Saturday, January 19, 2008

Teaching IDiots About Evolution

 
The National Academies (Science, Engineering, Medicine) (USA) have just published their latest book on the evolution/creationism controversy. You can download it for free on their website [Science, Evolution, and Creationism].

The book attempts to define evolution and it doesn't do a bad job of describing a minimal definition that would be acceptable—that is if you only look at the actual definition. Here it is from page 5.
Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.
Sandwalk readers will know that this is the kind of definition that I prefer as well [What Is Evolution?]. This sort of definition is neutral with respect to mechanisms. It doesn't matter whether evolution occurs by natural selection, random genetic drift, of something else entirely. That's just as it should be because the explanation of how evolution occurs lies properly in the domain of evolutionary theory. Thus, we can say that evolution is a fact because we see it happening and we have overwhelming evidence that has happened in the past. We can be confident that it is a fact even though we may not be as certain about how it happened.

Once we start committing to an explanation we can no longer talk about facts, in many cases, since the exact mechanism of evolution is often disputed. The National Academies book begins with a wonderful description of Tiktaalik, a fossil animal that shares characteristics of both fish and primitive tetrapods. It is strong evidence in support of the evolution of tetrapods from fish and that lineage is now considered to be a well established fact.

However, it would be wrong to use Tiktaalik as support for a particular mechanism of evolution. The fossil suggests that natural selection is playing a role but random genetic drift is not ruled out. We know from other sorts of data that natural selection and random genetic drift are facts, as well as being part of evolutionary theory, but it's a good idea to draw a distinction between evolution, the process, and theories about how it occurs. This is especially true when trying to explain things to IDiots.

Unfortunately, the authors of Science, Evolution, and Creationism don't do as good a job in this regard as they should have. For example, the (reasonably correct) definition that I quoted above is found at the end of a paragraph that weakens it considerably. Here's the entire paragraph ...
If a mutation increases the survivability of an organism, that organism is likely to have more offspring than other members of the population. If the offspring inherit the mutation, the number of organisms with the advantageous trait will increase from one generation to the next. In this way, the trait — and the genetic material (DNA) responsible for the trait — will tend to become more common in a population of organisms over time. In contrast, organisms possessing a harmful or deleterious mutation are less likely to contribute their DNA to future generations, and the trait resulting from the mutation will tend to become less frequent or will be eliminated in a population. Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.
The next paragraph then goes on to describe natural selection. There is no mention of random genetic drift anywhere in the book, although there is a passing reference to the fact that neutral mutations can be fixed. This reference is found on page 29 near the end of the book.

The net result is that evolution the process, is intimately connected to the mechanism of natural selection in this book. Readers will assume that scientists equate evolution with natural selection and use the terms interchangeably.

Why is this a problem? Well, for one thing, it's wrong. Normally that should be a good enough reason to avoid such errors, but these days there's a movement afoot to frame evolution in a way that resonates with the general public. Perhaps it's okay to define evolution as natural selection if it helps educate the average person? I object to such reasoning in the strongest possible terms. The essence of science is being honest and accurate and those goals should never be sacrificed for political gain. It may be easier to avoid confusion by not mentioning other mechanisms of evolution but the end result is that the public is not being educated correctly about evolution. You can't then turn around and complain that the public doesn't understand evolution.

The IDiots are upset about this book. They have found many ingenious ways of criticizing the contents. Here's a perfect example from Casey Luskin [The Facts about Intelligent Design: A Response to the National Academy of Sciences’ Science, Evolution, and Creationism].

I don't have the time, or the patience, to correct everything that's wrong with this article but there's one point I'd like to address. Here's what Casey Luskin says about evolution.
The NAS unscientifically elevates evolution to the status of unquestionable dogma.

The NAS defines evolution as evolution by natural selection and claims that “[t]here is no scientific controversy about the basic facts of evolution,” asserting that evolution is “so well established that no new evidence is likely to alter” it. In doing so, the NAS treats Neo-Darwinian evolution like an unquestionable dogma, not like a science. Such proclamations from the NAS are dangerous because they threaten the prestige of the NAS as an objective and trustworthy voice advising society.

Moreover, the NAS’s claim that there is no controversy over evolution is a bluff, for there is significant scientific dissent from the view of evolution by natural selection. Leading biologist Lynn Margulis, who opposes ID, criticizes the standard Darwinian mechanism by stating that the “Darwinian claim to explain all of evolution is a popular half-truth whose lack of explicative power is compensated for only by the religious ferocity of its rhetoric.”[7] She further observes that “new mutations don’t create new species; they create offspring that are impaired.”[8] In 2001, biochemist Franklin Harold admitted in an Oxford University Press monograph that "there are presently no detailed Darwinian accounts of the evolution of any biochemical or cellular system, only a variety of wishful speculations.”[9] Other scientists have gone much further.

Over 700 doctoral scientists have signed a public statement asserting their agreement that they "are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life."[10] But what are these scientists to do when the top scientific organization in the U.S. proclaims that evolution is as unquestionable as the existence of atoms or the heliocentric model of the solar system? Clearly the NAS’s statements threaten the academic freedom of scientists to dissent from Neo-Darwinian evolution.
In the past it has been easy to show that the IDiots are either mistaken or lying when they make comments like this. I've said many times that they deliberately try to confuse people by making it seem as though evolution, the fact, is the same as natural selection, the mechanism. They know full well that there's a difference between controversies over the sufficiency of natural selection and whether evolution, per se, is overwhelmingly support by hard evidence. They know that evolution is not the same as Darwinism and attacks on Darwinism are not the same thing as attacks on evolution.

This rebuttal is now a bit more difficult with the publication of Science, Evolution, and Creationism. Nowhere in the book do the authors deliberately make the distinction between natural selection and evolution and nowhere do they mention any other mechanism of evolution (e.g., random genetic drift). When reading the book, most of us recognize that there are abundant, oblique, references to the fact that the authors are not stupid, but that is only apparent to scientists who know about evolution.

Casey Luskin has taken advantage of this lost opportunity on the part of the National Academies to make it look like they are being dogmatic and forcing everyone to accept Darwinism. When I decided to write about Luskin's silly article, I thought it would be easy to refute what he was saying by referring back to the book. I thought the book would make it clear that evolution is not the same as natural selection. Unfortunately, there's nothing I can quote from the book that explicitly makes that point even though it's there implicitly. That's a missed opportunity that I hope can be remedied in future printings.


13 comments :

  1. Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.

    This definition is identical to this one: offspring of organisms are not identical to their parents. Hardly a revolutionary insight.

    Any meaningful definition of evolution must include the concept of change influenced by selective pressure.

    It is understandable that they would try to pick a definition with the least potential for disagreement, but unfortunately in this process they miss the entire point.

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  2. '...any meaningful definition of evolution must include the concept of change influenced by selective pressure...'

    ^^^Missed the whole point of the post, apparently.

    Say, 'anonymous'... you sound familiar...

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  3. Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.

    They forgot the "undirected, unguided, impersonal" part of the definition.

    What an intelligently designed vague and useless definition.

    "This definition is identical to this one: offspring of organisms are not identical to their parents. Hardly a revolutionary insight."

    I agree. Darwinists don't want to be specific lest their religious theory gets falsified (assuming it is falsifiable, of course).

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  4. Oh dear. It looks like I didn't explain myself very well 'cause anonymous and mats completely missed the point.

    Hmmm ... one's an adaptationist and the other is a creationist. Maybe it's impossible for either group to see the point no matter how hard I try.

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  5. L.M.:Hmmm ... one's an adaptationist and the other is a creationist. Maybe it's impossible for either group to see the point no matter how hard I try.
    I hope now that we've got the labeling and belittling out of the way, we can actually discuss the issues.

    Evolution was such an enormous advance in biology for several reasons:
    1) it was non-obvious
    2) it was a tremendous conceptual advance if true
    3) it was testable
    4) it survived the most rigorous testing that could be thrown at it

    Some people don't buy it. That's ok, that's part of the process. If that makes those people go out and perform experiments to help either confirm or refute the concept, this is how science works. Unfortunately, there is also a movement to dogmatically deny the science.

    Here's a parallel from astrophysics:
    "The earth revolves around the sun, not the other way around."
    This is also revolutionary and shares the same characteristics: non-obvious, conceptually significant, testable, and survived the testing. It also historically shared the same kind of dogmatic resistance, happily now largely overcome.

    Now, I understand that you think the dogmatic resistance is a problem. I agree with you. However, I think your methods of overcoming this resistance are misguided. Look at the title of this post: "teaching idiots about evolution". This is not a useful teaching frame of reference.
    1) some people will simply never be convinced, regardless of evidence presented. Your approach (and indeed all approaches) accomplishes nothing with this group.
    2) some people are unconvinced, but are potentially open to discussion and willing to look at the evidence. This is the group you need to be addressing. Unfortunately, you start right off with an insult.
    3) some people have already examined the evidence, and are convinced. (I'm in this category). Nevertheless, your inflammatory approach is disagreeable and disappointing.

    So, to try again at meaningful discourse, what is wrong with this definition:

    Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another. It is populations of organisms that evolve, not individual organisms.

    For the sake of argument, lets accept this as the definition. Now, imagine a world in which there is no selective pressure at all. Mutations and alterations happen at random just the same, but they all have exactly equivalent reproductive fitness (we know that this is not the case of course). In this selectionless world, you don't ever get new species, just a gradual homogenously amorphous entropic divergence of characteristics. Do you still call this evolution? It fits the definition. You might disagree, but I would NOT call this evolution. I would call this something like "phenotypic divergence".

    It is the fitness differences between offspring under selective effects that give a net positive direction to organismal fitness (or at least not a net negative direction) and explain what we see in the real world. This isn't to say that all, or even most, alterations are beneficial, just that the overall direction is. This isn't news to you of course.

    You might disagree, but I see the value of evolution in that it explains observations in the world. It doesn't do this unless it incorporates the concept of selection. Pandering to those who are never going to be convinced anyway by completely defanging the definition of evolution to the point of scientific uselessness is, in my opinion, not the way to go.

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  6. Anonymous said..

    For the sake of argument, lets accept this as the definition. Now, imagine a world in which there is no selective pressure at all. Mutations and alterations happen at random just the same, but they all have exactly equivalent reproductive fitness (we know that this is not the case of course). In this selectionless world, you don't ever get new species, just a gradual homogenously amorphous entropic divergence of characteristics. Do you still call this evolution? It fits the definition. You might disagree, but I would NOT call this evolution. I would call this something like "phenotypic divergence".

    I’m not a natural historian, and I opt for the ‘pluralist’ view of evolution simply because my ignorance is unable to rule out the various evolutionary mechanisms that that term may embrace. However the above quote from anonymous seems to me to be the start of a fairly robust observation: attempting to ‘dry run’ ‘the drift mechanism’ in one’s head leads to this ‘spread effect’ (=sigma, in statistics). In finite populations the ‘average’ is likely itself to drift, thus giving rise to Larry’s non-committal ‘changes in heritable traits…’, but unless some kind of process is keeping sigma clipped we arrive at populations with large spreads of traits. Keeping sigma down itself seems to require some kind of selection or population bifurcations (leading to speciation perhaps). The sinistral/dextral thing in snails may be the model example: once the choice between sinistral or dextral was made, sexual selection then reinforces what looks to be a trait that is selection neutral - that is, once it is randomly selected sinistrality or dextrality then gets ‘locked in’. Hence, my conclusion, for what it’s worth, is that drift and selection have to work together. (???)

    Strictly I suppose a pluralist view could even in embrace a sprinkling of ID here and there in the history of life! A little bit of magic dust!!!

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  7. Anonymous asks,

    For the sake of argument, lets accept this as the definition. Now, imagine a world in which there is no selective pressure at all. Mutations and alterations happen at random just the same, but they all have exactly equivalent reproductive fitness (we know that this is not the case of course). In this selectionless world, you don't ever get new species, just a gradual homogenously amorphous entropic divergence of characteristics. Do you still call this evolution? It fits the definition. You might disagree, but I would NOT call this evolution. I would call this something like "phenotypic divergence".

    In other words, you maintain that fixation of alleles by random genetic drift is not evolution. You maintain that Neutral Theory has nothing to do with evolution.

    Furthermore, you are forced to say that most speciation events events aren't evolution since they often begin with a founder effect.

    Your example does not correspond to reality, by the way. Many species become subdivided geographically and each population proceeds to evolve on their own by random genetic drift. Over time they can become incapable of interbreeding without any assist from natural selection. This is thought to be one of the main mechanisms of speciation but according to your view it could never happen. Why?

    You certainly have a right to advocate a change in the definition of evolution so that you restrict it to adaptation. But right now the consensus is not on your side. Right now, the evolution textbooks all include random genetic drift as a mechanism of evolution.

    You would do well to preface your remarks with a disclaimer. You should make it clear to readers that it is you who is advocating a change in the definition and not me.

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  8. LM: Many species become subdivided geographically and each population proceeds to evolve on their own by random genetic drift. Over time they can become incapable of interbreeding without any assist from natural selection. This is thought to be one of the main mechanisms of speciation but according to your view it could never happen. Why?

    Clearly, this happens. To illustrate with geographical separation, lets start with a model 4 individual population, A, B, C and D. We stipulate that before geographical separation the relative fitness of all combinations of A, B, C and D is identical (AB = AC = AD = BC = BD = CD = 1). After geographic separation of A and B from C and D, the relative fitness of AB = CD = 1, but the relative fitness of AC = AD = BC = BD = 0. How can this change in relative reproductive fitness not be called selective?

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  9. They forgot the "undirected, unguided, impersonal" part of the definition.


    How utterly bizarre! Mats is actually more absurdedly clueless than usual, entirely missing what could easily be abstracted away as a general observation on science, or even analysis, at large - definitions and observations will be less theory laden if one distinguish between (testable, of course) mechanismless definitions of phenomena and theories on their mechanisms.

    Just to show that it easy to grasp, unless one wants to be obtuse, a simple analogy:

    A minimal definition of the process of gravitation would be: Gravitation is a process that results in an acceleration in a (test) mass by another mass.

    This is an observable (testable) process, so a fact. By inserting different theories on mechanisms such as Newton's theory of gravitation or general relativity one can test and distinguish the theories. If the theory wasn't neutral on theories, we would in principle end up with different "gravitations" that would have to be specifically tested to be commensurable in each instance.

    Note that of course there is no "undirected, unguided, impersonal" part of the definition. The absence of teleological agents arise from a) observed repeatibility of observations and b) parsimony of theories. It is entirely, ..., um, natural, in the context. Nothing is precluded before testing.

    Now compare with Moran's minimal definition of the process of evolution. (Evolution is a process that results in heritable changes in a population spread over many generations.)

    If Mats solves the riddle (fat chance, he doesn't want to test his preconceptions) he will see why the rest of the comment is equally absurd.

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  10. Torbjörn Larsson,
    You keep making the same darwinian mistake your religous brothers make. You keep comparing something that we can see happening today with a theory that speculates about what (suposedly) happened millions of years ago.

    Secondly, the cardinal tenet of darwin's myth is that nature, by itself, was able to generate the complex systems we see and admire.

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  11. Larry said…

    Many species become subdivided geographically and each population proceeds to evolve on their own by random genetic drift. Over time they can become incapable of interbreeding without any assist from natural selection.

    Yes, accepted, but I’m still not clear why the drift should be more significant than the spread in traits; that is, I understand that randomness is likely to cause an overall drift, but why is the drift so significant that it can stand out against the background noise of increasing spread/diversification of traits amongst a population? I’m not trying to catch you out Larry, this is something that genuinely befuddles me.

    Let me give you an analogy: In England many medieval churches stand by themselves, no longer surrounded by a village. Although the Black Death and village abandonment accounts for many of these isolated churches, it is also said that in some cases, as village buildings were knocked down and replaced by newer buildings, the village randomly walked away from its ecclesiastical center. However, the village itself didn’t smear out over the landscape; the village remains a tight cluster because people tend to cluster together. So if this analogy can be applied, may I ask what keeps the traits clustered together in a population as its genetic “center of gravity” drifts?

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  12. FWIW, catching up on old threads:

    @ Mats:


    You keep comparing something that we can see happening today with a theory that speculates about what (suposedly) happened millions of years ago.


    Not at all, nested hierarchies is a prediction of evolution, and that is a test that the fossil record passes.

    You keep comparing natural processes through deep time with natural processes through your own reference frame. They are still the same.

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  13. back some 10 years ago NATIONAL GEOGRAPHIC showed a specimen dinobird which they claimed was proof that birds evolved from dinasours it was later proven a fake and now we have this idiot JOHN HORNER who wants to recreate dinasours by tampering with the DNA of birds JUST HOW IGNORANT IS HE?

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