeds, and bees. Here, he gives a well-structured and terribly interesting whistle-stop tour of the nascent field of climate change biology and some of the fascinating research that is underway.

Hurricane Lizards and Plastic Squid: How the Natural World is Adapting to Climate Change, written by Thor Hanson, published by in Europe by Icon Books in February 2022 (hardback, 281 pages)

Part of what makes Hurricane Lizards and Plastic Squid a very readable book is its logical organisation. Hanson sets the stage with the history of our discovery that the world was not constant but subject to change, and the discovery of carbon dioxide. But the book revolves around the challenges that organisms face, their responses, and the results. All three hold diverse surprises. To flesh out this framework, each chapter discusses several examples of exciting research, glued together with autobiographical anecdotes.

As the climate changes, so does the timing of seasonal events (the study of which is known as phenology). When for instance plants flower earlier, pollinators might still be absent or in hibernation. Increasingly, species “find themselves in the right places at the wrong times” (p. 39). Rising temperatures can push animals to the edge of their comfort zone, and work on lizards shows they spend more time sheltering to avoid overheating, which is time not spent foraging. Work by Drew Harvell and colleagues on starfish has shown that heat pulses can encourage disease outbreaks, contributing to marine epidemics. On land, forests in North America and Canada are suffering from one of the largest insect outbreaks in history, with bark beetles moving north almost unimpeded. Thousands of species are on the move, though rarely at the same speed or even in the same direction, making the situation so chaotic as to be unpredictable. Biologists have started talking of global weirding as whole ecosystems are now unravelling and rearranging themselves, challenging both the species remaining behind and the invaders trying to settle into new environments. Part of the reason that organisms move is that certain requirements in their habitat are no longer met and research on various mollusc species reveals how they struggle to build, maintain, and repair their shells as the oceans absorb carbon dioxide and acidify.

“Thousands of species are on the move, though rarely at the same speed or even in the same direction […] Biologists have started talking of global weirding as whole ecosystems are now unravelling and rearranging themselves”

But all is not lost, “nature is not defenseless” (p. 82). Plants and animals can and do respond, and biologists often summarize it with the acronym MAD: Move, Adapt, or Die. Though, as Hanson goes on to show, that rather undersells it. Earlier chapters already discussed moving as a response, and populations can redistribute themselves surprisingly quickly. Even trees move, a story which has a fascinating deep-time component not mentioned here. However, there are limits to how far polewards or upslope you can go. Near the top of both you run out of habitat, and work on mountain top specialists amongst birds has demonstrated species winking out of existence. Other species, the plastic squid of the book’s title, are incredibly flexible, whether in their behaviour or morphology. Humboldt squid in the Gulf of California seemingly disappeared in response to heat stress, until scientists realised they matured in half the normal time, staying much smaller as a result. There is also some delightful work described here on the titular hurricane lizards that documented an evolutionary response in Caribbean anole lizards in the wake of hurricanes, involving both long-term meteorological data and a leaf blower. Hanson’s chapter on refugia is absolutely fascinating. There are places where stable microclimates allow plants and animals to hunker down and ride out the storm, with sites in Europe and North America still harbouring survivors from the last ice age. “Modern climate change may have shifted that process into high gear, but the pattern is an ancient one” (p. 146), Hanson adds.

As the book progresses, Hanson managed to draw me in further with ever more fascinating ideas and clever explanations. I was sold on his pitch for the final part of the book where he explores the results from the interplay of challenges and responses. He covers the “potentials and pitfalls of prognostication, how models are made, how surprises are certain, and how the clearest sign of what to expect may lie in what has already happened” (p. 151). He nimbly explains the concept and history of the Holdridge Life Zone System. This has become a staple of ecology textbooks that combines certain climate variables to predict vegetation and habitat conditions and has been ground-truthed and refined over the decades. But model predictions can mislead, and checking what actually happens on the ground can give surprising insights. The little auk is a bird species that lives near the North Pole and feeds at the edge of the ice shelf. It was predicted to follow the retreating ice northwards, but instead has turned to a new local food source: zooplankton shocked to death by freshwater pulses from melting glaciers. Joshua trees, meanwhile, are an evolutionary anachronism, “haunted and hampered by the past” (p. 185). They cannot spread northwards because our ancestors extirpated their seed disperser, the giant ground sloth. And in what seems to be applied lessons lifted straight from Felisa Smith’s textbook Mammalian Paleoecology, Hanson discusses what the past can reveal, because “while the drivers of this episode may be different […] climate change is nothing new” (p. 187). He delves (literally) into the value of packrat middens (thanks to Smith, these fossilised refuse heaps encased in crystallized rat pee were my favourite discovery of 2022) and discusses the relevance of the Paleocene-Eocene Thermal Maximum as the best past analogue for what is in store for us.

“As the book progresses, Hanson managed to draw me in further with ever more fascinating ideas and clever explanations. I was sold on his pitch for the final part of the book where he explores the results from the interplay of challenges and responses.”

Given that this book is a whistle-stop tour of climate change biology, it is inevitable that some topics are not explored. Fortunately, other books pick up that slack, with e.g. Greenhouse Planet discussing what all that extra atmospheric carbon dioxide means for plant growth. And Hanson only dips his toes into the impact of climate change on humans by referencing a smidge of environmental history (specifically the impact of the Little Ice Age) and pointing out that our responses today often mirror those of animals and plants. Gaia Vince, for example, has just published a major book on climate change-related migration.

It has been a few years since I reviewed Hanson’s last book and I am embarrassed to admit that I forgot just how captivating and accessible his writing is. An enthusiastic science communicator, he seems to have the enviable ability to find researchers working on underreported topics and get them to spill their beans. Hanson effortlessly combines accessible reporting with insights into fundamental biological and climatological processes. To this, he adds a spoonful of endearing personal anecdotes to make for a delightfully smooth introduction to climate change biology.

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

Hurricane Lizards and Plastic Squid

Other recommended books mentioned in this review:

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2022 was a year in which I went down a few rabbit holes with really big books that took a lot of my time. As such, I read and reviewed 52 books this year.

What follows is my personal top 5 of the most impactful, most beautiful, and most thought-provoking books I read during 2022.

1. Otherlands: A World in the Making

This kills me. I prematurely awarded Steve Brusatte a place in my top 5 for his fantastic The Rise and Reign of the Mammals but Thomas Halliday’s debut with publisher Allen Lane, Otherlands, inched him out. The awards and praise heaped on this book are well deserved. This is a spellbinding tour of extinct worlds while its carefully crafted yet poetic reflections on evolution and deep time are a masterclass in science communication. Read more…

2. An Immense World: How Animal Senses Reveal the Hidden Realms Around Us

As I was drafting this post, Ed Yong’s newsletter announced that this book has already been featured on 38 end-of-year lists. Well, make that 39. Taking some downtime from reporting on the COVID-19 pandemic for The Atlantic, Yong returned to publisher The Bodley Head and churned out An Immense World, a book on how animals perceive the world that had me so utterly captivated I did not want it to end. Read more…

3. The Ocean’s Whistleblower: The Remarkable Life and Work of Daniel Pauly

Originally published in French, Greystone Books did the world a favour by translating David Grémillet’s outstanding biography of marine biologist Daniel Pauly. The Ocean’s Whistleblower impresses with its balanced coverage, thorough research, and excellent science communication. Read more…

4. Mammalian Paleoecology: Using the Past to Study the Present

Johns Hopkins University Press surprised this year with the advanced-level text Mammalian Paleoecology. Not sure what palaeoecology is? Ecologist and evolutionary biologist Felisa A. Smith provides the reader with a neatly crafted package that gives you all the required background knowledge before delivering satisfying payoffs at the end. To find out why packrat middens are my new favourite discovery, read more…

5. The Guests of Ants: How Myrmecophiles Interact with Their Hosts

Ants make it to my top 5 for the third year running. Harvard University Press has built a reputation for publishing stellar books on ants and The Guests of Ants joins that line-up. Veteran entomologist Bert Hölldobler and Christina L. Kwapich have written a beautifully illustrated, wide-ranging, and critical literature review of myrmecophiles: the many creatures that make their home in and around ant nests. Read more…

If you are looking for more recommendations, do check out my top 5s for 2021, 2020 and 2019. Or browse the archive listing all reviews.

It has to be one of the more delightful details of the natural world: the ecosystem of an ant’s nest is home to its own constellation of creatures that specialise in living within or nearby it. Daniel Kronauer’s book Army Ants first drew my attention to these so-called myrmecophiles and their sometimes bizarre adaptations. I was stoked when Harvard University Press announced it would publish a monograph focusing on just this aspect of ant biology, authored by entomology professors Bert Hölldobler (a frequent co-author to E.O. Wilson) and Christina L. Kwapich. The Guests of Ants gives a beautifully illustrated, wide-ranging, and critical literature review of this delightful corner of myrmecology. Will ants make it to my personal top 5 for a third-year running? This book is a very strong contender.

The Guests of Ants: How Myrmecophiles Interact with Their Hosts, written by Bert Hölldobler and Christina L. Kwapich, published by Belknap Press (a Harvard University Press imprint) in July 2022 (hardback, 559 pages)

Before delving in, a quick word on what is not in the book. Excluded are the large topic of interactions between ants and plants, the subject of trophobiosis (i.e. the bugs and some butterflies that provide honeydew to ants and in return are protected by them), and the hundreds of socially parasitic ant species that exploit other ants^[1]. This book is also not an exhaustive listing of all known myrmecophiles, as done in review papers and books such as Parasites in Social Insects and The Ants. Instead, Hölldobler & Kwapich use numerous examples to review the behavioural mechanisms by which myrmecophiles coexist and often exploit their hosts. How do they break the internal communication codes that otherwise make ants such a successful superorganism? This self-imposed limitation nevertheless leaves plenty of material and the first thing that will strike you is the book’s sheer size. Measuring some 24 × 24.5 cm it is as big as Army Ants, though it is a good deal thicker. What it shares is that it is chock-a-block with glorious macro-photography. The acknowledgements thank no fewer than 84 people for providing (mostly) photos and illustrations and the book is a feast for the eyes.

So who are these guests? Beyond two chapters on the really small (bacteria, internal parasites, and fungi such as crowd-pleaser Ophiocordyceps) and the really large (vertebrates including birds, lizards, and amphibians), most myrmecophiles are arthropods. Some flies and beetles rely on chemical mimicry to blend in and e.g. hitch a ride on ant bodies, lay their eggs inside the protected environment of ant nests, or forage here for detritus and ant corpses. Caterpillars of lycaenid butterflies possess glands that secrete so-called appeasement substances, allowing them to live amidst ants as mutualists, parasites, or even predators. Refuse sites inside the nest, and foraging trails outside it, host numerous beetles and flies that steal booty and prey the ants bring home, or attack the ants directly. Crickets behave as thieves, technically as kleptoparasites. Using a mixture of chemical stimuli, such as odours, and tactile stimuli, such as antennae and mouthparts with which they tickle ants, they either get ants to regurgitate liquid food for them (as seen on the book’s cover) or get in between two ants practicising what biologists call trophallaxis, the transfer of food between each other. But the most mind-blowing chapter showcases the unbelievable morphological and behavioural mimicry of certain spiders. Some spiders, as they grow larger, resemble different ant species in turn. Other spiders use parts of their body such as chelicerae (mouth parts) and fold these in front of their heads to resemble an ant carrying a nestmate.

“Hölldobler & Kwapich use numerous examples to review the behavioural mechanisms by which myrmecophiles coexist and often exploit their hosts.”

The above is just a small selection of a mind-bogglingly diverse cast of myrmecophiles. Two further chapters focus more on underlying explanations. One looks at a possible evolutionary pathway that explains how free-living insects became fully integrated into ant nests, illustrating it through studies on different rove beetles. The other chapter looks at various ant ecosystems and their guests, including harvest ants, wood ants, and army ants. It also discusses studies that have tried to apply network analyses to document foodweb interactions (i.e. myrmecophiles eating ants and each other), and studies that have looked at links between colony traits, such as genetic diversity, and rates of myrmecophile infestation.

A few things struck me in particular about this book. First is the amount of detail. The authors thoroughly show just how diverse are myrmecophiles and the ways in which they trick ants. If I have to sound a critical note, it is that, though the individual chapters are organised around themes, I was missing a final chapter to tie it together and provide some sort of overview or tabulation. The bewildering diversity, fascinating as it is, now remains just that: bewildering. But perhaps that is the nature of the beast. Second was a fascinating lesson on cuticular hydrocarbons. These are carbon-and-hydrogen-containing chemicals that insects sport on their outer layer, their cuticle, as a kind of chemical signature. You would think that mimicking or acquiring cuticular hydrocarbons is key for myrmecophiles to be accepted or ignored by ants, rather than attacked and killed. But numerous studies have thrown up conflicting results: “we have to guard against a hasty conclusion that the hydrocarbon match represents the effective mechanism for the acceptance of myrmecophiles by their hosts” (p. 147). Other chemicals as well as behaviour seem to play an overriding role in some species. Third and final was a welcome critical attitude from the authors in their review. They frequently point out shortcomings in experimental protocols, comment on the appropriateness of certain methods, and tone down sweeping conclusions. None of this is mean-spirited but is done to encourage rigorous experimental protocols. The ecosystem of ants and their guests is incredibly complex and studying them is hard; drawing firm conclusions requires excluding alternative explanations.

The Guests of Ants is a must for myrmecologists and entomologists, but also more generally for biologists with an interest in social insects and insect ecology. The book provides a welcome entry point into a remarkably rich literature (45 pages of references are provided). The work is detailed and fairly, but not overtly, technical; effectively this is at the level of a series of literature reviews as one might find in e.g. Trends in Ecology & Evolution. There is nothing here that avocational entomologists or an interested lay audience could not handle, with a 14-page glossary taking care of technical terms. For my part, I have to congratulate the publisher for producing yet another exquisitely presented, in-depth monograph on ants that highlights a thoroughly engrossing aspect of these fascinating insects.

1. ↑ Regarding that last group, the authors write that “this is an exciting field in evolutionary myrmecology, which awaits coverage in a separate volume” (p. 479). Oh my, should I interpret this as them saying this deserves a dedicated book, or, more tantalizing, that this is something they are working on? How exciting would that be!

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

The Guests of Ants

Other recommended books mentioned in this review:

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