Tuesday, December 30, 2008

An Adaptationist View of Stephen Jay Gould

 
In last week's issue of Nature, Steve Jones reviews Stephen Jay Gould: Reflections on His View of Life. Jones is part of the British school of Darwinism, along with Richard Dawkins, the late John Maynard Smith, and others.1 This group shares many perspectives on evolutionary theory including an emphasis on natural selection. They are also united in their dislike of, and misunderstanding of, Stephen Jay Gould.

The misunderstanding shows up in several places in the Jones review [A wonderful life by leaps and bounds].

Being part of the anti-Gould school means that Jones is obliged to trot out the famous quotation by Maynard Smith (it's part of their oath of allegiance).
Gould held fast to Darwin's maxim that "All observation must be for or against some view if it is to be of any service", and was among that band who felt that those not for him must be against him — which was not much help in keeping friends. The great biologist John Maynard Smith wrote that most evolutionists saw Gould as "a man whose ideas are so confused as to be hardly worth bothering with, but as one who should not be publicly criticized because at least he is on our side against the creationists".

Gould was hurt by that acidulous statement, which was without doubt unfair.
Of course it was unfair—so why repeat it? The statement says more about the British Darwinists than about Gould. The fact that they find Gould's ideas "confusing" isn't something to be proud of.

One of Gould's major contributions to evolutionary theory was punctuated equilbiria, with Niles Eldredge. The basic idea is that the fossil record shows millions of years of stasis (no change) and when change occurs it takes place relatively quickly during speciation by cladogenesis (splitting). After that, the two species (parent and daughter) continue to exist together in the same environment.

The morphological changes that occur when a new species is formed are not dramatic. They are similar to the differences between closely related modern species. In many cases it takes an expert to even recognize the new species in the fossil record.

Punctuated equilibrium is a theory of speciation and stasis. The changes during speciation may be due to natural selection or some form of random genetic drift. That's not what's important about punctuated equilbria—what's important is that change is coupled to speciation and nothing happens for most of the life of a species.

Here's what Steve Jones has to say about it.
Whatever the importance of sudden leaps in the fossil record, his notorious idea of punctuated equilibria, nicknamed 'punk eek' and referred to as 'evolution by jerks' by some of its critics — their own views characterized by Gould as "evolution by creeps" — gave the fossilized field of palaeontology a much-needed kick in the pants. Gould saw punk eek as a "coordinating centrepiece" that "congealed into a coherent critique" of evolutionary theory. Many biologists, by contrast, insist that what look like palaeontological leaps can be explained by simple Darwinism. To them, an instant in geology may represent almost an infinity in biology, leaving plenty of time for evolution by natural selection to do its normal job.
He just doesn't get it, does he? The speciation event takes place over a period of about one hundred thousand years as Gould and Eldredge explained. That's plenty of time for selection, or drift, or founder effect, or whatever. Punctuated equilibria is not a challenge to natural selection, it's a challenge to gradualism.

Furthermore, anyone who refers to punctuated equilibria as "sudden leaps" is revealing an understanding of the theory that's no better than that of the creationists. As is anyone who thinks that "Darwinism" explains speciation.
His other great passion, contingency — the notion that evolution goes on with sudden bangs rather than protracted whimpers — has also not held up particularly well. Wonderful Life, Gould's 1989 book on the Burgess Shale, suggests that the obscure fauna of the late pre-Cambrian represents a lost universe wiped out by some unknown disaster, but now we know that they have descendants among modern animals. Even so, scientific ideas often change, and that volume, like most of his others, remains a rattling good read. The fact that nature must build on what it has, and not on what it wants, is still at the centre of evolutionary thinking.
Talk about confused thinking! When did Gould ever say that contingency is "the notion that evolution goes on with sudden bangs"?

Gould and Lewontin made great play with the parallels between the Spandrel School and the many evolutionists who say that every character in every animal is there for an adaptive reason and if you look hard enough you'll find it.

There's some truth in their argument, but to accept it as the only truth is basically to give up and walk away, to stop being an ornithologist and turn into a bird-watcher. You become somebody who observes rather than analyzes. What they're saying to lots of biologists is, "Abandon hope, go home, and become a liberal-arts graduate!" I may be overcriticizing the Lewontin and Gould view; both of them like to poke people with their sharp pitchforks. The spandrels were a particularly successful poke. But what happened as a result of the famous spandrel paper? The answer is, not much.

Steve Jones in
The Third Culture
As for Wonderful Life, it is, indeed, a book about contingency—just like the movie from which it takes its title. One wonders whether Steve Jones has actually read the book, or seen the movie.

While it's true that some of the unusual Cambrian species that Gould once thought were separate phyla have now been lumped into modern phyla, it's also true that there are many that haven't. Gould's point is that some of those enigmatic Burgess Shale species have left no descendants and, if you could have observed them back then, you would not have been able to pick out the eventual winners and losers. In other words, if you re-wind and replay the tape of life it will come out differently.

Jones is not referring to these species however. He's talking about the "pre-Cambrian" fauna—presumably the Ediacara biota. It's not an important part of Gould's book. As far as I know the relationship between Ediacaran species and modern species is still very controversial. Perhaps Jones has studied this in more detail that I have.

One of the ideas to come out of punctuated equilibria is the idea of species sorting. This makes sense when you think about it. If most speciation occurs by cladogenesis and not by gradual transformation, then over time the number of species in a clade doubles every five to ten million years. Eventually there will be hundreds of similar species. The reason this doesn't happen is that species go extinct. They die.

If species within a clade are "born" and "die" then this looks an awful lot like evolution at a different scale than the birth and death of individuals within a population. The idea of species sorting, where the species in a clade are treated like the individuals within a population, is part of Gould's hierarchical theory of evolution. He claims that it is an extension of the Modern Synthesis.

Whether he's right or wrong doesn't matter. What matters is whether his critics have the intelligence to understand hierarchical theory in general, or species sorting in particular. I don't have much respect for evolutionists who refuse make a modest attempt to understand; it's not rocket science.

Here's what Steve Jones says.
Backwards ran his sentences, and some of his ideas were equally opaque. In support of punk eek, for example, he wrote that "species are individuals ... by all vernacular criteria", which is at best obscure, and at worst obscurantist.
No, Professor Jones, it is not obscure and it is not obscurantist. Gould explains it very well to those who can read his works with an open and intelligent mind. He's talking about species sorting and treating species as "individuals" that are selected within a clade.
As Reflections portrays, its hero showed an increasing regard for style over content, and was resistant to the notion that anyone should dare to edit his writings. The pinnacle — the very summit, crown and peak — of his great Olympus of orotundity was his last voluminous volume, The Structure of Evolutionary Theory, published in the year of his death. All the authors agree that this is not a book to be lightly tossed aside, but their motives for saying so vary. Its reviews are quoted with a certain relish: "an elephantine opus"; "pathological logorrhea"; "billowing clouds of verbal flatulence" — but Gould had no doubt of its value. In it he came out with the idea of life as a series of interlocking hierarchies and of a grand unification of its sciences into some post-Darwinian consilience, comprehensible only to the chosen.
The Structure of Evolutionary Theory is long and tedious but those who criticize its ideas are the ones who confuse style over content. I don't agree with many of Gould's ideas about species sorting and hierarchical theory and therefore I stand as the exception to Steve Jone's claim. It was comprehensible to this unchosen one so it must also be comprehensible to others who disagree with Gould. You just have to make the effort.

If you don't make the effort to understand Gould then you should refrain from criticizing him. It doesn't make you look good.


1. For examples of the Steve Jones perspective on evolution see Have Humans Stopped Evolving? and Steve Jones Says Human Evolution Is Over.

[Image Credit: The Cheltenham Ladies' College]

17 comments:

  1. The morphological changes that occur when a new species is formed are not dramatic. They are similar to the differences between closely related modern species. In many cases it takes an expert to even recognize the new species in the fossil record.

    A crucial and almost always missed point. Thank you for making it!

    He just doesn't get it, does he? The speciation event takes place over a period of about one hundred thousand years as Gould and Eldredge explained. That's plenty of time for selection, or drift, or founder effect, or whatever. Punctuated equilibria is not a challenge to natural selection, it's a challenge to gradualism.

    Not really. It's a challenge to constant rate-ism. Read Kevin Padian, a major Gould fan, on the term "gradual" here:

    http://www.sciohost.org/ncse/kvd/Padian/Padian_transcript.html#day9pm295

    The term "gradual" is related to "graduation", "graduated cylinder", etc. Gradual = stepwise. In other words, Punk Eek is gradual.

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  2. The British adaptationist/gradualist school is so wrong, they're not even wrong.

    Also, Larry, you have confused species sorting with species selection; sorting is fairly uncontroversial and doesn't require higher-level processes, but selection is and does.

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  3. Nick Matzke says,

    Not really. It's a challenge to constant rate-ism.

    No, that's the adaptationist response.

    We're talking about morphological change coupled to speciation by cladogenesis, followed by stasis when there's no change in a stable species.

    That's not the same as fast evolution followed by slow evolution, which is what the adaptionists would have you believe. It's two different modes of evolution.

    To interpret punctuated equilibria as just something different than constant speedism is to misunderstand the entire concept.

    Shame on you, Nick, I though you were on top of this stuff.

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  4. Joseph Knight says,

    Also, Larry, you have confused species sorting with species selection; sorting is fairly uncontroversial and doesn't require higher-level processes, but selection is and does.

    Species sorting is the correct term. Species selection implies that the differential birth and death of species is due to natural selection when, in fact, it could be due to random processes analogous to random genetic drift at the population level.

    By using the term "species sorting" for the higher level process you don't make an unnecessary commitment to the process.

    Gould explains it very well in The Structure of Evolutionary Theory on page 669.

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  5. One of Gould's major contributions to evolutionary theory was punctuated equilbiria ...
    Punctuated equilibrium is a theory of speciation and stasis ... what's important about punctuated equilbria is that change is coupled to speciation and nothing happens for most of the life of a species


    Sigh. I could never understand what exactly punctuated equilibrium is and what it is a theory of. Since Gould's own explanations appear to me as much a kitchen sink as Jablonska's epigenetics, perhaps you could be bothered to define the term?

    Wthout a definition and given the ambiguity of "species", wording like "change is coupled to speciation and nothing happens for most of the life of a species" seems ambiguous to the point of being meaningless.

    Alternatively, screw definitions (a good idea, perhaps) and just illustrate the theory of punctuated equilibrium using evolution of hominins as an example.

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  6. Sorry, Larry, I think you've got Steve Jones wrong if you think he's in the same 'British school' as Dawkins. Just because two people are critical of a third doesn't mean they're in cahoots. On the subject of evolutionary psychology, for example, Jones is far more Gouldian than Dawkinsian. Isn't disagreeing with your colleagues supposed to be what good science is all about?

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  7. I have just completed reading the book by the biologist Sean Carroll, "The Making of the Fittest." My impression from reading it is that Prof. Carroll is from the Dawkins school of adaptationism, in addition to being a proponent of Evo-Devo. Since Prof. Moran is, to say the least, skeptical of both of those schools, I wonder if he has read the book and if so what his impression is.

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  8. "billowing clouds of verbal flatulence"

    Structure strikes me more as a concise realization of a comprehensive and well-thought-out view of what evolutionary theory is and what it has been. The historical parts of the book fascinate.

    I admit that I've never taken the time go get past the first few hundred pages. It's slow going, not because it's bad writing, but because there's so much to think about.

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  9. Larry,

    Perhaps you have to send a letter to Nature magazine about this issue.
    What do you think?

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  10. "one who should not be publicly criticized because at least he is on our side against the creationists"

    What an idiot. Why should we let dumb ole craetionists thwart scientific debate?

    Some "evolutionary scientists" truly are more about anticreationism than evolution. Simply pathetic.

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  11. We're talking about morphological change coupled to speciation by cladogenesis, followed by stasis when there's no change in a stable species.

    That's not the same as fast evolution followed by slow evolution, which is what the adaptionists would have you believe. It's two different modes of evolution.


    This is hairsplitting at best. Your own description is basically fast evolution followed by slow evolution, just with the hypothesized causative process. Shame for invoking the word shame over such trivialities!

    If you really want to split hairs, punk eek is basically Ernst Mayr's ultra-neo-Darwinian "gradualist" "beanbag" "popgen" view of speciation -- i.e. speciation occurs relatively rapidly in small localized populations -- applied to the fossil record. So really, punk eek is a direct derivative of the Modern Synthesis, not a challenge to it.

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  12. Nick Matzke says,

    This is hairsplitting at best. Your own description is basically fast evolution followed by slow evolution, just with the hypothesized causative process. Shame for invoking the word shame over such trivialities!

    Nick, Nick, Nick. It's not "hairsplitting" to point out the fundamental difference between punctuated equilibria and the more traditional way of thinking about evolution.

    Punctuated equilibria are patterns of evolution where change is coupled to cladogenesis and in the absence of speciation no change occurs. That's not just fast and slow evolution.

    You could create all kinds of different patterns of evolution by just varying the rate of population level events but the resulting patterns would look nothing like those of punctuated equilibria, especially if you ignored the importance of speciation.

    If you really want to split hairs, punk eek is basically Ernst Mayr's ultra-neo-Darwinian "gradualist" "beanbag" "popgen" view of speciation -- i.e. speciation occurs relatively rapidly in small localized populations -- applied to the fossil record. So really, punk eek is a direct derivative of the Modern Synthesis, not a challenge to it.

    You are certainly correct that the punctuated equilibria patterns of evolution could arise by allopatric speciation. They probably do. You are also correct to point out that the pattern of punctuated equilibria is consistent with the mechanisms of natural selection and random genetic drift. Nobody challenges that.

    However, the consequences of this observed pattern are important. Once you accept that this is a real pattern, you have to start thinking about macroevolutionary events at a much larger scale than individual and populations. The Modern Synthesis is basically an evolutionary theory that focuses on natural selection between individuals within a population. Punctuated equilbira force you to think about the role of populations and speciation in a way that was completely purged from the hardened version of the Modern Synthesis.

    Here's the version of the Modern Synthesis that I'm talking about

    The term "evolutionary synthesis" was introduced by Julian Huxley in Evolution: The Modern Synthesis (1942) to designate the general acceptance of two conclusions: gradual evolution can be explained in terms of small genetic changes ("mutations") and recombination, and the ordering of the genetic variation by natural selection; and the observed evolutionary phenomena, particularly macroevolutonary processes and speciation, can be explained in a manner that is consistent with the known genetic mechanisms.

    Ernst Mayr (1980) "Some Thoughts on the History of the Evolutionary Synthesis" in The Evolutionary Synthesis, E. Mayr & W.B. Provine eds. Harvard University Press


    Read my essay at The Modern Synthesis of Genetics and Evolution.

    Gould objected to the "gradualism" of that definition and, in addition, he wanted to extend the Modern Synthesis to include mechanisms operating at different levels above and below the level of individual organisms within a population. According to Gould, those mechanisms (e.g. species sorting) are consistent with natural selection and random genetic drift but are not fully explained by those population level events.

    That's why a complete evolutionary theory will be an extension of the Modern Synthesis.

    It's really hard for adaptationists to understand this stuff because their way of thinking about evolution is so narrowly focused on competition between individuals and on timescales measured in years and not millions of years. Nevertheless, with a bit of effort it's possible for even the most confirmed adatationists to grasp the essence of hierarchical evolutionary theory.

    You don't have to agree with it (I don't agree with all of it) but you do have to understand it if you are going to mock it.

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  13. Guy Montag says,

    Oh, well, Ernst Mayr led me astray then.

    You're in good company. Mayr led many people astray ... including himself.

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  14. DK says,

    Sigh. I could never understand what exactly punctuated equilibrium is and what it is a theory of. Since Gould's own explanations appear to me as much a kitchen sink as Jablonska's epigenetics, perhaps you could be bothered to define the term?

    These might help.

    Macromutations and Punctuated Equilibria.

    Charles Darwin Was a Gradualist

    ... just illustrate the theory of punctuated equilibrium using evolution of hominins as an example.

    Can't do it. We don't have enough data on hominid evolution to determine whether it fits the pattern of punctuated equilibrium, although it looks like it might.

    The pattern of punctuated equilibrium is only seen when we have almost complete fossil records spanning million of years. There have to be thousands of fossils covering the entire time period.

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  15. Yeah, I don't understand Ernst Mayr. He set the stage for punctuated equilibria, then rebuked its importance. In his book What Evolution Is, he rejected species selection by saying that the process could be reduced to differential organismal success—sorting, or so he said. But in the book Macroevolution: Pattern and Process, by Steven Stanley—which was devoted to evincing both punk eke and species selection—Mayr was listed as one who reviewed an early draft copy, or part of it. Surely he must have understood what species selection really was, and why its action is irreducible to organisms. Still, his contributions to biology were much needed.

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  16. "No, Professor Jones, it is not obscure and it is not obscurantist. Gould explains it very well to those who can read his works with an open and intelligent mind. He's talking about species sorting and treating species as "individuals" that are selected within a clade."

    Actually, both Larry and Jones have missed the fact that the origins of individuality theory lie with Michael Ghiselin. Unfortunately, Gould did not cite this historical development of the concept > see Ghiselin, M. T. (2002) An autobiographical anatomy. Hist. Phil. Life Sci. 24: 285-291.
    also his excellent essay in J Hist Biol 38: 123-136

    A pdf of Ghiselin (2002) is downloadable at http://www.stephenjaygould.org/reviews/

    Deserving kudos for discovering that stasis is real rests with Niles Eldredge (see his 1971 essay in the journal Evolution 25:156-167). Eldredge says much more
    about the importance of the term in macroevolution, and the real patterns it distinguishes in his readable book "Reinventing Darwin" (1995), and most recently in an autobiographical essay in the journal he edits: Evolution, Education and Outreach (2008) 1:107–113

    It is unfortunate that Steve Gould took things too far, not least in reinterpreting "punk eek" in about 3 different ways

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