Will the real Neutral Theory please stand up?
|April 23, 2014||Posted by vjtorley under Intelligent Design|
What kinds of structural, functional and behavioral complexity can the neutral theory of evolution account for, and what kinds of complexity can’t it account for? According to Professor Larry Moran, to evince confusion on these vital questions is a sure sign of being an “IDiot.” But it is the “neutralists” themselves who are confused on these issues, as I intend to show in today’s post. (I have chosen to use the term “neutralist” to describe someone who adheres to the neutral theory of evolution, as Nature magazine uses that term, although Professor Moran evidently prefers the term “mutationist.”)
In a recent post titled, Sal Cordova tries, and fails, to understand evolution by Professor Larry Moran (April 22, 2014), Professor Larry Moran tears into Sal Cordova for asserting that “if most evolution had been non-Darwinian, one would rightly argue it would have been a random walk, and thus not much better than a tornado going trough a junkyard,” and for attributing to Professor Moran the view that “evolution is a random walk and we are obviously junkyards and you’re an IDiot if you think biological organisms are mostly functional.” These remarks prompted Moran to retort:
It’s very, very, difficult for me to believe that Cordova isn’t lying through his teeth. He can’t be that stupid, can he?
But the assertion that the neutral theory of evolution would be more appropriately described as “random-walk evolution” can be found in Ernst Mayr’s classic text, The Growth of Biological Thought: Diversity, Evolution, and Inheritance (Belknap Press, 1982, p. 593). And given that Professor Moran believes that “90% of the human genome consists of junk DNA,” I find it rather odd that Moran should take offense when Sal Cordova paraphrases this statement (in layperson’s language) as: “we are obviously junkyards.” Finally, the question of whether “biological organisms are mostly functional” obviously depends on the way in which you decide to look at them, but it should be clear that on Moran’s view, if you examine them at the genetic level, they will turn out to be mostly non-functional.
In a 2006 essay, Evolution by Accident, Professor Moran acknowledged the important role of natural selection in evolution, but he also argued that “evolution is fundamentally a random process, although this should not be interpreted to mean that all of evolution is entirely due to chance or accident.” Moran adds that “speciation — one of the most important events in evolution — is largely by accident,” which means that “the tape of life will never replay the same way.” He concludes his essay with the words: “I think the term ‘evolution by accident’ is an accurate description of how evolution occurs.”
If we look at the history of the neutral theory, however, we can discern an increasing trend on the part of its proponents to ascribe evolutionary changes at both the morphological and molecular levels – including the appearance of complex structures – to chance. Motoo Kimura (1924-1994), one of the founders of the neutral theory of evolution, was quite modest about what it could and couldn’t explain: he argued that molecular evolution was dominated by neutral evolution, but at the phenotypic level, natural selection probably accounted for most changes in characteristics, rather than genetic drift.
In a scientific paper titled, The neutral theory of evolution and the world-view of the neutralists (Genome, vol. 31, 1989, pp. 24-31), Kimura voiced his conviction that “The Darwinian theory of evolution by natural selection has served as a great unifying principle in biology,” adding that his neutral theory “does not deny the role of natural selection in determining the course of adaptive evolution, but it assumes that only a minute fraction of DNA (or RNA) changes are adaptive.” The reason, he wrote, why “Darwinian evolution appears to be so prevalent at the phenotypic level” is that natural selection “eliminates phenotypically extreme individuals and preserves those that are near the population mean,” and thereby acts as a stabilizing factor.
Kimura expressed his views more plainly, in a 1985 article in New Scientist (pp. 41-46, cited here), titled “The neutral theory of molecular evolution”:
“Of course, Darwinian change is necessary to explain change at the phenotypic level – fish becoming man – but in terms of molecules, the vast majority of them are not like that.”
Biologist Gert Korthof, in a review of Motoo Kimura’s ground-breaking book, The neutral theory of molecular evolution, comments:
This is an important admission. If evolution is defined at the morfological (sic) level, the evolution of adaptations such as eyes and brains, then natural selection is very important.
In his review, Korthof suggests that Kimura’s willingness to cede a dominant role to natural selection when accounting for the origin of morphological complexity was the decisive factor that rendered his theory acceptable to his Darwinist contemporaries. He also cautions his readers:
Please note that ‘the neutral theory of evolution’ is not sufficient to explain complex life and adaptations. In that sense it is not a theory of evolution. (Emphasis mine – VJT.)
However, Motoo Kimura’s colleague, neutralist Masatoshi Nei, made much stronger claims for the explanatory power of the neutral theory, in a 2005 paper titled, Selectionism and Neutralism in Molecular Evolution (Molecular Biology and Evolution (December 2005), Volume 22, Issue 12, doi: 10.1093/molbev/msi242, pp. 2318-2342), in which he concluded: “It appears that mutation (including gene duplication and other DNA changes) is the driving force of evolution at both the genic and the phenotypic levels.”
More recently, neutralists PZ Myers and Larry Moran have spoken out even more boldly, arguing that most of the complexity that we see in the biological world could be largely the result of chance, although they do not wish to rule out a role for natural selection. In a post entitled, Complexity is not usually the product of selection (11 December 2012), PZ Myers roundly criticized evolutionist John Wilkins for maintaining that “selection is the only process that results in complexity over any time,” refuting it with a detailed scenario for how new versions of a gene that codes for an enzyme might appear and spread through a population, even though “selection plays no role” (Myers’ italics). Commenting on the evolution of globin genes, Myers wrote: “The origin [of these genes – VJT] was not a selection event, but the refinement to specific roles probably was.” Myers also described the evolution of a biochemical pathway studied by Joe Thornton as having being “driven by an initial combination of chance mutation, drift, and subsequent selection” (italics mine – VJT). Myers was fully aware that the implications for the evolution of complexity during the history of life on Earth were very profound, and said as much:
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…
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.
Professor Larry Moran subsequently endorsed PZ Myers’ article, in a post of his own, entitled, On the Evolution of Complexity (11 December 2012), in which he wrote:
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. Just think of our complex genome and read The Origins of Genome Architecture by Michael Lynch.
Want a more simple example? Read the latest post by PZ Myers: [αEP: Complexity is not usually the product of selection]1.
This is an important point. You can’t just assume, without question, that a complex trait must be an adaptation and must have arisen by natural selection. That applies to molecular complexes and also to complex behavior.
So I’d like to ask Professor Moran a few questions:
1. Do you agree or disagree with the view expressed by Motoo Kimura that natural selection is necessary to explain evolution occurring at the morphological level?
2. How do you respond to Dr. Gert
Kothof’s Korthof’s claim that the neutral theory “is not a theory of evolution,” because it “is not sufficient to explain complex life and adaptations”? If not, why not?
3. Can you point to any complex structures, functions or behaviors which you believe could not have arisen in the absence of natural selection? (You’ve already nominated the change occurring in the human brain over the past few million years as an event in which natural selection played an indispensable role; what else would you put on your list?)
4. In which of the following events do you see natural selection as having played a decisive role: the origin of eukaryotes, the origin of multicellularity, the 20-million-year Cambrian explosion, the origin of land animals, the origin of the amniote egg, the origin of angiosperms, and the radiation of mammals immediately after the extinction of the dinosaurs?
5. Or is it simply your contention that natural selection, while not playing an important role in the origin of complex structures and novel morphological features, exerts a refining and purifying effect subsequent to their appearance, weeding out non-viable life-forms?
Five questions is enough for one day. In the meantime, I’d strongly recommend that readers of this post familiarize themselves with the articles below, as they raise a number of interesting issues that will be the topic of future posts of mine.
Recommended background reading
Evolution: A View from the 21st century by James Shapiro.
Shapiro and Intelligent Design
Non-supernatural ID?: University of Chicago microbiologist James Shapiro works with ID guys, dismisses Darwinism, offers third way by News at Uncommon Descent (July 4, 2011)
Is James Shapiro a Design Theorist? by Professor William A. Dembski (January 12, 2012)
“Is James Shapiro a Design Theorist?”: James Shapiro Replies by Professor James Shapiro (January 16, 2012)
Following the Evidence Where It Leads: Observations on Dembski’s Exchange with Shapiro by Dr. Ann Gauger (January 17, 2012)
Let Science Be the Arbiter: A Reply to James Shapiro by Dr. Douglas Axe (January 17, 2012)
A Response to Ann Gauger’s and Douglas Axe’s Comments by Professor James Shapiro (January 18, 2012)
Joining the Conversation: Perspectives on the Discussion with James Shapiro by Jonathan McClatchie
Doug Axe Knows His Work Better Than Steve Matheson by Anika Smith (June 10, 2012)
James Shapiro vs. Jerry Coyne
What Is the Key to a Realistic Theory of Evolution? by Professor James Shapiro (February 16, 2012)
Reply by James Shapiro (February 16, 2012), in a comment on Professor Jerry Coyne’s thread. Shapiro refers to “non-random (i.e., regulated, targeted, reproducible) changes to the genome.”
A colleague wrongfully disses modern evolutionary theory by Professor Jerry Coyne (February 18, 2012)
Jim Shapiro continues his misguided attack on neo-Darwinism by Professor Jerry Coyne (April 7, 2012)
Does Natural Selection Really Explain What Makes Evolution Succeed? by Professor James Shapiro (August 12, 2012)
Cell Mergers and the Evolution of New Life Forms: Symbiogenesis Rather Than Selection by Professor Jerry Coyne (August 21, 2012)
James Shapiro goes after natural selection again (twice) on HuffPo by Professor Jerry Coyne (August 22, 2012)
Larry Moran reviews Shapiro’s anti-Darwinian book; and another new anti-evolution book is about to appear by Professor Jerry Coyne (August 30, 2012)
Bob Dylan, ENCODE and Evolutionary Theory: The Times They Are A-Changin’ by Professor James Shapiro (September 12, 2012)
Why the ‘Gene’ Concept Holds Back Evolutionary Thinking by Professor James Shapiro (November 30, 2012)
James Shapiro gets evolution wrong again by Professor Jerry Coyne (December 2, 2012)
Inconvenient Truths: Why Are Self-Styled Defenders of Evolution so Resistant to Lessons From Molecular Genetics? by Professor James Shappiro (December 4, 2012)
James Shapiro, in his attempts to forge a new evolutionary paradigm, is reduced to going after my commenters by Professor Jerry Coyne (December 5, 2012)
James Shapiro vs. Larry Moran
Professor Larry Moran’s review of James Shapiro’s book, Evolution: A View from the 21st Century. In Report of the National Council for Science Education, Vol. 32, No. 3, May-June 2012.
Revisiting the Central Dogma in the 21st Century by Professor Larry Moran (August 26, 2012)
James Shapiro Claims Credit for Predicting That Junk DNA Is Actually Part of a “highly sophisticated information storage organelle” by Professor Larry Moran (September 13, 2012)
The meaning of “random”
What’s in a Word? “Randomness” in Darwinism and the Scientific Theory of Evolution by Dr. Jay Richards (April 2, 2012)
Seeking an Official Definition of “Randomness”: A Reply to Dr. Jay Richards by Professor Alvin Platinga (April 3, 2012)
So Where Does the Conflict (with Alvin Plantinga) Really Lie? by Dr. Jay Richards (April 5, 2012)
Where My Conflict with Jay Richards Really Lies by Professor Alvin Plantinga (April 6, 2012)
Evolutionary Theory and Theism (Reasonable Faith, #253 – Response by Professor William Lane Craig to a question from Andrew)
Who speaks for science? (Reasonable Faith, #269 – Response by Professor William Lane Craig to a question from Dr. Jay Richards)
Unguided or Not? How Do Darwinian Evolutionists Define Their Theory? by Casey Luskin (August 11, 2012)
Is “Unguided” Part of Modern Evolutionary Theory? by Professor Larry Moran (August 11, 2012)
Responding to Moran – Is “Unguided” Part of Modern Evolutionary Theory? by Jonathan Bartlett (August 12, 2012)
An Example of “Directed” Mutation and an Idiotic “Gotcha” by Professor Larry Moran (August 13, 2012)
Larry Moran Responds Regarding Directed Mutations by Jonathan Bartlett (August 16, 2012)
Statistical and Philosophical Notions of Randomness in Creation Biology by Jonathan Bartlett (director of the Blyth Institute)