Darwin in the Guardian

Posted by jrosenhouse on February 11, 2008
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In other news, the Guardian newspaper has posted a series of articles about various evolution related topics.

First up is this characteristically lucid entry from Richard Dawkins. I especially like this:

But what makes natural selection so special? A powerful idea assumes little to explain much. It does lots of explanatory “heavy lifting”, while expending little in the way of assumptions or postulations. It gives you plenty of bangs for your explanatory buck. Its Explanation Ratio – what it explains, divided by what it needs to assume in order to do the explaining – is large.

If any reader knows of an idea that has a larger explanation ratio than Darwin’s, let’s hear it. Darwin’s big idea explains all of life and its consequences, and that means everything that possesses more than minimal complexity. That’s the numerator of the explanation ratio, and it is huge.

Yet the denominator in the explanatory equation is spectacularly small and simple: natural selection, the non-random survival of genes in gene pools (to put it in neo-Darwinian terms rather than Darwin’s own).

Explanation ratio. I like that!

I do get a little uncomfortable, however, when people say that evolution explains life. That’s too imprecise for my taste. Evolution explains how it is possible, via natural mechanisms alone, for a relatively simple sort of life a billion years ago to propagate and diversity into the enormous variety of complex life forms we see today. But it surely does not explain, nor is it intended to explain, where life comes from in the first place.

I’m also a little uncomfortable with this:

You can pare Darwin’s big idea down to a single sentence (again, this is a modern way of putting it, not quite Darwin’s): “Given sufficient time, the non-random survival of hereditary entities (which occasionally miscopy) will generate complexity, diversity, beauty, and an illusion of design so persuasive that it is almost impossible to distinguish from deliberate intelligent design.” I have put “which occasionally miscopy” in brackets because mistakes are inevitable in any copying process. We don’t need to add mutation to our assumptions. Mutational “bucks” are provided free. “Given sufficient time” is not a problem either – except for human minds struggling to take on board the terrifying magnitude of geological time.

I would feel better if Dawkins had said that non-random survival can lead to complexity, diversity and all the rest. I don’t think it’s assured that such things will arise as the result of the prolonged action of natural selection. On evolutionary questions I tend to think Dawkins gets things right far more often than his critics, but on this one I definitely side with Stephen Jay Gould. Complexity is not something that inevitably happens; it is merely one of many things that might happen in the course of evolution.

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Comments

  1. #1 A P Rudy
    February 11, 2008

    Taking your argument one step further… that evolution will, all by itself, generate beauty and the illusion of intelligent design is hyperbolic silliness as neither the culture-bound character of beauty or the anti-scientific culture of ID is inevitable…

  2. #2 bob koepp
    February 11, 2008

    Since we’re quibbling over relatively minor points of logic, I’ll note as well that the notion that “Darwin’s big idea explains all of life and its consequences” assumes a pan-selectionist millieu. Hardly anybody thinks that _all_ biological traits can be explained as adaptations.

  3. #3 SLC
    February 11, 2008

    I have to agree with Prof. Rosenhouse relative to his criticism of Prof. Dawkins who is not being sufficiently careful to distinguish between the origin of life and the evolution of life. Where creationists abound, one can not afford to be in any way, shape, form, or regard careless in the use of language.

    I would suggest that proponents of the Theory of Evolution, in order to make it perfectly clear so that there be no misunderstanding, make the following statement when discussing origins and evolution.

    “The Theory of Evolution and the Theory of the Origin of Life are entirely separate theories which are completely orthogonal to each other. In particular, the Theory of Evolution in no way, shape, form, or regard depends on how life originated.”

  4. #4 vhutchison
    February 11, 2008

    Hear! Hear! SLC’s last statement is correct and those who accept evolution should always follow that statement. Some of Dawkin’s statements quoted in the main post really harms our arguments with creationists.

  5. #5 Adrian
    February 11, 2008

    From what I recall, Gould argued exactly that natural selection must lead to greater complexity (for life as a whole, not necessarily individual species). He showed that complexity (and size, blueness, fuzziness, whatever) have a fixed lower bound and so with random fluctuations the median, mode and especially the extremes will push further and further to the right. That means that even though individual mutations don’t take us in any given direction, the overall trend must be towards greater complexity.

  6. #6 Jason Rosenhouse
    February 11, 2008

    Adrian-

    Gould’s argument was that there is no trend toward increasing complexity in the evolutionary process. Increasing complexity is something that might happen in the course of evolution, but it is neither necessary nor even likely. In Full House he argued that what people sometimes perceive as a trend in the level of average complexity over time, is really just a probabilistic artifact of the fact that there is an absolute lower bound to the level of complexity. As I recall, he was quite keen on the point that the modal form of life has always been the bacterium, suggetsing that complex life is an unusual anomaly that is not the typical outcome of the evolutionary process. Also, in Wonderful Life he was quite clear that he viewed the evolution of highly complex forms of life as something that was highly contingent, and not something that was the inevitable outcome of the evolutionary process itself.

  7. #7 Adrian
    February 11, 2008

    Jason,

    Re-reading your post and elaboration, I see now that you’re arguing about the distinction between does and can. I’m sorry, I think I misunderstood.

    Given the subtleties and that fact that the necessary conditions for multicellular/complex life to form, it is evolution which has caused it to explode so I don’t see the two statements as being very far apart. Perhaps I would react differently if this was written for a book rather than an editorial.

    Thank you for your explanation.

  8. #8 Kevin
    February 11, 2008

    “Hardly anybody thinks that _all_ biological traits can be explained as adaptations. Posted by: bob koepp | February 11, 2008 6:21 PM ”

    I think that.

  9. #9 SLC
    February 11, 2008

    Re Kevin

    This issue of adaptations and the varying ideas about them is discussed in Michael Shermers’ book, “Why Darwin Matters.” As he points out, there is a significant divide on the issue with biologists like Richard Dawkins representing the extreme adaptationist position, biolgists Stephen Jay Gould representing a more moderate position re Mr. Koepp, and the extreme anti-adaptationist position are represented by biologists like Larry Moran. I am not a biologist so have no opinion on the matter but it appears to me that the issue is definitely not settled.

  10. #10 divalent
    February 11, 2008

    I think Adrian got it right the first time. The statement by Dawkins that “…non-random survival of hereditary entities … will generate complexity, …” does not imply that a given line of descent *must* get more complex, only that some lines of descent *will* get more complex. This is in accord with what Gould describes in Full House.

    The reason why some *will* get more complex is because they can. (If they couldn’t, then we wouldn’t be here discussing it).

  11. #11 Lorax
    February 11, 2008

    So what do we mean by complexity? The superkingdom of bacteria, all by itself, contains tremendous complexity. I want to ensure we are not focusing on multi-cellular organisms that look and act much like ourselves as the default position of complexity.

  12. #12 Kevin
    February 12, 2008

    “Hardly anybody thinks that _all_ biological traits can be explained as adaptations”

    I don’t know what you mean by hardly but I believe that all biological traits that an animal has ARE the result of adaptations to the environment. Whether they can be explained is a different story.

    They adaptations could be not longer needed, they may be currently disadvantageous, they may be prompted by other organisms interactions with the animal, they could be random and neutral, but adaptive in the sense they don’t make things worse and I think genes are duplicated unless they are maladaptive.

    So that even not very useful traits are still carried along, cause I think the genome “does” this (okay not in any consious way) like having a toolkit full of junk because you never know when you might need something…unless it gets too heavy and you start throwing things out. and these developments are “adaptations” to the environment.

    SO anyone else agree? Is two more than hardly any?

  13. #13 bob koepp
    February 12, 2008

    Kevin -
    “neutral but adaptive”!? Like dimples, I suppose.

  14. #14 vincent
    February 12, 2008

    Happy B-Day CD!

  15. #15 Kevin
    February 12, 2008

    Kevin -
    “neutral but adaptive”!? Like dimples, I suppose.
    Posted by: bob koepp | February 12, 2008 7:48 AM

    Or the wierd double joint thing I have in my first knuckle..runs in the family…

  16. #16 DGS
    February 13, 2008

    SLC: I would suggest that proponents of the Theory of Evolution, in order to make it perfectly clear so that there be no misunderstanding, make the following statement when discussing origins and evolution.

    “The Theory of Evolution and the Theory of the Origin of Life are entirely separate theories which are completely orthogonal to each other. In particular, the Theory of Evolution in no way, shape, form, or regard depends on how life originated.”

    Sorry, SLC, but based on my direct experience this statement is quite wrong. Models of plausible scenarios for the origin of life can have a lot in common with models of contemporary fine-scale molecular evolution; molecular dynamics are much the same, and the players involved (nucleic and amino acids, etc.) are identical. This is especially true for models addressing the individual origin of just about any ubiquitous molecular feature. For example, start looking into models for the origin of the various selfish elements and you could quickly find yourself back in an RNA world, and beyond.

  17. #17 Michael Ralston
    February 13, 2008

    Kevin: I would very much claim some features of animals today are in no way the result of adaptation.

    Features have three possible statuses at any given moment in time: adaptive, neutral, or maladaptive.

    A feature found in populations today can be pretty safely said to have never fallen into the third category for a significant length of time (as it would have either failed to achieve fixation, or lead to extinction of the population), but it ALSO need never have fallen into the first category; it could have achieved fixation via drift, and simply not been replaced yet.

    There’s also the argument I’ve seen made by Wolfram and the like that some complex features of organisms (the spot patterns on leopards, say), are only adaptive in that they hold some general property also held by many other possible complex features, and simply happen to be the one first “discovered” by that lineage.

  18. #18 ctw
    February 13, 2008

    “I would feel better if Dawkins had said that non-random survival can lead to complexity …”

    I suspect that that the original statement is intentionally imprecise in deference to the target audience and possibly as a tactical ploy. For example, “will” may substitute for “with probability one”, an expression totally inappropriate to that audience. And “can” might be an invitation to attack from the opposition (“well, anything can happen in theory”).

    I don’t understand the biology enough to formalize the statement, but my guess is that Dawkins is referring to evolutionary events that can be thought of as statements about the outcomes of endlessly repeated random trials with essentially equivalent probability distributions. Then the correct statement depends on the assumed probability of a given event E. If it is non-zero, then “given sufficient time” (ie, in a sufficiently large number of trials), E occurs with probability one, ie, it “will” occur. If the probability of E is zero, it only “can” occur.

    If my guess is correct, then “can” seems to open the door to criticism from the opposition without actually being any more precise than “will” given the overall imprecise context.

    - Charles

  19. #19 Kevin
    February 13, 2008

    “A feature found in populations today can be pretty safely said to have never fallen into the third category for a significant length of time ”

    bull. what is a “significant length of time” how do we know that some traits animals have now are not, in fact, maladaptive? Is sickle cell animia good or bad?

    “I would very much claim some features of animals today are in no way the result of adaptation.”

    Oh-keee… what would you claim they are the result of?

  20. #20 Explicit Atheist
    February 14, 2008

    Even if the evolution of life and the evolution to life are substantially different phenomena, such as between the first DNA life and some pre-RNA pre-life evolution, should such pre-RNA pre-life be deemed a necessary step to “life”, they are still both evolutionary phenomena, with some variation of the competitive natural selection mechanism playing a key role. Some types of complex chemistry that occur in far from equlibrium, but short of chaotic, conditions can probaby be understood as such an evolution by natural selection mechanism phenomena. If creationists somehow mistakenly think this assertion is to their advantage then so much the worse for the logic of creationists.

  21. #21 SLC
    February 19, 2008

    Re DGS

    Not being a biologist, I am in no position to dispute Mr. DGS’ statement. Perhaps, the problem is what is meant by the origin of life. If the origin of life is defined as the origin of the first replicators (e.g. RNA), then my statement is correct. Perhaps with the proviso that the development of replicators is a necessary but not necessarily sufficient condition for the beginning of life.

  22. #22 Mike from Ottawa
    February 20, 2008

    … an illusion of design so persuasive that it is almost impossible to distinguish from deliberate intelligent design …

    I would take issue with this bit. I think it concedes far too much to circular reasoning, vacuity and ignorance of the attributes of actual organisms.

  23. #23 Sean Wills
    March 2, 2008

    As much as I like and admire Richard Dawkins, lately I can’t shake the feeling that he’s not being nearly careful enough in his writing. I remember when I first read The God Delusion that I could find almost no holes in his arguments – because I had never before been exposed to atheistic or religious arguments. On reading it a second time, there were several sections that had me rolling my eyes and wondering why he was giving Christian commentators so much free ammo.

    While Evolution is certainly a powerful theory, I think he’s going a bit overboard with it here.