Don’t say “Darwin” when you mean “evolution” (part 1)

Part I,Dalton and Darwin

Don’t say “Darwin” when you mean “evolution”. Don’t say “theory of evolution” when you mean the established historical facts of change over time and common descent. And above all, don’t say “Darwin’s theory of evolution” except in the historical context of the evolution of ideas. If you do, you are guilty of scientific, logical, historical, and pedagogical errors, and playing into the hands of our Creationist opponents.

Dalton is to the modern atomic theory, and the modern atomic theory is to chemistry, as Darwin(not to forget Wallace) is to evolution, and as evolution is to biology. But we don’t call our present perspective on atoms “Dalton’s theory”, and indeed, unless we are speaking historically, it sounds odd to even talk about “atomic theory” when we discuss atoms. So why should we refer to “Darwin’s theory”, and indeed why should we talk about the “theory of evolution” when we really mean the fact that evolution has taken place? I argue here that we shouldn’t, and that, given the ongoing opposition to the central facts of biology, it is actively damaging to do so.

John Dalton produced his “atomic theory” in the early 19th century. He arrived at it by way of a theory of gas pressure that we now know to be totally erroneous. Wielding Occam’s Razor rather too energetically, he assumed that the simplest compound between two elements contained just one atom of each, so that water would have the formula HO. He rejected what now seems to us perhaps the most striking validation of his theory, Gay-Lussac’s observation that gases combine according to simple ratios, because it pointed towards what later became known as Avogadro’s Hypothesis, which in turn required some gaseous molecules to be divisible,[1] and when it came to gaseous elements Dalton had not grasped the distinction between atoms (the fundamental particles of chemical composition) and molecules (the fundamental particles of gas pressure). It was half a century before his theory was generally accepted, and even then some remained sceptical, on the grounds that no one had ever observed the effects of individual atoms or molecules, until in 1905 Einstein pointed out that that was exactly what people were doing when they looked at Brownian motion. These days, however, individual atoms are routinely observed by the methods of high resolution transmission electron microscopy, and scanning tunnelling microscopy, both of which depend on concepts far beyond any available to Dalton.

Charles Darwin produced his theory of the mutability of species as the result of natural selection (he did not himself use the term “evolution”) in the mid-19th century. Central to the theory is the existence of sufficient heritable variation to explain the diversity of life, and a major stumbling block is the prospect that favourable variations will disappear through dilution.[2] He appealed to the experience of animal breeders, but as a solution to the problem of dilution this is grossly unfair, since breeders can and do deliberately select rare variants to breed between. He lamented the absence of fossil evidence, in terms still quoted by creationists despite the tons (literally) of such evidence that have been unearthed (literally, again) in the intervening 150 years. He was unaware of the digital nature of inheritance, as established by his contemporary, Gregor Mendel, but not widely known until that work was rediscovered (or more accurately, perhaps, reinterpreted)[3] at the beginning of the 20th century. He fully realised that evolution required many millions of years, and had no good answer when Lord Kelvin, one of his “sorest troubles”, used thermodynamic arguments to show (correctly) that the then known sources of energy could only have kept the sun shining for a mere 20 million years or so. He had no inkling of the nature of the genetic material, and could not have conceived of the methods of molecular biology that now allow us, using much the same kind of evidence that the courts use to establish paternity, to compare related species and to chart their divergence in exquisite detail. Least of all did he have any notion of the source of the variations of which evolution depends, or of how the supply of variants is constantly replenished by mutation, a process that we can now observe at the level of an individual’s DNA.

The first half of the 20th century saw the formation of what became known as “the neo-Darwinian synthesis”, bringing together by the 1940s the concept of selection and the methods of population genetics. (The expression “neo-Darwinian” should now properly be restricted to the evolutionary thought of that time, although Creationists persist in applying it to current biology, for reasons to be discussed in part II).  The second half saw an explosion in our understanding of inheritance, based on laboratory studies, while the final decades saw breakthroughs in our understanding of human evolution, with the discovery of the fossilised remains of over a dozen species of our early relatives in eastern and southern Africa. By the end of the 20th century, evolution denial could fairly be compared with Holocaust denial. Given what we have learnt from molecular biology in the present century, it could now more fairly be compared with denying that Hitler ever invaded Poland in the first place.

So why does the name of Darwin still provoke controversy, why do people still speak of  “the theory of evolution”, when as often as not they are referring, not to theory, but to the established historical facts,  why does it matter, and how should we respond? These topics will be the subject of my next posting on this subject, “Naming and Framing”.

(You will find  more on Dalton  and his times, and on Kelvin and the age of the earth,  in my book, From Stars to Stalagmites, and the arguments in these two posts are developed at greater length in an article that I wrote with Britt Holbrook; Putting Darwin in his Place; the Need to Watch our Language. ) This post first appeared on The 21st Floor

Refs


[1]  Two volumes of hydrogen combine with one volume of oxygen to make two volumes of steam. If, as required by Avogadro’s Hypothesis, equal volumes of gas contain equal numbers of molecules, then each molecule of oxygen must contain (at least) two atoms, as shown in the way we now write this equation: 2H2 + O2 = 2H2O

[2] Imagine a favourable red variant in a population of white flowers. Under the blending theory of inheritance then current, its first generation offspring will be deep pink, the second generation somewhat paler, and so on until the descendants are indistinguishable from the general population.

[3]  See Genesis; the Evolution of Biology, Jan Sapp, OUP, 2003, pp 117-122

About Paul Braterman

Science writer, former chemistry professor; committee member British Centre for Science Education; board member and science adviser Scottish Secular Society; former member editorial board, Origins of Life, and associate, NASA Astrobiology Insitute; first popsci book, From Stars to Stalagmites 2012

Posted on July 18, 2012, in Charles Darwin, Creationism and tagged , , , , , , , . Bookmark the permalink. 13 Comments.

  1. Regarding James and Paul’s discussion, above, about Richard Dawkin’s language use: I have found that British scholars — whether scientists or philosophers of science — tend to use “Darwinism” as a synonym for evolution much more than North American ones. Paul is entirely correct that this usage is confusing a historical set of ideas (what Darwin thought in the 19th C) with a modern, much more fully fleshed-out explanation. This can mislead nonscientist members of the public (and even scientists unfamiliar with evolutionary biology!) into thinking that evolution somehow depends on what Darwin knew back in the 1800s.

    But Brits (Dawkins, Michael Ruse come to mind) I think naturally fall into using that terminology, maybe because Darwin was their guy. Whatever, it’s good to break habits of communication that mis-communicate, which Paul has illustrated very well. And this is independent of whether opponents of evolution use Darwinism as an epithet! So whether you are concerned with antievolutionism or communicating science, it’s best to avoid the term Darwinism as a synonym for evolution. Another take on the same idea is http://www.springerlink.com/content/n47h34357743w4p0/
    Thanks so much, Paul!
    Genie

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  2. Indeed, James, you’re getting MY drift (sorry,couldn’t resist). My point. precisely, is that it is as artificial to call present-day evolution science Darwinism as it would be to call present-day molecular science Daltonism. Of course, Creationists do so obsessively; the next posting discusses why they do this, and why the scientific community shouldn’t.

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  3. I very much doubt whether Richard Dawkins would object to being classified as a Darwinist or neo-Darwinist: He has often done so in his works.

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    • Interesting point, but you have to be a little bit more specific about context. Our present science is a mosaic of Darwinian, post-Darwinian, and now post-neo-Darwinian elements. Does Dawkins accept Darwin’s ideas of common descent, speciation, and natural selection? Yes. Does he imagine that that is all there is to the subject? No. Consider for example what happens after gene doubling, or incorporation of DNA derived from an endogenous retrovirus. The duplication or incorporation are processes not envisaged by Darwin, nor is subsequent genetic drift, but Darwinian selection may kick in if that drift happens to bring the relevant DNA to the point of having a use for which it can be selected.

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  4. We know we can change the features of organisms over time (within limits). Dog breeders knew this, botanists knew this, chemists knew this–long before Darwin’s claim that everything came from a common ancestor. Long before he claimed that we cam from apes and, as human beings, “evolve” at different rates.

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    • What’s your point here? I mention how Darwin drew on the experience of animal breeders. I don’t see how chemists come into it, and if (as I suspect) you want to attack the science of evolution, the whole point of my article is that you need to do so the way the science is now,not how it was in 1859 or 1871.

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      • The thing is Paul, is that there is no fossil evidence desccribing the detail you say exists. There are a minute amount of chains. There should be more intermediary fossils than that of established species and there is not. You will find many variations of adaption granted although a bird remains a bird and soforth. The slow transitional picture most evolutionists speak of does not exist.

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      • You have been lied to. We have something like a score of more or less intermediate forms (whether grandparents or great-uncles, we cannot tell, but that’s not the point) just between humans and their common ancestor with other apes. There are something like 19 separate orders, let alone intermediate species, known between modern whales and their terrestrial ancestor; see http://link.springer.com/article/10.1007%2Fs12052-009-0135-2 (free download), and for the proliferation of links elsewhere in the fossil record, see Prothero’s What the Fossils Say and Why it Matters. You might look up the origin of birds there, since that particularly concerns you.

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