During the Last Ice Age, Europe was home to groups of hunter-gatherers that were virtually indistinguishable from humans alive today. Commonly known as Cro-Magnons, they seem to have overlapped in time with Neandertals, even exchanging genetic material with them. Who were these people and what do we know about them? Palaeoanthropologist Trenton Holliday has studied the ice age Europeans for the last 30 years and in this, his first book for a popular audience, he gives you a detailed picture of their lives as it played out over some 30,000 years.

Cro-Magnon: The Story of the Last Ice Age People of Europe, written by Trenton Holliday, published by Columbia University Press in July 2023 (paperback, 280 pages)

The last popular book that I know of specifically looking at Cro-Magnons was the eponymous book by Brian Fagan published in 2010. Given that Fagan writes about many different archaeological topics, 14 years have passed, and Holliday is a specialist, this book provides the reader with an informative and in places very detailed update. Several chapters provide you with background information on important topics in archaeology and palaeoanthropology that apply to human evolution more generally. For instance, how did humans make stone tools and how did these evolve, where and when did Homo sapiens first appear and thence disperse, or how do the predominant four models of the evolution of modern humans differ? Important second players in this story are the Neandertals (here spelt without an “h”) who have been the subject of numerous popular books (most recently Wragg Sykes’s Kindred and Slimak’s yet-to-be-reviewed The Naked Neanderthal). Holliday provides a potted history of their discovery, the genetic evidence of interbreeding with our ancestors, and the archaeological evidence that the two overlapped and interacted in time in Europe. This leaves only the last four chapters to deal “exclusively” with Cro-Magnons, discussing their bioanthropology (including skeletal morphology and ancient DNA), hunting gear and diet, art, and their response to the planet’s fluctuating climate.

The organisation of the book overall is good. Holliday uses subheadings to divide each chapter into manageable and clearly signposted sections while several chapters contain maps to all the sites mentioned in the text. Two early chapters use separate boxes for technical minutiae about different European lithic industries (i.e. stone tools) and craniofacial differences between Neandertals and Cro-Magnons, giving you the option to skip this material. Even so, he goes into quite intense technical detail in places. For example, in chapter 5 he repeats an earlier principal component analysis to compare the body proportions of Neandertals and Cro-Magnons, supplemented here with additional data. This shows the latter to have more heat-adapted bodies with comparatively longer limbs and narrower trunks. Similarly, in chapter 7 he repeats an analysis of comparative brain sizes amongst hominins using encephalization quotients, here supplemented with additional data. Needless to say, it is not very common to present new or refreshed analyses of data in popular works. In chapter 8 he admits to getting into the weeds on the stratigraphy of different lithic industries in various European caves. The reason is that certain classes of stone tools, here Châtelperronian and Aurignacian, are ascribed to respectively Neandertals and Cro-Magnons. In some caves, these tools are found in alternating layers, suggesting alternating habitation by, and possibly interactions between, Neandertals and Cro-Magnons. Heated debates have flared up about whether these tool sets are indeed unique to each of these hominins, and whether the observed stratigraphy is original or the result of e.g. later erosion, burrowing animals, or even backfill of undocumented excavations jumbling everything up. In short, this is a factual book and though he includes a few fictional vignettes to add flavour, his writing is not nearly as evocative as that of for instance Rebecca Wragg Sykes, Elsa Panciroli, or Thomas Halliday.

“Holliday eschews simple narratives in favour of the rich diversity and complexity that come with an imperfect archaeological record and different proxies, neither of which yield straightforward answers.”

There are two things that Holliday does do well and consistently. First, he provides enlightening overviews of the history of the field. This logically includes the discovery of the first Cro-Magnon and Neandertal remains, but also the historical baggage of race science in anthropology and how there never was any agreement on how many races there were or how they were circumscribed (which are obviously the least problematic aspects of this sordid history). Very interesting is the overview of how different models of modern human evolution developed throughout the twentieth century and by 1984 crystallized into four palaeontological models. These all agree that modern humans came out of Africa, but disagree on how much archaic humans outside of Africa contributed to today’s humans. The models range from “none” (African hominins completely outcompeted and displaced others) to “quite a lot” (extensive gene flow between different hominin populations was the norm). Ancient DNA analyses have revealed that the answer lies somewhere in the middle. The second aspect Holliday highlights is that almost every finding and opinion is contested, which adds further layers of detail. After saying it a few times, he jokingly reminds you: “Have I mentioned that scientists are a skeptical lot?” (p. 78). Which hominin made the Châtelperronian lithics? Are the wooden spears from Schöningen, Germany, really projectile weapons? Are salmon remains in caves evidence of a dietary switch to fish or were they left by other carnivores? How old is the cave art in Chauvet Cave, France? And so forth.

The only thread I feel he left hanging is that you might reach the end of the book and ask “What happened to the Cro-Magnons?” The warming of the Holocene seems to have been the biggest climatological challenge they had yet faced. As he points out at the start, the term Cro-Magnon has fallen out of favour in scientific circles as we cannot tell these people apart from modern humans in any meaningful biological sense. So, did we just stop calling them Cro-Magnons as they became us, making it a historical term that has fallen out of favour? If so, he does not clarify or analyse when we stopped using it. I imagine this will have been a gradual trend, rather than an agreed-upon decision to stop using “Cro-Magnon” from this day forward. Confusingly, the Wikipedia entry on Cro-Magnon refers to work by the research group of Svante Pääbo and David Reich that suggests they were a genetically distinct group. Holliday here also references that paper and on page 235 speaks of Epipaleolithic people as their descendants. I am tempted to throw my lot in with the ancient DNA crowd who argue for a long history of genetic churn and turnover, but Holliday leaves the eventual fate of the Cro-Magnons unresolved and unexamined.

Having said that, Cro-Magnon is a rewarding read. Holliday eschews simple narratives in favour of the rich diversity and complexity that come with an imperfect archaeological record and different proxies, neither of which yield straightforward answers. He gives a very realistic, full-bodied picture of the discipline: this is popular anthropology for grown-ups.

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

Cro-Magnon

Other recommended books mentioned in this review:

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Though humans have shrouded it in ritual, cultural, and religious meaning, death is fundamentally a biological phenomenon. As both a biologist and someone with an abiding interest in the gothic subculture, death has thus never been a topic I shy away from. Two recent books, The Biology of Death (2022), and The Evolutionary Origins of Life and Death (first published in 2020), provided the perfect excuse to indulge my morbid curiosity.

The Biology of Death: How Dying Shapes Cells, Organisms, & Populations, written by Gary C. Howard, published by Oxford University Press in January 2022 (hardback, 291 pages)

The author of The Biology of Death is a bit of an enigma. From the biography provided by the publisher and the website of the Rotary Club of Castro Valley, where he is (or was?) president, here is what I could puzzle together. Howard obtained a BA in zoology and an MA and PhD degree in biology, did two postdocs, spent 11 years at two small biotech companies, and then 22 years until his retirement as a science writer at Gladstone Institutes. That last one is a non-profit biomedical research organization I had never heard of, except that (oh really?) Jennifer Doudna, co-discoverer of the gene-editing technology CRISPR, is one of their senior investigators. The tagline for Howard’s book is “Death is more than dying” and in 16 short chapters, he provides a panoramic overview of the many facets of the biology of death.

To give you some examples, Howard mentions the borderline of life and death, the struggle we have with defining life, and some of the organisms that populate the grey zone between life and non-life. He mentions major causes of death today (with an honourable mention of the mosquito), and what killed us in the past (including a list of some major pandemics). He mentions symptoms of ageing and some major theories as to why we age. He mentions the gruesome details of death and decomposition, and how we lay the dead to rest then and now (a topic that has given rise to more than one engrossing memoir by undertakers). There is a brief mention of forensic entomology, though not forensic botany. He mentions programmed cell death and the different ways cells die, including apoptosis, autophagy, and necrosis. He mentions death at its grandest, i.e. mass extinctions, and some of the ideas about how we came to be the last ape standing. He mentions research on ageing and the bioethical quandaries thrown up by the quest to live longer. And, finally, he mentions promising new technologies that could help stave off age-related diseases, as well as new and emerging threats that could undo it all (including antibiotic resistance and climate change). A panoramic overview indeed.

“Howard’s approach is to provide you with facts, facts, and then some more facts […] For such a fascinating topic, the writing is rather, well, lifeless.”

You will notice my frequent use of the word “mentions”. Howard’s approach is to provide you with facts, facts, and then some more facts. Here are the 12 major causes of death in the USA today. Next topic. Here are nine physiological manifestations of ageing. Next topic. Here are eight processes in human development that are shaped (quite literally) by programmed cell death. Next topic. There is little in the way of synthesis here and those looking for an engaging narrative might want to consider e.g. Bernd Heinrich’s Life Everlasting and Jules Howard’s Death on Earth. For such a fascinating topic, the writing is rather, well, lifeless and The Biology of Death faces stiff competition from many other titles.

Now, do not get me wrong, there are some interesting nuggets in here. The fear of premature burial was so great in the 18th century that one inventor was granted a patent for a warning device that could be fitted in coffins. I was amazed to read the long list of different forms of programmed cell death that I had never heard of, even though I spent an internship studying apoptosis in plants. Do animals understand death? Though Howard is not convinced, he does mention the anecdotal evidence of grieving in animals—stay tuned for more on this topic in the upcoming Playing Possum. And I was intrigued by the idea that the many hominid species evolving after Homo erectus might be a single chronospecies that through continuous evolution transitioned into H. sapiens, meaning that many of the names you are familiar with are little more than a taxonomic mirage. Frustratingly, he omits the reference where he got this idea from.

However, the book is marred by a series of mistakes that suggest the manuscript could have done with more feedback and revision. Relatively innocent are the occasional sentences that have extraneous words or typos in them, such as consistently writing of hunter-gathers instead of hunter-gatherers, or writing that the Triassic ended 18 million years ago, suggesting a digit was missed out (though two sentences earlier he correctly pegs the end-Triassic at 201 million years ago). Page 50 incongruously shows an image of a dividing E. coli cell that is neither referenced nor relevant to the paragraph discussing what we fear (e.g. flying) and what actually kills us (obesity, heart disease, etc.). Another example is discussing the World Health Organisation’s global mortality estimate for 2016 and providing a table with leading causes of death that instead shows data for the USA in 2017. These errors are infrequent but noticeable enough to suggest that the text would have benefited from more careful proofreading.

“there are some interesting nuggets in here [but] the book is marred by a series of mistakes that suggest the manuscript could have done with more feedback and revision.”

More worrisome, though, are some notable errors and omissions. When listing theories for how life started, he mentions Darwin’s warm little pond, panspermia, and the famous Urey–Miller experiments, but makes no mention of hydrothermal vents, which is another leading theory in the field of abiogenesis. He mentions a study claiming to have revived bacteria recovered from 250 million-year-old salt deposits. However, as discussed in Remnants of Ancient Life, this study was challenged on several grounds and it seems likely these bacteria instead resulted from later intrusion of water. He confidently asserts that the dinosaurs were already in decline before the asteroid hit. This is far from a consensus view. As discussed by Steve Brusatte in The Rise and Fall of the Dinosaurs, work by his and other groups shows that, though a few groups were in decline in North America, most other groups in most other places were doing just fine. A real howler is his casual mention that during the Jurassic “the dinosaurs flourished on the land and even moved into the sea and air” (p. 196). Errr, no. Other than contributing to the general misunderstanding that pterosaurs and ancient marine reptiles were dinosaurs (they are not), they certainly did not evolve from dinosaurs. These are just some of the topics I happen to be familiar with, but it left me feeling uncertain about how trustworthy the rest is. My impression is that his presentation of the biomedical and biochemical details of death is reasonably accurate and balanced, but that other topics would have benefited from more background research. Input and feedback from specialists in their respective fields could have much improved his manuscript.

Overall then, though this book is an earnest attempt at providing a wide-ranging overview of the biology of death that succeeds in showing that there is more to death than dying, it suffers from its lacklustre writing style and a range of errors and omissions.

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

The Biology of Death

Other recommended books mentioned in this review:

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In Being a Human, Charles Foster attempts to inhabit three past eras to find out first-hand how humans came to be who they are. He lives like an Upper Palaeolithic hunter–gatherer, an early farmer in the Neolithic, and he briefly visits the Enlightenment—or so we are promised. When I received this book, I was, admittedly, slightly unsure. Any attempt to live like past humans, especially hunter–gatherers, is fraught with difficulties as so many things have irrevocably changed: the flora and fauna, the landscape, the knowledge most of us have gained (you cannot really unsee germ theory) but also lost (who here can kill and prepare an animal or make a fire without modern tools?), or the fact that we lived in large communal groups. When the flap text also mentions shamanic journeys I was fearing the worst: am I about to witness yet another affluent man’s mid-life crisis?

Being a Human: Adventures in 40,000 Years of Consciousness, written by Charles Foster, published in Europe by Profile Books and in the USA by Metropolitan Books in August 2021 (hardback, 272 pages)

In short, the answer is no. Or at least, not immediately. Foster, an erstwhile veterinary student who is now a barrister teaching medical law and ethics, previously wrote Being a Beast in which he tries to inhabit the world of several animals. Here he takes this exercise in method-acting to the human world. The book is divided into three parts and purposefully spends most pages on life in the Upper Palaeolithic, fewer on the Neolithic, and only a short section on the Enlightenment, commensurate with how long humans inhabited these periods. He also makes it clear from the outset that this is less re-enactment and more thought experiment, an attempt to enter the mental and spiritual world of these people. Fair enough on both points, and I was happy to read the book in that spirit.

I found the first part very enjoyable, revolving as it did around four long wild-camping trips with his 13-year-old son in each season. Here, he shows a healthy amount of humility and self-deprecation. He admits that “we are just messing around” and how the vicinity of the nearby village shop “means that we’re bogus” (p. 29), how “the grumble of [a nearby] road makes a nonsense of our experiment” (p. 45). Or how, when his son gets into the spirit of things, he is put out: “This is my project, not his. I’m the sensitive one, the one with the psychic pretensions” (p. 96).

“[The first] part is a gonzo road trip into the birth of consciousness, symbolism, and language [and] features some amazing writing”

It also features some amazing writing, in places poetic and rich with metaphors such as when listening out for the sound of water dissolving rock: “The scouring has its own sound […] the hum of eroding rock resonating with the eroding cells of my own body, and it brings a sort of macabre comfort. It’s quite something to share solidarity with a limestone cliff, even when the solidarity is in the fact that we’re both dissolving” (p. 139). In others, it is base and pungent: “The last thing I ate was a hedgehog. That was nine days ago. From the taste of them, hedgehogs must start decomposing even when they’re alive and in their prime. This one’s still down there somewhere, and my burps smell like a maggot farm. I regret its death under the wheels of a cattle truck far more than its parents or children can possibly do” (p. 71). This part is a gonzo road trip into the birth of consciousness, symbolism, and language, accompanied by carefully annotated diversions into archaeology and anthropology.

But then.

The shorter part covering the Neolithic is quite a contrast. Instead of the full immersion attempted above, Foster is more an observer, occasionally mentioning short periods helping out at various farms. It is a shame, as he had the opportunity: two Welsh friends are doing an honest attempt to recreate life in this period. Why did he not sign up with his son for several apprenticeships throughout the seasons? Gone, too, are the humility and self-deprecation; my impression is that Foster comes to this period with strong preconceptions. He largely rehashes the “agriculture was our fall from grace” narrative that others such as Harari and Diamond have expounded. He gives a serviceable summary of some points raised in Against the Grain; e.g. how farming was slow to catch on, and how it seems to have spread by farmers pushing out hunter–gatherers, rather than the latter adopting farming practices, a finding supported by ancient DNA studies. I agree with many things he says, but also feel he is a tad too confident in his assertions, glossing over both subtleties and uncertainties. He catches himself in a few places (“I’m generalising too wildly. I’m judging the whole by the worst. I have tendencies that way” (p. 219), or “I’m doing it again—libelling a whole massive epoch” (p. 222)) but then goes ahead and does it anyway.

“Foster comes to [the Neolithic] with strong preconceptions […] I agree with many things he says, but also feel he is a tad too confident in his assertions, glossing over both subtleties and uncertainties.”

When we get to the Enlightenment section the book derailed completely for me. Instead of an attempt to inhabit this period we get a 35-page screed against the dogma of materialism. How did we get here? The setting is a dinner with several Oxford scholars, with the inviting professor rather patronisingly making fun of his project and asking him: “why all this theological mumbo-jumbo?” (p. 305). Foster’s response: “The experiences you choose to call supernatural are completely natural ones” (p. 306). Pipes up one of the guests: what are we talking about here? The list Foster gives includes, but is not limited to, clairvoyance, out-of-body experiences, precognition, telepathy, etc. In his eyes, Enlightenment thinking exorcised mind and soul from the non-human world, leading to dualism and then materialism, with everything else unworthy of study. Rather than, in true Enlightenment spirit, questioning everything, he feels “the fingers of the thought police on my collar, and the chill of stifled dissent” (p. 314). “For the Enlightenment Taliban, science isn’t a method: it’s a religion” (p. 315). When he then trots out Rupert Sheldrake and quantum mechanics I, momentarily, lost my shit.

The reason I am disappointed with how the book devolves is not that I disagree with his ideas (though I do), but with how poorly written it is. To be clear, I agree that scientific developments have been used to exploit the natural world. When he mentions the universal use of the phrase “natural resources”, I was reminded of Eileen Crist’s excellent book Abundant Earth. However, as before, he catches himself—”I hate the shrill fundamentalism in me that’s elicited by the Professor’s shrill fundamentalism” (p. 310)—and then proceeds regardless. Foster is honest and does not hold back, I will give him this much, but there is little nuance here. Five generalisations and logical fallacies stood out in particular for me.

“the Enlightenment section [is where] the book derailed completely for me. Instead of an attempt to inhabit this period we get a 35-page screed against the dogma of materialism.”

First, I agree that some of the ridicule he experiences is unwarranted and that some academics are closed-minded, but for Foster this corrupts the whole scientific enterprise, which is a gross exaggeration. Do I think there is more between heaven and earth? We cannot rule it out, but the evidence in favour so far is not convincing. Leading to point two; trying to throw Enlightenment values back at science is a favourite tactic of peddlers of the paranormal. Fact is, in the last three centuries scientists have questioned, and answered, many things. My impression is that some people do not like the answers. Leading to point three; many supernatural ideas, such as telepathy mentioned here, have simply not stood up to scrutiny, and we cannot replicate its extraordinary claims. Foster falls back on special pleading: “outside the laboratory […] in the realm of well-attested story, the effects are often much more dramatic” (p. 325) and “the laboratory experiment necessarily excludes the conditions that are the usual context and justification for direct Mind-to-Mind interaction of the dramatic kind” (p. 326). I find it hard to believe that I have to mention that the plural of anecdote is not data, and that humans are notoriously prone to wishful thinking, seeing patterns in noise, confirmation bias, etc.

Fourth, I do not really understand quantum mechanics, but as physicist Sean Carroll points out, neither do physicists. Foster admits to no such thing and instead confirms my suspicion that quantum mechanics must be one of the most abused notions in science, taken out of context at every turn. I am not sure that we can scale up from quantum entanglement to telepathy (Foster admits this much but points to the ideas of physicist Erich Joos to prop it up. I would like to hear the thoughts of Joos and others on this). And fifth, because it gets better, Foster claims that the reason there has been no systematic investigation of these phenomena (which contradicts what he wrote earlier) “is, simply, fear that the existing paradigm, on the basis of which all modern scientific careers in the biological and related sciences have been built, might be destroyed” (p. 325). And there we have it, we tie a neat little bow around it all with claims of a grand conspiracy of silence.

Overall, then, I found this book a decidedly mixed bag. I really enjoyed how it started, but was very disappointed by how it veered off course from its promised attempt to inhabit these three historical periods and ended in an incoherent diatribe.

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

Being a Human

Other recommended books mentioned in this review:

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7-minute read
keywords: evolutionary biology, genetics

Books can be like buses: nothing is written on a topic for ages and then two books appear in quick succession. The subtitle of Life as We Made It resembles that of the recently-reviewed Life Changing. Both books indeed cover the same topic: how humans have shaped the genetics and evolution of plants and animals around them. Despite some inevitable overlap, Beth Shapiro draws on two decades of her career as a geneticist to make Life as We Made It a beast all of its own. I found myself both thoroughly enjoying her fantastic science communication while disagreeing with her outlook.

Life as We Made It: How 50,000 Years of Human Innovation Refined – and Redefined – Nature, written by Beth Shapiro, published in Europe by Oneworld Publications in October 2021 (hardback, 352 pages)

Shapiro, who is a Professor of Ecology and Evolutionary Biology at UC Santa Cruz, previously won several awards for her book How to Clone a Mammoth. Her particular speciality is ancient DNA: the DNA recovered from extinct organisms and archaeological remains. These genetic time capsules have given us astounding insights and Shapiro gives you a taster of the history of this research field. Her book is divided into two parts, one looking at our past through the lens of ancient DNA, the other looking to our future through the lens of biotechnology.

The first half of the book is an absolute joy to read, showing what ancient DNA reveals about the influence of humans on life around them. This includes the evolution of the bison, charting their decline during the last ice age, their temporary recovery afterwards, and then their near-demise at the hands of humans. She shows human evolution is a complex history of mixing and migration, reiterating the picture presented in Who We Are and How We Got Here. She examines megafaunal mass extinction, Paul Martin’s Pleistocene overkill hypothesis, and the ongoing debate over how much can be attributed to past climate change and how much to our hunting ancestors. She covers the process of animal domestication and how it affected both the genetics of animals and ourselves. And, finally, she looks at very recent extinctions (e.g. the passenger pigeon), the problem of invasive species, and the rise of the conservation movement.

The second half of the book looks ahead, tackling the genetic modification of crops and livestock and the broad resistance it encounters in society. Shapiro looks at length at some of the initiatives that use biotechnological tools to help pull species back from the brink of extinction. She carefully and cautiously considers the topic of de-extinction and comes away not entirely convinced that resurrecting species is a good idea. Simultaneously, the recent development of gene editing tools has raised the possibility of ridding the world of certain pests and disease vectors, such as the mosquito species that carry malaria. There is an extended discussion about gene drives, CRISPR, and the science and ethics of editing the human genome.

“despite the range of subjects covered [Shapiro] retains the finesse and detail of these complex topics, repeatedly demonstrating how careful research refines simplistic narratives.”

What stands out is just how accessible all this material is, despite the range of subjects covered. Shapiro has a knack for communicating clearly, throwing in amusing anecdotes and self-deprecating humour as she recounts some of her academic bloopers. The annotated bibliography is a welcome bonus. More importantly, she retains the finesse and detail of these complex topics, repeatedly demonstrating how careful research refines simplistic narratives. Take one of archaeology’s most enduring discussions: how we peopled the Americas. Analysis of bison bones suggests that humans coming over the Bering land bridge had already moved southwards, using a coastal route to bypass the glaciers covering North America before an ice-free corridor opened up. Similarly, popular science articles often exclaim how other animals, e.g. ants, also farm. Although such mutualisms look like domestication, “neither species intentionally modified the other” (p. 113), which is a key difference from what humans do. And the ability of humans to digest lactose does not correlate strictly with the practice of dairy farming, either now or in the past.

Despite thoroughly enjoying Shapiro’s presentation of complex scientific topics, I also found myself disagreeing with her optimistic techno-driven outlook. This is perhaps nowhere more apparent than when she writes that “we are too embedded, our technologies too advanced, our population too large to disentangle ourselves from the habitats that we have invaded over the last 200,000 or so years […]. We must use our increasingly advanced technologies to shape the future into one in which people can thrive alongside other species” (p. 102).

I beg to differ.

Before I climb on that soapbox, let me clarify that I am not anti-science. I share Shapiro’s frustration about people’s irrational resistance to GMOs and have previously written about the appeal to nature fallacy. For me, horizontal gene transfer is proof positive that nature beat us at the game of transgenics ages ago. Maybe it was not her intention, but it is a bit of a straw man to paint all opponents of biotechnology as either hostile to, or not knowledgeable about science. There are other reasons to have concerns.

“[Biotechnological] tools are not the only option available to us, nor always the best. […] How about us not always getting what we want? If behavioural change and cultivating an ethos of self-limitation […] can address problems, should we not consider this first?”

Shapiro recognizes that overpopulation and overconsumption are at the root of many environmental problems. I ask you: since when have technofixes ever caused us to want less of something? Since when, as she mentions throughout this book, have new technologies not caused new problems or had unintended consequences? To propose that we embrace our role as Earth’s stewards takes human dominance of the planet as a given, the only solution being “to science the shit out of this“, to quote The Martian.

Let me be clear: I do not think this is an either-or proposition. However, having reviewed both Abundant Earth and Limits I question the anthropocentric notion that we are entitled to keep shaping the world around us for our benefit first and foremost. Appealing to our long history of doing this is no justification. Shapiro concludes that “the world is changing, and people and animals and ecosystems are suffering. Biotechnologies give us the power to help” (p. 290). I agree that we will need the best science can give us and she gives good examples where these solutions are desirable, such as introducing disease resistance genes into the nearly-extinct American chestnut. However, these tools are not the only option available to us, nor always the best. In many cases, biotechnology will only encourage the status quo of more economic growth and more consumption, not less. She observes that “we are aware in ways that our ancestors were not of the consequences of getting what we want” (p. 132). How about us not always getting what we want? If behavioural change and cultivating an ethos of self-limitation, both on an individual and societal level, can address problems, should we not consider this first? It strikes me that currently this notion rarely enters the conversation. That is my challenge to her and the research community at large, to consider that prevention is better than a cure and, with that in mind, to re-evaluate proposed technofixes.

This difference in outlook did not stop me from tremendously enjoying Life as We Made It. Shapiro is a fantastic science communicator who addresses the many nuances of each topic she touches, and she can be disarmingly funny. I heartily recommend you read this book, but I also invite you to afterwards critically reflect on her ideas in light of what I have written above.

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

Life as We Made It

Other recommended books mentioned in this review:

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History will forever associate Charles Darwin with the theory of evolution, but the idea was in the air. Had not Darwin published his famous book, someone else would have likely snatched the prize. Husband-and-wife duo John and Mary Gribbin here examine the wider milieu in which Darwin operated and the many thinkers who preceded him. Given their previous collaborations, the first two parts of On the Origin of Evolution read like a well-oiled machine, but the book falters when they turn their eyes to the legacy of Darwin’s ideas.

On the Origin of Evolution: Tracing ‘Darwin’s Dangerous Idea’ from Aristotle to DNA, written by John Gribbin and Mary Gribbin, published in Europe by William Collins (a HarperCollins imprint) in November 2020 (hardback, 288 pages)

When you study the history of science, it seems there is just no way around Aristotle. In the context of this book, his legacy is the idea of the great chain of being: the notion that life can be ordered from simple to complex forms, with humans at the top as creation’s crowning glory. It was readily adopted by Christian thinkers and hamstrung evolutionary thinking for millennia.

Still, as the first third of this book shows, some people did ponder both man’s place in nature and the relationships between living beings. Liberally quoting from their writings, the authors introduce you to notable characters and their brilliant early flashes of insight. For example, Thomas Aquinas, writing in the 13th century, allowed for species to develop in their striving for perfection but rejected the idea of new ones arising after God’s act of creation. Fossils were long misunderstood, neither recognized as ancient nor as the remains of extinct creatures. I was therefore particularly fascinated by 17th-century British polymath Robert Hooke who may well have been one of the first to recognize fossils for what they were. His ideas on species formation and extinction seem prescient. In the 1770s, Lord Monboddo already argued that humans descended from apes. And yet, the dots were not connected into a bigger picture. Particular sticking points were extinction and the age of the Earth, a puzzle to which James Hutton and other geologists would later contribute much.

When the book gets to Darwin, the tempo slows right down and the middle third of the book examines Darwin’s life and simultaneous developments around him. The Gribbins sketch how Darwin, ever careful, worked on his ideas for decades, also because he felt that, as a geologist, one could not “examine the question of species who has not minutely described many” (p. 134). Something he subsequently spent years on. The history of how Alfred Russel Wallace later came to similar conclusions and ran them past Darwin in a letter, and how Charles Lyell and Joseph Hooker presented both their work at a meeting of the Linnean Society, is well-known. What the Gribbins here clarify is that, if it seems strange to us now that Wallace’s letter was publicly presented by a third party without his consent, this was the custom of the time. Communications of scientific interest were expected to be made public as quickly as possible. Various quotes from Wallace indeed show nothing but a man who was very chuffed to have his work mentioned alongside Darwin’s.

“[…] the first two parts of On the Origin of Evolution read like a well-oiled machine, [numerous] details left me with the impression that the authors have been meticulous […]”

The Gribbins also pay attention to Erasmus Darwin (Charles’s grandfather) and relevant contemporaries such as Jean-Baptiste de Lamarck and Georges Cuvier. They give Lamarck his due and note the irony of him accepting evolution but denying extinction, and Cuvier denying evolution but accepting extinction. If the two had not ended up bitter enemies they might have put two and two together. Another lesser-known figure who came tantalisingly close, and virtually coined the term natural selection, was arborist Patrick Matthew who buried his thoughts in the appendix to a book on naval timber. Darwin was unaware of his work despite Matthew’s later public charges, the Gribbins write. Other notable details are a public admission to a change of heart over whether a letter from Darwin to Wallace was intended to warn Wallace off. The Gribbins used to think so, but are now persuaded it was not. They also clarify the oft-repeated factoid of On the Origin of Species selling out on the day of publication: “this is only true in the sense that all the copies had been bought up by the bookshops, ready to sell on to their customers” (p. 166). An observation that, working for a bookseller myself, rings true. These and other details left me with the impression that the authors have been meticulous up to this point. (I admit this is a risky thing to say; whole academic careers have been built on studying Wallace and Darwin’s lives, so cue people more knowledgeable than myself pointing out errors next).

On the Origin of Evolution competes for your attention with Rebecca Stott’s 2012 book Darwin’s Ghosts, which similarly traced Darwin’s intellectual forebears. That book ended with the above-mentioned presentation at the Linnean Society, so the Gribbins have the opportunity to set themselves apart with the last third of their book, which examines the development of Darwin’s ideas by later scientists. Although I enjoyed the book up to this point, the last part is where it fell a bit flat for me.

The Gribbins weave their narrative through the work of Gregor Mendel and its triple rediscovery decades later; the discovery of the structure of DNA, honouring the long course described in Unravelling the Double Helix; and the discovery of how DNA codes for amino acids. It touches on horizontal gene transfer, epigenetics, and twin studies and the discovery of polygenic traits. All important topics for sure, but they omit so many others as to make this part of their history rather haphazard.

“[…] the last third of their book, which examines the development of Darwin’s ideas by later scientists. […] omits so many [topics] as to make this part of their history rather haphazard.”

Two oversights stand out. They discuss how extinction ultimately became accepted but leave out the next chapter: the mass-extinction debates, which was a conflict between uniformitarianism and catastrophism. Similarly, they recognize Wallace as the grandfather of biogeography but leave out how the long-resisted idea of plate tectonics explained palaeobiogeographic patterns. Basically, they completely ignore the rise of palaeobiology and its contributions to evolution. Beyond these, they mention horizontal gene transfer, but not Carl Woese and his proposal of a Last Universal Common Ancestor. They feature Thomas Hunt Morgan’s research on Drosophila, but not the emergence of evolutionary developmental biology. They profile Barbara McClintock’s struggle to get her discovery of mobile genetic elements accepted but not Lynn Margulis‘s struggle to get endosymbiosis recognized. And although the Sources and Further Reading section lists other major thinkers, there is no discussion of, say, Ernst Mayr and the problem with species definitions, the work of Stephen Jay Gould, or the debate on levels of selection. Sexual selection and phylogenetics are completely absent.

They cram this last part in a mere 70 pages while repeatedly mentioning not being able to go deeper. I am not sure why. At 253 pages of text, the book is not particularly long. Had they spent another 50 or even 100 pages, I feel they could have done it more justice. I will be the first to concur that writing such an overview is challenging. Part of the problem, I think, is that the authors (John a science journalist with a PhD in astrophysics, Mary a teacher) do not have a thorough background in (molecular) biology and reach into unfamiliar territory, as evidenced by some elementary mistakes. On p. 218 they mention DNA contains three purines and one pyrimidine, and correct themselves two sentences later (there are two of each). They mix up the DNA base pairs on p. 226 (CT and AG pairs) but get it right on p. 227. And on p. 244 they mention the human genome consists of 6 billion base pairs which is double the actual number. Anyone who has had to study Alberts’s brick will have had these facts drummed into them, but their acknowledgements are silent on whether fellow biologists provided feedback on the manuscript. Now, I do not want to blow a few factual errors out of proportion, but together with the brevity of the material included, and the many other topics not covered, this last part left me less than satisfied.

Overall then, this book is an excellent introduction to the history of evolution before and up to Darwin that retains important detail despite being relatively brief. I was less impressed with the coverage on the developments since Darwin, which would benefit from supplementary reading. I hope a future review of The Black Box of Biology will fill in some of the blanks regarding molecular biology.

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

On the Origin of Evolution

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After three previous books in this format on fossils, rocks, and dinosaurs, geologist and palaeontologist Donald R. Prothero here tackles the story of evolution in 25 notable discoveries. More so than the previous trio, this book tries to be a servant to two masters, resulting in a mixed bag.

The Story of Evolution in 25 Discoveries: The Evidence and the People Who Found It, written by Donald R. Prothero, published by Columbia University Press in December 2020 (hardback, 360 pages)

Prothero has organised The Story of Evolution in 25 Discoveries in a logical fashion. After convincing the reader that the universe and our planet are, indeed, really old, he considers some of Darwin’s lines of evidence for evolution, followed by several great transitions in evolution as revealed by the fossil record, more recent evidence from genetics and molecular biology, and, of course, evidence for the evolution of humans.

As in his previous books, Prothero manages to dig up some remarkable stories. For example, Darwin initially mistook the finches on the Galápagos for wrens, blackbirds, and other species. Only when he handed them to the famous ornithologist John Gould for a second opinion did it become clear that these were all finch species adapted to local conditions on the different islands. It later fell to others such as Peter and Rosemary Grant to do the long-term studies that elevated them to the icon of evolution they have become. Meanwhile, Othniel Charles Marsh’s monograph on primitive birds that still had teeth was unexpectedly branded a waste of taxpayer’s money when US congress was looking for excuses to cut funding to the US Geological Survey in the 1890s.

In many places, Prothero is careful and balanced in his coverage. He highlights the contribution of the historically overlooked Alfred Russel Wallace who independently hit on the idea of natural selection after Darwin had already been labouring on it for decades. And while Ernst Haeckel was accused of fraud over his famous drawings showing the embryonic development of different vertebrates, Prothero explains how there is a kernel of truth to Haeckel’s claim that ontogeny recapitulates phylogeny, even if “he may have been a bit overzealous in his drawings” (p. 69). On Jean-Baptiste de Lamarck and his ideas, Prothero clarifies how there was much more to him than the caricature of the “guy who got evolution wrong” (p. 198) that he became.

“In many places, Prothero is careful and balanced in his coverage […] he clarifies how there was much more to Jean-Baptiste de Lamarck […] than the caricature of the “guy who got evolution wrong””

There are classic topics such as convergent evolution, the evolution of the eye, and Lynn Margulis and her theory of endosymbiosis. The relatively young branch of evolutionary developmental biology and the discovery of Hox genes showed that, actually, yes, nature does make leaps and does not always result in slow and gradual changes. Throughout, Prothero repeatedly reminds you that the evolutionary relationships between organisms are like a bush, and not a linear progression from primitive to more advanced creatures. He explains that evolution does not always result in perfect adaptations—they only have to be good enough to help in producing the next generation. And he points out that natural selection can only ever work with the material at hand, resulting in many jury-rigged contrivances, including in humans.

Now, Prothero is also a noted sceptic. A good deal of this book has the secondary aim of showing that creationism is an utterly flawed idea and that the evidence for evolution reveals no traces of intelligent design whatsoever. The thing is, he already did this exercise in Evolution: What the Fossils Say and Why It Matters, so does it need repeating? He spends no fewer than seven chapters here on examples of transitional fossils that provide a detailed picture of fish leaving the water, whales returning to it, birds evolving from dinosaurs, giraffes evolving longer necks and elephants longer trunks, horses losing their toes and snakes their legs, and turtles acquiring shells. You almost get the feeling that he just cannot help himself.

I have few gripes with the topics that Prothero chose to include here, but I felt somewhat disappointed by all the topics he left out as a consequence of this secondary mission. Two notable omissions are the process of domestication, even though Darwin used numerous examples of it in On the Origin of Species and then wrote a separate book about it. The same is true for Darwin’s other big idea: there is no mention of sexual selection, sperm competition, or mate choice.

“[…] this book has the secondary aim of showing that creationism is an utterly flawed idea […] but I felt somewhat disappointed by all the topics he left out as a consequence […]”

Beyond these, there is little on speciation and biodiversity, the formation of higher taxa, or the difficulty with species concepts. Epigenetics is mentioned, but not by name. The textbook example of the peppered moth is included, but there is no further discussion on camouflage, mimicry, or warning signals. Richard Dawkins has to make do with two brief mentions, but there is nothing about the different levels of selection, whether selfish genes or group selection. And I am sure Prothero could have beautifully explained the difference between the modern and extended syntheses.

The focus on convincing the reader of the evidence against design raises the question of who this book is written for. For evolutionary biologists like myself, Prothero is preaching to the choir, while creationists are unlikely to pick this book up. The best this might achieve is to remind biologists of the evidence for evolution if we ever find ourselves debating creationists.

Prothero is a fantastic science communicator, and I really enjoy this format of 25 vignettes by which to examine the many facets of a topic. The material that he did choose to include is written with verve and balance. In my opinion, however, the dual motive underlying The Story of Evolution in 25 Discoveries means that he left out many relevant topics and has written a book of narrower focus than the title might suggest.

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

The Story of Evolution in 25 Discoveries

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Advances in medical research mean we have come to grips with numerous diseases and health conditions over the decades. But, like a game of whack-a-mole, you solve one set of problems to only have other, often more complex problems take their place. There is valid criticism to be had of medicine and its reductionist approach and What Is Health? sees neurobiologist Peter Sterling offer a critique grounded in physiology.

What Is Health?: Allostasis and the Evolution of Human Design, written by Peter Sterling, published by MIT Press in December 2019 (paperback, 257 pages)

Much medical thinking and education, writes Sterling, revolves around homeostasis: self-correcting negative feedback loops, comparable to the thermostat in your house. These allow the body to regulate physiological processes, e.g. blood pressure, without involving the brain. However, he found that many endocrine cells, those that release hormones, do have nerve endings terminating on them. Homeostasis is part of the story, but “error-correcting feedback offers no basis for a full model of human design” (p. xxx*). Together with Joseph Eyer, he coined the term allostasis in the 1980s: the brain is involved by predicting the body’s needs and mobilising resources to meet expected demand, temporarily up- or downregulating processes when an organism’s environment changes. In simple terms, homeostasis corrects, allostasis predicts. This also gives us Sterling’s definition of what health is: “the capacity to respond optimally to fluctuations in demand” (p. 154).

This idea has been criticised from various sides as resulting from too narrow a reading of homeostasis, “a travesty that has taken root in textbooks and is widely taught to students as the only kind of control system“, that is not offering anything “that was not already apparent, or at least readily derivable, from an accurate reading of the original concept of homeostasis“. I am receptive to such criticism. Though I was not trained as a physiologist, my layman biologist understanding of it is that e.g. a healthy blood pressure already falls between a range of values and that what is considered optimal depends on whether you are at rest or exercising. Do we really need allostasis as a separate concept? Especially Carpenter is fierce in his criticism: “there is a need to reassert the unitary nature of homeostasis and the variety of forms it can take, so that we are not obliged to reinvent what was common knowledge even 30 years ago, nor to introduce artificial distinctions and boundaries within a field that is in truth perfectly unified.“

“In simple terms, homeostasis corrects, allostasis predicts. But do we really need a separate concept? I am not sure that disagreements over definitions make much difference to Sterling’s point that modern life can break this physiological control system.”

Having read the rest of this book, however, I am not sure that disagreements over definitions make much difference to Sterling’s argument that modern life can break this physiological control system. Before getting to that discussion, though, he spends the first four chapters on a deep evolutionary history tour to trace the origins of the components of allostasis. This tour encompasses the molecular details of the genetic code, protein functionality, and ATP synthesis and hydrolysis to store and release energy at a cellular level. It encompasses the evolution of multicellularity and what we inherited from our worm-like ancestor in the way of cellular clocks, early brains, and feedback regulation between the different parts. (Side note, this is likely where dopamine was introduced as the brain’s reward signal for useful behaviour, enabling learning.) It encompasses the evolution of endothermy and the respiratory and cardiovascular adaptations enabling it. And, finally, it encompasses the evolution of Homo sapiens when it left Africa some 150,000 years ago. Sterling argues that changes to our brain allowed us to oust our Neanderthal cousins. Summarising from his book Principles of Neural Design, he gives a bird’s-eye-view of how the brain is organised for optimal functioning, what we inherited from our primate ancestors, and what we changed.

Overall, these chapters are well written and full of fascinating information, though I am not sure all of it is necessary to understand allostasis. Also, there are a few minor points I take issue with. I understand that phrases such as “a reptile evolved two new features and came out as a mammal” (p. xxv) and “At the pinnacle of life’s energy-driven complexity, perches—precariously—Homo sapiens” (p. 1) are shorthand. However, they could be mistaken for outdated linear thinking about evolution, even if Sterling’s writing in the rest of the book suggests no such thing. We did not evolve from reptiles. We share a common ancestor with them but they have been on an equally long evolutionary journey. Furthermore, Sterling strongly argues that evolution has produced optimal structures or, where tradeoffs make something seem suboptimal, optimal trade-offs. His endnotes explain that e.g. our appendix and the seemingly backwards design of our retina are actually functional, and he concludes that “[…] clear examples of suboptimality are scarce, if they exist at all” (p. 9). I am not sure I agree. The circuitous loop taken by the recurrent laryngeal nerve or the design of our throat that puts us at constant risk of choking are but two of many examples that Nathan Lents discussed in his book Human Errors. We know that evolution cannot simply start from scratch and that it reuses, repurposes, and rejiggles existing structures for new functions. Furthermore, Daniel S. Milo’s Good Enough criticized adaptationist storytelling and made an interesting argument for the persistence of the mediocre. Perhaps these are just issues of semantics and, seeing they do not really bear on his central argument, I will not dwell on them further.

“the simple pleasures of life were sources of regular small pulses of dopamine. These eroded, first gradually with the advent of agriculture, then rapidly with the Industrial Revolution, leading to our modern, dopamine-deprived lifestyle.”

Having taken the deep evolutionary tour, chapters 5 and 6 are where Sterling finally drops the payload and delivers the goods. The mechanism of allostasis breaks down when demand is excessively high for sustained periods. The body responds by shifting its operating range upwards and what used to be exceptional becomes the new normal. In the example of blood pressure you end up with chronic hypertension. Something similar happens with our reward circuits. We evolved as socially living hunter-gatherers that had regular physical exercise, where children of different ages played together unsupervised, where we learned and perfected skills such as hunting over decades, and where the elderly contributed to care of the young. Call them the simple pleasures of life but that is the whole point, they were sources of regular small pulses of dopamine. Sterling argues that instead we now try to get our dopamine hit from alcohol, nicotine, drugs, food, gambling, pornography, or shopping. And many of these activities deliver greater surges, with allostasis adapting us to take such surges as the new normal, fostering addiction. By his reasoning, the Western epidemic of hypertension, obesity, depression, suicide, alcoholism, and addiction to drugs and gambling are all a consequence of our modern, dopamine-deprived lifestyle. He will even throw in climate change, resulting as it does from excessive consumption of goods, meat, and (air) travel.

There is no shortage of recent books arguing that we are the victim of an evolutionary mismatch with instinctive brain circuits that cause us to e.g. overeat; that we have become unfit for purpose and our hunter-gatherer origins mean that we are poorly adapted to modern life. Sterling puts neurological flesh on the bones of that argument. More importantly, he pleads with us not to blame our evolutionary heritage. This reward circuit “inherited from worms […] works exactly as it is supposed to—just not for what it was intended. This has been termed a “mismatch” […] but that euphemism avoids facing squarely that “how we live now” is intolerable to a large fraction of our population” (p. 138). The tragedy is that medical practitioners try to combat this epidemic of apparently intractable chronic illnesses with pharmacotherapy—a pill here, a beta-blocker there—in a vain attempt to correct specific physiological parameters without recognizing that “the underlying biochemical and neural circuits are not actually broken” (p. 165).

“contrasting our hunter-gatherer lifestyle with “how we live now” raises the question: what of the intervening [time]? […] did we suffer the same epidemic of lifestyle diseases that we see now?”

By and large, I am on board with Sterling’s line of reasoning. We did indeed live as hunter-gatherers for the vast majority of our evolutionary history, and the argument of our current dopamine-deprived lifestyle is attractive.

However.

I am always a bit wary of single-cause, killer hypotheses that seek to explain a wide range of topics with one causative agent. Some claims here do seem rather sweeping, and to write, for example, that “it is sobering to notice that the growth of smartphones and Facebook parallels the growth of mass shootings” (p. 132) risks conflating correlation and causation. But more importantly, contrasting our hunter-gatherer lifestyle with “how we live now” raises the question: what of the intervening ten to fifteen thousand years that Sterling skips over? He limits himself to writing that our drip-feed of regular, small dopamine pulses eroded, first gradually with the advent of agriculture, then rapidly with the Industrial Revolution that “accelerated the process and exaggerated it grotesquely” (p. 131). Archaeology and palaeopathology tell us that the shift from foraging to agriculture was a Faustian bargain that initially took a heavy toll on our health. Our stature diminished and especially our teeth recorded the effects of this dietary change. But did we suffer the same epidemic of lifestyle diseases that we see now? Or was it the Industrial Revolution and especially the Great Acceleration that pushed us over the edge? In the latter case, it would seem there are more ways than the hunter-gatherer lifestyle to live a fulfilling life.

Are there solutions? Fortunately, Sterling does not advocate we head back to the caves and draws attention to the, I think, underappreciated argument that history has acted as a ratchet: “higher population densities gradually disallowed any return to the wild” (p. 128). One option is to work with the body’s mechanism of allostasis, not against it, through what he dubs “system therapy”, which is basically what rehab is for drug addicts. It is hard and slow, but the only way to resensitize our body’s reward circuit to more modest dopamine pulses. Preventative strategies would involve changes to modern life to restore physical and mental challenges, lifelong learning, and social relationships between the generations. These suggestions are, to my taste, rather generic and I would have loved for him to develop this part of the book fuller.

Given that neurobiology can be a technical topic, Sterling writes accessibly and makes good use of numerous illustrations to clarify principles further. I found the detour into deep evolutionary history particularly interesting, even if not all of it was relevant to the central argument. Though I am on the fence regarding some of the material here, What Is Health? is overall a cogently argued book that provides both reason for concern and food for thought.

* Have I forgotten to insert a page number here? No, this quote is taken from the first 32 Roman-numeral-numbered pages of prefatory material.

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

What Is Health?

Other recommended books mentioned in this review:

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Can we predict what aliens will look like? On some level, no, which has given science fiction writers the liberty to let their imagination run wild. On another level, yes, writes zoologist Arik Kershenbaum. But we need to stop focusing on form and start focusing on function. There are universal laws of biology that help us understand why life is the way it is, and they are the subject of this book. If you are concerned that consideration of life’s most fundamental properties will make for a dense read, don’t panic, The Zoologist’s Guide to the Galaxy is a spine-tingling dive into astrobiology that I could not put down.

The Zoologist’s Guide to the Galaxy: What Animals on Earth Reveal about Aliens – and Ourselves, written by Arik Kershenbaum, published by Viking in September 2020 (hardback, 356 pages)

Fundamental to answering the question of what alien life might be like, Kershenbaum argues, is to recognize that evolution by natural selection is the most important law in biology, “an inevitable mechanism, not just restricted to planet Earth” (p. 8). Rather than trying to answer particulars (Will aliens have two legs? Six? Or none?), he focuses on process: “Movement, communication, cooperation: these are evolutionary outcomes that are solutions to universal problems” (p. 11). Thus each chapter discusses “some feature of animal behaviour on Earth that is not unique to Earth—that can’t be unique to Earth” (p. 14). These three quotes nail down how Kershenbaum managed to hook me in right from the start of his book.

A key observation to support his argument that natural selection will not be limited to planet Earth is convergent evolution. I find this one of the most exciting topics in evolutionary biology and have written about it extensively last year when reviewing three books in The Vienna Series in Theoretical Biology from MIT Press. Brief refresher should you need it: convergent evolution refers to the ubiquitous pattern of evolution repeatedly hitting on the same or similar solutions to a problem in different organisms. Kershenbaum introduces it here with some examples and also touches on the contingency vs. convergence debate, of which Stephen Jay Gould and Simon Conway Morris are the most prominent spokesmen. Convergent evolution can hold lessons for astrobiology, though George R. McGhee’s book Convergent Evolution on Earth did not quite deliver on its promise to do so. Kershenbaum, however, does. There is no reason to think that convergent evolution would be limited to life on Earth because “we live in a universe where not everything is possible” (p. 46). The laws of physics circumscribe a limited set of possibilities, something that so memorably expressed by writing that “physics is life’s silent commander“.

So what are these characteristics that we can expect to evolve universally? Kershenbaum considers six, from very basic to likely rarer: movement, communication, intelligence, cooperation, information exchange, and language. Even though these are very fundamental properties of life that you could talk about in abstract terms, what makes The Zoologist’s Guide to the Galaxy so accessible is Kershenbaum’s pithy writing style. I will highlight three examples to give you a taster.

“[Kershenbaum] focuses on process: “Movement, communication, cooperation: these are evolutionary outcomes that are solutions to universal problems“”

Take movement: “We move because we must, not because we can […] Life needs energy, and if energy is not evenly distributed, life must go in search of it” (p. 70–72). Earth life has tried pretty much every mechanism we can think of to move in a fluid medium (air or water) or on the interface between a fluid and a solid, so expect alien life forms to float, paddle, or develop legs.

Cooperation similarly seems likely. There is a range of benefits to individuals cooperating, not in the least the threat of predation. “Predation is universal, because no ecosystem can exist for long without someone trying to take a bite out of somebody else; the selective pressure on acquiring as much energy as possible is just too strong” (p. 171). When and whether it is evolutionarily advantageous to evolve cooperation is something we can answer mathematically using game theory, “a simple technique, applicable on any planet” (p. 192). We should not be surprised to find aliens with complex social structures, dominance hierarchies, and reciprocal behaviour.

A full-blown language, on the other hand, seems uniquely human. This chapter leads you through the difficulty in defining language and grammar, the contentious topic of language evolution, and an interesting dive into xenolinguistics, or how you would recognize whether a signal carries the signature of language. These are all areas of active research where no consensus has been reached between different schools of thought. Nevertheless, Kershenbaum identifies two fundamental features that an alien language would have: it is a means to communicate complex concepts, and it evolved by natural selection.

“There is no reason to think that convergent evolution would be limited to life on Earth because “we live in a universe where not everything is possible“. The laws of physics circumscribe a limited set of possibilities […]”

This core of six chapters is padded out with a fascinating chapter that considers artificial life forms. After all, evolution as we know it acts blindly, without foresight. “But what if it were all different? What would life look like if it did know where it was going?” (p. 258). Well, perhaps not all that different. “Game theory […] is ruthlessly inevitable” (p. 280), so expect conflict and cooperation. Furthermore “some things like mutation, and even death, can’t be eliminated just by being incredibly smart” (p. 286).

The whole is bookended by two more philosophical chapters. The first asks what an animal is and whether aliens would be considered animals. Though we would not share ancestry, the point of this book is to show that we would likely share fundamental processes and properties. The last chapter considers the impact that the discovery of alien life would have on us and whether we would recognize such life forms as a fellow form of humanity. Throughout, there are footnotes to general literature, and an annotated list of suggested reading provides plenty of material if you want to delve deeper.

Kershenbaum admits that you probably wanted him to tell you what aliens look like, and his book contains less speculative zoology than e.g. Imagined Life. However, by the same logic of giving a man a fish vs. teaching him how to fish, understanding the rules that life follows is ultimately more rewarding. Kershenbaum’s smooth writing style makes it a proper page-turner.

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

The Zoologist’s Guide to the Galaxy

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 wake of the COVID-19 pandemic, many publishers have seen an opportunity to reissue previously published books on viruses and pandemics. As a reader, it is always difficult to know whether you are actually getting any updated content beyond the obligatory new preface or afterword, or whether this is just a quick cash-grab. Fortunately, the third edition of Carl Zimmer’s famous virology primer A Planet of Viruses is here to prove those suspicions wrong.

A Planet of Viruses, written by Carl Zimmer, published by the University of Chicago Press in March 2021 (paperback, 144 pages)

A Planet of Viruses was first published in 2011, followed by the second edition in 2015, and now the third edition in 2021. The book is a collection of short essays, many of which were originally written for World of Viruses, a National Institutes of Health-sponsored pop-science project to communicate virology to a wider audience.

In Zimmer’s trademark crisp prose, each of the twelve essays focuses on a particular virus or class of viruses while simultaneously explaining certain virology concepts. Thus the chapter on tobacco mosaic virus discusses how viruses were discovered and led to breakthroughs in microbiology, while the essays on rhinoviruses and influenza explain how our immune system combats viruses and how rapid evolution means viruses and their hosts are locked in a perpetual arms race. But there is hope. The short history of smallpox introduces the important concepts of variolation and vaccination, and how some viruses can, in principle, be eradicated.

Although each essay is short, Zimmer has the enviable quality to highlight interesting facets in each story. The essay on HIV explains the crossing of species boundaries by infectious diseases, zoonosis, the origins of HIV, and how this virus, to quote David Quammen, has since diversified “like an infectious starburst“. A piece on the West Nile Virus shows how viruses can go global, and how insect vectors such as mosquitoes can assist. And then there are the viruses that infect bacteria, bacteriophages, that outnumber us to a mind-boggling degree. As two of the essays here show, our world is a virosphere rather than a biosphere.

“Although the placenta is one of the features that made us mammals, this is ultimately thanks to a viral stowaway.”

Other essays delve into virus evolution. Studies of ancient DNA have not only revealed that our ancestors interbred with Neanderthals, but also that we may have acquired some of their viruses, such as the cancer-causing human papillomavirus. Retroviruses, meanwhile, go far beyond taking over a host’s cellular machinery: they nestle themselves into its DNA and remain there. Our genetic material is riddled with such endogenous retroviruses, one of which produces the protein syncytin that is vital for the formation of the placenta during pregnancy. This infection has ancient roots, as the virus’s genetic code is found throughout the mammalian family tree. Although the placenta is one of the features that made us mammals, this is ultimately thanks to a viral stowaway.

Viruses even force you to ponder philosophical questions such as the definition of life. Viruses are typically considered to be non-living. Yet, the essay on giant mimiviruses and their large genomes containing thousands of genes shows that these lines are blurred. Consider this essay a taste of things to come in Zimmer’s new book Life’s Edge. And as he did in She Has Her Mother’s Laugh when discussing genetic mosaics, he can implode your sense of identity with a single sentence. When discussing retroviruses he concludes that “There is no us and them—just a gradual blending and shifting mix of DNA” (p. 71).

“It was not until I looked at the references that I realised each essay has been updated with new research published in the last six years.”

By now you might be chomping at the bit. What about COVID-19? New to this edition is the essay “The Pandemic Age”, which has replaced “Predicting the Next Plague” on Ebola from the second edition. This introduces coronaviruses more generally, briefly chronicles how the SARS and MERS outbreaks proceeded and how COVID-19 differs, and discusses some of the molecular details, such as how it enters the host cell. This essay felt a bit thin on the ground and did not provide all that much new information, especially given that Zimmer has written interesting pieces on vaccines and the virus’s structure for the New York Times. I guess book publication and news cycles will forever be out of step with each other.

Now, before you conclude that this is a somewhat disappointing update on the previous edition, let me stop you there. It was not until I looked at the references that I realised each essay has been updated with new research published in the last six years. It would have been easy to just slap in the COVID-19 essay, send it off to the printers, and call it a third edition. This is not the case, however, which reflects very well on both the author and the publisher. Furthermore, this edition features stylish woodcut-like illustrations from Ian Schoenherr that open each chapter (though, unfortunately, there are no illustrations included to explain biological concepts).

A Planet of Viruses is a captivating primer to the world of viruses that requires zero background in biology. The brevity of the essays and the small size of this book make it a suitable first introduction to this fascinating part of our world. Even for a biologist such as myself, there is much to admire in Zimmer’s writing: these essays are miniature masterclasses in science communication. If, for some reason, you have so far missed out on this book then what are you waiting for? At this price and this size, you have no excuse not to indulge.

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

A Planet of Viruses (3rd edition)

Other recommended books mentioned in this review:

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