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

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

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

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 In that sense, Wallace’s Species Notebook is a goldmine of the unpublished arguments he was considering and Costa’s analysis expands on the appendix in On the Organic Law of Change which only considered Wallace’s critique of Lyell.

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

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

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

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

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

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

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

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

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

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

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

Wallace, Darwin, and the Origin of Species

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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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