Coyne vs Shapiro

Interesting exchange between Jerry Coyne and James Shapiro at Coyne’s blog, Why Evolution is true: A colleague wrongfully disses modern evolutionary theory.

(Hat tip to news at Uncommon Descent)

I’ve only skimmed Coyne’s piece and Shapiro’s response so far, but it seems to me that they are talking past each other to some extent.  And Coyne says something silly about cats and dogs.

Have at it.  Gotta run.

21 thoughts on “Coyne vs Shapiro

  1. Just to clarify, Coyne quotes Shapiro thus:

    Dogs may vary widely as a result of selective breeding, but they always remain dogs.

    Is this what you mean by Coyne saying something silly? Are you in agreement with Shapiro claiming that speciation from an ancestral dog population in any conceivable scenario is impossible?

  2. Alan Fox: Are you in agreement with Shapiro claiming that speciation from an ancestral dog population in any conceivable scenario is impossible?

    I can’t answer for Elizabeth. But that sure looks to me like a case of talking past one another.

    I take Shapiro as saying that if you are depending on selection alone, you always get dogs. But Coyne is ignoring that contextual implication, that Shapiro is only commenting on the limits of selection.

  3. So Shapiro in full:

    The first problem with selection as the source of diversity is that selection by humans, the subject of Darwin’s opening chapter, modifies existing traits but does not produce new traits or new species. Dogs may vary widely as a result of selective breeding, but they always remain dogs.

    But it’s a non sequitur. Who proposes selection as a source of variation?

  4. Alan Fox:
    So Shapiro in full:

    But it’s a non sequitur. Who proposes selection as a source ofvariation?

    Natural selection includes (random) variation as NS is the result of differential reproduction due to heritable (random) variation.

  5. Alan Fox: But it’s a non sequitur. Who proposes selection as a source of variation?

    Shapiro is making a rhetorical point. He is not criticizing evolution in the sense of common descent with change over time. His disagreement is specifically with the neo_Darwinian account which he sees as giving too much credit to natural selection.

    Keep in mind that the Huffington Post piece was written for a general audience.

  6. Alan Fox:
    Just to clarify, Coyne quotes Shapiro thus:

    Is this what you mean by Coyne saying something silly? Are you in agreement with Shapiro claiming that speciation from an ancestral dog population in any conceivable scenario is impossible?

    The silly thing that Coyne said (IMO) was this:

    You’ll recognize this as the old creationist canard. Yes, of course we can’t turn a dog into a cat by artificial selection, because that would take millions of years, and we’ve only been selecting on dogs for a couple of thousand years.

    I know what he means, but it is badly put. We can’t ever turn a dog into a cat by artificial selection, although we might breed a cat-like dog, or even a flying dog, or a purring dog, or a dog that we no longer call a dog, it bears so little resemblance to any canonical dog.

    But it won’t be a cat, because cats are on a different branch from dogs and only by some kind of artificial HGT could we get a cat from a dog.

    But I also think Shapiro is being silly – attacking a complete straw man – by saying that natural selection can’t create diversity. It’s just a playing with words, and inserting a razor where no razor should be inserted.

    Sure, genetic variation is the primary (not sole) source of heritable variation, but that heritable variation includes reproductive success, and to try to carve differential reproductive success aka natural selection from variation-production seems at best, foolish.

    Without variation-generation there would be no natural selection, and without heritable variation in reproductive success, all we’d have is a diverse population of critters minimally adapted to their environment, and probably unicellular at that.

    tbh it’s like the old canard that photographers aren’t really creative, but painters are. All creative activity (in the human realm, so in the normal sense of the word) involves selection, whether you are a photographer or a potter. But you can’t select without options, and if all you have are options but never make a selection you won’t create anything.

    But the important point is that separating the two is actually meaningless, when it comes to biology. Heritable variance in reproductive success in an given environment is what natural selection is, and can’t exist in the absence of, well, heritable variance.

  7. Elizabeth: Heritable variance in reproductive success in an given environment is what natural selection is

    I’m not entirely sure what you mean here. Reproductive success itself is obviously not heritable, only the characters that confer reproductive success. And, I think it is quite useful to “carve off” the concept of natural selection from the sources of variation. Natural selection can be understood very well without knowing a thing about the sources of variation (as Darwin’s original work testifies to).

  8. Norm: I’m not entirely sure what you mean here. Reproductive success itself is obviously not heritable, only the characters that confer reproductive success.And, I think it is quite useful to “carve off” the concept of natural selection from the sources of variation.Natural selection can be understood very well without knowing a thing about the sources of variation (as Darwin’s original work testifies to).

    OK, let me rephrase. Genetic variants that tend to lead to phenotypic features that tend to lead to reproductive success are heritable.

    And yes, natural selection can be understood without understanding the sources of variation – Darwin had no clue as to the sources of variation, yet understood natural selection. But embedded in his concept of natural selection is the notion of heritable variation, and therefore of heritable variation generation.

    And it’s important to the concept of natural selection that heritable variation should include variants that lead to reproductive success in some environments. Variation that is selectively neutral in all environments wouldn’t lead to adaptation, and while it might lead to diversity, would not lead to adaptive diversity, and my hunch is that it would lead to less diversity over all. Certainly that’s what computer models suggest.

  9. Chapter IV of prominent geneticist Giuseppe Sermonti’s book Why is a Fly Not a Horse? is titled “Wobbling Stability”. In that chapter he discusses what I have been talking about in other threads- that populations oscillate. The following is what he has to say which is based on thorough scientific investigation:

    Sexuality has brought joy to the world, to the world of the wild beasts, and to the world of flowers, but it has brought an end to evolution. In the lineages of living beings, whenever absent-minded Venus has taken the upper hand, forms have forgotten to make progress. It is only the husbandman that has improved strains, and he has done so by bullying, enslaving, and segregating. All these methods, of course, have made for sad, alienated animals, but they have not resulted in new species. Left to themselves, domesticated breeds would either die out or revert to the wild state—scarcely a commendable model for nature’s progress.

    (snip a few paragraphs on peppered moths)

    Natural Selection, which indeed occurs in nature (as Bishop Wilberforce, too, was perfectly aware), mainly has the effect of maintaining equilibrium and stability. It eliminates all those that dare depart from the type—the eccentrics and the adventurers and the marginal sort. It is ever adjusting populations, but it does so in each case by bringing them back to the norm. We read in the textbooks that, when environmental conditions change, the selection process may produce a shift in a population’s mean values, by a process known as adaptation. If the climate turns very cold, the cold-adapted beings are favored relative to others.; if it becomes windy, the wind blows away those that are most exposed; if an illness breaks out, those in questionable health will be lost. But all these artful guiles serve their purpose only until the clouds blow away. The species, in fact, is an organic entity, a typical form, which may deviate only to return to the furrow of its destiny; it may wander from the band only to find its proper place by returning to the gang.

    Everything that disassembles, upsets proportions or becomes distorted in any way is sooner or later brought back to the type. There has been a tendency to confuse fleeting adjustments with grand destinies, minor shrewdness with signs of the times.

    It is true that species may lose something on the way—the mole its eyes, say, and the succulent plant its leaves, never to recover them again. But here we are dealing with unhappy, mutilated species, at the margins of their area of distribution—the extreme and the specialized. These are species with no future; they are not pioneers, but prisoners in nature’s penitentiary.

    The point being, that IF it were left to direct scientific observations, evolutionism fails miserably and all that is left is wishful thinking supported by speculation.

  10. Joe G,

    Do you think there is any significance in the fact that the US publisher of Sermonti’s book is the Discovery Institute?

    ETA grammar. Teach me to play grammar troll!

  11. Shapiro’s problem is he writes for a general audience and has a tin ear for the creationist/ darwinist controversy. He simply isn’t a careful writer. Perhaps he knows what he is doing and thinks generating controversy will increase book sales. I do not know his motives.

    Regarding the main controversy, he emphasizes environmental triggers for the accelerated production of mutations. Specifically for the production of the larger, genomic mutations as opposed to point mutations.

    He likens this to the activity of the immune system is trying lots of variations quickly when stressed. He does clearly say that the mutations do not anticipate need. Only the rate is responding to need. He does say that this is a kind of intelligence.

    Someone at Panda’s thumb argued that these kinds of mutations in metazoans are likely to be severely detrimental, or fatal. The mechanism would be more useful in microbes.

    My own thought is that sperm cells share fecundity with microbes. Millions are produced for every one that engages in reproduction. It is an observable fact that a high percentage of sperm cells are defective. Perhaps this is a cake and eat it situation. Slow reproducing species can retain some of the advantages of high mutation rates without investing as much energy as would be required bring marginally viable offspring to term.

  12. Joe G:
    Chapter IV of prominent geneticist Giuseppe Sermonti’s book Why is a Fly Not a Horse? is titled “Wobbling Stability”. In that chapter he discusses what I have been talking about in other threads- that populations oscillate.

    Yes indeed. Jonathan Weiner makes this point in The Beak of the Finch.

    However, the fact that a population oscillates when environmental conditions oscillate (in the case of the Grants’ finches, with El Nino events) doesn’t prevent it shifting overall in a particular direction if the environmental conditions shift in a particular direction, indeed it suggests that that is highly likely. If a population can adapt measurably between one generation and another in response to reversible environmental change, how much further can it go in response to irreversible climate change?

    You would, presumably, answer “up to a limit”. My response would be: “what makes you think there is a limit”?

  13. What people tend to forget when talking about the limits of natural selection with respect to diversity, is that what drives selection is environmental context. If the environment were static, then selection would indeed put a fairly narrow set of limits on diversity. (Although drift would continue unhindered). But the environment is at least as dynamic a process as is biological variation. Its changes are often rapid and drastic, far too much for selection to keep up with. As a result, species are often not optimally adapted, and there is a chaotic flux in operation that demands diversity in response.

  14. Following on from what llanitedave said, it’s also important to remember that other organisms form part of a species’s environment. Competition, predation, mutualism are all significant selective pressures that fluctuate markedly over space and time. Think of the drastic impacts that invasive species can have on ecosystems, benefitting some species and driving others towards extinction. Given a species survives for long enough, some evolution and perhaps speciation could result.

  15. Elizabeth,

    One thing missing from the ID movement is a clear voice of reason that rejects stupid arguments and counsels some restraint in the making of claims.

    I’m tempted to cite Behe, since he limits his discussion to certain hard problems in molecular biology. He does not openly deny common descent. He does not openly question the antiquity of the earth. He does not openly question any of the mainstream mechanisms of evolution.

    He limits his dissent to a few obscure systems for which there is no well established history. But he borders on dishonesty by not counseling ID advocates to abandon losing arguments. His silence gives assent to folks who would generalize the lack of history for e.Coli and malaria to a general denial of evolution.

  16. YEC here.
    The spin I put on this IS that its all about lines of reasoning and fossils, fossils, fossils.
    In fact here Coyne pushes that gradualism is proved(evolution) because of sequences of fossils.
    Yet this is not a biological fact but only a biological conclusion upon a geological presumption.
    In all this conversation evolutionists show again evolutionary biology is not the result of biological investigation.
    Its something else.
    As it only could be if evolution was not true, not evidenced, and yet the biologists are skillful people in biological research.
    they simply are not doing it in these attempts to explain origins.

  17. Robert Byers: YEC here.

    At least you are open about that.

    In fact here Coyne pushes that gradualism is proved(evolution) because of sequences of fossils.

    I somewhat prefer Shapiro’s view to Coyne’s. But that’s no help to the YEC position.

    Coyne and Shapiro both agree (more-or-less) on common descent with change over time. Coyne supports the traditional Darwinist view, that the change is wrought by natural selection thought of as a designer. Shapiro supports the alternative account, that the change is wrought by the biological organism, modify themselves so as to avoid negative selection.

    Both are really describing pretty much the same thing, but describing in a different direction. Both see evolution as the result of interaction between the background environment and the populations of organisms, with Coyne wanting to emphasize the role of the background environment and Shapiro wanting to emphasize the role of the populations.

  18. Shapiro’s heresy is that variation is optimized. His analogy is with the immune system. He thinks it is optimized to the extent that it can be called a kind of intelligence. He doesn’t really speculate on how it got that way.

    As the write of a Weasel program I can say without doubt that the effectiveness of such programs can be influenced by fiddling with variation. The one rule that cannot be broken is that variation must not know anything about what is needed.

    But within that restriction, there are many kinds of variation. I suspect that Shapiro believe there are mechanisms within cells that fiddle with rates and kinds of variation, and that these affect evolvability. Why this is considered inconsistent with selection, I don’t understand.

    It’s a testable conjecture. I see nothing wrong with it as a hypothesis.

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