Tuesday, February 9, 2010

The Persistence of Saltationism

One of Charles Darwin's predictions was that evolution occurs gradually via variations within populations. His friend Thomas H. Huxley was concerned that Darwin had assumed "an unnecessary difficulty in adopting Natura non facit saltum [nature does not make leaps] so unreservedly." But Darwin's theory would have been much less compelling without it. Imagine if evolution had included the caveat that saltations—rapid leaps—can occur by unknown mechanisms such that new fossil species can appear fully formed. This would have destroyed Darwin's premise that species evolve by natural processes and we wouldn’t be talking about him today. Yes the fossil record suggested that nature does take jumps, but it was safer for Darwin to question the data than to admit them into his theory.

In order for evolution to succeed Darwin would need to steer clear of the supernatural, or anything that could be interpreted as supernatural, and argue for a strictly naturalistic origin of species. Darwin could hardly argue for a naturalistic origin, and then propose a theory that suggested a supernatural interpretation.

In its first century evolution maintained Darwin's hope that the fossil record was incomplete. Aside from a few heretics such as Richard Goldschmidt and his hopeful monsters, most evolutionists carefully avoided the problem of stasis and abruptness in the fossil record. But scientific evidence doesn’t go away.

Today the specter of saltational evolution persists, and probably is here to stay. In recent years evolutionary studies have increasingly appealed to saltational evolution to explain a variety of biology’s wonders. For the angiosperm flower to Cirripedes (a Darwin favorite) and the turtle, evolutionists are saying saltational evolution should be considered in addition to the many other explanatory mechanisms.

Of course the appeal to hopeful monsters is certainly not evolution’s first or only use of one-time or strange events. From history changing endosymbiosis events to meteorite impacts, evolution is the story of contingencies. So why not a saltational event now and then? As evolutionist Ernst Mayr wrote, "Laws and experiments are inappropriate techniques" for explaining evolutionary events and processes. Anything can happen in this theory.

21 comments:

  1. According to your cite, "Few contemporary biologists will doubt that gradualism reflects the most frequent mode of evolution, but whether it is the only one remains controversial."

    We already know of polyploidalism in plants, where entire genomes can be duplicated. We also know that small changes in developmental genes can cause large changes in an organism's body plan. Saltations would also vary considerably in impact on the organism, most being what you may consider minor, but scientists would consider significant. Saltation would presumably be followed by rapid optimization through natural selection.

    According to network theory, we expect most modifications to be small, some larger changes, a few major events, and the very rare revolution (resembling scale invariance). This is the modern view of how evolutionary processes should work.

    In any case, did you have a broader point?

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  2. Cornelius Hunter: evolutionists are saying saltational evolution should be considered in addition to the many other explanatory mechanisms.

    Of course it should be considered. Whether the evidence supports saltation, the specifics of how it may work, and its frequency, are all dependent on the evidence.

    Alessandro et al., Saltational evolution of trunk segment number in centipedes, Evolution & Development 2009: Here we provide for the first time evidence of major phenotypic saltation in the evolution of segment number in a lineage of centipedes

    Rubinoff & Le Roux, Evidence of Repeated and Independent Saltational Evolution in a Peculiar Genus of Sphinx Moths, PLoS ONE 2008: Such rapid evolution of novel traits in individual species suggests that the pace of evolution can be quick, dramatic, and isolated—even on the species level.

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  3. The problem with evolution is aptly demonstrated by Z's response.

    Evolution is a world view and not even a hypothesis much less a theory. There is nothing that could occur or be discoverd that can negate or disprove evolution, because every finding is incorporated within it--even if that finding is completely contrary or contradictory or previous evolutionary beliefs. Because evolution explains everything, it explains nothing. Forget about the impossibility of falsification of evolution (not that falsification is a necessary characteristic of science), evolution cannot even be an inference based on reasoning to the best explanation. EVERY finding is reasoned back to and incorporated into evolution. The edifice of ad hoc explanations is monstrously large, but allegedly justified or clarified by what we are sure to find around the next corner or over the next mountain (the bear went over the mountain, the bear went over the mountain, the bear went over the moun-tain . . . )

    regards,
    #John

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  4. #John1453: There is nothing that could occur or be discoverd that can negate or disprove evolution, because every finding is incorporated within it--even if that finding is completely contrary or contradictory or previous evolutionary beliefs.

    Saltation still means that each new organism is a modification of an existing organism sharing common ancestry with the rest of life. Only the exact tempo of adaptation is at issue, and while adding a new segment to an existing segmented organism may be an abrupt change, it is hardly magically improbable.

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  5. One might wonder, Cornelius, what you are trying to say. Saltation events do occur - Zachriel gives a few examples above - so why shouldn't evolutionary theory be able to encompass them?

    I am unsure why you would bother with examples from the fossil record as being evidence for saltation. A geological instant is hardly an evolutionary instant.

    Perhaps if you were familiar with the literature of the last 30 years you would realise what you claim is a 'specter' is no such thing.

    Incidentally, 'saltation' is not a mechanism of evolution as you state. The mechanisms behind saltation events have been well described in the literature.

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  6. Evolutionary biology is sceptical of drastic change without proof or mechanisms - as Darwin was of saltation in his time.

    However, the field does adopt changes over time when explanatory mechanisms for such claims arise and are found to be at play in nature.

    This entirely contradicts your long-running and false premise that evolutionary biology is a non-scientific discipline that resembles a religion.

    You simply cannot have it both ways.

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  7. abimer:

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    Perhaps if you were familiar with the literature of the last 30 years
    =====

    I wish that were the case.


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    The mechanisms behind saltation events have been well described in the literature.
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    The fact of evolution lowers the bar to the point that speculation becomes scientific description.



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    However, the field does adopt changes over time when explanatory mechanisms for such claims arise and are found to be at play in nature.
    =====

    "For example, while we already have a quite
    good understanding of how organisms adapt to the environment, much less is known about the mechanisms behind the origin of evolutionary novelties, a process that is arguably different from adaptation. Despite Darwin’s undeniable merits, explaining how the enormous
    complexity and diversity of living beings on our planet originated remains one of the greatest challenges of biology."

    http://www.ncbi.nlm.nih.gov/pubmed/19224263


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    This entirely contradicts your long-running and false premise that evolutionary biology is a non-scientific discipline that resembles a religion.
    =====

    Correction: The fact of evolution entails non scientific (religious / metaphysical) claims. Evolutionists claim evolution is a fact as much as is gravity, and there is no proof of this that does entail non scientific claims.

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  8. Cornelius, I can only assume you provide a quotation from Theissen's abstract because you conflate Darwinism and evolutionary biology.

    While it is plainly true that we know less about the origin of the rarer evolutionary novelties than we do about classical adaptationism, this is not to say that we know nothing at all about it. Far from it. Further, explaining the whole complexity and diversity of life is rather a different task than explaining the good fit between a single organism and its environment, so there is little value in comapring the two.

    I have suggested that your premise regarding evolutionary theory as religion is false because evolutionary theory does not have the rigidity of a religion and is instead based on reason, testing and revision.

    You believe otherwise because you suggest evolution contains non-scientific claims. However, evolution in the broad sense has stood as a theory for 150 years. No alternative scientific theories exist, while substantial evidence exists for evolution. In this sense, after 150 years of scrutiny, evolution is a fact as far as anything can be in a scientific sense. That is not a religious claim.

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  9. abimer:

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    However, evolution in the broad sense has stood as a theory for 150 years. No alternative scientific theories exist, while substantial evidence exists for evolution.
    =====

    Correction: Substantial evidence exists *against* evolution. I'm not the one here who has made a mockery of science. My conscience is clear.

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  10. Cornelius -

    "Correction: The fact of evolution entails non scientific (religious / metaphysical) claims."

    Can you please sum up these claims in a few lines? Can you please spell out precisely WHAT religious / metaphysical claims you believe evolution makes?

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  11. Cornelius, it's wonderful to hear that your conscience is clear but that is not an argument.

    Evolution is granted the same status that is granted to any theory that is long-standing and has not been refuted. Evolutionary theory is not granted a special status.

    I'm unsure what your substantial evidence against evolution might be. You have already said that you are not particularly familiar with the past 30 years of literature, so I wonder if you aren't just considering evidence against an outdated, classical Darwinian model of evolution.

    Do you have substantial evidence, for example, refuting an important tenet of evolution such as common descent? Or are you satisfied that if a pre-genetics Darwin predicted everything in evolution must be gradual, and it turns out things are more complicated than that, then the whole theory is forever bunk?

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  12. Gee, I like to play the same game, too:

    "However, evolution in the broad sense has not stood as a theory for 150 years. No alternative scientific theories have been investigated, even though substantial evidence exists against for evolution. In this sense, after 150 years of scrutiny, evolution is as far from fact as anything can be in a scientific sense. Evolution is a religious claim."

    I feel so much better for having made such a convincing argument.

    There is not a single example of a stepwise change from one species to another with a correspondence between DNA and morphological or other structures at each step. Not one. Which is one reason why I remain rather unconvinced.

    Evolution makes metaphysical claims such as materialism, etc. Moreover, it requires us to believe that the operation of the four fundamental forces on particles with a random starting arrangement can, over time, result in the appearance of a telecommunications satellite orbiting the earth.

    regards,
    #John

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  13. Ritchie

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    Can you please sum up these claims in a few lines? Can you please spell out precisely WHAT religious / metaphysical claims you believe evolution makes?
    ===========

    Go here for starters:

    http://darwins-god.blogspot.com/2009/12/joe-felsenstein-de-novo-genes-trumped.html

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  14. abimer:

    "Evolution is granted the same status that is granted to any theory that is long-standing and has not been refuted."

    You mean like geocentrism?


    "I'm unsure what your substantial evidence against evolution might be. You have already said that you are not particularly familiar with the past 30 years of literature,"

    Correction, I said I wish that were the case.


    "so I wonder if you aren't just considering evidence against an outdated, classical Darwinian model of evolution."

    No.


    "Do you have substantial evidence, for example, refuting an important tenet of evolution such as common descent?"

    Do UCEs count?


    "Or are you satisfied that if a pre-genetics Darwin predicted everything in evolution must be gradual, and it turns out things are more complicated than that, then the whole theory is forever bunk?"

    No. Please see Section 1 here:

    http://www.darwinspredictions.com/

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  15. Cornelius Hunter: Do UCEs count?

    The Theory of Evolution would predict that ultra-conserved elements have a function. However, laboratory tests have yet to find a function. That could mean a problem with the Theory of Evolution, or it could mean a problem with the tests. Because the Theory of Evolution is so scientifically fruitful, a single anomaly would indicate a problem with the test, not the Theory. Possible problems are redundant copies of the genes, or a loss of fitness that is not readily apparent in the laboratory conditions.

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  16. Cornelius -

    "Go here for starters:"

    Well the link wasn't exactly what I was after. If you think evolution rests on religious claims, then WHAT religious claims do you think they rest on. I am not asking you to support your position (at the moment), just to clarify it.

    What religious claims/position do you think the theory of evolutionis built on?

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  17. Ritchie:

    =====
    Well the link wasn't exactly what I was after. If you think evolution rests on religious claims, then WHAT religious claims do you think they rest on. I am not asking you to support your position (at the moment), just to clarify it.

    What religious claims/position do you think the theory of evolutionis built on?
    =====

    That figure shows about a dozen religious and metaphysical traditions, many of them inter related. I give a very brief introduction here:

    http://www.darwinspredictions.com/#_6.2_Other_process

    If you want more details regarding the traditions, then you'll have to study the history of the thought. You can find some of these beliefs in antiquity, such as with the Epicureans and Lucretius (De Rerum Natura). But I think the story is easier to trace and makes more sense if you take the beginning of modern science, say the 17th century, as your starting point.

    I do have a chapter on this in *Science's Blind Spot* that can get you going, but it is just an introduction. The history is fairly obvious once you see it, but it is not simple either, as it involves a spectrum of traditions from within the church. IOW, this is not a story about the Anglicans or Lutherans or Roman Catholics, etc. It involves all of these traditions. The bottom line is that evolution was mandated long before Darwin was even born. What the likes of Laplace and Darwin did was to supply the theories to fulfill the pre existing fact of evolution.

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  18. Zachriel:

    "The Theory of Evolution would predict that ultra-conserved elements have a function. However, laboratory tests have yet to find a function."

    No, functions have been identified. But, to your point, they don't seem to require such high sequence identity, from an evolutionary perspective.


    "That could mean a problem with the Theory of Evolution, or it could mean a problem with the tests. Because the Theory of Evolution is so scientifically fruitful, a single anomaly would indicate a problem with the test, not the Theory."

    Usefulness and realism are two different matters on which you seem to be equivocating. Geocentrism is fruitful too, but we wouldn't use that fact as a protectionist device against falsification.

    No one doubts the fruitfulness of evolution. The issue at hand is the evolutionist's truth claim that evolution is an objective fact, which is absurd.

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  19. Cornelius -

    At the link you provide, all I see in the figure is odd things like the Problem of Evil and Infinite Regress. What on Earth have these to do with evolution?

    Your thinking here is so muddy. The arguments in your diagram look far more like traditional arguments against theism. Are you trying to say that evolution is built on the presupposition of atheism?

    If so then you may be right, but no more so than any other scientific theory. Every scientific theory seeks to explain how certain aspect of the universe operates without invoking the supernatural.

    But the biggest problem I can see is that the theory of evolution is not built on any position of the Problem of Evil or Infinite Regress.

    It is built on nothing more than the observed relatedness between all living creatures on Earth.

    You have totally mixed the theory of evolution up with atheism in your head (I suspect due to some paranoid conviction that evil evolutionists are out to discredit God and everything atheistic and scientific is mixed up into a threatening, conspiratorial 'other'). There is no need for any of this.

    Science seeks to explain how the univer operates. To do this, it must assume the supernatural does not intervene in the operation of the world.

    Science is made up of theories. The theory of gravity explains the force of attraction between objects with mass, germ theory explains illness and diseases, and the theory of gravity explains the relatedness between all life on Earth.

    It really is as simple as that.

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  20. Ritchie:

    "I suspect due to some paranoid conviction that evil evolutionists are out to discredit God"

    That's quite an ad hominem. But this is where it usually goes with evolutionists. You provide the evidence and they provide the fallacies.

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  21. Cornelius -

    It is indeed quite an ad hominem, true, but in the spirit of honest debate I thought I'd throw in this opinion, because I truly cannot make sense of your train of thought any other way.

    "But this is where it usually goes with evolutionists. You provide the evidence and they provide the fallacies."

    Saying this does not make it true.

    You want evidence for evolution? How about the entire field of genetics? How about the entire field of genomics? Are these not evidence enough?

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