It’s a moment every serious evolutionist dreams of – the first time you get misrepresented on a creationist website – and it finally happened to me recently, when the site Creation Evolution Headlines (CEH) used my recent review of Niles Eldredge’s book Eternal Ephemera (in the magazine Science, 17 April 2015) to add a little confusion to a non-existent “debate” around evolution. (I can’t tell you who wrote it, I’m afraid, because CEH’s contributor preferred not to put their name to their opinions.)
Eldredge’s book is not about whether evolution happened (as CEH tries to pretend); it’s about how it happened, what combination of factors best explains the phenomena we see around us. There’s no doubt in his mind (or in mine) that evolution has happened and the modern theoriy of evolution is the best explanation we currently have of the diversity of life on Earth. However, evolutionary biologists recognise that complex scientific processes have complex causes and there are often debates within science about which causes are (or have been) the most significant. In the case of evolution, there’s some debate about whether species are changing continuously or remain stable for long periods once they’ve evolved. I am not a biologist, and don’t pretend to be qualified to comment, but it’s an interesting historical issue because different ideas about the mechanism and pace of evolution have dominated at different historical times; I reviewed Eldredge’s book because it looks at that history.
(1744–1829)
Eldredge notes that before Darwin, there were two main approaches to evolution: the Frenchman, Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (1744–1829) – better known simply as Lamarck – argued that species had not all been created at the same time, but had changed and developed over time. He assumed that each living thing began as the simplest possible form of life and then developed into a series of increasingly complex organisms. In Lamarck’s scheme, species do not split into multiple new species; each follows its own evolutionary path. Some species look more evolved than others because they started their evolutionary development earlier and thus have moved further up their particular evolutionary escalator. One of the interesting implications of Lamarck’s view is that there are really no such things as “species”, since all living things are changing continuously (albeit, too slowly for us to see the changes as they happen); the groups of more-or-less similar creatures that science names as species are really just snapshots of something that is always on its way to becoming something else. The fossils they leave behind embody this; they record an arbitrary moment in the organism’s progress. (And for Lamarck, evolution was very much a record of progress; organisms didn’t just change, they improved). The reason we don’t find lots of fossils of creatures that are clearly in-between known species (usually known as intermediate forms) is that fossils are rare; most dead creatures never become fossils, so of course there are lots of gaps. Lamarck argued that if everything were fossilised, we would have a continuous sequence of organisms that blend seamlessly into an unbroken series of links.
One of the most interesting things about Eldredge’s book is that it highlights the existence of an alternative model of evolution (also before Darwin), that was developed by the Italian geologist Giambatista Brocchi (1772–1826), who saw species as very like individuals, they are born and eventually they die. They may give birth to new species (a process that biologists now call speciation), but they do not usually change steadily and gradually over time. For Brocchi, the lack of intermediate forms is not a result of poor fossilisation; such forms are incredibly rare because species are usually stable. It was only in the most unlikely circumstances – such as a small group of organisms becoming isolated from the rest of their species and having to survive in radically new circumstances – that a new species would arise. In Brocchi’s view, the appearance of new species was a very uncertain business – genuinely random factors were involved – whereas Lamarck’s stately mechanism guaranteed progressive development, onward and upward to ever-more-perfect forms.
Brocchi’s alternative model never really caught on in his day and his work is now all-but forgotten, but one of the many interesting historical facts that Eldredge highlights is that Charles Darwin himself was dubious about Lamarck’s version of evolution and – for a fairly brief period during and after the voyage of the Beagle – more interested in Brocchi’s. However, by the time On the Origin of Species (1859) appeared, no trace of Brocchi’s ideas remained. One of the historical ironies that Eldredge highlights is that most histories of evolution see Lamarck as the bad guy, the one who got evolution wrong and whose ideas Darwinism eventually managed to remove, yet conventional Darwinism looks rather “Lamarckian” in some respects, not least because it has always emphasised slow, gradual change. Darwin himself emphasised the imperfection of the fossil record as explaining the lack of intermediate forms:
We should not be able to recognise a species as the parent of any one or more species if we were to examine them ever so closely, unless we likewise possessed many of the intermediate links between their past or parent and present states; and these many links we could hardly ever expect to discover, owing to the imperfection of the geological record. (Origin of Species, p. 464)
Or, as he put is even more succinctly, “The crust of the earth with its embedded remains must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare intervals” (p.487). Ever since Darwin, this view has largely prevailed and it is, as Eldredge notes, strikingly similar to Lamarck’s view (although there are, of course, many differences between Darwin and Lamarck’s views on many other points).
Eldredge thinks Brocchi was closer to the truth than Lamarck because Brocchi’s view is similar to his own theory of punctuated equilibria (developed with the late Stephen Jay Gould). “Punk Eek”, as it’s sometimes known, argues (as Brocchi did) that the fossil record is fairly accurate; species are stable throughout their lifetimes, and new species arise during relatively brief periods of speciation, usually in geographically isolated populations. There is no innate tendency for species to change, much less for them to progress; chance dominates. So Eldredge is left with a puzzle; why did Darwin once agree with him, and why did he change his mind? Why did the “Brocchian” strand in Darwin’s thinking disappear and why has it remained marginal in evolutionary circles ever since.
(As an aside, Punctuated Equilibria has never become a widely held view among evolutionists. I’m not qualified to judge why, but I’ve often wondered whether that’s because it’s not clear what the consequences of adopting it would be: if Gould and Eldredge are right, the fossils remain the same and the fact of evolution is untouched, and it is not obvious that it would make any significant change to the day-to-day practices of palaeontologists, taxonomists and evolutionary biologists. New scientific theories tend to be successful because they prompt new experiments, new questions, and new ways of solving problems. It’s not clear to me that Punk Eek does any of those things, but that’s probably just a reflection of my profound ignorance of palaeontology.)
As a historian, I don’t find Eldredge’s puzzle at all puzzling. As I noted, Lamarck saw evolution as progress and so did virtually every nineteenth-century evolutionary thinker. Just think about fossils; the recent ones are more like modern species (that have survived), less like earlier ones (that are extinct). What’s that if not a record of progress? Modern evolutionary biologists generally reject the very idea of progress. They describe evolution as a process of successfully adapting to a specific evolutionary niche; if your niche disappears, so do you, and it may be sheer dumb luck that deprives you of your niche (think of the dinosaurs; what possible adaptation could prepare you for a massive meteorite impact?). However, I’m not aware of any nineteenth-century evolutionist who thought in those terms, least of all Darwin. As his well-known conclusion to the Origin argued:
Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. (p.490)
Note that “higher” (better) animals have developed from a “simple beginning”, and they are “exalted”, “beautiful” and “wonderful”. It’s all-but-impossible not to read this as a claim for progress. And the tense of the last sentence is, I would argue, very revealing if you are trying to understand why so many of Darwin’s contemporaries accepted the fact of evolution (and they often did, despite the religious controversy and persistent doubts about whether natural selection was sufficient to achieve everything Darwin claimed). Many of Darwin’s fellow gentlemen of science were impressed with his dignified and modest tone, the great weight of evidence, and by Darwin’s personal respectability. But all readers of the Origin were left with a vision of potentially limitless future progress: “have been, and are being, evolved”. The wonders we see around us (including ourselves) are no more than a taste of the beauty and wonder to come. Many of Darwin’s contemporaries read Darwin (quite plausibly, I would say) as saying that progress was a law of nature, and his book’s full title gave them further reason to hope: On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. “Races” could and did mean “varieties of animals or plants”, but of course it could also mean “varieties of human being” and many of Darwin’s readers concluded that the British ruled the world’s largest empire because they were superior to all other “races”; the fittest had not only survived, but come to dominate all others. There’s a famous cartoon of Darwin in later years that mocks him for publishing an entire book on earthworms (it was to be his last book). Look at the wildly implausible evolutionary sequence that surrounds the elderly, bearded sage; its pinnacle, its “most exalted object”, is an English gentleman in a top hat. There was not just grandeur in this view of life, but considerable self-satisfaction too.
Whether or not Darwin intended his book to be read that way is a topic for another day (but if you’re really interested in my view, you could read my introduction to the Cambridge University Press edition of the Origin, 2009). However, there’s no doubt that Darwin borrowed the key metaphors of his argument from the world around him. Like many of his contemporaries, he saw the world’s first industrialised, capitalist economy as one in which competition was producing continuous, gradual progress (expecially for wealthy gentlemen, like Darwin, with substantial investments in the railways). Darwin effectively saw nature as a perfectly efficient free market at a time when Victorian capitalism was gradually placing the fruits of industrialisation, in the form of cheap, mass-produced consumer goods, within many people’s reach. The Victorian middle-classes assumed that this progress, built on competition within and between nations, was why Britain had avoided the revolutionary upheavals that beset their less-successful competitors. Under these circumstances, it’s difficult to imagine Darwin formulating a radically Brocchian view of evolution, a chancier, more random process that instead of guaranteeing progress, promised only eventual extinction. But even if he had, it’s impossible to see his fellow gentlemen of science accepting it. This, in essence, is my critique of Eldredge’s history; he’s too steeped in the nitty gritty of Darwin’s theorising and tends to ignore its broad socio-cultural context. (If you’re interested, you can read my Review of Eldredge here.)
So, you may be wondering what does any of this have to do with Creationism? The answer, of course, is nothing. Yet CEH quotes my criticisms of the way Eldredge uses history and concludes with the supposedly shocking revelation “So are there current evolutionary debates? Endersby just admitted as much.” Well, duh, of course there are current evolutionary debates; evolution is a science, not a faith, it doesn’t deal in eternal, unchallengeable truths, but in evidence and open debate about the meanings of that evidence. CEH announces that: “It appears Endersby would prefer to put a bandage on that old sore spot by questioning Eldredge’s credibility”. Actually, I’ve done nothing of the sort; I said quite specifically that I doubted whether the historical argument added anything to the credibility of Eldredge’s view of evolution, but it was up to biologists to judge the usefulness of Punctuated Equilibria itself.
Nevertheless, CEH continues:
What [Endersby] has done, though, may be more damaging. He has agreed, in some detail, that evolutionary theory itself has evolved since the pre-Darwinian speculations, all through the 19th and 20th centuries, till the present day. But if evolutionary theory evolves, it could evolve into its converse in the future.
It is, of course, in the nature of scientific theories that they change over time; they are always provisional hypotheses, subject to debate and always potentially open to disproof (otherwise it wouldn’t be science). Evolutionary theory has changed (several times) since Darwin mainly because scientists have tested it and tried to improve it. Some of the changes, like the addition of genetics (which didn’t exist in Darwin’s day), have been adopted by almost all biologists; others are still being discussed. Could evolution “evolve into its converse in the future” (by which I assume CEH means, could a religious view displace it)? It’s impossible to say with complete certainty, of course, but it’s most unlikely; a mature scientific theory like evolution by natural selection has withstood over 150 years of critical testing and close scrutiny by some very smart people. And, as a result, the scientific community’s confidence in its correctness has grown, but that confidence could never reach 100% so there’s a small (and diminishing) chance that some new piece of evidence could force scientists to dramatically revise or even abandon current theories of evolution. However, what I will predict (with considerable confidence) is that if that were to happen, the modern theory of evolution would be replaced by an alternative scientific theory, based on rigorous evidence, not by an unsubstantiated faith in the literal truth of the Bible (or in any of the world’s other creation myths).
Naturally, I don’t expect anyone who believes the CEH view of the world to accept any of this, because their beliefs aren’t founded on testable evidence. I have no objection to that; I just wish they’d acknowledge it, stop pretending that they are interested in science, evidence or facts – and stop lying about what other people have or haven’t said about evolution.