Thursday, February 01, 2018

Kevin Laland's view of "modern" evolutionary theory (again)

Kevin Laland has just published another critique of modern evolutionary theory. This one appears in Aeon [Evolution unleashed]. His criticism is based on a naive and outdated view of modern evolutionary biology. That view has been widely criticized in the past but Laland continues to ignore such criticisms [e.g. Kevin Laland's new view of evolution].

Here's how he describes the state of modern evolutionary biology.
If you are not a biologist, you’d be forgiven for being confused about the state of evolutionary science. Modern evolutionary biology dates back to a synthesis that emerged around the 1940s-60s, which married Charles Darwin’s mechanism of natural selection with Gregor Mendel’s discoveries of how genes are inherited. The traditional, and still dominant, view is that adaptations – from the human brain to the peacock’s tail – are fully and satisfactorily explained by natural selection (and subsequent inheritance). Yet as novel ideas flood in from genomics, epigenetics and developmental biology, most evolutionists agree that their field is in flux. Much of the data implies that evolution is more complex than we once assumed.
Count me as one who is confused. I don't believe that modern evolutionary biology is the same as the synthesis from 50 years ago. I think it changed considerably in the late 1960's to incorporate the latest discoveries in population genetics. It expanded to place more emphasis on random genetic drift and Neutral Evolution. Those were significant changes. Modern evolution textbooks are very different from those in the 1960s.

Let's take a look at one of these textbooks. The following quotation is from Evolution (2nd ed.) by Douglas Futuyma (p. 322). This is not the latest edition; it was published in 2009.
In developing the theory of selection so far, we have assumed an efffectively infinite population size. However, in a finite population, allele frequencies are simultaneously affected by both selection and chance. As the movement of an airborne dust particle is affected by both the force of gravity and by random collisions with gas molecules (Brownian movement), so the effective size (Ne) of a population and the strength of selection (s) both affect changes in allele frequencies. The effect of random genetic drift is negligible if selection on a locus is strong relative to the population size—that is, if s is much greater than 1/(4Ne), i.e. if 4Nes>1. Conversely, if s is much less than 1/(4Ne) (that is, if 4Nes<1), selection is so weak that the allele frequencies change mostly by genetic drift: the alleles are nearly neutral. The critical value is 4Nes: genetic drift predominates if selection is weak or the effective population size is small.
The blind worship of natural selection is not evolutionary biology. It is arguably not even science.

Michael Lynch
Thus, even something as fundamental as the idea that adaptations are "fully and satisfactorily" explained by natural selection is not part of modern evolutionary theory. It's been known for many years that both selection and drift play important roles in adaptation [Learning about modern evolutionary theory: the drift-barrier hypothesis].

The statement in Futuyma's textbook was not the way evolutionary biologists thought about evolution in the heyday of the Modern Synthesis back in the 1950s. This change in our way of thinking about evolution may not have been a "paradigm shift" but it was pretty close.

I want to make two points.
  1. The modern view of evolution is much different that the views of 50 years ago in spite of what Kevin Laland says.
  2. Most of the proponents an Extended Evolutionary Theory (EES) share Laland's out-of-date views on modern evolutionary theory. They missed the revolution that took place 50 years ago.
Douglas Futuyma, and others, made these points repeatedly at the 2016 Royal Society conference on EES [The Extended Evolutionary Synthesis - papers from the Royal Society meeting]. Not only did they explain the changes in our way of thinking about population genetics since the 1960s, they also described other developments over the past 50 years that have been incorporated into modern evolutionary theory and our understanding of the history of life.1

Apparently, Kevin Laland and his EES colleagues weren't paying attention during that part of the meeting.


1. The history of life is not the same as evolutionary theory. Evolution is the underlying process that explains the history of life. Our understanding of developmental biology helps us recognize the particular directions that lineages took over the course of millions of years but evolution still requires changes in the frequencies of alleles in a population and that's what evolutionary theory is mostly about [Replaying life's tape].

11 comments :

  1. "1. The history of life is not the same as evolutionary theory. Evolution is the underlying process that explains the history of life. Our understanding of developmental biology helps us recognize the particular directions that lineages took over the course of millions of years but evolution still requires changes in the frequencies of alleles in a population and that's what evolutionary theory is mostly about..."

    I'm not altogether certain it's truly useful to distinguish plate tectonics from geological history of the continents, or the principles of astrophysics from the history of the universe. Nor for that matter am I altogether certain that the multiplication of species is understandable apart from the separation of populations (which makes it hard to understand what 4Ne might mean.)

    But I am altogether certain that looking on from the outside as a layman that whatever paragraphs may be in the textbooks at the beginning acknowledging random genetic drift, by the time it gets out to the mass population, it's all natural selection. From that perspective, these vigorous assaults on every seeming dissent from the consensus serve as defenses of panadaptationism.

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    1. "From that perspective, these vigorous assaults on every seeming dissent from the consensus serve as defenses of panadaptationism."

      That is to say, this is how it looks from the perspective of those who are ignorant of the last half-century of development of the theory of evolution. Which, I believe, is Larry's main point.

      One would reasonably expect someone with the credentials of Kevin Laland to not be so ignorant.

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  2. Geologists are interested in working out the history of plate movements on Earth. The accuracy of their predictions starts to fall off dramatically beyond one billion years ago. They may even get the history wrong from time to time. It is improved by better data.

    The accuracy of the ancient history has very little bearing on the theory of plate tectonics and on the massive amount of evidence that supports it. It’s important to distinguish between the reconstruction of particular and unique events in history and the scientific theories that help explain those events retroactively.

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  3. If LaLand's point was to communicate to the profession, he was really stupid to pick Aeon, a popular website. I believe the audience at Aeon is firmly convinced the prevailing opinion of professionals is that natural selection optimizes all traits (usually with the added proviso the gene is the unit of selection, not the organism.)

    Massimo Piglucci has been commenting on chapters of Laland. In the latest, Piglucci represents LaLand's thinking on a suitable theory of the evolution of language as follows:

    "Kevin proceeds by listing six criteria (and adding a seventh of his own) that a successful theory of language’s origin should meet in order to be further considered (I refer the reader to the chapter itself for more in-depth explanations concerning each criterion):

    The theory must account for the honesty of early language. (If words are easy and cost-free, why should anyone believe what others say?)
    The theory should account for the cooperativeness of early language. (Why should people, early on, have gone out of their way to help others by passing to them valuable information?)
    The theory should explain how language was adaptive from the onset. (As it is hard to imagine how it could have been a spandrel.)
    The concepts proposed by the theory should be grounded in reality. (That is, how did words acquire meaning in the first place?)
    The theory should explain the generality of language. (As opposed to the specificity characteristic of every other animal communication system.)
    The theory should account for the uniqueness of human language. (Why us and not anyone else?)
    The theory should explain why communication needed to be learned. (Why is it that language needed to be socially learned and capable of changing rapidly?)"

    It is not clear to me that LaLand is a malicious incompetent destroying public understanding of science.

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  4. In his recent book Kevin writes:

    "Evolutionary biology teaches us that in small populations, chance factors dominate and the dynamics of evolving populations are dictated by drift, but as populations get larger, natural selection starts to become more important and advantageous mutations become more likely to propagate."

    ...and...

    "Larger populations typically mean faster rates of biological evolution, due to increases in the numbers of novel mutations, and a stronger effect of natural selection relative to genetic drift."

    Kevin knows about genetic drift. However, his proposals are not to do with adding drift to evolutionary theory. Everyone knows that is not needed, including Kevin. They are mostly about adding developmental factors to evolutionary theory. Developmental biology was left out of the modern synthesis. None of the contributors were expert in that field. Development was mostly just modeled as an impenetrable black box, transforming genes and environemnt into phenotypes by some unknown process. Numerous developmental biologists have been sore about this ever since.

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    1. Then why are people so angry? Because that undercuts the primacy of DNA sequences, aka genetic determinism?

      LaLand's comment that larger populations typically have faster rates of biological evolution identifies optimization by natural selection with evolution. I wasn't aware that the multiplication of species by adaptation via natural selection had been established as *the* cause of multiplication of species. So far as change in frequency of alleles go, I rather that there were many instances where genetic drift was quite important. This is rather more like the situation in pop science where random genetic drift gets an occasional mention, but optimization by natural selection is always the default, and the default is universal.

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    2. Laland is too revolutionary for some, and not revolutionary enough for others. Any shift in emphasis towards developmental biologists is likely to result in less grant money for everyone else. Evolutionary theory has long been a controversial topic, people still get hot under the collar about it.

      It is generally true that Laland likes to do straw man attacks on modern evolutionary theory, as though it hasn't moved on since the 1940s. The modern synthesis is still having a large stultifying effect though; complaining about its ongoing influence seems legitimate to me.

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  5. I never have seen a public portrayal of evolution has having had a revolution/paradigm shift in the last fifty years.
    They seek to persuade audiences that evolution is true as a Darwinian idea that has stood the test of time. Selectionism on mutation all the way.
    however as evolutionary speculation is examined its found wanting. So revolutions must keep coming to keep it moving on the road.

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    1. If you've never seen any change in evolutionary theory in the past 50 years then you haven't been paying attention. (I'm not surprised at that.) If you think that modern evolutionary biologists believe in "selection on mutation all the way" then you are either very poorly informed or deliberately disingenuous (probably both).

      Darwinism is so well established that it is difficult to think of evolution except in terms of desirable characteristics and advantageous genes. New technical developments and new knowledge, such as the sequential analysis of proteins and the deciphering of the genetic code, have made a much closer examination of evolutionary processes possible, and therefore necessary. Patterns of evolutionary change that have been observed at the phenotypic level do not necessary apply at the genotypic and molecular levels. We need new rules in order to understand the patterns and dynamics of molecular evolution.

      King, J. L., and Jukes, T. H. (1969) Non-darwinian evolution. Science, 164:788-798. [PDF]

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    2. This is not what I meant.
      I meant that any presentation to the public , in tv shows,science shows, youtube, magazine articles etc, NEVER says revolutins etc have taken place since Darwin
      They always say its selection on mutations since darwin.
      I know there has been important changes in evo theory and learned some here on this forum.
      Indeed a creationist would make this point and face criticism for changing the history.
      YES as in the quote you make they did see a need for new rules.
      A creationist would say, like me, these new rules really mean better ideas because previous ideas are failing under modern research.
      Thats my point. evolutionary biology keeps having to invent itself as time/research goes forward.
      yet in the public world this is not preached.

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  6. Yes, God created the universe...
    thus, God created the earth
    THROUGH evolution.
    They go handNhand.

    'the more you shall honor Me,
    the more I shall bless you'
    -the Infant Jesus of Prague

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