Natural selection is a choice – 2

I left off last time  by mentioning that the “time honoured status of natural selection,” which habitually appears as the basis of evolution’s incontrovertibility in discussions, is in fact a historical myth. It’s an easily documented one, too. My source in this piece is principally the Wikipedia entry on “The eclipse of Darwinism,”  which nicely summarizes the authoritative history by Peter Bowler.

The Wiki author points out that “interphase” has been proposed as a better term than “eclipse”, because natural selection had essentially run out of steam, rather than being a fruitful research area, when it occurred. From around 1880 to (according to Ernst Mayr) as late as 1930 – that’s half a century – “the belief that natural selection was the most important factor in evolution was a minority viewpoint.” In other words, natural selection as a master theory petered out (at least for the first time) only 21 years after it was introduced.

B B Warfield, who had followed evolutionary theory closely throughout his life, in a book review of 1916 and, according to his editors Mark Noll and David Livingstone, “reflecting the scientific judgement of 1916”, wrote:

The discrediting of [Darwin’s] doctrine of natural selection as the sufficient cause of evolution leaves the idea of evolution without proof, so far as he is concerned – leaves it, in a word, just where it was before he took the matter up.


Darwin and Wallace’s theory, popular with the educated lay public from the start, only gained acceptance from scientists slowly. It’s worth noting the qualified support of many of its main proponents, too. Asa Gray (and even Wallace) believed that variation was intelligently teleological, and natural selection only a winnower of that teleological input. Herbert Spencer promoted evolution as a universal progressive principle, and realised that natural selection need not entail that. Even Thomas Huxley, “Darwin’s Bulldog,” was slow to be convinced by natural selection – he championed it mainly because it alone had naturalistic explanatory power. Even Darwin himself added Neo-Lamarckian mechanisms in later editions of the Origin of the Species, because he had been persuaded that natural selection had only limited explanatory power.

The Wikipedia entry lists five early objections that were made to natural selection, only one of which (Lord Kelvin’s chronology) has been rendered false by time, though perhaps irrelevantly when one considers the relatively short time-spans into which major evolutionary events are crammed in punctuated equilibria theory. Wikipedia adds as a sixth the proof that Darwin’s particular theory of variation would in fact obviate natural selection.

But he might also have added a seventh, still valid objection to the theory as a whole, rather than to natural selection alone (still pointed out by scientists like Jim Shapiro) – the limited variability of species. Selective breeding, the analogy Darwin used, invariably leads in the end to decreased overall fitness, and the Victorians knew this as much as protestors at this year’s Crufts Dog Show. Now we have genetic evidence that, for example, dog varieties have arisen almost entirely by the disabling or loss of functional wolf genes – such loss-of-function adaptation can explain my labrador, but not the wolf it came from. There seems little sign that 20,000 years+ of selective breeding have pushed back the boundaries of dog variability significantly, and at the boundaries is an abundance of ill-health: Great Danes, for example, live on average only four years, I am told by my dog-breeder friend.

Limits are also drawn around variation by the finding that artificially inducing mutations late in embryonic produces only minor changes, whilst inducing them in early gestation, necessary for significant selectable changes to bauplans, is invariably fatal. Nature has, apparently, routinely done by accident, and always off-camera, what we have invariably failed to do in the laboratory with concerted effort. The failure of Darwin to account for the arrival of the fittest was noted from the start, and is still covered over by the mere assertion, against such evidence, that life is endlessly variable, and by focusing the attention on natural selection’s all-explanatory wizardry.

Accordingly, Bowler records, whilst Evolution #2 and #3 (in the scheme of my previous article) displaced the Idealist, non-evolutionary, theories of those like Agassiz, the predominant theories from 1880 onwards were all non-Darwinian: Neo-Lamarckism (inheritance of acquired adaptations), Structuralism (lawlike constraint of form), and Vitalism (inherent life-force), and later Mutationism (saltational change – hopeful monsters), all of which could be summed up in Orthogenesis, or directed evolution, the idea that displaced natural selection except as a subsidiary, fine-tuning, process.

Wikipedia points out how most of these theories were eventually weakened either by discoveries in Mendelian genetics, or by the pattern of the fossil record, though all have returned to science in recent years to some extent. So far, the discontinuity (or stasis/saltation) of the fossil record and its top-down organisation have tended not, for some reason, to consign “RV & NS” to the same fate, although they have been known since Darwin’s time. However, Darwinism was amongst the nineteenth century casualties of Mendelian genetics, with which it seemed incompatible.

I’ve missed out another major player during the “Darwinian Interphase”, and that is Theistic Evolution, in order to focus on it separately. This variation on Darwin was a major player at first. I’ve recently written on theistic science in the nineteenth century, and Bowler also confirms that “British science developed in the early 19th century on a basis of natural theology…”. Consequently a significant proportion of the original Darwinians accepted the theory of natural selection only as part of a divinely-ordered teleological process. The word most often used was “design,” which was held to be self-evident in living things. It is important to note how theistic evolution was never, like the other theories, discredited, but simply came to be considered “un-scientific” only by a new generation of scientists raised on the naturalist precepts of Huxley et al. In other words, theistic evolution was excluded from science by demarcation, not by any lack of fit to reality.

For the same reason it’s important to note how different modern theistic evolution is from the original kinds back in the nineteenth century, and why, in order to avoid the previous fatal clash with naturalism, the modern movement has either tended to deny teleology (eg van Till’s “Robust Formational Economy Principle”) or insisted that it is so hidden in mystery that, effectively, chance and necessity are sufficient explanations for atheists and Christians alike. It therefore always occupies an unstable position somewhere between naturalist science and a minimally-defined creationism, whereas the nineteenth century version was both theologically robust and scientifically mainstream.


The next phase of the story was, of course, the birth of the Modern Synthesis in the 1920s and 1930s, which via population genetics restored the explanatory power of natural selection in conjunction with Mendelianism.

Or rather, once some epicycles were added, it did so. For the mathematical claim of the first Neo-Darwinians like Fisher was that existing genes were sufficient to account for evolution. Population genetics was a conscious rejection of mutationism in favour of “change of allele frequency”, with perhaps a grudging acceptance that the gene pool would be topped up occasionally by mutations. Fisher’s maths, however, did not even include mutation as a factor, so unimportant did he consider it. But in fact, his own formulation would actually lead only to maximal fitness followed by stasis. Within a decade or so it began to be evident that this “gene pool” evolution was simply untrue, and that it was, indeed, mutations that were the major driver even of microevolution. This is a situation we now take for granted as the basis of the “Modern Synthesis,” rather than its being a correction of its error that existing variation within populations would be sufficient to drive evolution.

But natural selection itself soon began to show its limitations again. In particular, the calculations that limited the number of genes that could conceivably be under selection at any time led (via the protracted and sometimes bitter “adaptationist controversy”) to the now dominant near-neutral theory of evolution of Kimura et al.

That numerical limit on selection has been compounded as a problem by the realisation that a multitude of non-coding control-network genes, as well as protein coding genes, must also be included in the total under selection to account for major evolutionary changes. By far the majority of “random” genetic changes, it now appears, are deleterious (whereas Fisher assumed there was a normal distribution between benefit and detriment). The worst are removed by purifying natural selection, but the vast majority are near-neutral, leading to gradual degradation of the genome below the “radar” of adaptive selection.

The role of adaptive natural selection seems not entirely clear in the near-neutral theory (or else there would presumably have been little quarrel with the adaptationists: if selection is the final common path anyway, why argue about drift, since it was always part of the syntheis anyway?), but in a review of the modern state of evolutionary theory, Eugene Koonin wrote:

Natural (positive) selection is an important factor of evolution but is only one of several fundamental forces and is not quantitatively dominant; neutral processes combined with purifying selection dominate evolution.

But that, too, he qualified:

The majority of the sequences in all genomes evolve under the pressure of purifying selection or, in organisms with the largest genomes, neutrally, with only a small fraction of mutations actually being beneficial and fixed by natural selection as envisioned by Darwin.

…the complexity of the genomes of multicellular eukaryotes is interpreted as evolving, primarily, not as an adaptation ensuring organizational and functional complexity but as a “genomic syndrome” caused by inefficient purifying selection in small populations.

The rate of beneficial mutations is astonishingly small, as is confirmed by the wide variation amongst estimates, down to one in a million or less. They are just too rare to measure accurately. And most of those that are seen are near-neutral and hence not selectable.

In one literature survey of nearly half a million papers mentioning “mutation,” only 186 mentioned “beneficial” mutations, and in every case in that series, these mutations all produced benefit by loss of function (just as damage to wolf genes produced my labrador). However, to produce the wolf from its last common ancestor, or the genus Homo from its putative ape precursors, requires a whole raft of new functions. Do an internet search on “beneficial mutations” and those few that are not “loss-of-function” (sickle cell trait being on every list) are exceptionally rare in the population, and so clearly not undergoing fixation. Truly beneficial mutations are rather like lemming mass-suicides a few decades ago – everybody knew the suicides happened regularly, evolutionary explanations were formulated, they were cited by atheists as evidence against a loving God in TV debates… but nobody happened to have seen one except in a Walt Disney film, and this was later shown to be faked.

Critically reviewing James Shapiro’s book on Natural Genetic Engineering (which denies the centrality of selection), evolutionary biologist Adam Wilkins wrote:

The arguments from paleontological evidence for the importance of natural selection largely concern the observed long-term trends of morphological change, which are visible in many lineages. It is hard to imagine what else but natural selection could be responsible for such trends, unless one invokes supernatural or mystical forces such as the long-popular but ultimately discredited force of orthogenesis.

Wilkins, once more, establishes NS only by excluding theistic evolution by demarcation decree, providing no solid evidence for the millions of “creative” mutations necessary for the biosphere, as contrasted with the neutral or deleterious mutations overwhelmingly seen in population genetics. It is true that population genetics uses proxies for genes “under selection”, but as the late Austin Hughes wrote:

Contrary to a widespread impression, natural selection does not leave any unambiguous “signature” on the genome, certainly not one that is still detectable after tens or hundreds of millions of years. To biologists schooled in Neo-Darwinian thought processes, it is virtually axiomatic that any adaptive change must have been fixed as a result of natural selection. But it is important to remember that reality can be more complicated than simplistic textbook scenarios.

His paper expands on that at length. Furthermore, even those vanishingly rare beneficial mutations cannot be assumed, in practice, actually to benefit the species. A paper by Ard Louis describes some of the issues, and concludes:

Taken together, these arguments suggest that the vast majority of possible phenotypes may never be found, and thus never fix, even though they may globally be the most fit: Evolutionary search is deeply non-ergodic. When Hugo de Vries was advocating for the importance of mutations in evolution, he famously said “Natural selection may explain the survival of the fittest, but it cannot explain the arrival of the fittest”. Here we argue that the fittest may never arrive. Instead evolutionary dynamics can be dominated by the “arrival of the frequent.”

And that would be a fine, though pessimistic, view on the inefficiency of “evolution by natural selection” if life were found to be dominated by the frequent, whereas from “endless forms most beautiful” to an endless supply of new taxon-specific Orfan genes, via the astonishing optimization (here and here) of many biological organs and systems and the close adaptive fits found in nature – it is actually dominated by the uncommonly wonderful. Planet Earth 2 and Blue Planet 2 do not appear to demonstrate merely the arrival of the frequent.

Meanwhile, ecologists point out the evidence that animals, at least, don’t wait around waiting for the environment to adapt them – they actively seek out niches that suit them, and even change the environment to their needs. This is very clever, but at least must lessen the role of natural selection by those environments, and also leaves unanswered the question of why stasis-plus-niche-construction should give way to new, very different, taxa: the wolves (naturally?) select their best environment – but how did the wolves themselves originally arise?

One more thing… it is genes that mutate, but phenotypes that are selected, and the link between the two has proved much more complicated over recent years than was ever assumed. Just as one dramatic illustration, the eugenics movement so tangled up with evolutionary theory from Galton to the Holocaust has been abandoned not only because it was immoral, but because virtually all the traits then considered to be inhibiting human evolution – criminality, imbecility, sexual deviation, Jewishness etc – would not be removed from the species by eugenics anyway. Complex traits are not closely linked to genetic variants – and being a human, rather than an ape (for example – a mollusc rather than an echinoderm will do equally well) is a highly complex trait compared to lactase persistence – and even that is genetically multifactorial.

I think I have shown that natural selection has been severely challenged during much of the last 160 years, when it has not been established science. Rarely can any proposal in science have had such a roller-coaster ride of acceptance and denial. Is there good evidence that it occurs? Undoubtedly – not even Creationists deny it. Is there good evidence that it is what drives the whole trajectory of evolution? That’s more questionable – the arguments for that often seem to be along the lines of “What else could do it (given naturalism)?” That appears to me more a faith position than one based on the empirical evidence.

In other words, contrary to what we are often told, the theory of natural selection did not arise by orthogeneis – it is not a law of nature, and it remains unclear whether natural selection itself is a law, a mechanism, or just a tautology. Each one of us is a unique cognitive environment, and we may select it or not according to whether we judge it’s fit for purpose from the various evidences provided. Which seems appropriate enough to the subject of evolution versus fixism.

But if that is so, then we need to reconsider Warfield’s words as carefully as we would have done in 1916, as regards the origin of the species that concerned him as it concerned Darwin:

The discrediting of [Darwin’s] doctrine of natural selection as the sufficient cause of evolution leaves the idea of evolution without proof, so far as he is concerned – leaves it, in a word, just where it was before he took the matter up.

Warfield does not define “evolution” is this quotation, as I tried to in the previous post. Does it mean Warfield commited himself to literalist fixism? There were, after all, many other evolutionary theories in 1916. What, I think, he meant is also valid today: once natural selection is displaced as “the sufficient cause” of evolution, the conclusion is not at all trivial, for natural selection provides the only plausible ateleological mechanism for evolution, even now. To quote another early theistic evolutionist, Asa Gray, (out of context, I confess), it “leaves design where it was before.”

Jon Garvey

About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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8 Responses to Natural selection is a choice – 2

  1. Ian Thompson says:

    Jon,
    If I may presume to speak for the collective readership:
    We are not commenting directly, because everything you say seems eminently reasonable, and quite believable as an historical account.
    We wonder, though, where this goes! Can you (or us) say anything, based on these analyses, that help to understand what actually goes on just before the fittest arrive?

    • Jon Garvey Jon Garvey says:

      Hi Ian

      I’m afraid there’s no breakthrough theory of adaptation to replace natural selection coming from here any time soon, though I I do hope in a couple of posts’ time to see how one might view the arrival of the fittest differently (what’s missing is not natural selection, but sufficient beneficial mutations).

      A major aim here, though, is to straighten out the history for those who may not know it, and so open up the possibilities beyond RM & NS as “settled science”, as historical assessment so often does challenge assumptions. A second aim is to help us recognise when apparently disarded ideas are being offered as if they were conventional Darwinism.

      For example, I see that Deb Haarsma has posted here on how God uses laws of nature and chance to produce his intended aims in evolution. Though there’s an unfortunate (and often challenged) confusion between the order of snowflakes and the organisisation of DNA in living things, and more seriously an incoherent element of ontological randomness (a designed random process???), the overall idea is a kind of Orthogenesis, which takes us back before the Modern Synthesis to 1916, only without apparently recognising the fact:

      Evolutionary creationists, however, believe that God created the biological information in our DNA and protein sequences through the natural laws and random processes that he designed and sustains. In other words, God created biological information through evolutionary mechanisms in ways analogous to how God creates the information needed to describe each new snowflake, each new tree, each new ecosystem, and every new human being.

      The Epicurean weakness of the orthogenesis in her model shows up in her conclusion, having discussed the massive combiunatorial possibilities of a chess game based on a few pieces and squares and limited rules:

      When we humans create plastic toy bricks or games like chess, where a few simple pieces and a few simple rules can combine into possibility spaces so extensive that we couldn’t explore it all in the lifetime of the universe, we are imitating one aspect of how God chose to create our universe.

      This of course misses the entire problem of understanding life: get a random number generator to play chess and you’ll never get a decent game simply because of all those possibilities. You need, instead, planned moves – which seems a very obvious problem as soon as you “dilute” orthogenesis with randomness. Even chess algorithms only work well because they soak up the games of grand-masters down the ages.

      In that scenario, though basically (as I said) orthogenetic, natural selection has to be as powerful as the grandmasters to produce anything good – and that’s what seems to me in doubt, leaving a serious gap to be filled when it’s more closely examined.

      My next episode, before looking at one rather more theistic model, is to look at what natural selection actually is, and therefore why, like chance, it cannot be a true cause.

  2. swamidass says:

    I do believe that is Loren’s article, not Debs. I agree that is a very weak article that does more to confuse than elucidate. For example, your critique of the chess analogy is on point.

    • Jon Garvey Jon Garvey says:

      Rats, Josh – another factual error on my part. Mea culpa.

      Still (as Eddie points out), it’s odd for Loren to use such weak arguments (and Deb to publish them!), specifically against Intelligent Design, when for something like a decade core arguments by ID people have included the differentiation of complex order from complex organisation, the (hard to define) difference between Shannon information and specified information, the combinatorial problems of chance, etc.

      Not only does the article not answer these ID arguments – it demonstrates a woeful lack of comprehension of them.

  3. Edward Robinson Edward Robinson says:

    I agree with Joshua: Loren Haarsma’s article is weak, with flawed analogies. But this is nothing new for BioLogos folks In the past, both Ard Louis and Kathryn Applegate have posted similarly weak arguments, based on analogies of magnetized half-spheres coming together when jumbled in a lottery machine, etc. (As if providing half-spheres known in advance — *designed* in advance — to be geometrically perfect fits with each other, and magnetizing the spheres with a sufficient magnetic strength — calculated in advance to make it inevitable that the spheres will, though moving, come together sooner or later, doesn’t load the dice toward a predictable order.) In the case of Applegate, the legitimacy of the sphere analogy was challenged, but she declined to respond to critics of the analogy on the comments page. At BioLogos, it remains true that any old ad hoc argument for the infinite creative powers of “randomness” will apparently do, if it persuades some readers to come on board with the BioLogos party line. Intellectual rigor matters not at all.

  4. GD GD says:

    Hi Jon,

    While I acknowledge that I have been very critical of NS as the foundation of (whatever) current view is of biological evolution, I also remind myself (and perhaps others) that variation and NS is the basis for the biological paradigm – and such things will not change easily.

    My constructive comment is that as Christians, we need to keep a healthy distance between theology and scientific paradigms that claim some sort of theological relevance. Science tends to correct itself (with much ink and blood spilt), whereas theological error is often harder to correct once it has taken hold in some places.

    • Jon Garvey Jon Garvey says:

      GD

      I can’t disagree with you there. It is certainly the case that natural selection addiction is not going to be overturned by a retired doctor’s blog. But I can raise questions that may send others after answers. And I can point out that natural selection was found wanting before, is found wanting now by many, and may well be scheduled for more serious criticism again.

      Unlike, say, the glories of industrial chemistry, Joe Public has a vested interest in evolution by natural selection – for as Joshua says in a comment on the previous post, it concerns their own conception of how they got here, as some media scientists and school textbooks constantly remind them.

      The assertions from popular science are themselves theological, and erroneous of course, when they tell us that random natural forces, without purpose, put us here rather than a Creator (and that science demonstrates that). Yet like yourself, I don’t think it helpful when others reply, “Yes, those natural forces do fully explain us, but behind it, in some metaphysically incoherent way, perhaps God was at work… at least in the case of mankind… or at least for some special aspects of mankind… or in fact unguided natural forces are good when God makes them…”

      • GD GD says:

        “It is certainly the case that natural selection addiction is not going to be overturned by a retired doctor’s blog.”

        I am not suggesting you stop blogging Jon, far from it. I understand that evolution has become almost a religion amongst some, and this needs to be countered.

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