Stephen Jay Gould (1941–2002) was a well-known evolutionary biologist, palaeontologist, and science populariser. Amongst his many achievements stand the 300 popular essays that appeared from 1974 to 2001 in the magazine Natural History, published by the American Museum of Natural History. Many of these were collected in bestselling volumes that have been reprinted repeatedly. To celebrate this legacy of essays, his friends and close colleagues Bruce S. Lieberman and Niles Eldredge, themselves evolutionary biologists and palaeontologists of considerable renown, here present thirteen of their own essays that do exactly what the subtitle promises. They entertain as often as they intrigue in a collection that draws serious and, looking at the chapter titles, sometimes not-so-serious connections between macroevolution and palaeontology on the one hand, and popular culture, philosophy, and the history of science on the other. To my shame, I have to admit that I have never read Gould’s essays or his many books (while having several on my shelves). Macroevolutionaries convinced me that this gap in my knowledge needs closing.

Macroevolutionaries: Reflections on Natural History, Paleontology, and Stephen Jay Gould, written by Bruce S. Lieberman and Niles Eldredge, published by Columbia University Press in September 2024 (hardback, 216 pages)

Despite being a towering intellectual figure, or perhaps because of it, there is no book-length biography of Gould as far as I know. However, over the years, books have reflected on his intellectual life, his political views, his humanism, and (still forthcoming) his criticism of biases in science. Macroevolutionaries is similarly not a biography but adds to this growing body of work engaging with Gould’s views. Furthermore, the book is also not an uncritical celebration of Gould. Though they respected him greatly and will defend him where they feel he is no longer given the credit he is due, “that doesn’t mean that we agreed with him on each and every last thing” (p. 40). They rather candidly write that he sometimes went solo and modified ideas cooked up with others, in the process “getting more than his share of the credit and attention” (p. 7).

This characterisation of Macroevolutionaries as neither biography nor hagiography also extends to the essays themselves. Not all of them invoke Gould, instead standing on their own two feet. The essay Expanding Evolution: Organisms and Species, the Soma, and the Technosphere explores how the logic underlying evolution by natural selection can be expanded to e.g. cancer cells (somatic evolution) and material culture (technospheric evolution). Eldredge here draws on his passion for musical instruments by exploring “convergent evolution” between trumpets and cornets, a by now similar-looking instrument. In Darwin in the Galápagos: Running the Beagle Tape Backward, Eldredge provides an answer to an intriguing thought experiment a historian once put to him: would Darwin have come up with the same ideas had his trip on the Beagle happened in reverse, with the Galápagos being the first port of call? Eldredge thinks not and highlights key observations Darwin made during his trip that changed his initial views on transmutation: “there were things Darwin needed to see first to comprehend the significance of what he would see in the Galápagos in August 1835” (p. 147).

“This characterisation of Macroevolutionaries as neither biography nor hagiography also extends to the essays themselves. Not all of them invoke Gould, instead standing on their own two feet.

Other essays do engage explicitly with Gould’s ideas. A recurrent touchstone is the theory of punctuated equilibria that Gould and Eldredge developed in a 1972 paper (drawing on earlier work by Eldredge): the idea that speciation in the fossil record alternates between long periods of stasis and periods of abrupt change. This contrasted with Darwin’s original view of slow and steady change. How do such long periods of evolutionary stasis come about? In their essay, the authors point out how Gould initially argued for the importance of developmental constraints, though he later downplayed their role. Punctuated equilibria is such an influential idea that Belknap Press posthumously reprinted the long chapter on it in Gould’s magnum opus as a separate book in 2007, notably only with Gould’s name on it; Eldredge wrote about the conception of the idea separately in his 1985 Time Frames.

Gould is similarly famous for his thought experiment of “replaying the tape of life” and asking whether the outcome would be the same (an idea that has come up here in previous reviews). He answered “no” and in the process made a case for the importance of contingencies in the history of life. What I did not realise, and the authors here clarify, is how Gould’s views on the relative importance of contingency and natural laws swung back and forth over the course of his career. One more example of engagement with Gould’s ideas will have to do. When Is a Raptor a Parrot? The Curious Case of the American Kestrel starts as an essay about bird phylogeny before pivoting to Gould & Lewontin’s famous spandrels paper and Gould & Vrba’s exaptation paper. In these, Gould and colleagues argued against adaptationist explanations for every single trait an organism shows, while proposing a new term (exaptation instead of adaptation) for traits that initially evolved in one context or were neutral, and were later coopted in another context.

“A second strong component in this collection is the history of science; an area that is relevant as it also interested Gould.

A second strong component in this collection is the history of science; an area that is relevant as it also interested Gould. In several essays, the intellectual movers and shakers that influenced Darwin come up, notably Giambattista Brocchi, Georges Cuvier, and Jean-Baptiste Lamarck. Brocchi had some ideas about sudden evolutionary transitions that lined up nicely with punctuated equilibria. Cuvier championed catastrophism and species extinction^[1]. And Lamarck was at loggerheads with Cuvier by arguing for slow and gradual change of species. The authors contend that he, rather than Lyell, should be credited for influencing Darwin’s gradualist take on evolution. Elsewhere, Eldredge has at length sought a rehabilitation of Lamarck and here reiterates this. “We grew up hearing the same sort of smack about Lamarck that is still au courant [but] Lamarck was Darwin’s hero, and not the Darwinian anti-hero we were taught to believe” (pp. 57–58). Fascinating, too, was the essay Of Cultural Nationalism, Hamlet, and the Cloaca Universalis: Why Citation is the Best Policy that wonders out loud why Charles Lyell is venerated as the father of geology when in his time he had a reputation for blatant plagiarism.

These are but some of the major themes in these intriguing essays. Take it from me that there are others—it’s a worthwhile collection. Overall, the essays are very readable and often rather informal in tone: the authors are on first-name terms with many people and Gould is praised as “bloody brilliant” (p. 13), “we respect the dude a lot” (p. 40), and (together with Lewontin) given “mad props and kudos” (p. 176) for the audacious title of their spandrels paper. Occasionally, the authors swerve into rather verbose writing that had me reach for the dictionary. Similarly, the significance of certain references to US-specific lore and history (e.g. stuntman Super Dave or journalist Walter Winchell), while briefly explained, might be lost on an international audience.

Readers who miss Gould’s essays or are enthralled by his ideas are warmly recommended to pick up a copy of Macroevolutionaries. Lieberman & Eldredge celebrate his legacy while writing fine essays that can stand on their own two feet. For me, this collection additionally highlighted a gap in my knowledge (and on my shelves) that I intend to fill while reminding me that I have unread books by both Gould and Eldredge that I should carve out time for.

1. ↑ Mind you, mass extinctions were not fashionable yet: one essay highlights the role of Gould’s mentor Norman Newell in making this idea more palatable.

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

Macroevolutionaries

Other recommended books mentioned in this review:

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Gould’s collected Essays On Natural History:

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Having just reviewed James T. Costa’s biography of Victorian naturalist Alfred Russel Wallace, I was keen to read more about one of the most remarkable episodes in the history of science: how two scholars independently hit on the same idea and how history has largely forgotten one of them. Wallace, Darwin, and the Origin of Species brings together many lines of evidence and analysis to argue that Wallace deserves recognition on the same footing as Charles Darwin as the co-discoverer of evolution by natural selection. This is a companion book to On the Organic Law of Change, presenting an analysis of this crucial notebook that Wallace kept during his travels around the Malay archipelago. Hence, you are getting a two-for-one as this review continues the previous one.

Wallace, Darwin, and the Origin of Species, written by James T. Costa, published by Harvard University Press in June 2014 (hardback, 331 pages)

Now that you know what Wallace’s Species Notebook contains and why it is interesting, Costa here steps back to look at the bigger picture. One thing that Darwin and Wallace shared was that their arguments were consilient. Coined by 19th-century philosopher William Whewell as “consilience of inductions”, what this means is that they were drawing together many independent lines of evidence to build a convincing argument. It is a powerful way of reasoning and the stuff sound scientific theories are made of. Appropriately, I think Costa applies the same logic in this book, looking at this historical episode from many different sides.

Costa sets the scene by describing why Wallace travelled to the Amazon and the Malay archipelago, who his influences were, and what discoveries and publications his journeys produced. Two papers are of particular importance and are explored further here. Instead of their ornate Victorian titles, science historians refer to them as the Sarawak Law paper (1855) and Ternate essay (1858). In (very) brief, these papers respectively proposed that species change and how species change. Remember that this was when most naturalists, including prominently geologist Charles Lyell, were opposed to transmutation (as evolution was called), maintaining that species were divinely created, unchanging entities. In that sense, Wallace’s Species Notebook is a goldmine of the unpublished arguments he was considering and Costa’s analysis expands on the appendix in On the Organic Law of Change which only considered Wallace’s critique of Lyell.

The superficial narrative that Wallace and Darwin hit on the same idea at the same time is just that: superficial. To refine this story, Costa next compares the Species Notebook with Darwin’s On the Origin of Species (Origin hereafter), his pre-Origin notebooks, and his Natural Selection manuscript^[1]. True, there are striking similarities in their conclusions and how they reached them, but there are also notable differences. Similarly, hindsight has compressed the timeline. Darwin had it figured out 21 years before Wallace but only shared his ideas with a few confidants, possibly made headshy by the strong condemnation of Robert Chamber’s book Vestiges of the Natural History of Creation. Thus, their discovery of natural selection was contemporaneous, but not simultaneous; and it was similar, but not the same. Costa drives home these points because they are “an important first step toward realizing the independent nature of their respective insights” (p. 107).

“One thing that Darwin and Wallace shared was that their arguments were consilient. […] Appropriately, I think Costa applies the same logic in this book, looking at this historical episode from many different sides.”

Until 1857, Darwin and Wallace were unaware of each other’s thoughts on evolution but that would soon change. Darwin did not attach much importance to the 1855 Sarawak Law paper though at Lyell’s urging had started writing his Natural Selection manuscript. This would have become his big book until Wallace unintentionally forced his hand. First contact happened in April 1857 with a letter from Wallace, telling Darwin about his ideas on species change. Darwin sent an encouraging reply, noting they were thinking along the same lines and, “Oh, by the way”, he had been working on the species question for 20 years already and was making good progress on a book. In Radical by Nature, Costa brilliantly summarised what happened next: “If Darwin had a plan, it backfired” (p. 212 therein). By February 1858, Wallace had had his great insight, penned his Ternate essay, and enthusiastically replied to Darwin, attaching the essay with the request to forward it to Lyell if Darwin thought it had merit. When Darwin received this in June 1858 he was shocked, sending several anguished letters to Lyell. He had been scooped! He did not want to see years of hard work go to waste, but how could he possibly publish honourably at this point? In response, Lyell, together with Darwin’s other confidant botanist Joseph Dalton Hooker, quickly organised the famous July 1st 1858 meeting at the Linnean Society.

To analyse this episode, Costa switches gears again and presents annotated facsimiles of all the key papers: the Sarawak Law paper and the papers read at the 1858 meeting; Darwin’s hastily written extracts of earlier material and Wallace’s Ternate essay. This is followed by a detailed analysis where Costa goes into the weeds on what their respective understanding of evolution was at this point in time. To give you a taste: the key difference Costa highlights is how they envisioned natural selection acts. Darwin thought speciation was primarily sympatric (species overlap in space) and driven primarily by competition leading to e.g. niche partitioning and diversification (his principle of divergence). Wallace, focused as he was on biogeography, thought speciation was allopatric (species are isolated in space) and driven primarily by environmental factors. Darwin was already discussing other modes of selection such as sexual selection (which Wallace long resisted) and colony-level selection in social insects. Reading the original papers is surprisingly fun. Beyond the somewhat flowery language and dated terminology that Costa clarifies, the logic shines through. Especially Wallace’s essays show how clued-in he was. For example, the fittest do not always survive: “there may be many individual exceptions; but on the average the rule will invariably be found to hold good” (p. 204). Environmental change can render well-adapted species less fit, and evolution happens “by minute steps, in various directions” (p. 212). To me, this shows a Wallace aware that evolution has no ultimate goal but is a never-ending game of organisms chasing shifting peaks in a fitness landscape. These are the kinds of subtleties we still need to remind people of today.

“Costa’s analysis next turns to the conspiracies and claims of misconduct. […] showing there is little more to them than the seductive scent of scandal.”

Costa’s analysis next turns to the conspiracies and claims of misconduct. Darwin has been accused of receiving Wallace’s Ternate essay earlier than mid-June, filching details from it, hastily rewriting sections of his manuscript and then using his influence to suppress Wallace’s claim to fame. Well now. Costa instead patiently dismantles these claims, showing there is little more to them than the seductive scent of scandal. He delivers, I think, an even-handed and fair discussion that earnestly explores suspicious-seeming details. What leaves the door open to “speculation and innuendo” (p. 234) is that several key letters are missing. And despite creative sleuthing by historians, Costa concedes that it is possible that Darwin received the Ternate essay earlier than he said. But what of it? He did not hide or destroy the evidence, forwarding it to Lyell as requested. More importantly, Costa’s preceding analysis has highlighted all the ideas Darwin proposed that are absent from Wallace’s essay and the Species Notebook. Thanks to plenty of documentary evidence (notebooks, manuscripts, and correspondence), historians have reconstructed how Darwin developed his ideas over the preceding years. Costa admits that Darwin might have been impressed, even influenced by the Ternate essay, but that “is not tantamount to intellectual theft” (p. 254). Furthermore, he thinks that Lyell and Hooker’s move is unethical by both contemporary and modern standards; they should have asked for permission before presenting these papers.

A final, interesting strand of the analysis considers some counterfactuals. What if Wallace had sent his essay straight to an editor for publication? Would Darwin still have published his book? Though we cannot know, Costa offers insightful speculation here. This all leads to the question of why we have forgotten Wallace but remember Darwin. There are several likely factors. The Darwin family was already famous thanks to grandfather Erasmus, and Darwin was admittedly poor at acknowledging others. Simultaneously, as Costa tells in Radical by Nature, Wallace’s generosity was near-pathological and he never stopped deferring to Darwin. He also championed questionable and controversial causes that raised eyebrows in scientific circles. Costa feels it is high time to right this wrong: “the scientific and broader intellectual community needs to do better by Wallace” (p. 262). However, as stated here and reiterated recently in Radical by Nature: “honoring Wallace certainly need not come at the expense of Darwin” (p. 414 therein).

You may be left wondering if you can read On the Organic Law of Change by itself. You could, but then it is more of a historical curio. To get the most out of it you need this book. So, could you read Wallace, Darwin, and the Origin of Species by itself? In principle, yes, it is mostly self-contained, but… just look at the two of them, do they not make a fine pair?

Also, note that the online version of the Species Notebook on the website of the Linnean Society has no transcription or annotations. So, to fully immerse yourself in this fascinating chapter of science history I would recommend you read them both. Costa has done a tremendous job on what clearly has been a labour of love. I commend the publisher for seeing the value in it and not forcing this into an abridged format.

1. ↑ Side-note here: Costa’s book acquainted me with a wealth of earlier work by science historians previously unknown to me, something that always increases my enjoyment of a book.

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

Wallace, Darwin, and the Origin of Species

Other recommended books mentioned in this review:

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The deep sea is often mentioned as one of the last remaining unexplored areas on the planet, but there is another, closely related world: the subterranean realm of caves. Edited by cave ecologist J. Judson Wynne, Cave Biodiversity brings together fifteen experts in biospeleology to discuss several notable invertebrate and vertebrate groups. A scholarly yet readable overview, this is a welcome addition to the small number of books on this topic.

Cave Biodiversity: Speciation and Diversity of Subterranean Fauna, edited by J. Judson Wynne, published by Johns Hopkins University Press in February 2023 (hardback, 327 pages)

Cave Biodiversity is divided into two parts. The core of the book is the five chapters that discuss subterranean molluscs, two groups of cave beetles, cave salamanders, and cavefishes (the only group for which there is a previous dedicated book). It seems two factors played into this selection: Do we know enough about these groups to write a substantial chapter? And has knowledge of these groups so far been scattered in numerous journal papers?

This core is preceded by two chapters providing a general introduction. If, like me, you have not read Cave Biology, The Biology of Caves and Other Subterranean Habitats, or Encyclopedia of Caves, the first chapter is particularly welcome (though be warned, I want to read these books now). It familiarises you with the basic principles of how cave environments shape life underground and explains principles and terminology used throughout the rest of the book. Though no glossary is provided, you will come out understanding the difference between troglobionts, troglophiles, and trogloxenes (i.e. from more to less specialized in cave life; the prefix stygo- instead of troglo- is used for the aquatic counterparts). It explains the basic mechanisms of cave formation and the different environments, from the entrance to the deepest zones where the air is stagnant and humid. It points out that caves come in different sizes and that you need to think of them more in terms of interconnected networks of fissures, voids, and cracks at different scales, many of which are simply too small for human access. And it discusses a long list of biotic and abiotic factors that influence caves both positively and negatively. What stands out is the importance of events at the surface. For example, nutrients enter caves as a steady stream of biological material such as leaf litter, bat guano, and the delightfully named frass (insect poop and related material). At the same time, aboveground changes such as erosion, deforestation, dam construction, etc. negatively impact underground hydrology and climate.

“edited collections […] can either end up as a dumping ground for unrelated technical articles, or they can offer valuable summaries. […] Cave Biodiversity firmly falls into the latter camp”

The second chapter offers a very interesting overview of different models of speciation. How does cave life become established? A popular model is that caves host ice-age relics that evolved from surface organisms that took shelter in caves during interglacial periods. However, many other scenarios are possible. Speciation can occur after species become established underground; there are different degrees of spatial overlap; and different degrees of genetic exchange with existing species at the surface. And did a single, widespread surface species initially colonize several caves and give rise to different isolated cave populations; or do isolated cave populations reflect multiple, independent colonizations by different surface species? There is, perhaps not surprisingly, convergent evolution aplenty, which complicates our attempts at finding answers. Note, also, how caves resemble islands, meaning principles of island biogeography apply. Given my background in evolutionary biology, I gobbled this chapter up.

Now here is the thing about edited collections: depending on the nature of the contributions they can either end up as a dumping ground for unrelated technical articles, or they can offer valuable summaries. I am happy to report that Cave Biodiversity firmly falls into the latter camp and Wynne undoubtedly played an important role behind the scenes as editor. You cannot tell that three chapters have non-native English speakers as the first or only author, and the overall readability and flow are excellent. Despite this being an academic book, none of these chapters loses themselves in obscure technical detail (though they provide plenty of references to papers containing these), and all make liberal use of headings and subheadings to organise their thoughts. I particularly appreciated Grego’s chapter on molluscs and Niemiller et al.‘s chapter on salamanders for providing complete coverage of a large taxon. The chapter on cavefishes is restricted to China, though this fauna is particularly rich and most books on this topic are in Chinese (except for one translated work), so this is a welcome overview. In comparison, the two chapters on beetles seem rather specialist, covering the subfamily Cholevinae of Italy and the subfamily Trechinae of Eastern North America. The latter has a particularly interesting discussion on competing hypotheses to explain their evolutionary history and current species distribution.

For each group, these five chapters discuss what we know about their taxonomy, morphological adaptations, habitats and ecology, diversity and distribution, and colonization and adaptation. Two overarching themes emerge. First is just how hard it is to study these organisms, and how little we know about the biology of many species. Many invertebrates largely live in so-called mesocaverns: the network of fissures and voids that are too small for us to access. Several authors caution that observed distribution patterns and presumed endemicity (an endemic is a species unique to a single location) likely reflect sampling bias and research effort. Much of this field is still in the descriptive stage of simply cataloguing what is out there. Second are conservation concerns, something each chapter concludes with and Stuart Pimm also highlights in his foreword. With nutrients being limited, life underground happens in the slow lane, making these ecosystems particularly vulnerable to human disturbances. The threats are many and diverse: mining, deforestation, groundwater pollution, illegal harvesting for animal trade, cave tourism, and so on. Few environments have been assessed, many species are found to be data deficient (meaning there is too little information to decide if species are endangered), and few countries have conservation legislation in place or prioritize protection of the subterranean biosphere. Species are winking out of existence before we even had a chance to describe them, meaning that caves are at the forefront of unknown biodiversity loss.

“With nutrients being limited, life underground happens in the slow lane, making these ecosystems particularly vulnerable to human disturbances.”

In light of these conservation concerns, I have two minor points of critique. First, I am surprised the book does not make more out of environmental DNA (eDNA). Organisms leave behind a trail of DNA in their environment through e.g. skin cells, hairs, urine, faeces, and whatever else they shed and excrete. In recent years, scientists have explored this as an alternative to direct sighting or trapping in biodiversity surveys. This topic only comes up in the chapters on salamanders (for whom it has been successfully used) and cavefishes (where it still needs to be developed in the Chinese context). Niemiller, who co-authored these chapters, has published elsewhere on the use of eDNA for sampling crayfish and cavefish, cautioning it can complement, but not replace, traditional surveys. But what of invertebrates? A cursory search turned up a recent paper by a group of Italian scientists that explored the use of eDNA from insects and springtails. A more in-depth discussion of this subject would have been an additional cherry on this cake.

A second minor critique I have is that two notable groups are absent, though both omissions are understandable. There is no discussion of Mexican cavefishes; then again, there has been a dedicated book on this topic in 2015. And what of bats? Obviously, bats are a huge topic, and there are no troglobionts in this group; they merely roost in caves and are mentioned here for the nutritious guano they leave behind. I wonder if, much like charismatic mammals elsewhere, bats could act as flagship species in cave protection.

Finally, who is this book for beyond the small community of biospeleologists? The focus on speciation and biodiversity makes this of interest to both evolutionary and conservation biologists. But what about recreational cavers? That depends on your background and interests. Cave Biodiversity is a pricey and academic book, though, as mentioned, accessibly written. It certainly should be in the reference libraries of caving clubs. Overall, I consider this to be a very welcome addition to the existing literature, especially in providing several global overviews.

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

Cave Biodiversity

Other recommended books mentioned in this review:

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Where evolution is concerned, the city is a cauldron exerting its own unique mix of selection pressures on the organisms living here. The metronome beating at the heart of this process is sex. For this book, retired physician Kenneth D. Frank has explored his hometown of Philadelphia in the Eastern US state of Pennsylvania and documented the astonishing variety of sex lives playing out right under our noses. Many of these organisms can be found in cities around the world. Remarkably well-researched and richly illustrated with photos, this collection of 106 one-page vignettes shows what avocational naturalists can contribute both in terms of observations and in terms of highlighting the many basic questions that are still unanswered.

Sex in City Plants, Animals, Fungi, and More: A Guide to Reproductive Diversity, written by Kenneth D. Frank, published by Columbia University Press in May 2022 (paperback, 175 pages)

That animals get up to all sorts of reproductive shenanigans is something I would know. I spent five years for my PhD degree looking at the sex life of a small fish, the three-spined stickleback, and especially how males have different options when it comes to siring offspring, known as alternative reproductive tactics. Frank, however, opens the book with some 30-odd vignettes on plants, reminding me that I really do not appreciate plants enough.

Take purple cliffbrake fern (Pellaea atropurpurea) that does not need to be fertilized by sperm and whose embryos emerge from somatic (i.e. body) cells. Jewelweed (Impatiens capensis) can form big showy flowers that are cross-fertilized (i.e. the regular bees-and-flowers story) or it can form smaller flowers that fertilize themselves under conditions of drought and shade. St. John’s Wort (Hypericum perforatum) can do it all: self-fertilization, cross-fertilization, double fertilization^[1], single fertilization, or no fertilization. All these species are well adapted for variable conditions in city environments. Meanwhile, a tree such as Norway maple (Acer platanoides) can change its sex over the course of days, producing male flowers followed by female flowers, or vice versa. This prevents self-fertilization, which is a measure of last resort from an evolutionary point of view as it produces offspring that are less genetically diverse.

“[…] this collection of 106 one-page vignettes shows what avocational naturalists can contribute both in terms of observations and in terms of highlighting the many basic questions that are still unanswered.”

The next major group Frank covers are insects and other invertebrates whose sex lives are just wicked. Male European paper wasps (Polistes dominula) are a lekking species, which means they congregate in a small area, the lek, to collectively advertise their presence in the hope of picking up a female. (One could theoretically argue that nightclubs fulfil a similar function in humans.) Male blue dasher dragonflies (Pachydiplax longipennis) are territorial and defend areas preferred by egg-laying females. The females can mimic the male in appearance and it seems these mimics avoid harassment by males. A problem for both sexes is light reflected by metal and glass, which is polarized—the light waves vibrate predominantly in one direction—and resembles light reflected by water. Some dragonflies end up defending the shiny surface of a car bonnet rather than a pond. Milkweed aphids (Aphis nerrii) are such pests as they reproduce through parthenogenesis: eggs develop into embryos without requiring fertilization, and all grow into females that will never mate. The bridge spider (Larinioides sclopetarius) thrives around outdoor lights, which form hubs where spiders “eat, meet, and mate” (p. 76). Males have secondary genitalia and first transfer their sperm to two so-called pedipalps: pom-pom-like appendages in front of their head that they use to inseminate females with.

In comparison, vertebrates seem tame. As in many other reptiles, sex in red-eared slider turtles (Trachemys scripta elegans) is temperature-dependent. What I did not know is they simply have no sex chromosomes! Male bluegill fish (Lepomis macrochirus) build nesting areas to which they attract females. Afterwards, they nurse the broods on their own. Some males, sneaker males, forego all this effort and simply intrude on an ongoing mating, releasing their own cloud of sperm in the water (the sticklebacks I studied do the same). Male eastern gray squirrels (Sciurus carolinensis) leave a mating plug in the female’s genital tract which is hypothesized to have one or more functions (including a sperm blocker to other males, a hormone booster, or maybe an anti-aphrodisiac pheromone releaser). European starlings (Sturnus vulgaris) are a fine example of a species that is socially but not sexually monogamous, as paternity tests have shown. Notably missing from the book are mammalian predators such as and coyotes that also thrive in city environments.

“Frank highlights where we know or suspect that certain strategies result in organisms either thriving or struggling in urban environments; not every organism can radically reorganise its sex life to take advantage of the city.”

The above is a small sample from the wide range of reproductive diversity on display in urban environments. Frank highlights where we know or suspect that certain strategies result in organisms either thriving or struggling in urban environments; not every organism can radically reorganise its sex life to take advantage of the city. Obviously, Frank has not observed all these phenomena first-hand, and the amount of research that has gone into this book is impressive. The reference section spans 32 pages, which is a lot considering the vignettes take up only 106 pages. Many include facts and data from five to ten different papers. He also uses this opportunity to highlight how many basic biological questions remain unanswered. For example, does nocturnal light pollution interfere with moths fertilizing flowers of white campion (Silene latifolia)? How do female dragonflies mimicking males mate and could this be a post-fertilization adaptation? Does artificial crowding in city parks cause male squirrels to become less aggressive over time? What Frank has done is track down nearly all the species discussed here: the book is richly illustrated with his (macro)photography, with some contributions by others.

As much as Sex in City Plants, Animals, Fungi, and More is a nicely curated collection of interesting nuggets, it lacks an overall narrative. In particular, the bigger picture of how reproduction translates into longer-term evolutionary changes is only occasionally hinted at. Menno Schilthuizen wrote a very entertaining account in Darwin Comes to Town, but it has become a serious subfield of evolutionary biology. As such, this is a popular science book that is great for dipping into (whether it would make for suitable bedtime reading depends entirely on what you are into…). And if you are looking for inspiration for student or PhD projects, the book provides numerous ideas of biological mysteries at your doorstep.

1. ↑ double fertilization is the default in flowering plants. One fertilized cell forms the embryo, and the other forms endosperm that offers nutritional support to the developing embryo.

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

Sex in City Plants, Animals, Fungi, and More

Other recommended books mentioned in this review:

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It is tempting to call animal domestication humanity’s oldest and longest-running experiment, but professor of palaeobiology Marcelo R. Sánchez-Villagra would beg to differ. It is worth opening with a quote from The Process of Animal Domestication to set the tone: “domestication is actually pretty poor as experiments go; there are too many variables involved with little control, and no records of how things started” (p. 206). The excellent structure prevents the book from becoming an overwhelming infodump, making this a valuable synthesis of data across a large number of disciplines that will interest a wide range of researchers.

The Process of Animal Domestication, written by Marcelo R. Sánchez-Villagra, published by Princeton University Press in March 2022 (paperback, 296 pages)

Before delving in, let us consider the scope of this book. The Process of Animal Domestication focuses on genetics, evolution, development, and morphology. Such is the amount of research done on these topics that animal behaviour is barely touched on here. This would require a separate book and Sánchez-Villagra refers you to two texts published by CABI, to which I would add Grandin’s book on behavioural genetics. The bulk of the research covered here is on mammals (dogs feature prominently) and birds, with fish and insects getting two brief chapters at the end of the book.

Since many people own pets, and many more have been around pets or farm animals at some point, I am sure most of us think we understand domestication. How appropriate, then, the first chapter, that I would like to characterise as “everything you thought you knew about domestication is wrong”. Forget the notion of centres of domestication, or of it being a historic event: “Domestication is a process, a transition, without clear boundaries in place and time” (p. 25). Forego a human-centric view that sees domestication as an intentional and goal-oriented decision on our part. Consider instead the option we had no long-term vision, and that animals have agency too, some possibly choosing domestication, as Stephen Bonduriansky has argued. Forget the dichotomy between wild and domesticated, think rather of “a continuum […] of gradually intensifying relationships” (p. 1). The search for the “first” or “oldest” example is thus misguided; there are many other, more relevant questions to ask in zooarchaeology. And comparing current wild and domestic populations is fraught with difficulties: “no living population is any group’s ancestral population” (p. 14). Wild populations of now-domesticated forms are often extinct. In short, this chapter read like a sobering reality check and was the highlight of this book for me.

“Since many people own pets, most of us probably think we understand domestication. Appropriately, the first chapter could be characterised as “everything you thought you knew about domestication is wrong””

Chapters 3 to 7 form the core and cover genetics, evolution, development, and morphology. There is so much material here that I can only give you a subjective highlights reel. What is notable is that the author discusses both how domestic animals shed light on biology, and how biology sheds light on domestic animals. In other words, he discusses both studies that use domestic animals as model organisms and studies on the biology of domestication.

So, Thomas Hunt Morgan and Sewall Wright studied domestic animals to make pioneering contributions to genetics, while studying genetics has revealed how traits of domestic animals come about, e.g. the mutations underlying different head crests in pigeons. An interesting question is whether the same genes are involved in domestic phenotypes across species. The answer so far is no. Given different phylogenetic histories, different genes are responsible for producing similar phenotypes. In studies of evolutionary developmental biology or evo-devo^[1], domestic animals are model organisms in e.g. comparative embryology^[2], while evo-devo studies have revealed e.g. developmental biases during digit formation. In pigs, gene downregulation during early limb patterning means some digits do not form, while in horses they do, but increased cell death then sculpts the tissue around the remaining toes.

The chapter on ontogeny (the development from egg to adult) focuses on what studies using domestic animals have taught us about the developmental mechanisms resulting in different phenotypes. The next chapter on life history and growth focuses mostly on how domestication affects ontogeny, e.g. growth, fecundity, seasonality of reproduction, litter size, gestation length, sexual maturity, tooth eruption, and lifespan. The chapter on morphological diversification similarly shows how domestic animals have been favourite study subjects to explore the concept of morphospace (the “universe of potential phenotypes” [p. 172]) and how domestication has resulted in variation in e.g. coat colour, body size and proportion, brain size and anatomy, and size and shape of skulls and teeth.

“The core of this book covers genetics, evolution, development, and morphology and discusses both how domestic animals shed light on biology, and how biology sheds light on domestic animals”

These core chapters are followed by one rather interesting chapter on some odds and ends. Here, Sánchez-Villagra argues feralization is not just domestication in reverse. Feral animals never fully return to a wild state, and environments have usually changed in the meantime, frequently because of disturbance by humans. He discusses domestication experiments on chickens, rats, the famous long-term study on silver foxes, and the existence or not of the domestication syndrome. This is the idea that selection for tameness results in a suite of co-occurring phenotypic changes, a “package deal” that includes floppy ears, reduced aggression, and smaller brains. Sánchez-Villagra is more circumspect: though there are some generic changes across mammals, there are few universal domestic features: “domestication produces, as it happens in evolution, wonderful variation and a lack of universals” (p. viii). Finally, this chapter asks whether domestication accelerates rates of evolution. The studies discussed here had mixed outcomes and it seems that “human intervention per se does not necessarily accelerate evolutionary rates of organisms” (p. 217).

A synthesis of this calibre is obviously going to be a mile wide and an inch deep, but that is the whole point. The Process of Animal Domestication is a perfect entry point if you want to dig deeper into the biology of animal domestication, with 59 pages containing some 1500 literature references. What prevents this book from becoming an overwhelming infodump is its excellent structure. Each chapter is divided into many short, headed sections of 2–3 pages, with boxes used for asides.

“Domestication has depended on more than just animal traits; there is also a human cultural component to it. Not all people in history pursued it. “

A final point I appreciated is how outspoken Sánchez-Villagra is on topics of broader relevance. Domestication has depended on more than just animal traits; there is also a human cultural component to it. Not all people in history pursued it. Why? Because of “the different worldview or logic guiding the relations […] with other animals“. Understanding this cultural component will hopefully make us “realize the singular as opposed to universal nature of the Western world view” (p. 32). Our Western paradigm of prosperity through perpetual economic growth has stimulated the production of animal protein at the lowest cost, disregarding environmental and animal welfare issues. Selective breeding for (economically) optimal traits can cause suffering and pain. Changing this, the author argues, will require changes in consumer behaviour and economic imperatives, even embracing “the idea that limitations on industrial and population growth can make sustainable and healthy human life and environmental protection possible” (p. 167).

The Process of Animal Domestication is a fascinating book that comes highly recommended. Its synthesis of a large body of research makes it incredibly valuable to evolutionary and developmental biologists, geneticists, anthropologists, and (zoo)archaeologists. However, the writing is accessible enough that (under)graduate students wanting to read up on animal domestication can safely turn to this book as well.

1. ↑ A quick definition of evo-devo is useful, if only because Sánchez-Villagra gives such a clear one: if developmental biology studies “how a cell becomes a completely formed organism“, then evo-devo studies “how that process has changed over the course of evolution” (p. 91).

2. ↑ Domestic animals are often used out of practical considerations such as cost or ease of breeding in the laboratory. This unfortunately means we lack information on other workhorses in evolutionary biology such as cichlid fish or Anolis lizards.

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

The Process of Animal Domestication

Other recommended books mentioned in this review:

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Our planet has been many different worlds over its 4.5-billion-year history. Imagining what they were like is hard—with our limited lifespan, deep time eludes us by its very nature. Otherlands, the debut of Scottish palaeontologist Thomas Halliday, presents you with a series of past worlds. Though this is a non-fiction book thoroughly grounded in fact, it is the quality of the narrative that stands out. Beyond imaginative metaphors to describe extinct lifeforms, some of his reflections on deep time, taxonomy, and evolution are simply spine-tingling.

Otherlands: A World in the Making, written by Thomas Halliday, published in Europe by Allen Lane in February 2022 (hardback, 385 pages)

The 16 chapters in Otherlands, each accompanied by a gorgeous illustration from Beth Zaiken, step back in time by millions or even tens of millions of years to visit a place on Earth and describe its ecosystems and organisms. Halliday includes well-known sites such as end-Cretaceous Hell Creek (66 million years (Ma) ago) and the Carboniferous world of Mazon Creek (309 Ma ago) or Lagerstätten (sites of exceptional fossil preservation) such as the Cambrian Chengjiang biota in China (520 Ma ago) and the Australian Ediacara Hills during the Ediacaran (550 Ma ago). Far more interesting are the little-known eras and places such as the Italian promontory of Gargano during the Miocene Messinian Salinity Crisis (5.3 Ma ago), the sweltering warmth of Seymour Island in Antarctica during the Palaeocene–Eocene Thermal Maximum (41 Ma ago), or the underwater life around the Silurian Yaman-Kasy vent in Russia (435 Ma ago).

Stylistically, Otherlands is a narrative non-fiction book. What that means is that, though everything is grounded in fact, Halliday does not get lost in the details^[1]. Where competing hypotheses exist he picks one and runs with it, rather than detailing the academic debates and different schools of thought. It is a stylistic choice that I can get behind given the quality of the writing that follows.

Because make no mistake, Halliday knows how to craft captivating prose. He won the Hugh Miller Writing Competition in 2018 and the John C. Marsden Medal from the Linnean Society for the best doctoral thesis in biology in 2016. Reading Otherlands, it is easy to see why. I do not know what they feed Scottish palaeontologists, but I was reminded of Elsa Panciroli’s Beasts Before Us. (This might not be a coincidence, she is prominently acknowledged for inspiring him to participate in the above-mentioned competition.) Let me back up my enthusiasm with some quotes that can only touch on a fraction of what is on offer.

“A recurrent theme in this book is that of impermanence: “gatherings of species in time and space may give the illusion of stability, but these communities can only last as long as the conditions that help to create them persist“”

There are the obvious imaginative metaphors to describe animals. The Triassic gliding reptile Sharovipteryx mirabilis (225 Ma ago) is imagined looking rather inelegant once landed “with its membrane retracting and limbs thrown all directions like a collapsing deckchair” (p. 159), while the Ediacaran sedentary animal Dorothy’s Rope (550 Ma ago) resembles upright towers “composed of bulges like knotted rope, as if Gaudi had designed an industrial town” (p. 277). Other descriptions are more poetic. Basilosaurids, the first fully aquatic whale ancestors in the Eocene (41 Ma ago), have yet to evolve the melon organ. They “can listen to the music of the oceans, but they have not yet learned to sing” (p. 86).

Particularly powerful are his reflections on deep time. A recurrent theme in this book is that of impermanence: “gatherings of species in time and space may give the illusion of stability, but these communities can only last as long as the conditions that help to create them persist” (p. 18). Some ecosystems never return. The long-lived Jurassic crinoid colonies (155 Ma ago) that made a home on floating logs blown into the sea during storms disappeared when the evolution of shipworms made “this way of life impossible, something that can and will never be replicated in quite the same way again; wood just doesn’t float for as long as it used to” (p. 151). We now similarly worry about coral bleaching: “continent-scale coral reefs might just end up being one of those ecosystems that never returns, a distinctively Cenozoic phenomenon” (p. xix). And while the world feels old in our day, it is easy to forget the world was already old in the deep past. The mountains of the Triassic (225 Ma ago) “are built from the deep sea“, within which can be seen “the coils and shapes of the long-extinct creatures of the Carboniferous seas, well over 100 million years old even now” (p. 158).

“What made my hair stand on end were Halliday’s reflections on phylogenetics. […] I love how he drowns scientific concepts in poetic language.”

What made my hair stand on end were Halliday’s reflections on phylogenetics, the evolutionary relationships between animals. I love how he drowns scientific concepts in poetic language. Take the Paleocene Baioconodon (66 Ma ago). Beyond one of the earliest placental mammals, we do not really know what it was. “Their anatomy is too non-committal, too similar to and yet too distinct from too many living orders to be placed with confidence. […] They are an unspecialized, Platonic placental, a lump of living clay from which all others are stretched, pinched and pulled into shape” (p. 105). We cannot even describe its young as kits or calves: “it does not yet make sense to talk of cattle or dogs, of monkeys or horses. None of these groups exist yet […] names lose tangibility in the depths of the past, and our language has no description for the young of common ancestors” (p. 104). You start to see why Halliday wrote his way backwards from the present. He makes a similar observation about the Ediacaran biota. Alien to us, “they are aberrant only from a modern perspective” (p. 282). Our confusion is partially because “we are trying to define them the only way we can: on the basis of those few survivors to have found paths to the present“, while the dead-end branches “by the simple fact of having not survived, forfeit a common name” (p. 283).

Similarly spine-tingling are his explanations of evolutionary processes. Species names are artificial designations for a continuous phenomenon. The way palaeontologists deal with this can be compared to rivers. Just as a river can split and its two branches be called by two names from that point in space forward, so can a species that spatially separates be called by two names from that point in time forward. And why did so many higher taxa appear during the Cambrian explosion? One idea is that, once in place, fundamentals cannot be changed easily: “evolution today can only be played within the constraints set by the past“. Another idea is that “there is nothing intrinsically impossible about a new body plan developing today, were it not for the existence of others“. Gould wrote of filling the ecological barrel and Halliday puts it thus: “establishing the basic roles within an ecosystem is like adding large rocks into a barrel […] evolutionary processes […] adding in finer and finer divisions of ecological processes, pebbles and sand falling into the barrel between the gaps left by the larger stones, structures built on other structures” (p. 258). Not only does this ring true, but it is also truly beautiful language.

Otherlands is an exceptional debut that can be savoured like a fine wine. I found myself reciting passages to anyone within earshot. Beyond a fascinating tour of extinct lifeforms, Halliday’s carefully crafted yet poetic descriptions of scientific concepts are a masterclass in spellbinding science communication.

1. ↑ The relevant references are collected paragraph by paragraph in endnotes. One minor annoyance is that Halliday omits the titles of journal articles, which I normally find the most informative bit. No doubt done to save space, I cannot imagine this will bother many people.

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

Otherlands

Other recommended books mentioned in this review:

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Ever since humans appeared on the scene, we have been altering life on Earth. Where once our actions could be considered part of nature’s fabric, our influence has become outsized and our options to exercise it have multiplied. Though the subtitle of Life Changing does not make it explicit, science writer Helen Pilcher focuses on our impact on the genetics and evolution of life around us. A book that stands out for its balanced tone, it managed to surprise me more than once, despite my familiarity with the topics considered.

Life Changing: How Humans Are Altering Life on Earth, written by Helen Pilcher, published by Bloomsbury Publishing in February 2020 (hardback, 391 pages)

Life Changing is told in three acts. Pilcher first examines the species we have purposefully engineered, then looks at the many animals unwittingly caught up in the advancing human juggernaut, and finally considers how we might wield our knowledge for good in conservation efforts. Examining the work of numerous scientists, she takes the reader through topics as diverse as domestication, cloning, invasive species, urban evolution, de-extinction, and rewilding. Two aspects of her writing stood out for me in particular: she gets the nuances of these technical topics right, and she is balanced, not letting personal prejudice get in the way.

First, those nuances. As a former reporter for Nature and with a PhD in cell biology, Pilcher understands the biology and knows how to communicate it. Right off the bat, she clarifies that domestication is simply another form of genetic modification. Making a distinction between this and modern, laboratory-based methods, as GMO opponents are often wont to do, is a good example of the appeal to nature fallacy. The difference is one of degree, not of kind. She similarly puts the record straight on cloning: clones are not 100% genetically identical. Although you duplicate the nuclear DNA, you will need an egg cell in which to do so. The egg donor contributes its own mitochondrial DNA, which is a small but not insignificant fraction. With time, further differences accrue due to mutations and epigenetics (processes that change the way DNA is expressed without changing the DNA sequence). “We are all far more than the sum total of our DNA” (p. 136), remarks Pilcher. The last example is de-extinction, the subject of one of her previous books. Often misrepresented as resurrecting an extinct species, in reality it means genetically modifying a closely related species to resemble its ancestor. The result is “a hybrid modern-day facsimile” that “doesn’t mark a return to bygone eras; instead it marks an entirely new phase in the evolutionary story” (p. 138).

The second strong suite of Life Changing is Pilcher’s balanced reporting. Cloning has found many uses in animal breeding, but we must not forget that it is a notoriously inefficient process with most clones dying before birth—which is one reason why she would not want to clone her dog. When discussing the genetic changes wrought by trophy hunting, she admits finding the whole business repugnant but recognises how South Africa has shown that the money ploughed back into wildlife reserves benefits wildlife overall. “Although it may seem counter-intuitive, sometimes, hunting can actually help wildlife” (p. 63). And while invasive species have a bad reputation, she also speaks at some length to ecologist Chris D. Thomas. In his book Inheritors of the Earth, he pointed out how many invasive species simply slot right into an ecosystem without disturbing the locals. New Zealand now has nearly double the number of plant species. “Despite what you might have heard, invasive species aren’t all bad” (p. 229).

“[…] de-extinction [is] often misrepresented as resurrecting an extinct species, in reality it means genetically modifying a closely related species to resemble its ancestor.”

Particularly interesting is the topic of hybridisation. There is much concern about closely related species hybridising as climate change causes home ranges to shift, with pizzlies (polar–grizzly bear hybrids) being one example. But, just as humans contain some Neanderthal DNA, studies have shown grizzly bears to contain some polar bear DNA; one example of the book surprising me with something I did not know yet. It is estimated that the two species have occasionally interbred for the last 40,000 years. So should we panic? This is perhaps where Pilcher’s logic lapses slightly. When she introduces extinction and climate change she admits that, yes, these are natural processes that have always happened, but it is the current high rate that is worrisome. That same logic is not applied to her discussion of hybridisation. On the flip side, it can also be a conservation tool. The northern white rhino is functionally extinct as only two females remain. Using frozen sperm from the last, now deceased male, researchers inseminated a female southern white rhino, creating two hybrid embryos. Are we diluting the northern white rhino genome or preserving a significant fraction of it? “In some instances, maybe it’s better to have a hybrid than it is to have nothing at all” (p. 216).

Besides nuance and balance, Life Changing has several other things going for it. As a comedy writer, Pilcher has a wicked sense of humour. Regarding artificial insemination in cattle breeding, she declares: “Romance is dead, replaced by a glorified bovine turkey baster” (p. 53). Her description of zoologist Mark Carwardine’s encounter with an amorous kakapo simply has to be read; I will just leave you with the words “demented pair of sex-mad avian earmuffs” (p. 290). Sometimes, the humour is acerbic. Industrial animal farming is a major driver of the global decline in biodiversity. If somebody were to populate a new ark to reflect this shift in abundance, she half-jokes, the roll call would go “chicken, chicken, chicken, chicken, chicken, chicken, cow” (p. 353).

Pilcher knows when not to provide too much information. Whole books have been written about e.g. the long-running fox domestication experiment in Siberia, evolution in urban settings and the textbook example of the peppered moth evolving in response to changes in air pollution, the gene-editing tool CRISPR, or the stratigraphical definition of the Anthropocene and what marker will be suitable (it might just be chicken bones). For all of these topics, she manages to provide the relevant details in just a few pages.

“[…] just as humans contain some Neanderthal DNA, studies have shown grizzly bears to contain some polar bear DNA […] It is estimated that the two species have occasionally interbred for the last 40,000 years.”

In other cases, she goes into great detail. This book could be a rather depressing read, so in the last part, she explores in-depth some examples of how our knowledge and technical skills can stem the tide of biodiversity loss. Some researchers have figured out how to make coral spawn on-demand in the lab, allowing the reintroduction of live coral to sites affected by bleaching. There is the intensively managed Kakapo Recovery Program in New Zealand, and the hands-off approach of rewilding, such as the Knepp Estate in the UK. The topic of rewilding is where I find Pilcher at her least critical and most starry-eyed. Although there are places where she hints at human population numbers multiplying our impact, she never mentions overpopulation out loud. And beyond some hints at eating less meat, she does not really address what limits we ought to impose on ourselves if we want large-scale rewilding efforts to exist side-by-side with 8 billion people. Admittedly these are huge and divisive topics without easy answers that are outside of the scope of this book, but they are barely acknowledged here.

In her introduction, Pilcher pithily states: “Life is changing. Humans are responsible“. Life Changing is a very enjoyable piece of popular science writing that shows the many ways in which this is true. I was particularly pleased that, despite my familiarity with the topic, she still had surprises in store for me.

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

Life Changing

Other recommended books mentioned in this review:

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You would think that science and monsters are strange bedfellows. And yet, there are plenty of science geeks, myself included, who get a good giggle out of pondering the science behind mythical beings and worlds. Clearly, somebody at the Royal Society of Chemistry has a similar sense of humour, for they have just published Vampirology. Here, chemist and science communicator Kathryn Harkup trains a scientific lens on the fanged fiend—not so much to ask whether vampires do or do not exist, but whether they could exist given our scientific understanding today.

Vampirology: The Science of Horror’s Most Famous Fiend, written by Kathryn Harkup, published by the Royal Society of Chemistry in June 2021 (paperback, 262 pages)

In ten chapters, Harkup investigates a diverse range of vampiric traits or facts associated with vampire lore. For some, she does not necessarily provide a scientific blueprint for how vampires would achieve what are obviously supernatural feats but looks at how other animals achieve something comparable. Could you actually live on a diet of blood? Vampire bats can, but they have had to make all sorts of compromises to manage it. If vampire metabolism is anything like a human’s this presents problems: blood is not very energy-rich, it is poor in the needed minerals and vitamins, and it is far too salty and iron-rich. Or what of Dracula’s ability to transform himself into other animals? Given the relationship between mass and energy, Dracula would not be able to rapidly transform into a much smaller bat, which “would release the sort of energy seen in atomic explosions [which] would result in the total destruction of [London]” (p. 130). But some animals are capable of extreme feats of camouflage or mimicry of objects. Octopuses can squeeze themselves through very small openings, as long as their hard beak can fit, so that is the kind of flexibility Dracula would need to squeeze himself through small cracks. And the question of how Dracula might crawl up and down vertical walls naturally leads to a piece on the way geckos adhere to surfaces.

Equally often Harkup will use vampires as a springboard to marvel at the natural world inside and outside of us. There is, for example, an extended section on how blood works and the hit-and-miss character of early blood transfusions when blood compatibility was not yet understood. And the question of whether vampires might exist alongside us as another species of Homo leads into a discussion on human evolution and the revelations of ancient DNA, how large a viable population would need to be, and what genetic changes would have to evolve to, for instance, ensure extreme longevity.

“Our limited understanding at the time of how the human body decomposes led people to take anything out of the ordinary as evidence of a vampire [alllowing] Harkup to discuss all sorts of delectable details of decay”

Another approach Harkup employs is to try and find rational explanations for historical reports on vampirism. Several researchers have suggested that the symptoms of diseases such as tuberculosis and cholera fed into vampire lore, while the Spanish neurologist Juan Gómez-Alonso theorised the same for rabies. As Harkup discusses here, not all of these claims can stand the light of day. Other powers, especially psychic ones, are harder to explain. Dracula’s mastery of the weather? This is something we are not capable of even today. The psychic connection that Dracula formed with Mina? Equally unlikely, though it could well reflect the Victorian craze for mesmerism and spiritualism at the time that Bram Stoker wrote his famous book.

The state of human knowledge, or lack thereof, is particularly useful when it comes to explaining the eyewitness testimony of people exhuming the corpses of suspected vampires. Our limited understanding at the time of how the human body decomposes led people to take anything out of the ordinary as evidence of a vampire. This allows Harkup to discuss all sorts of delectable details of decay, such as the suspiciously ruddy complexion of some corpses (due to blood vessel and tissue breakdown), the blood-stained lips (so-called purge fluid being forced out of the mouth), and their occasional well-preserved appearance (due to the formation of grave wax or adipocere on the skin when fatty tissues are broken down). There is a range of environmental factors that influence how decomposition proceeds and death can be a restless respite: corpses move.

“One particular challenge in writing a book like this is that our conception of what a vampire is has changed through time: from sinister fiend to seductive villain”

From the above, it is clear that Harkup takes stabs at her topic from many angles. One particular challenge in writing a book like this is that our conception of what a vampire is has changed through time: from sinister fiend to seductive villain. As the introduction explains, they have a surprisingly long lineage in history and folklore. Our picture today, however, is still strongly influenced by Stoker’s Dracula, with subsequent theatre plays and the 1931 movie starring Bela Lugosi adding certain tropes such as the opera cape. Even Nick Groom, who charted the history of the vampire before Dracula in his well-received book The Vampire, could not get away from him, writing that: “all the paths of the (un)dead lead to Dracula, just as they all lead away from it” (p. xv). Stoker, for example, introduced the association with bats. An interesting tidbit Harkup reveals here is that the sensitivity to sunlight was, however, an invention of F.W. Murnau’s 1922 movie Nosferatu—Dracula walked the streets of London in broad daylight. That knowledge makes attempts at explaining this particular vampiric trait by retrofitting medical conditions look a bit silly. This has been attempted for pellagra and porphyria where patients are very sensitive to sunlight.

Although I do not have it at hand, a quick comparison with Ramsland’s book The Science of Vampires suggests that, despite some inevitable overlap, the two authors have different takes on the subject. Ramsland comes at it as a forensic psychologist. Vampirology is entirely in keeping with Harkup’s previous macabre trio of books with Bloomsbury on the science of Frankenstein and how Shakespeare and Agatha Christie shoved their characters off this mortal coil. I expect that any negative reviews will probably come from the small contingent of people who take vampires and vampirism extremely seriously. For the vast majority of us mere mortals there is less at stake here. Vampirology is a fine piece of popular science that has its tongue firmly planted in its ruddy cheek and comes recommended if you enjoyed e.g. Kaplan’s book The Science of Monsters.

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

Vampirology

Other recommended books mentioned in this review:

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In the field of palaeoanthropology, one name keeps turning up: the Leakey dynasty. Since Louis Leakey’s first excavations in 1926, three generations of this family have been involved in anthropological research in East Africa. In this captivating memoir, Meave, a second-generation Leakey, reflects on a lifetime of fieldwork and research and provides an inspirational blueprint for what women can achieve in science.

The Sediments of Time: My Lifelong Search for the Past, written by Meave Leakey and Samira Leakey, published by Houghton Mifflin Harcourt in November 2020 (hardback, 396 pages)

With The Sediments of Time, Meave* follows a family tradition. Her husband Richard, and his parents Louis and Mary have all been the subject of (auto)biographies, now many decades old. Science writer Virginia Morell later portrayed the whole family in her 1999 book Ancestral Passions. Much has happened in the meantime, and though this book portrays Meave’s personal life, it heavily leans towards presenting her professional achievements, as well as scientific advances in the discipline at large. Thus, Meave’s childhood and early youth are succinctly described in the first 15-page chapter as she is keen to get to 1965 when a 23-year-old Meave starts working with Louis in Kenya.

Whereas Louis and Mary were famous for their work in Olduvai Gorge in Tanzania, Richard and Meave have made their careers around Lake Turkana in northern Kenya. The first two parts of the book take the reader chronologically through the various excavation campaigns. These include the decade-long excavations in and around Koobi Fora, one highlight of which was the find of Nariokotome Boy (also known as Turkana Boy), a largely complete skeleton of a young Homo erectus. The subsequent campaign in Lothagam yielded little hominin material but did reveal a well-documented faunal turnover of herbivore browsers being replaced by grazers with time. Meave has also described several new hominin species. This includes Australopithecus anamensis, which would be ancestral to Australopithecus afarensis (represented by the famous Lucy skeleton), and Kenyanthropus platyops, which would be of the same age as Ardipithecus ramidus. That last name might sound familiar, because…

“Woven into Meave’s narrative of exploration and excavation is an overview of how palaeoanthropology developed as a discipline, and what are some of its big outstanding questions.”

Having just reviewed Fossil Men, which portrayed the notorious palaeoanthropologist Tim White, I was curious to see what Meave had to say about him. In Fossil Men, Kermit Pattison already mentioned that she described White “with a note of sympathy” (p. 5), and she affirms that picture here, writing that he is “a meticulous scientist […] intolerant of bad science […] outspoken and frank […] although he was charming and a gentleman in less formal situations” (p. 136). And though they meet more than once to compare fossils, notes, and ideas, they remain at loggerheads over certain claims.

Woven into Meave’s narrative of exploration and excavation is an overview of how palaeoanthropology developed as a discipline, and what are some of its big outstanding questions. A recurrent theme is the influence of climate on evolution, often by impacting diet and available food sources. There is the difficult question of naming species and how much difference is enough to recognise a separate species, which ties into the whole lumpers vs. splitters debate in taxonomy. The latter readily name new species whereas the former (White being an example) point to sexual dimorphism and morphological variation and recognize only one or very few hominin species. Your stance in that debate affects what you think of Meave’s descriptions of Au. anamensis as being part of a lineage towards Au. afarensis, and whether K. platyops is a species distinct from Ar. ramidus (White obviously thinks not).

This discussion of topics relevant to palaeoanthropology strongly comes to the fore in the book’s third part, by which time Meave is examining the Homo lineage and the question where we appeared from. This sees her tackling topics such as human childbirth and the role of grandmothers, Lieberman’s hypothesis of endurance running as a uniquely human strategy to run prey to exhaustion, palaeoclimatology and the mechanism of the Milankovitch cycles, the spread of Homo erectus around the globe (the Out of Africa I hypothesis), and the use of genetics to trace deep human ancestry. I feel that Meave overstretches herself a little bit in places here. Though her explanations are lucid and include some good illustrations, some relevant recent literature, on e.g. ancient DNA and Neanderthals is not mentioned.

“Meave can draw on a deep pool of remarkable and amusing anecdotes that are put to good use to lighten up the text. And though the focus is on her professional achievements and the science, real life interrupts work on numerous occasions.”

Meave can draw on a deep pool of remarkable and amusing anecdotes that are put to good use to lighten up the text. And though the focus is on her professional achievements and the science, real life interrupts work on numerous occasions. Some of these are joyful, such as the birth of her daughters Louise and Samira. Some are a mixed blessing, such as Richard’s career changes, first when Kenya’s president hand-picks him to lead the Kenya Wildlife Service and combat rampant elephant poaching, then when he switches to attempting political reform. It removes him from palaeoanthropology and their time together in the field. Other occasions are outright harrowing, such as Richard’s faltering kidneys that require transplantations, or the horrific plane crash that sees him ultimately lose both legs despite extended surgery.

Illustrator Patricia Wynne contributes some tasteful drawings to this book, though the figure legends do not always clarify the important details these images try to convey. And I would have loved to see some photos of important specimens, whether during excavation or after preparation, especially given how much Meave focuses on the scientific story in this book. Many specimens are described in great detail but the colour plate section mostly contains photos of the Leakeys and collaborators in the field. Another minor point of criticism is that I was not clear on Samira’s part in writing this book. The dustjacket mentions her as a co-author, but the story is told exclusively through Meave’s eyes, and the acknowledgements do not clarify Samira’s role. I am left to surmise that Meave and Samira together drew on their store of memories for this book.

These minor criticisms notwithstanding, I found The Sediments of Time an inspiring memoir that provided a (for myself long-overdue) introduction to the Leakey dynasty. Meave has led a charmed existence and she is a fantastic role model for women in science.

* I normally refer to authors by their last name but, for obvious reasons and with all due respect, I will be deviating from that habit here and mention the various Leakeys by their first name.

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

The Sediments of Time

Other recommended books mentioned in this review:

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The idea that extinction is a bad thing and diversity a good thing seems self-evident to us. But, by surveying more than two centuries of scholarship, science historian David Sepkoski shows that this was not always the prevailing belief. Rather than a book discussing mass extinction, Catastrophic Thinking is more meta than that, discussing how we have been discussing mass extinction. So, we have an interesting premise, but also an interesting author because—bonus detail—the work of his father, J. John (Jack) Sepkoski Jr., was instrumental in recognizing the Big Five mass extinctions. I could not wait to get to grips with this book.

Catastrophic Thinking: Extinction and the Value of Diversity from Darwin to the Anthropocene, written by David Sepkoski, published by The University of Chicago Press in October 2020 (hardback, 359 pages)

Extinction was long considered a theological non-starter in Western philosophy; God’s creation is perfect after all. But once some naturalists finally accepted fossils for what they were, extinction became a possibility and this is where Sepkoski starts to chart our thinking on extinction through four transitions. In the Victorian era extinction was initially seen as a regular process that was the logical consequence of natural selection. After the trauma of World War I it morphed into a cyclical process, extinction being the result of species reaching the end of their “life span”. The invention and deployment of nuclear weapons and the shadow cast by the Cold War prepared the way for a more catastrophic interpretation so that when the Alvarez team proposed a fiery end to the reign of the dinosaurs, it found fertile ground in the popular imagination. And that concern gave way to considering extinction as a ongoing slow-motion biodiversity crisis.

This exceedingly brief and simplified outline can barely do justice to the many subtleties and insights that Sepkoski unearths. Catastrophic Thinking stands out for the depth of its scholarship; next to careful reading of books and journal articles, he has interviewed some key figures and dives into private correspondence held in archives. Sepkoski previously wrote Rereading the Fossil Record in which he charted the rise of palaeobiology as a discipline, and he draws on that book here. For palaeontologists and evolutionary biologists there are thus plenty of fascinating science history details.

For example, how Charles Lyell’s uniformitarian views of slow and gradual change won out over Georges Cuvier’s ideas of periodical catastrophic revolutions and went on to influence Charles Darwin’s thinking. Sepkoski is at pains to explain that the uniformitarianism-versus-catastrophism dichotomy is itself an oversimplification and was only one of the concerns, another being the question of intrinsic versus extrinsic causes of extinction. Somewhat later, the rise of cyclical thinking questioned Darwin’s assumption that the fossil record is very fragmentary and incomplete; perhaps the sudden disappearance of species was not an artefact after all.

“Catastrophic Thinking stands out for the depth of its scholarship […] For palaeontologists and evolutionary biologists there are […] plenty of fascinating science history details.”

This, in turn, paved the way for catastrophic thinking when the question of the fossil record’s completeness got an empirical boost in the 1950s through the work of first Norman Newell and later Sepkoski’s father on fossil marine invertebrates. As Sepkoski explains, their remains are so plentiful, several orders of magnitude richer and more complete than vertebrate fossils, that they are considered to offer a true and reliable picture of the history of life. And this record was revealing five big mass extinctions and potentially many other smaller ones. This raised questions whether natural selection and Darwinian evolution might be suspended during such crises, which David Raup pithily summarized in the title of his book Extinction: Bad Genes or Bad Luck?

The catastrophic school of thought, too, planted the seeds for the next transition. After all, mass extinctions reveal themselves as a rapid and precipitous drop in biological diversity. Already in 1992, none other than E.O. Wilson argued that biodiversity loss due to human-caused habitat loss and climate change are plunging the world into a sixth mass extinction. This concept was further popularised in 2014 by Elizabeth Kolbert although, as Sepkoski explains, there is some pushback from palaeontologists.

I could go on, but the biological story is only one side of this book. Catastrophic Thinking is part of Chicago’s science•culture series which contains books examining the intersection of the two. A central theme for Sepkoski, reiterated throughout, is how he sees science and culture as inseparable: “[…] cultural and biological values surrounding extinction mirrored and reinforced one another” (p. 84). Attempting to disentangle the two is a fool’s errand that will confront you with “a serious chicken-and-egg problem” (p. 287). At any given historical period, science and culture combined to form an extinction “imaginary”, an academic term he borrows from art. This may sound somewhat abstract but once Sepkoski gets underway it quickly becomes clear what he means.

“A central theme for Sepkoski, reiterated throughout, is how he sees science and culture as inseparable: “[…] cultural and biological values surrounding extinction mirrored and reinforced one another“”

So, Darwin’s ideas were used to justify imperialism, slavery, and racism—the “extinction” of “primitive” tribes encountered by colonialists being perceived as a regrettable but also inevitable result of the strong vanquishing the weak. Sepkoski emphasizes how we cannot simply blame Darwin for this, even though his ideas fed off, and in turn fed into, Victorian-era culture and politics. The later cyclical thinking echoed contemporary historical accounts that emphasized the cyclical rise and of fall of civilizations. The idea of dinosaur-extinction-by-asteroid hit a collective nerve, especially when Carl Sagan and others made direct links with the potential consequences of a nuclear winter in case atomic weapons were to be used. And most recently the idea of biological diversity as a sign of a healthy planet has been applied to culture, as exemplified by the UNESCO Universal Declaration on Cultural Diversity.

The only nitpick I have is regarding the supposed periodicity of mass extinctions, roughly every 26 million years, that Sepkoski mentions several times. Without going into the nitty-gritty, he leaves out two recent books arguing in favour, but, more importantly, he does not mention that this idea is not widely accepted. Raup, who originally proposed it together with Sepkoski’s father, wrote in his 1999 afterword to The Nemesis Affair that “[…] the periodicity question is firmly planted on the back burner.” and is not supported by the consensus (p. 217). Indeed, Ted Nield wrote in 2011 that “the theory seems unable to go further. […] The jury awaits further evidence.” (p. 141), while Michael Benton added in 2019 that “The debate rumbles on […] but most have abandoned the idea of periodicity” (p. 264).

Leaving aside that minor detail, I found Catastrophic Thinking a thoroughly enjoyable and convincing read. My impression is that there has not been a reflection of this kind, at least in book form, since The Mass-Extinction Debates in 1994. Catastrophic Thinking presents a far wider and more inclusive take on the topic though and is positively bristling with fascinating insights. Obviously, this is a must-read for science historians, but palaeontologists and evolutionary biologists interested in the history of their discipline can also safely pick this up. Furthermore, thanks to the compelling arguments and accessible writing, this book should appeal strongly outside of these disciplines to anyone with an interest in palaeontology, evolution, or mass extinctions.

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

Catastrophic Thinking

Other recommended books mentioned in this review:

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