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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Fifty years ago, US President Richard Nixon declared a “war on cancer” when he signed the National Cancer Act. Despite fantastic progress on some fronts, overall it is clear that we are not winning this battle. Cancer remains one of the leading causes of human mortality. But what if the tired war-metaphor is getting it all wrong? Brimming with thought-provoking questions, The Cheating Cell looks at cancer through an evolutionary lens and forces the reader to radically reconsider cancer; not as a bug, but as a feature of life.

The Cheating Cell: How Evolution Helps Us Understand and Treat Cancer, written by Athena Aktipis, published by Princeton University Press in March 2020 (hardback, 238 pages)

Athena Aktipis came to the research field of cancer evolution in the mid-2000s, just as it was getting a boost from various researchers, including Mel Greaves, who started to apply ideas from evolutionary biology to cancer research. She describes herself as working at the interface of cooperation theory, theoretical evolutionary biology, and cancer biology. Her background in psychology, with a specific interest in cooperation and conflict, might seem little relevant to cancer research but turns out to be highly appropriate.

The basic premise of this book is that cancer is an evolutionary phenomenon that has been with us for as long as life has been multicellular and is best thought of as cellular cheating. If that seems like a lot to take in, I am trying to distil into one sentence what Aktipis spends the first three chapters developing. Let us go through these in reverse order.

First, this notion of cheating. The hallmarks of cancer in humans is unchecked cell division, frequently forming tumours in the most unwelcome of places and, in some forms, spreading throughout the body in a process known as metastasis. But this is rather a narrow definition for understanding cancer’s deep evolutionary history. To compare organisms with a very different underlying biology, such as plants and animals, you need to think at a more fundamental level. What cancer cells are ultimately doing is cheating on the pact that cells form when cooperating to form a multicellular organism. They divide out of control, they refuse to self-destruct via programmed cell death (apoptosis), they hog the body’s resources, they do not stick to their assigned job, and they trash their environment, damaging and destroying the host’s body as they go.

“What cancer cells are ultimately doing is cheating on the pact that cells form when cooperating to form a multicellular organism.”

Second, this notion of its deep history. The option for some cells to go rogue and cheat became available as soon as life evolved multicellularity. As also further explored in chapter 5, some form of cancer is found in almost every animal group and even in plants, where it is known as fasciation. This chapter also explores Peto’s Paradox: how larger body size is associated with increased cancer risk within, but not between species. Large and long-lived species consisting of many cells, such as elephants and whales, are very resistant to cancer.

Third, this notion of an evolutionary phenomenon. Individual cancer cells reproduce rapidly and, just like organisms, are subject to natural selection. Populations of cancer cells show variation, heritability, and differential fitness—this is how they thwart our medical interventions, developing resistance to drugs and chemotherapy. Even if the time-scale is short and cancer ultimately kills its host, until then the calculus of evolution through natural selection still applies. Furthermore, selection is happening simultaneously at multiple levels. There is an arms race between rapidly evolving cancer cells and the body that, through division of labour, can draw on more complex defence strategies. Aktipis introduces you to three mechanisms that offer a certain redundancy in keeping cells from misbehaving. There is the intrinsic mechanism formed by the cancer suppressor gene TP53 that acts as a central node, incorporating information from many sources to decide whether to initiate DNA repair, apoptosis, or block cell replication. There is a neighbourhood mechanism, with cells requiring so-called survival signals from their neighbours so as not to initiate apoptosis. And there is the systemic mechanism of our body’s immune system detecting and destroying inappropriately behaving cells. Cancer can break or hijack all of these mechanisms.

Probably the biggest eye-opener for me was what I mentioned first: cancer being a feature, not a bug. In chapter 4, Aktipis outlines how cancer is with us from “womb to tomb”. The reason evolution has not overcome cancer is trade-offs. The very processes that, when they malfunction, cause cancer are the basic mechanisms that, when they function, allow us to exist as multicellular organisms in the first place. “Many important systems that help us survive and thrive require cells to do things that are “cancer-like” including proliferating rapidly, moving around the body, and invading tissues” (p. 55). Think of wound healing and tissue regeneration, for example. Aktipis introduces the metaphor of life walking a tightrope: there needs to be enough cellular freedom to allow an organism to grow and develop, but not so much that cell division runs rampant. This, here, is why the war metaphor is unhelpful: “We can’t completely eradicate something that is fundamentally a part of us” (p. 10).

“The very processes that, when they malfunction, cause cancer are the basic mechanisms that, when they function, allow us to exist as multicellular organisms in the first place. […] This, here, is why the war metaphor is unhelpful […]”

Aktipis has many more arrows to her bow. A long sixth chapter probes the frontiers of cancer research by asking what lesson from ecology we can apply to the tumour’s microenvironment. Can dispersal theory be applied to metastasis? Is the cooperation seen amongst cancer cells an adaptation, a by-product of other processes, or a transitory, random process? Can we draw lessons from kin selection theory or social insect colonies? What of the interaction between cancer and the microbiome? And can selfish genetic elements such as transposons influence our susceptibility to cancer? There is a huge blind spot here, claims Aktipis, in that current genomic sequencing technologies cannot detect extrachromosomal DNA, so it is hard to make links to cancer. The consequences could be dramatic: “the theoretical foundations of much of the field of cancer evolution would have to be reconsidered if cancer is, in part, a result of selection at the gene level favoring selfish genetic elements […]” (p. 158).

All of the above should force us to rethink how we treat cancer, leading to seemingly counterintuitive treatments. Our current strategies of radiation and chemotherapy rain down fire and brimstone but often lead to drug resistance. Rather than total eradication, adaptive therapies would aim for coexistence with tumours at a level that is not too damaging for the patient. For other cancers, feeding tumours and providing a comfy, stable environment could prevent the more disruptive result of metastasis. These are but some of the options and ideas considered here.

Aktipis is very interested in science communication and has enlisted Alex Cagan to provide infographics. I found her writing a tad repetitive in places, saying something in one paragraph and then repeating it in slightly different words in the next paragraph. Hopefully, the flipside of this particular quirk is that few people will be left feeling they did not understand concepts. And this is, in a way, a good thing: The Cheating Cell bristles with fascinating ideas, there are many other tangents and questions Aktipis raises that I have not mentioned.

“All of the above should force us to rethink how we treat cancer, leading to seemingly counterintuitive treatments.”

One final question to consider (I swear books are like buses sometimes; you wait for ages and then two come along in quick succession): how does this book compare to Rebel Cell? Published in 2020, science writer Kat Arney explores the same topic. Though I have not read it, a critical reviewer on Amazon UK felt it does not reference its sources properly. This is where The Cheating Cell shines, backing up statements with published research in a 30-page notes section.

The Cheating Cell makes for fascinating reading and forces a radical reconsideration of what cancer is and how we should deal with it. I will leave you with what I consider Aktipis’s most powerful and sobering call to action: “We have much to gain from accepting that cancer is a part of us and preparing for a long-term strategic interaction with it as an unpredictable and adaptive counterpart. It takes courage to face this truth and accept an uncertain future with cancer rather than hanging onto false hope that we will one day find a magical weapon that can target and eliminate cancer from the world.” (p. 182).

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

The Cheating Cell

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

Other recommended books mentioned in this review:

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Understanding the eye is only the first step to understanding how we see. Vision is as much about perceiving, which means understanding how the brain works. We Know It When We See It is the swansong of neuroscientist and ophthalmologist Richard Masland, who passed away in December 2019. His research career spanned over four decades and he was lauded internationally for his work on retinal neurobiology. In this book, his love for teaching shines through, and it was a pleasure to join him on one last trip through the neurobiology of vision.

We Know It When We See It: What the Neurobiology of Vision Tells Us About How We Think, written by the late Richard Masland, published by Oneworld Publications in January 2021 (hardback, 272 pages)

Masland follows the process of vision from its start when light enters the eye and hits the retina, to the processing of information in the brain’s visual areas. This logical start-to-finish approach is as much a journey through the history of scientific discovery as it is a story that proceeds from well-established fact to informed speculation.

One of the things that I never appreciated about the eye is just how complex the retina is (until you realise that it is effectively a part of the brain that is pushed out into the eye during development). Masland introduces the various types of cells, how they were discovered, and how they function. Three layers of cells—photoreceptor cells, bipolar cells, and ganglion cells—are interlinked at two levels by horizontal cells and amacrine cells. All of these exist in many types, not all of which we understand. Interestingly, no single type numerically dominates. Instead, the retina contains roughly equal proportions of each type. Some are sensitive to motion, others to light-dark contrasts, that is, edges. Some are densely clustered, others spread out more diffusely. The result is that the eye does a surprising amount of pre-processing before passing information to the brain: “the visual image is decomposed by the retina into roughly thirty parallel streams, each reporting on its own specific feature of the visual world” (p. 87).

What happens next is where things get more complicated, but also more exciting. As Masland points out, the vision of vision that he describes here is at the frontier of developing knowledge and deviates from the textbooks. The optic nerve carries information from the retina to two brain centres, the superior colliculus and the lateral geniculate nucleus or LGN. The former is charged with visual orienting: what part of the image presented to the brain is of interest, and what should the eyes focus on next? The latter passes information to the visual cortex at the back of the brain. But the LGN is not just a relay station. A large number of neurons also return information from the visual cortex, forming an “immense feedback circuit” of uncertain function.

“[…] the eye does a surprising amount of pre-processing before passing information to the brain”

The visual cortex in turn is not a single entity, but a patchwork of visual areas distributed throughout the brain. Masland frankly admits that from this point forward we really do not understand things all that well. Everything seems to communicate with everything else. He highlights some of the areas we do understand, and I found those dedicated to the recognition of faces particularly interesting. As with the retina, information here is broken down, with different cell types responding to different elements: some to the pattern of two neighbouring dots (eyes), others to the presence of a nearby vertically oriented line (a nose). “It has been proposed that what these cells are doing is measuring a selection of parameters […] to decide whether something is a face” (p. 115). The system is not fool-proof, and though Masland does not explicitly mention it, it explains the phenomenon of pareidolia: the seeing of faces in everyday objects.

From here, Masland goes into the fuzzy concepts of perception, object recognition, and memory formation. Vision is as much about seeing as it is about remembering: we learn to recognize objects. This is the result of neurons forming connections, so-called Hebb synapses, after repeated activation together. Someone once memorably phrased this as “neurons that fire together wire together”. This wiring together forms nerve nets that feature as much in neuroscience as they do in machine learning. As Masland shows, these two disciplines meet each other in the challenge of understanding vision. The formation of nerve nets based on modifiable synapses is also an incredibly elegant evolutionary solution to one of life’s conundrums. How do you develop a perception machine without knowing in advance what you will have to learn to recognize throughout life? Life’s answer: develop a general pattern recognition machine. A final topic Masland considers is the transition of perception into thinking and consciousness. This is a grey area, and he gladly admits to entering speculative territory as he attempts to give the reader a rough idea of what we do understand.

“The formation of nerve nets based on modifiable synapses is also an incredibly elegant evolutionary solution to one of life’s conundrums.”

This exhilarating dive down the rabbit hole of neurobiology is lightened up by the occasional biographical sketch of key players: Donald Hebb of the above Hebb synapse, student-of-the-retina Brian Boycott who is commemorated by the Boycott Prize, connectome-pioneer Winfried Denk who has developed mind-blowing microscopy techniques, and several others. Masland’s forte is to not drown you in technical detail, giving you the principles instead. And by adding the daily grind at the lab bench, he brings you back down from the heady territory of theoretical neurobiology. Appropriately for a book about vision, what helped me grasp the ideas presented here were the numerous, small, inline illustrations, the way a teacher might combine writing and drawing on a blackboard. This feels like a lost art form, but interrupting your text with a small doodle or graphic can be incredibly helpful.

Amidst all this, Masland decidedly underplays the applied side of his work. He was interested in clinical applications and, as per his webpage at the Harvard Medical School Department of Ophthalmology, “a potential therapy for blindness, based partly on his work, is currently under clinical trial“. It will fall to other writers to celebrate his achievements in these fields. His obituary in Neuron mentions that, amazingly, he wrote this book from start to finish after having been diagnosed with cancer. While I am saddened he will not enlighten us further, we can all be grateful that he was able to finish this book.

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

We Know It When We See It

Other recommended books mentioned in this review:

The history of life is punctuated by major transitions and inventions: fish that moved onto land, reptiles that turned into birds. But how did these happen? In Some Assembly Required, Professor of Organismal Biology and Anatomy Neil Shubin provides an up-to-date and utterly engrossing account of the latest thinking on the great transformations in evolution. And he has one clue for you: nothing ever begins when you think it does…

Some Assembly Required: Decoding Four Billion Years of Life, from Ancient Fossils to DNA, written by Neil Shubin, published in Europe by Oneworld Publications in March 2020 (hardback, 271 pages)

When Charles Darwin formulated his ideas, he was candid about weaknesses and gaps in his thinking. Shubin opens the book with one vocal critic, St. George Jackson Mivart, who thought Darwin’s ideas were flawed. If evolution is a process of gradual changes via mutation and natural selection, then how are major transitions supposed to arise? It sounds like a sensible question and to this day creationists like to trot out this argument. Darwin had five words for Mivart (and I am not building up to an obscenity-laden punchline here): by a change of function. Shubin beautifully clarifies this on page 27: “innovations never come about during the great transitions they are associated with”. I am just going to step back while you read that sentence again.

What Shubin gets at is that evolution takes shortcuts. Rather than inventing new traits from scratch, it repurposes existing ones. Examples Shubin gives are air-breathing in fish, which was repurposed to make lungs in land animals, and feathers on dinosaurs that originally evolved in a different context, but were repurposed for flight. Shubin has spent a research career working on our fishy ancestor, Tiktaalik rosaea, which was the subject of his previous book.

This is but one of the many ways in which evolution can achieve rapid and major transitions. Subtle changes during embryonic development can have large impacts later in life. Shubin introduces German naturalists Karl Ernst von Baer, who observed that early-stage embryos of different species looked very similar, and Ernst Haeckel, who took that idea too far with his motto “ontogeny recapitulates phylogeny” and took some liberties with his famous embryo drawings.

The real kicker here? Walter Garstang and the sea squirt.

“innovations never come about during the great transitions they are associated with. I am just going to step back while you read that sentence again.”

Sea squirts hatch as free-swimming tadpoles, complete with nerve cord, gill slits, and a connective tissue rod, a sort of proto-backbone. Adult sea squirts lose all this when they metamorphose. Garstang proposed that the ancestor of all vertebrates resulted from the freezing of larval traits during sea squirt development. I came across this before when reviewing the rather technical Across the Bridge, where Henry Gee mentions it almost off-handedly on page 167: “Paedomorphosis produced the ancestor of vertebrates”. You would be forgiven for missing the significance of that sentence. Shubin’s talent lies in turning this observation from a “What…?” into an “Oh my god!” moment.

Or take Félix Vicq D’Azyr’s realisation that some body parts are copies of each other. Ray Lankester’s observation that species can evolve by losing traits. (The evolution of limbs repeatedly involves the loss or fusion of bones, always in the reverse order in which they are formed, a sort of last in first out principle: last formed first lost). Stephen Jay Gould’s thought experiment of “replaying the tape of life” and the question of how repeatable evolution is. (The answer: quite.) Lynn Margulis’s idea of endosymbiosis. Or Nicole King’s work on choanoflagellates: the single-celled creatures you have never heard of that can form colonies and are the closest living relative to multicellular life forms.

Time and again, Shubin shows how evolution can reuse, repurpose, or rejiggle already existing structures and processes. I don’t know about you, but these kinds of spine-tingling revelations were what drew me to study biology.

“Time and again, Shubin shows how evolution can reuse, repurpose, or rejiggle already existing structures and processes.”

Another powerhouse of innovation is DNA, and genetics can tell us much about evolution. These sections are a giddy ride where Shubin highlights one after another stupendous concept. Take the huge similarity between e.g. chimps and humans: genome sequencing revealed some 95%-98% similarity. Why are we so different then? Because DNA is not just a molecule containing gene after gene. Like a circuit board, it is a network, where some pieces of DNA function as switches that turn other genes on and off. This is the field of evolutionary development or evo-devo and offers another way for small changes to have big effects. (On a side-note, it would offer a possible mechanism for Noam Chomsky’s proposed single mutation that led to human language, see my review of Why Chimpanzees Can’t Learn Language and Only Humans Can.)

Hox genes control the development of whole body segments and can be repurposed to make other structures, such as limbs. Most DNA does not even code for anything and Susumu Ohno surmised it results from copying processes gone wild, whether gene, chromosome or whole-DNA duplication (biologists call this last one polyploidy, it is common in plants). And then there is Barbara McClintock’s discovery of jumping genes: selfish genetic elements that multiply and willy-nilly insert themselves all over a DNA molecule. If rogue replication sounds an awful lot like cancer, well, that is because it is – evolution and cancer are closely linked. And how about this? If such a jumping gene mutates and becomes a genetic switch, they can insert switches all over a genome. Dramatic new traits that at first sight would require an unlikely number of separate mutations suddenly become a whole lot more plausible. One example Shubin provides is the evolution of pregnancy.

Even viruses are not exempt. You might remember that a virus commandeers a host’s biochemical machinery for its own reproduction. Some viral genes can end up in the host’s DNA by accident or, in the case of retroviruses, by design. This viral DNA can be neutered and repurposed, offering another option for rapid evolution. We even have turned this into a powerful biotechnological tool, CRISPR, that allows fine-scale gene editing, rather than the previous blunt tools of genetic modification.

“DNA is not just a molecule containing gene after gene. Like a circuit board, it is a network, where some pieces of DNA function as switches that turn other genes on and off. This […] offers another way for small changes to have big effects.”

Shubin reveals there is a plethora of pathways to rapid evolution and sudden transformations. Some Assembly Required is a very pleasant mix of the latest science, the historical roots of ideas, and the people behind them. Not infrequently, these stories of discovery show multiple people converging on the same idea at the same time (as was the case for Darwin and Wallace). Or show people being far ahead of their time, resulting in them being ignored or even ostracized for heretical views. The latter, sadly, involves a fair share of brilliant women whose ideas were initially not taken seriously.

Like a spider in a web, this book sits in the centre of a large number of topics I have been reading about, lighting up paths of intellectual enquiry branching off in different directions. For a moment, while reading this book, I was a young student again, attending lectures, and getting acquainted with mind-blowing ideas. Frequently funny and always eloquent, Shubin’s power as a science communicator is to make you fall in love with evolutionary biology all over again.

* It took more than three years after this review, while reading another book, before it occurred to me to ask: wait a minute, is this not the same process that Stephen Jay Gould and Elisabeth S. Vrba termed exaptation in their 1982 paper? Indeed, their definition, “features that now enhance fitness but were not built by natural selection for their current role“, and their inclusion of feathered dinosaurs as an example for me confirm that Shubin is talking about the same process in this book. Though the book is no less brilliant for it, and he mentions Gould in another context, it is odd that he does not mention exaptation here.

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

Some Assembly Required paperback, hardback, ebook or audiobook

Other recommended books mentioned in this review:

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“Symphony in C: Carbon and the Evolution of (Almost) Everything“, written by Robert M. Hazen, published in Europe by William Collins (a HarperCollins imprint) in June 2019 (hardback, 290 pages)

As executive director of the Deep Carbon Observatory or DCO, a decade-long global research programme on carbon that was initiated in 2009, Hazen is uniquely positioned to write this sweeping overview. The story of how this came off the ground is a thrilling reminder that fundamental research is not dead yet and that the right person in the right place can unleash incredible energy and momentum in a research community. You would be forgiven for thinking that this book closely mirrors the research goals of the DCO, reporting its outcomes for a lay audience. The DCO features prominently throughout, but Symphony in C is instead loosely structured around the analogy of a musical symphony in four movements (Hazen is also a lifelong musician).

The first two movements, Earth and Air, tackle technical topics such as mineralogy and atmospheric chemistry – generally speaking not the kind of subjects that will electrify audiences. What a treat, then, to find Hazen writing sections that I cannot call anything else but riveting.

“Earth” traces the formation of our planet and its minerals, highlighting the surprising finding that many mineral species are incredibly rare. Not only has there been an ambitious project to build a global mineral database (going by the unlikely name of RRUFF), but scientists have even used mathematical models to estimate the number of “missing minerals” yet to be discovered. Similarly, Hazen makes topics such as X-ray crystallography accessible, revealing the unexpectedly different mineral world existing in the high-pressure environment of Earth’s interior.

“mathematical models have been used to estimate the number of “missing minerals” are yet to be discovered”

The story of Earth’s atmosphere is one of drama and fascinating questions. Drama in the form of the obliteration of Earth’s early atmosphere during the cosmic collision that formed our moon (see also The Big Splat: Or How Our Moon Came to Be). Fascinating questions in the form of the deep carbon cycle and whether the amount of carbon descending into Earth’s interior (e.g. through subduction or sedimentation) is balanced by what comes back up (e.g. through volcanoes).

Movement three, Fire, is a complete change of pace. In a mere 30 pages, Hazen gives a brief overview of carbon’s role in all our stuff. From fuels to synthetic materials, carbon’s physical properties make it eminently suitable to a very wide range of applications, with nanotubes and graphene sheets promising a future of even strong and thinner materials. This section seems to have little to do with the DCO research programme, and there is no mention of the people behind the science or of particular breakthrough experiments. Instead, Hazen writes a pop-science section that reminded me of Miodownik’s recent book Liquid: The Delightful and Dangerous Substances That Flow Through Our Lives.

The final section, Water, is the proverbial crowd-pleaser, exploring the for many fascinating topic of the origin of life and the role of carbon in it. Hazen reveals himself to be a nuanced thinker who prefers not to fall into the trap of false dichotomies. Did life start in the heat of deep ocean volcanic vents or in shallow pools of water lashed by lighting (as per the famous Miller-Urey experiment)? Hazen favours the idea that there is truth to all of these mechanisms, that “early Earth was an engine of organic synthesis”. Equally fascinating is the question “why carbon?” This question was also asked by Charles Cockell (see my review of The Equations of Life: The Hidden Rules Shaping Evolution), and Hazen gives a slightly less physics-heavy overview of why carbon’s atomic properties make it such a versatile and therefore useful building block for life.

“Hazen reveals himself to be a nuanced thinker regarding the origins of life, writing that “early Earth was an engine of organic synthesis””

This last section feels like the frenetic overture to Hazen’s symphony as the evolution of life added many layers and subtleties to Earth’s carbon cycle. From the surprising abundance of microbial lifeforms at great depths (see Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond), the mineral-microbe interactions that kick-started life (see Life’s Engines: How Microbes Made Earth Habitable), the colonisation of land by plants and then animals (see The Emerald Planet: How Plants Changed Earth’s History and Your Inner Fish: The Amazing Discovery of Our 375-Million-Year-Old Ancestor), the formation of most of our planet’s fossil fuel reserves during the Carboniferous (see my review of Carboniferous Giants and Mass Extinction: The Late Paleozoic Ice Age World), or radiocarbon dating (see Hot Carbon: Carbon-14 and a Revolution in Science) – this is the section where Hazen packs in topics that have received book-length treatments elsewhere. There are so many interesting things to tell here that the narrative almost derails under its own intensity.

Throughout, Hazen introduces the many researchers, past and present, who are behind the findings. A review in Nature faulted the book for leaving out certain historic figures, something I cannot really comment on given my unfamiliarity with the topic. Hazen does mention the story told here is inherently personal – “many symphonies of C are waiting to be written”. What I found missing were illustrations. The unnumbered colour plate section is a bit of a grabbag of useful diagrams and photos of scientists at work, but the text never refers to it, leaving the reader to figure out when to consult the plates. Illustrations in the body of the text could have been used to show certain concepts that are now described at length.

Symphony in C covers a vast range of topics, possibly at the risk of losing its structure. Although the narrative-as-a-symphony idea is original and Hazen can really run with it given his background, I did not feel it always worked. The saving grace that prevents this book from becoming a jumbled list of facts is Hazen’s excellent writing. I simply struggled to put the book down! I found the first two sections particularly eye-opening as they dealt with disciplines I am less familiar with. Interestingly, Cambridge University Press will publish Deep Carbon: Past to Present later this year, an edited collection on the DCO’s research written for an academic audience. If that book looks too intimidating then Symphony in C is exactly your ticket to understand why carbon is at the heart of pretty much everything.

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

Symphony in C paperback, hardback, ebook or audio CD

Other recommended books mentioned in this review:

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“The Tales Teeth Tell: Development, Evolution, Behavior”, written by Tanya M. Smith, published by MIT Press in November 2018 (hardback, 277 pages)

Following its subtitle, the book is divided into three parts of three chapters each. With the same kind of clarity she must be applying to her lectures, Smith gives the reader a thorough introduction to how teeth actually form during embryonic development and continue developing after birth. Interestingly, much like trees, developing teeth lay down “growth rings”, or really growth lines, on a daily basis. As Smith explains, there are other patterns repeating on longer time scales that are still poorly understood.

These growth lines react to environmental stressors, including (!) birth. The study of baby teeth has revealed so-called neonatal lines, indicating the moment a child is born. Although teeth stop growing at some point, this record of growth lines can be used to estimate the age of archaeological remains of children, outperforming other methods. Furthermore, diseases and other stressors affect the deposition of growth lines, some so clearly visible that no microscope is needed. As other authors have pointed out (see e.g. Built on Bones: 15,000 Years of Urban Life and Death and The Story of the Human Body: Evolution, Health, and Disease), the development of agriculture and urban civilization led to new kinds of diseases. The change to softer, more easily digestible food meant less tooth wear. But a bigger and more insidious problem is that our bodies showed an evolutionary response by reducing the growth of our jaws (see also Jaws: The Story of a Hidden Epidemic). This, in turn, has led to new problems in the form of crowding and misalignment of teeth.

“[…] the study of baby teeth has revealed so-called neonatal lines, indicating the moment a child is born.”

Smith’s coverage of evolution is similarly insightful. Starting with the earliest jawless fishes some 500 million years ago, she walks the reader through the evolution of teeth (see also Vertebrate Palaeontology and Your Inner Fish: The Amazing Discovery of Our 375-Million-Year-Old Ancestor). Did tooth-like structures on armour plating migrate into the mouth over time to form the first teeth, or did external skin teeth and internal oral teeth evolve separately? The jury is still out on this, writes Smith. But once they arrived on the scene, a spectacularly diverse array of dentitions evolved in fish, amphibians, reptiles, and mammals (for more technical coverage, see The Teeth of Non-Mammalian Vertebrates and Mammal Teeth: Origin, Evolution, and Diversity). And though modern birds are toothless, she describes some of the fascinating experiments that have shown they retain the potential to grow teeth.

Due to their high mineral content, teeth are basically ready-made fossils, and, under the right conditions, can even conserve DNA. I have enthused about ancient DNA before (see my review of Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past), something with which Smith has first-hand experience. That book and others such as Our Human Story: Where We Come from and How we Evolved reveal how the picture of human evolution has become rather complicated. The study of teeth can obviously add to that story (see also What Teeth Reveal About Human Evolution), though – spoiler alert – they do not necessarily make it any less complex. Take for example the reduction in tooth size during our evolutionary history. Though attractive as possible explanations, the timing of tool use and cooking (see Catching Fire: How Cooking Made Us Human) do not match up with the changes in tooth size detected in the fossil record.

“though modern birds are toothless […] they retain the potential to grow teeth.”

It is only during the third part of her book, where she looks at what teeth reveal about behaviour, that Smith overlaps substantially with some of the topics that Ungar covered. She is similarly critical of the Palaeolithic diet and reviews what dental microwear (microscopic patterns of wear and tear), fossilised dental plaque, and isotope analysis instead reveal about our past diets (see also Evolution’s Bite and Evolution of the Human Diet: The Known, the Unknown, and the Unknowable). And if you are not squeamish, she ends with a fascinating look at the use of teeth as tools (all those things your mum told you never to do!), stone age dentistry, and tooth decoration. That last one was practised in the past, and is still done so by some tribes, and refers to the filing, grinding, and drilling of teeth… while they are still in the mouth.

Smith writes enthusiastically about new technologies such as synchrotron imaging, which uses a type of particle accelerator to non-destructively scan the inside and outside of valuable archaeological samples. More importantly, she also shows them. MIT Press went to town on The Tales Teeth Tell, producing a full-colour book printed on slightly glossy paper. Smith has made good use of this and included many excellent colour photos and illustrations that bring her tales alive.

Although this is pure speculation on my part, it is tempting to think that Smith read Ungar’s book, took careful notes, and made sure to minimise overlap when writing hers (edit: the author has since confirmed this was not the case). Regardless, this book is just as good. (Should you pick one? No, get both!) Even if it gets technical in a few places, Smith’s writing is informative, absorbing, and manages to elegantly cover a wide range of topics.

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

The Tales Teeth Tell hardback or ebook

Other recommended books mentioned in this review:

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“Kin: How We Came to Know Our Microbe Relatives“, written by John L. Ingraham, published by Harvard University Press in June 2017 (hardback, 292 pages)

Kin starts with a short introduction on the older history of microbiology covering the fall from grace of spontaneous generation (see my review of Creatures Born of Mud and Slime: The Wonder and Complexity of Spontaneous Generation) and the rise of germ theory. Ingraham then centres his narrative on the Tree of Life that was drawn up and vigorously defended by American microbiologist Carl Woese and others.

From reading Quammen’s The Tangled Tree: A Radical New History of Life I was already familiar with parts of this story. Even so, there are some notable differences between the books. Whereas Quammen started researching his book after Woese passed away, Ingraham has lived through this period and met Woese personally. The Tangled Tree also focuses almost exclusively on the life and career of Woese, at the expense of the other important players in this story. Ingraham’s approach here is far more balanced and wide-ranging.

A second difference here is that, being a microbiologist, Ingraham’s story is more technical, going into the details of key experiments and breakthrough findings, rather than the lives of the people involved. Compared to today, many experiments were crude and required clever design as much as astute observation to yield useful information. Even so, Kin is accessibly written, and anyone with even a basic background in biology should easily be able to keep up.

“Researchers initially thought that DNA was too simple a molecule to be the bearer of heritable information. “

Woese’s discovery of a third domain of life, the single-celled Archaea, was obviously not made in a vacuum. Ingraham recounts how the despair of taxonomists that they could not use shape and structure to tell apart bacterial species led them to look elsewhere. An important figurehead was chemist Linus Pauling who, before DNA’s structure was clarified, suggested that macromolecules such as proteins, DNA, and RNA are information-bearing molecules that could reveal the evolutionary past. This ultimately led researchers to ribosomes, the cellular machinery that turns DNA, using RNA as an intermediary, into proteins, the actual workhorses in a cell (see also my review of Gene Machine: The Race to Decipher the Secrets of the Ribosome). Since all cells, whether from multicellular organisms or bacteria, rely on proteins, the ribosome is old. Very old. Just the thing you need to establish evolutionary relationships. Ingraham covers Woese’s discovery of the Archaea and the bickering before and afterwards over how to organise and name all this diversity.

And then there was the discovery of the structure of DNA (see also Watson’s DNA: The Secret of Life and my review of Unravelling the Double Helix: The Lost Heroes of DNA). Researchers initially thought that DNA was too simple a molecule to be the bearer of heritable information. The story of how that was clarified, and how some people received recognition in the form of a Nobel Prize when others did not, is worth reading. It was DNA after all. But how? Watson and Crick’s understated and much-quoted final sentence in their breakthrough Nature paper that “it has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material” proved to be prophetic. But next to this well-known chapter in history, Ingraham also reveals the work led by Marshall Nirenberg that led to the next code-breaking exercise. How does DNA actually code for proteins?

“One dirty little secret of microbiology is that many bacteria are impossible to grow in the lab. Instead [metagenomics] now allows scientists to simply gather DNA from inhospitable environments.”

By this point I was half-way through the book and had a nagging feeling. Wasn’t the whole point of Quammen’s The Tangled Tree that this Tree of Life metaphor looks increasingly shaky? I need not have worried. The second half of the book is dedicated to the discovery of the various forms of horizontal gene transfer (the exchange of genetic material within a generation, rather than between parents and offspring). Ingraham poses the very interesting question (the title of Chapter 7): “Can the receiving cell say no?” It is not always in a cell’s best interest to have foreign DNA enter. Next to restriction enzymes (one weapon in a cell’s defensive arsenal), this allows Ingraham to introduce the more recent discovery of CRISPR, which is a sort of bacterial immune system (see also my review of A Crack in Creation: The New Power to Control Evolution). Both have been turned into important molecular biological tools in research. Ingraham concludes that, despite horizontal gene transfer, the Tree of Life metaphor remains useful. One important reason is that ribosomes, still used to define bacterial species, are not exchanged horizontally.

Other topics that are covered are endosymbiosis (see also Symbiogenesis: A New Principle of Evolution and One Plus One Equals One: Symbiosis and the Evolution of Complex Life), the discovery of the microbiome (see these three books for introductions), and the various theories for the origin of life (Panspermia? Darwin’s warm little pond? An RNA world? Or rather a deep-sea origin near hydrothermal vents? See also The Emergence Life on Earth: A Historical and Scientific Overview). Finally, Ingraham instilled in me an understanding and appreciation of metagenomics. One dirty little secret of microbiology is that many bacteria are impossible to grow in the lab. Instead, improved DNA sequencing technology, increased computing power, and enormous databases now allow scientists to simply gather DNA from inhospitable environments to figure out how many microbes there are, without ever actually seeing eye to eye with them.

From the above, you can gather that Ingraham covers a huge number of topics, but he does so without getting lost in irrelevant asides. He provides quite a bit of technical detail, but does so without overwhelming the reader. The result is an intricately structured story that flows very well and shows how all these discoveries interlocked and influenced each other. As I mentioned at the start, it is not often that someone is willing or capable at the end of a long career to sit down and write a cogent eye-witness history of their discipline. That alone makes Kin a noteworthy and admirable achievement.

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

Kin hardback or ebook

Other recommended books mentioned in this review:

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“Eyes to See: The Astonishing Variety of Vision in Nature“, written by Michael F. Land, published by Oxford University Press in November 2018 (hardback, 204 pages)

Far from the in-depth overview his textbook offers, this pithy book nevertheless gives a complete introduction to the evolution of eyes and the eight principal types of eyes known in animals. People are often warned that what has been seen cannot be unseen, and so it was with evolution: once vision developed, there was no way back, and a scramble for visual dominance took off (see also In the Blink of an Eye: How Vision Kick-Started the Big Bang of Evolution). Time and again, solutions have evolved for organisms to perceive light and see the world. Darwin was initially concerned that eyes, with all their complex optics, could not have evolved to such a state of perfection through natural selection, going so far as to call this “absurd in the highest degree”. We now know of plenty of organisms displaying the intermediate steps along the way though, so next time a creationist tries to spin up that tired old argument, hand them a copy of OUP’s other great book on eyes, Evolution’s Witness: How Eyes Evolved.

The book then takes a tour of some of the more unusual eyes known. It gives the lowdown on compound eyes, explaining, for example, the striking occurrence of pseudopupils that make it seem as if insects are always looking back at you (they are not, it is a byproduct of how their eyes are constructed). Or the uncanny ability of flying insects to intercept moving targets with great speed and accuracy.

“[…] once vision evolved, there was no way back, and a scramble for visual dominance took off”

It also talks of the many adaptations to seeing (and prevent being seen) in the deep sea. If you have read my review of Deep-Sea Fishes: Biology, Diversity, Ecology and Fisheries, or have browsed more pictorial works such as Creatures of the Deep: In Search of the Sea’s Monsters and the World They Live in or Life in the Dark: Illuminating Biodiversity in the Shadowy Haunts of Planet Earth you will have seen the bizarre adaptations showcased by fish and invertebrates. From bulging barrel-shaped eyes pointing upwards to secondary eyes that are pointing downwards. But it is not just eyes. Fish scales have particular properties that render fish virtually invisible underwater. And bioluminescence is widely used to attract, confuse, or observe (see Bioluminescence: Living Lights, Lights for Living and Luminous Creatures: The History and Science of Light Production in Living Organisms for more on that topic).

But vision requires more than just eyes. Brains to process all this visual information are also required. Where these are lacking in complexity, organisms tend to use simple rules of thumb to make sense of their visual environment, and Land discusses how fiddler crabs tell predator from conspecific (Is it bigger than me? Yes? Then run for the hills), and how males of different species vary the timing and speed with which they wave their ridiculously large ornamental claw to attract females of the right species. Most spiders have no fewer than eight eyes, all adapted for different visual tasks. And the mantis shrimp made headlines for having twelve visual pigments, instead of the three that humans have, though Land is quick to dispel notions of super-vision. Their eyesight is actually quite poor and signals from these pigments are processed completely differently (though, in other respects their eyes are amazingly complex). In many of these examples, the eyes do all the hard work of processing and selecting visual information, rather than relegating this task to the brain.

But in other species, such as humans, brains do do a lot of the visual processing and Land has also worked on such questions as: “where do people look?” Whether that is when reading a book or sheet music, driving a car, making a cup of tea, or batting a ball during a game of cricket. Finally, he touches on the hard problems that have kept philosophers up since time immemorial. Is the red that I see the same red that you see? What is red anyway?

“Appropriately for a book on eyes, this book relies heavily on visual aids.”

Throughout, Land weaves in anecdotes of his own research. From the accidental dismantling of an interference microscope lend to him by his PhD supervisor, the very recognisable low-tech methods employed by field biologists (a cotton reel on a piece of string to entice fiddler crabs), or the first attempts at constructing miniature head-mounted cameras to observe eye movements in human study subjects.

I always make a song and a dance about illustrations and have previously complimented Oxford University Press on really going to town in providing well reproduced, instructive illustrations. Appropriately for a book on eyes, this book relies heavily on visual aids. In a book just under 200 pages long, Land manages to include 92 diagrams and black and white photos, as well as 8 colour plates, heavily plundering his earlier book Animal Eyes. These schematic drawings are of great help in explaining the optical mechanisms discussed in the text.

Eyes to See does not shy away from going into detail where optical principles or anatomical features are concerned. But with helpful illustrations, a glossary, and an understanding that some optical solutions to life’s challenges are really quite complicated and need careful explaining, Land has produced an intriguing and accessibly written little book on vision. If textbooks heavy on the physics of optics sound like hard work, then Eyes to See comes highly recommended as a place to start reading into this topic.

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

Eyes to See hardback or ebook

Other recommended books mentioned in this review:

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