On Sunday, November 25, Dr. Paul Nelson gave a video presentation at Pastor Rick Warren’s Saddleback Church in southern California, entitled, Darwin or Design? Watching the video, I thought that he did a brilliant job in exposing the inadequacy of natural selection to account for major evolutionary changes – especially, the origin of animal body plans. I strongly recommend that Uncommon Descent readers take the time to watch Dr. Nelson’s presentation. It’s one of the best critiques of neo-Darwinian evolution that I’ve ever seen. Devastating is the only word I can use to characterize it.
How Animal Body Plans expose the inadequacy of Neo-Darwinian Evolution, in a nutshell
Mutations that disrupt body plan formation are inevitably deleterious. (There’s only one class of exceptions; see below.) This is the main signal emerging from over 100 years of mutagenesis in Drosophila.
Text from one of my Saddleback slides:
1. Animal body plans are built in each generation by a stepwise process, from the fertilized egg to the many cells of the adult. The earliest stages in this process determine what follows.
2. Thus, to change — that is, to evolve — any body plan, mutations expressed early in development must occur, be viable, and be stably transmitted to offspring.
3. But such early-acting mutations of global effect are those least likely to be tolerated by the embryo.
Losses of structures are the only exception to this otherwise universal generalization about animal development and evolution. Many species will tolerate phenotypic losses if their local (environmental) circumstances are favorable. Hence island or cave fauna often lose (for instance) wings or eyes.
What that means is that even after 100 years of careful investigation, there’s no way known to science that unguided changes are capable of generating new, viable body plans for animals. And yet at some point in the past, these plans must have been generated: there are dozens of different phyla of animals, each with its own body plan. Dr. Nelson concludes that only a foresighted mechanism – intelligence – could have done the job.
Professor Coyne’s piqued response to Nelson
One person who hasn’t watched Dr. Nelson’s presentation (but who really should have) is Professor Jerry Coyne, who forthrightly declared in a recent post entitled, A Marshall McLuhan moment with creationist Paul Nelson: “I haven’t yet watched Nelson’s talk (some reader please do it and report back).” Among the 141 comments (as at the time of writing), I couldn’t find one which even attempted to provide a synopsis of Dr. Nelson’s talk. I found one sneering putdown which accused Nelson of mis-representing evolution, but made no attempt to refute his arguments, and another post by someone who admitted that (s)he was still “trying to at least have a general understanding of what biology is and how it works,” and who described the video as “extremely deceptive” (which it certainly wasn’t).
One thing I should mention about Dr. Nelson is that he has a Ph.D. in philosophy of biology and evolutionary theory from the University of Chicago, where Professor Coyne teaches. It is fair to assume, then, that Dr. Nelson is familiar with the views of leading thinkers in the field of evolutionary biology.
In his post, Professor Coyne quoted from an email that he’d received last week from Dr. Nelson, inviting him to comment on the presentation he gave at Saddleback Church. For Coyne’s benefit, Dr. Nelson summarized his argument as follows:
… I made a case (a) that natural selection is quite real, but (b) that the process faces genuine limits, set by the logic of selection itself, to explain macroevolution. (Emphases mine – VJT.)
Clear enough, one would have thought. In the same email, Dr. Nelson also criticized Professor Coyne for declaring, in recent posts on Why Evolution Is True, that the views of Dr. James Shapiro on natural selection are unrepresentative of biologists. Here’s the relevant excerpt:
Skepticism about the efficacy of natural selection is widespread within evolutionary biology (see below). Jim Shapiro is hardly alone in this regard. So when you tell your WEIT audience that natural selection is the only game in town for building complex adaptations, you can expect two consequences:
1. Readers who already know about the thinking of workers such as Eric Davidson, Michael Lynch, Andreas Wagner, John Gerhart & Marc Kirschner, or Scott Gilbert (all of whom, among many others, have recently expressed frank doubts about selection) must discount what you say about the centrality of natural selection to evolutionary theory — because they know that just isn’t so.
2. Readers who do not already know about Davidson, Lynch, etc. — upon coming across their ideas — must wonder why you told them that natural selection is the sine qua non of evolutionary explanation.
Either outcome is bad.
Nowhere in his email did Dr. Nelson deny the reality of natural selection, or its role in accounting for adaptations. What Nelson did deny is the proposition that all evolutionary biologists regard it as central to evolutionary theory, and view it as the only “game in town” for building complex adaptations.
Professor Moran defends Dr. Nelson
Even Intelligent Design critic Professor Larry Moran, of the University of Toronto, thought that Dr. Nelson had correctly paraphrased the views of the five scientists listed above. In a comment to Coyne’s post, he wrote:
I think this is basically correct. All of these authors question in some way or another the “centrality” of natural selection to evolutionary theory. We can quibble about the exact meaning of words and sentences but I, for one, don’t think Nelson is way off base here. Perhaps Nelson shouldn’t have said “expressed doubts about selection” because it could be taken to mean that the authors deny that positive natural selection exists. I don’t think that’s what Paul Nelson meant. He may be an IDiot but he’s not that stupid.
Sadly, however, Professor Coyne appears to have misconstrued Dr. Nelson’s email from the start, as belittling the importance of natural selection, when Dr. Nelson was really attacking its centrality in accounting for complex adaptations. In his post, he wrote:
True, I’ve had scientific disagreements with Davidson, Gerhart, and Kirschner about theories of “evolvability” and “modularity,” but I never saw them claiming that natural selection is unimportant in forging the adaptations of organisms. (Emphasis mine – VJT.)
Circling the wagons
But Coyne went further. He then emailed five of the biologists listed by Nelson (Davidson, Lynch, Wagner, Gerhart and Kirschner) and asked them to comment on Dr. Nelson’s claims. (Coyne enclosed Nelson’s email with his own.) Here is a selection from Professor Coyne’s email:
… I have read the papers of many of you, and while I know that several of you question aspects of modern evolutionary theory, I wasn’t aware that any of you denied the efficacy of selection in accounting for adaptations….
At any rate, if Nelson has accurately characterized your views, do let me know….
Professor Moran defends Dr. Nelson again!
Am I the only one who thinks that Professor Coyne was asking these scientists a loaded question? Evidently not. Professor Larry Moran was of the same opinion. In a comment to Coyne’s post, he wrote:
I don’t think Jerry’s question is fair. Paul Nelson was not accusing these authors of denying a role for natural selection in “obvious adaptations.”
The replies that Professor Coyne got back from these biologists affirmed their belief in the importance of natural selection to evolution – which Nelson had never contested in the first place! Rather, what Nelson claimed was that these scientists denied that natural selection was “the only game in town for building complex adaptations.” None of the replies Coyne received showed that Nelson was wrong on this vital point. I’ve quoted key excerpts from these scientists’ responses, so that readers can judge for themselves. Emphases are mine.
Of course I would not disagree for one second about the importance of adaptive selection for species specific characters of all kinds, whether on protein or regulatory sequences.
The ID crowd tends to misinterpret my embracing of what I call “nonadaptive” mechanisms of evolution (drift, mutation, and recombination) as implying a rejection of Darwinian processes.
You are correct that it is wrong to characterize me as someone who doesn’t believe in the efficacy of natural selection.
I do believe that natural selection is essential for evolutionary adaptation. I also believe that we can understand the diversity of life through entirely natural causes, natural selection being an important one of them.
I haven’t tracked down what Dr. Nelson said we said about natural selection — presumably that we don’t think it’s important. We do think it’s important, and our writing about the means by which organisms generate phenotypic variation wouldn’t make any sense without it.
I really do not know why any thinking person would believe that I question natural selection or the role of genetic change in evolution as agreed upon by population biologists… Whether evolutionary biologists dismisses what we write as beside the point, I still endorse the basic idea of genetic variation and selection. It is just that to go beyond the genes to the phenotype, which after all is under selection, we may want to learn how the phenotype is created.
Coyne’s Marshall McLuhan moment
There is a famous scene in Annie Hall in which Woody Allen and Diane Keaton are waiting in line for a movie, when an academic behind them starts pontificating about Fellini and Beckett. Allen is getting more and more annoyed by the pretentious bore. Finally, when the man starts talking about Marshall McLuhan, Allen steps out of the movie frame and confronts him with the real Marshall McLuhan, who tells the academic, “You know nothing about my work.” Allen then says, “Wouldn’t it be great if life were really like this?”
Professor Coyne evidently thought he’d had a Marshall McLuhan moment, for he seized on the responses he got from the five scientists he emailed, and waved them in front of his readers, concluding his post with the following message:
Nelson can consider himself pwned, though of course he’ll take the above and somehow make it seem that they agree with him… Nelson is either an outright liar or is completely ignorant of the views of these biologists. Nelson either hasn’t read their work, hasn’t understood it, or has read it and understood it but distorted it. Regardless, it’s ignorance, willful or not. But this is what creationists must do if they want to make their ridiculous views seem respectable.
Memo to Professor Coyne: there’s a big, big difference between saying that natural selection is “important” or even “essential” for evolutionary adaptation, and saying it’s “the only game in town for building complex adaptations.” And speaking of willful ignorance, why did you make no attempt to present Dr. Nelson’s case against neo-Darwinian evolution and then refute it? If I didn’t know better, I’d say you were hiding something.
When Dr. Nelson, in one of his replies to Professor Coyne’s post, adduced quotes from one of the scientists he’d cited (Michael Lynch) demonstrating that Lynch is much more of a skeptic of natural selection than most people would allow, Professor Moran began to get cold feet about his defense of Nelson. In a follow-up comment, he challenged Nelson, saying:
… I was giving you the benefit of the doubt.
Do you, or do you not, claim that Lynch and the others deny the existence of natural selection? Do you, or do you not, claim that all of these authors deny that adaptations are caused primarily by natural selection?
I will take your refusal to answer as evidence that Jerry was right and you really are ignorant (or lying) about the works of these authors.
Dr. Nelson’s reply was direct and to the point:
Seriously, Larry — nowhere did I say that any of the authors under discussion denied (a) the existence of natural selection, or that (b) natural selection produces adaptations.
Please re-read my original email to Jerry, which he quotes above. My point concerned the central role or relative strength of selection, as compared to other possible processes, in the thinking of workers such as Michael Lynch. Anyone still reading this thread should familiarize themselves with Lynch’s now-classic 2007 paper on the topic, “The frailty of adaptive hypotheses for the origins of organismal complexity,” PNAS May 15, 2007, available as open access here:
Is Dr. Nelson misquoting Lynch? You be the judge
I’d like to close with a collection of quotes from The frailty of adaptive hypotheses for the origins of organismal complexity (PNAS 2007 104 (Suppl 1) 8597-8604; published ahead of print May 9, 2007, doi:10.1073/pnas.0702207104) by Professor Michael Lynch, one of the scientists cited by Dr. Nelson in his email. My thanks to Dr. Nelson for providing the link in the comment above. Let readers judge whether Dr. Nelson has quoted him fairly:
…It has long been known that natural selection is just one of several mechanisms of evolutionary change, but the myth that all of evolution can be explained by adaptation continues to be perpetuated by our continued homage to Darwin’s treatise (6) in the popular literature. For example, Dawkins’ (7–9) agenda to spread the word on the awesome power of natural selection has been quite successful, but it has come at the expense of reference to any other mechanisms, a view that is in some ways profoundly misleading…
What is in question is whether natural selection is a necessary or sufficient force to explain the emergence of the genomic and cellular features central to the building of complex organisms…
First, evolution is a population-genetic process governed by four fundamental forces. Darwin (6) articulated one of those forces, the process of natural selection, for which an elaborate theory in terms of genotype frequencies now exists (10, 11). The remaining three evolutionary forces are nonadaptive in the sense that they are not a function of the fitness properties of individuals: mutation is the ultimate source of variation on which natural selection acts, recombination assorts variation within and among chromosomes, and genetic drift ensures that gene frequencies will deviate a bit from generation to generation independent of other forces. Given the century of work devoted to the study of evolution, it is reasonable to conclude that these four broad classes encompass all of the fundamental forces of evolution.
Second, all four major forces play a substantial role in genomic evolution. It is impossible to understand evolution purely in terms of natural selection, and many aspects of genomic, cellular, and developmental evolution can only be understood by invoking a negligible level of adaptive involvement (12, 13).
Natural selection is just one of four primary evolutionary forces. [Quote from Table 1]
There is no evidence at any level of biological organization that natural selection is a directional force encouraging complexity. In contrast, substantial evidence exists that a reduction in the efficiency of selection drives the evolution of genomic complexity.[Quote from Table 1]
The literature is permeated with dogmatic statements that natural selection is the only guiding force of evolution, with mutation creating variation but never controlling the ultimate direction of evolutionary change (for a review, see ref. 17)…
Most biologists are so convinced that all aspects of biodiversity arise from adaptive processes that virtually no attention is given to the null hypothesis of neutral evolution, despite the availability of methods to do so (32–34)…
The hypothesis that expansions in the complexity of genomic architecture are largely driven by nonadaptive evolutionary forces is capable of explaining a wide range of previously disconnected observations (13, 40) (Table 2). This theory may be viewed as overly simplistic. However, simply making the counterclaim that natural selection is all powerful (without any direct evidence) is not much different from invoking an intelligent designer (without any direct evidence)…
Certainly, many of the above-mentioned embellishments of eukaryotic genes have adaptive functions in today’s multicellular species, but observations on current deployment may have little bearing on matters of initial origins…
Multicellularity is widely viewed as a unique attribute of eukaryotes, somehow made possible by the origin of a more complex cellular architecture and, without question, with the assistance of natural selection. However, it is difficult to defend this assertion in any formal way…
Nevertheless, King (45) states that “this historical predisposition of eukaryotes to the unicellular lifestyle begs the question of what selective advantages might have been conferred by the transition to multicellularity;” and Jacob (46) argues that “it is natural selection that gives direction to changes, orients chance, and slowly, progressively produces more complex structures, new organs, and new species.” The vast majority of biologists almost certainly agree with such statements. But where is the direct supportive evidence for the assumption that complexity is rooted in adaptive processes? No existing observations support such a claim, and given the massive global dominance of unicellular species over multicellular eukaryotes, both in terms of species richness and numbers of individuals, if there is an advantage of organismal complexity, one can only marvel at the inability of natural selection to promote it. Multicellular species experience reduced population sizes, reduced recombination rates, and increased deleterious mutation rates, all of which diminish the efficiency of selection (13). It may be no coincidence that such species also have substantially higher extinction rates than do unicellular taxa (47, 48)…
…[C]ontrary to popular belief, natural selection may not only be an insufficient mechanism for the origin of genetic modularity, but population-genetic environments that maximize the efficiency of natural selection may actually promote the opposite situation, alleles under unified transcriptional control…
Although those who promote the concept of the adaptive evolution of the above features are by no means intelligent-design advocates, the burden of evidence for invoking an all-powerful guiding hand of natural selection should be no less stringent than one would demand of a creationist…
If complexity, modularity, evolvability, and/or robustness are entirely products of adaptive processes, then where is the evidence? What are the expected patterns of evolution of such properties in the absence of selection, and what types of observations would be acceptable as a falsification of a null, nonadaptive hypothesis?
Neutral evolution to the rescue?
Lynch, it seems, is a big fan of neutral evolution as an explanation for complexity. And it looks like Professor P.Z. Myers agrees with him, for in a recent post entitled, Complexity is not usually the product of selection, which criticizes evolutionist John Wilkins, Myers writes:
…[C]omplex traits are the product of selection? Come on, John, you know better than that. Even the creationists get this one right when they argue that there may not be adaptive paths that take you step by step to complex innovations, especially not paths where fitness doesn’t increase incrementally at each step. Their problem is that they don’t understand any other mechanisms at all well (and they don’t understand selection that well, either), so they think it’s an evolution-stopper — but you should know better.
This is the trap Michael Behe falls into, too. It’s the assumption that you have to have an adaptive scenario for every step, and an inability to imagine non-adaptive solutions. I think if selection were always the rule, then we’d never have evolved beyond prokaryotes — all that fancy stuff eukaryotes added just gets in the way of the one true business of evolution, reproduction.
So let’s work through a hypothetical scenario of increasing complexity, and you try to see where selection is essential. And then I’ll give some real world examples….
The bottom line is that you cannot easily explain most increases in complexity with adaptationist rationales. You have to consider chance as far more important, and far more likely to produced elaborations…
Even in something as specific as the physiological function of a biochemical pathway, adaptation isn’t the complete answer, and evolution relies on neutral or nearly neutral precursor events to produce greater functional complexity.
Readers who want to check out Professor Michael Behe’s responses to Thornton (a critic of Behe’s work, whom Myers cites in his article) can go here and here (the latter link has a good collection of articles).
Professor Larry Moran has endorsed P.Z.Myers’ article, in a recent post of his own, entitled, On the Evolution of Complexity (11 December 2012), in which he writes:
Can you go from some simple character to a more complex feature without invoking natural selection? Yes, you can. Complex features can evolve by nonadaptive means.
Missing the point of Dr. Nelson’s argument?
While I appreciate the general point that these scientists are trying to make, that neutral or nearly neutral random events can sometimes generate functional complexity, it seems to miss the whole point of Dr. Nelson’s argument, that mutations in the genes that control animals’ body plan aren’t just neutral – they’re deleterious. Either that, or they’re mutations that reduce functionality, rather than increasing it. If Dr. Nelson is right about these points, then his argument for the necessity of Intelligent Design is a telling one, not only against neo-Darwinists but also against advocates of a greater role for random, neutral evolutionary changes, such as Lynch.
Would it be too much to hope that one of the evolutionary biologists mentioned in this post will actually take the time and trouble to address Dr. Nelson’s original argument, which he made in his video presentation, that unguided processes – whether they be natural selection, mutation, recombination or genetic drift – are incapable of explaining the origin of animal body plans? Or would that be too difficult? Time will tell. Meanwhile, I’m not holding my breath. Expect a lot more academic obfuscation in the days to come.