Darwin's Origin of Species: notes for your reading group

I teach a graduate seminar on Darwin’s On the Origin of Species. We read and discuss the Origin and some related readings. It’s a lot of fun, for me and the students. If you haven’t yet read the Origin, or read it when you were too young to fully appreciate it, or haven’t read it in ages and don’t remember it that well, you really ought to (re-)read it. It’d be great choice for a graduate reading group–you could read a chapter a week and finish it in a semester. So here are a bunch of notes to help and encourage you to take the plunge.

Advice

• Read the first edition. Six editions of the Origin were published in Darwin’s lifetime. If you just go to a library or bookstore and pick a random copy of the Origin off the shelf, you’re probably picking up a copy of the sixth edition (if it’s got a whole chapter devoted to refuting the objections of a guy named “Mivart”, it’s the sixth edition). The sixth edition is mainly of historical interest, as the final statement of Darwin’s views. Those views were heavily revised from the first edition, in response to the many criticisms Darwin received. Unfortunately, most of those criticisms were off base, so the first edition actually is more correct than the sixth. So as a scientist who’s likely to be curious about how much Darwin got right, and who probably wants to be able to trace back modern ideas to their Darwinian roots, you’ll want to read the first edition. The first edition also is shorter, clearer, and more tightly argued, making it an easier read. It’s been aptly remarked that the sixth edition could have been titled “On the Origin of Species By Means of Natural Selection and a Whole Bunch of Other Things.” And the first edition is the edition that started the intellectual revolution–it’s the edition that changed the world. So why not read that?
• Consider which printing of the first edition you want. Darwin’s books have long since gone out of copyright, so you can read the first edition for free on various websites, such as this one. If you prefer a hard copy (and call me old fashioned, but I really think every biologist should own a hard copy), then I recommend The Annotated Origin. It’s a facsimile of the first edition, so it has the original pagination (helpful if you’ll also be reading scholarly articles about the Origin, as they all refer to the book using the original pagination). And as the title indicates, The Annotated Origin has extensive and very good marginal notes from biologist James T. Costa. This is the printing I plan to teach my class from in future. Another option, which I’ve used in my class in the past, is the famous Harvard facsimile edition first published for the Origin‘s 100th anniversary in 1959, which includes a famous and influential introduction by Ernst Mayr.
• Do a bit of background reading. The Origin is quite accessible. It’s not technical; it was written to be read by any educated person. And while the style may not be your cup of tea (though I actually like it, or at least don’t mind it), it’s not difficult reading. So you can get a lot out of the Origin without doing any background reading. But background reading can definitely help you get more out of it. I require my students to read Janet Browne’s Darwin’s Origin of Species: A Biography. It’s a short (readable in a few hours) introduction to the writing of the Origin, the social and scientific context, reaction to the book, etc. Browne’s mammoth two volume biography of Darwin is great too, but probably much more than you’d want to bite off for a reading group. And of course there are many other things you could read; it’s not for nothing that historians of science talk about the “Darwin industry”.
• Read it as part of a group. Read the Origin along with others so you can talk about your reactions as you go. Or just read along with John Whitfield, a science writer who back in 2009 did a nice series of blog posts called Blogging the Origin. He read the first edition and did a post on each chapter.

Food for thought

Here are a some suggestions for things to think about as you read the first edition of the Origin. Many of them reflect my own interests, of course, so just ignore them if you don’t share my interests. The Origin is a really rich book and there’s plenty in it for anyone.

• The quotations with which Darwin prefaces the book.  One is from William Whewell, an influential thinker of the generation prior to Darwin’s, and the other is from the “inventor of the scientific method”, Francis Bacon. Both quotes talk about how science, and scientific laws, don’t conflict with Christianity. These quotes are an attempt by Darwin not just to defend against charges of impiety or atheism, but also to defend against charges of being unscientific. At the time, the leading view on the origin of species was “special creation”, which actually had relatively little in common with the forms of creationism espoused (often in thinly-disguised form) by fundamentalists today. It’s important to understand that “special creation” was just one manifestation of the deep intellectual commitments of most senior scientists of the day. To those scientists, such as the geologist Adam Sedgwick (once a mentor of Darwin’s) the whole point of science was to read nature as the “Book of God”, to document natural order and patterns as a physical manifestation of God’s plan. To someone like Sedgwick, Darwin’s explanation for the origin of species wasn’t just wrong, it wasn’t even the sort of thing that counted as a scientific explanation at all. And conversely, Darwin argues in the Origin that “special creation” is not so much an incorrect explanation for the origin of species, as a non-explanation–it leaves all sorts of surprising patterns in nature “untouched and unexplained”. It’s difficult for a modern reader to really “get” the mindset of a special creationist, but it’s worth a try in order to understand the Origin as Darwin and his readers understood it.
  
• Darwin’s style. Note that the style is very cautious and modest (until the final, summary chapter, which is beautifully confident). Indeed, Darwin devotes a whole chapter to raising and then addressing objections to his ideas, and it’s clear from the way he writes (and from private correspondence) that he’s not just setting up straw men. He really does worry about these objections, perhaps even too much. It’s a far cry from the way most scientists write these days.
• Ordering of the material. Note that Darwin doesn’t start out with anything exotic (nothing about the Galapagos Islands, for instance, which are hardly mentioned in the book). Instead, he starts out talking about domestic animals. It’s an attempt to get readers on board, by talking about something ordinary and familiar. More broadly, note that in the first few chapters Darwin lays out his big conceptual idea–evolution by natural selection–and then in the remainder of the book discusses how that hypothesis fits with and explains the available data. One can ask, as philosopher Eliot Sober has, if Darwin wrote the Origin “backwards”. That is, he starts out with the mechanism of evolutionary change, and only then does he go on to argue for the fact of evolutionary change. Which seems a bit backwards, when put that way–shouldn’t you start by describing what needs explaining before you explain it? You may want to think about why Darwin ordered the material the way he did.
• What Darwin got right, and wrong, and the risk of mixing them up. Darwin gets a lot right in the Origin, including prefiguring almost every big idea in modern ecology (even trendy ecological ideas like biodiversity and ecosystem function!) My students are always shocked at just how much he gets right and how modern he sounds. He also gets some things wrong, of course (and not always because he was unaware of facts we’re aware of). But he gets so much right that it’s tempting to read into the Origin modern ideas that Darwin himself didn’t actually hold. Case in point: the book is infamous for not fully living up to its title because Darwin doesn’t really fully grasp how natural selection can generate new species from existing ones. That’s because he doesn’t really recognize the possibilities of spatially-varying selection (different variants favored in different locations) and frequency-dependent selection (relative fitness of different variants depends on their relative abundances). Instead, Darwin has what Costa aptly calls a “success breeds success” vision of how selection works–new, superior variants arise and then sweep to fixation everywhere they can spread to, replacing the previous variants. To get this “success breeds success” process to generate and maintain diversity, Darwin invokes what he calls his “Principle of Divergence”, which is the idea that parents will be fitter if they have divergent offspring (offspring that differ from one another in their phenotypes). The idea is basically to make the production of diversity itself a cause of evolutionary success. There are contexts in which this can work–but plenty of contexts in which it can’t (there are logical as well as empirical flaws to the idea as developed by Darwin). Now, I should note that I’m not an evolutionary biologist, and there are evolutionary biologists who read the Origin as presenting pretty much a fully-modern and correct theory of how selection affects speciation. All I can say is that I think they’re reading into the Origin, and in particular into the “Principle of Divergence”, something that just isn’t there. Read it and judge for yourself.
• Explanation and unification. It’s often said that Darwin’s great achievement in the Origin is to unify and explain many apparently-unrelated facts. The Origin links together and explains facts about everything from animal breeding to biogeography to embryonic development to the fossil record. Which raises many deep and interesting conceptual issues. For instance, is unification always a good thing in a scientific theory? Why? Is it because unification is a mark of truth? For instance, maybe unification is a sort of “indirect” or “circumstantial” evidence. If a theory seems to work well to explain facts A, B, and C, then perhaps we ought to take that as indirect or circumstantial evidence in favor of its explanation for fact D. But on the other hand, conspiracy theories also unify many apparently-unrelated facts–which is usually taken to indicate that they’re false, not true! Or maybe unifying theories are valuable because, true or not, they’re more productive as “working hypotheses”, guiding future investigations by suggesting what questions to ask and what data to collect. Darwin famously called his theory “a theory by which to work”. Then again, maybe not. For instance, progress on understanding the causes of variation and heredity (problems that famously vexed Darwin) came not just from the rediscovery of Mendel’s work, but from breaking the problem up and disunifying it. Muller and his followers figured out what we now call transmission genetics by explicitly setting aside and ignoring what we now call developmental genetics, regarding it as a separate problem. And what exactly does it mean to “explain” some fact or set of facts, anyway, and how are explanation and unification connected, if at all? For instance, do explanations have to be unifying if they’re to count as explanations at all? The intuition here is that every theory or hypothesis has to take something for granted. So if you produce a separate, independent explanation for every single thing you want to explain, then you’re effectively just changing the question, substituting one set of unexplained, taken-for-granted statements for another. At best, you’re just pushing the required explanations back a step (e.g., if you “explain” the origin of life on earth by saying “it arrived on an asteroid”, all you’ve done is change the question to “where did life on the asteroid come from?”) But if you have a unifying explanation, a single explanation for a bunch of different facts, you’re “killing many birds with one stone” and reducing the number of unexplained statements we just have to take for granted. See here and here and here for some longer posts I did on issues of explanation and unification for the class blog.
• Circular reasoning? Darwin developed his theory to explain lots of different facts about the world, and along the way he modified it in various ways as he discovered new facts. In light of that, isn’t it a bit (or even more than a bit!) circular to regard those facts as evidence for his theory, or as a test of his theory? Isn’t it circular (or maybe better, “double-dipping”) to use the facts to develop and inspire your theory, and then turn around and re-use those same facts to test the theory? After all, developing your theory so that it fits known facts guarantees that your theory will fit those facts! In philosophy of science, this is known as the “old evidence” problem: when does previously-known (“old”) evidence constitute evidence for a new theory? There are plenty of examples of the old evidence problem besides the Origin, so it’s a very general issue well worth thinking about (I emphasize I’m just throwing the issue out there as food for thought–I’m not saying whether I think Darwin’s argument is actually circular!)
• Comparative reception of the Origin. After you read the Origin, you’ll probably find yourself wanting to dig into all sorts of related topics. One related topic my class discusses is the comparative reception of the Origin in different cultures and religions. There are obvious reasons why North American and European biologists focus so much on how Christians, especially conservative ones, react to evolution. But it’s worth remembering that there are other strains of Christianity, and other religions, and it’s very interesting to compare and contrast the ways they reacted to Darwin’s ideas.