Wallace, Darwin, and the Origin of Species

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. 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: they were drawing together many independent lines of evidence to build a convincing argument. Appropriately, I think Costa applies the same logic in this book, looking at this historical episode from many different sides.

After setting the scene about what Wallace was up to, Costa explores two particularly influential papers in detail, 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 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 In that sense, Wallace's Species Notebook is a goldmine of the unpublished arguments he was considering and Costa's analysis expands on the appendix in On the Organic Law of Change.

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 Origin, notebooks, and manuscripts. 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. 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).

Until 1857, Darwin and Wallace were unaware of each other's thoughts on evolution but that would soon change. First contact happened in April 1857 with a letter from Wallace, telling Darwin about his ideas on species change. Darwin's reply notes that 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. Instead of backing off, Wallace replied enthusiastically, attaching his Ternate 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 and botanist Joseph Dalton Hooker quickly organised that famous 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 this meeting. 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, the key point being how they envisioned that natural selection acts. 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 and evolution happens "by minute steps, in various directions" (p. 212). 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. 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. The problem 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 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, 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, 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) though we can honour him without diminishing Darwin's achievements.

Can you 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? Though it is mostly self-contained, 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 and I commend the publisher for seeing the value in it and not forcing this into an abridged format.