More Recent Comments

Monday, July 09, 2007

What Is Darwinism?

Over on the thread Close, but no cigar we're having a little discussion about the meaning of the term "Darwinian." I explained it as "evolution by natural selection."

Pete Dunkelberg is one of those people who emphasize natural selection in their discussion of evolution and he didn't like my description of Darwinian evolution. Pete said,
Misbegotten terminology. "darwinian processes" is creationist coinage with no meaning.

Talking of "darwinism" in biology is akin to talking of "newtonism" in physics: a bad idea. Aren't you glad physicists don't use terms like that to make polemics against each other?

wolfwalker asks: Larry, what do people mean by [these unneeded terms]? Larry tells him what Larry means. But the terms have no standard meaning. Larry's official ruling is that Darwin never heard of variable rates of morphological evolution and also thought selection was all.
It is patently untrue that the term "Darwinian" has no meaning in biology. Pete's position is that "Darwinist" refers to evolutionary biologists who no longer exist. He seems to think that everyone has become a pluralist these days. I beg to differ.

Core Darwinism, I shall suggest, is the minimal theory that evolution is guided in adaptively nonrandom directions by the nonrandom survival of small hereditary changes.... Adaptive does not imply that all evolution is adaptive, only that core Darwinism's concern is limited to the part of evolution that is.

Dawkins, R. (2003) The Devil's Chaplain p. 81
In physics, everyone knows that Newtonian physics has been extended in the twentieth century so that it's no longer accurate to refer to oneself as a Newtonian physicist since it implies ignorance of relativity. But this is a bad analogy since there are a great many evolutionary biologists (and even more of the other kinds of biologists) who are proud to call themselves Darwinists. Modern Darwinists place a great deal of emphasis on adaptation and natural selection as the main mechanisms of evolution.

Pete is dead wrong when he claims that, "Larry's official ruling is that Darwin never heard of variable rates of morphological evolution and also thought selection was all." I never said any such thing. I'm well aware of the fact that Darwin considered variable rates of natural selection and I'm well aware of the fact that he accepted other mechanisms of evolution, such as a watered down version of Lamarckism. The problem here seems to be that Pete doesn't understand the meaning of gradualism and he doesn't understand that modern Darwinists do not attribute everything in biology to selection.

As for the standard meaning of "Darwinism," Pete is correct to say that there is no universally accepted definition but that shouldn't be a surprise to anyone. There's hardly anything that all biologists can agree on.

However, there is a considerable group of evolutionary biologists who agree with Ernst Mayr when he says ...
After 1859, that is, during the first Darwinian revolution, Darwinism for almost everybody meant explaining the living world by natural processes. As we will see, during and after the evolutionary synthesis the term "Darwinism" unanimously meant adaptive evolutionary change under the influence of natural selection, and variational instead of transformational evolution. These are the only two meaningful concepts of Darwinism, the one ruling in the nineteenth century (and up to about 1930) and the other ruling in the twentieth century (a consensus having been reached during the evolutionary synthesis). Any other use of the term Darwinism by a moder author is bound to be misleading.

Mayr, E. (1991) What Is Darwinism? in One Long Argument p. 107.
See Why I'm Not a Darwinist for an earlier use of this quotation. The point is that the modern meaning of Darwinism is usually taken to mean an emphasis on natural selection.

Mayr explains the standard adaptationist view of random genetic drift by equating it with Neutral Theory and mischaracterizing the entire controversy. (This seems to be a very common trait among the defenders of strict Darwinism.)
The neutralists are reductionists, and for them the gene—more precisely the base pair—is the target of selection. Hence, any fixation of a "neutral" base pair is a case of neutral evolution. For the Darwinian evolutionists, the individual as a whole is the target of selection, and evolution takes place only if the properties of the individual change. A replacement of neutral genes is considered merely evolutionary noise and irrelevant for phenotypic evolution. (ibid p. 152)
I'm not making this up. I'm trying to do my best to represent the standard—but not universal—description of the adaptationist position. It's quite wrong for Pete Dunkelberg to pretend that the definition of Darwinism and the adaptationists is something that I created. (BTW, most pluralists treat the individual as the unit of evolution. They just believe that populations can fix alleles, even alleles with visible phenotypes, by random genetic drift as well as natural selection.)

Mayr continues,
The Darwinian wonders to what extent it is legitimate to designate as evoluton the changes in gene frequencies caused by nonselected random fixation. In some of the older (particularly nineteenth century) literature on evolution, one finds discussions on how to discriminate between evolution and mere change. There it was pointed out that the continuing changes in weather and climate, the sequences of the seasons of the year, the geomorphological changes of an eroding mountain range or a shifting river bed, and similar changes do not qualify as evolution. Interestingly, the changes in nonselected base pairs and genes are more like those nonevolutionary changes than they are like evolution. Perhaps one should not refer to non-Darwinian evolution but rather to non-Darwinian changes during evolution. (ibid p. 153)
While this position may seem extreme by 2007 standards, I believe that there are many evolutionary biologists who tend to dismiss all nonselected evolutionary change as uninteresting and unimportant. They are Darwinists. The extremists among this group attribute all kinds of things to adaptation, including most animal behavior. They are the ultra-Darwinians.

Many books have been written about the controversy in evolutionary biology between the adaptationists and the pluralists. Michael Ruse, for example, tried to explain it all last year (2006) in Darwinism and Its Discontents. Ruse is a firm believer in Darwinism, which he defines as "natural selection as the chief causal process behind all organisms." This is a common definition as explained above. However, one must read between the lines to see how Darwinists interpret that definition. A key point is what they think about random genetic drift. Here's how the Darwinist Ruse treats Sewall Wright's concept of random genetic drift.
Wright's theory is not very Darwinian. Natural selection does not play an overwhelming role. Genetic drift is a key player in Wright's world. However, although many of these ideas were taken up by later thinkers, especially by Theodosius Dobzhansky in the first edition of his influential Genetics and the Origin of Species, drift soon fell right out of fashion, thanks to discoveries that showed that many features formerly considered just random are in fact under tight control of selection (Lewontin, 1981). Today no one would want to say that drift (at the physical level) is a major direct player, although, in America particularly, there has always been a lingering fondness for it.
Michael Ruse is not an evolutionary biologist but he represents the views of Dawkins and, to a lesser extent, E.O. Wilson. They have no use for drift especially when it comes to visible characteristics. That's the hallmark of modern Darwinism.

So, is it true that no evolutionary biologist would want to say that drift is a major player in evolution? Of course not. There are lots of them who say exactly that in spite of what Michale Ruse would have you believe. Does Ruse have an answer to these "discontents?" Yes, he does ...
At the risk of damning myself in the eyes of both scholarship and God, let me be categorical. All of the critics of Darwinism are deeply mistaken,
To which I reply, you took the risk and your scholarship has been discredited. I can't speak for God.


T Ryan Gregory said...

My take on it, with some flexibility for exceptions, is that "Darwinian" refers to natural selection. As in, Darwinian vs. Lamarckian theories of evolution or Newtonian vs. Einsteinian theories of gravity. "Darwinist" is primarily but not exclusively something that anti-evolutionists invoke, and is akin to "Einsteinist" for those who accept that gravity exists. "Darwinism" is a bit murkier, as it is used in both the "Darwinian" and "Darwinist" contexts, though a rejection of "Darwinism" in the sense of Ruse is not the same as a rejection of Darwinian mechanisms per se (only of their exclusive influence). Pluralists also may accept that Darwinian processes operate at levels above and below the organism.

Torbjörn Larsson said...

A bit OT perhaps, but the post got me waxing philosophical:

As far as analogies goes, darwinian mechanisms vs newtonian mechanics is perhaps not entirely appropriate. The overlap between newtonian mechanics and its modern extensions is severe, while it seems from the above that darwinian and non-darwinian mechanisms overlap mostly on "random genetic drift".

More interesting is that Newton's original formulation made an ad hoc and ill concieved choice to make space absolute and fixed at rest. Perhaps on religious and philosophical grounds and in any case deserving the description "newtonism". There is an analogy between newtonism and creationism there.

Perhaps not fully coincidentally, as in biology the replacement of "appearances" with a relative space and galilei invariance to make newtonian mechanics consistent with observations (specifically, the lack of tests for absolute rest) pointed towards a modern relative spacetime and lorentz invariance. Similarly, the classical extensions of lagrangian and hamiltonian mechanics made the bridge to quantum mechanics.

Per the above I would think that the proper analogy is that darwininian mechanisms are to non-darwinian mechanisms as relativity is to quantum mechanics. There are deep connections, the mechanisms are fairly separate as it seems, yet they can be combined in pluralism vs quantum field theories or semiclassical quantized gravity to treat most of all encountered phenomena.

Btw, I think I get the gradualism vs saltation phenomena. But what differs between this blogs "pluralism" and Gene Expression's "selectionism"? Because it seems to me that both groups are ready to treat the phenomena on the given data. Is it the adoption of neutral theory that is the distinction?

T Ryan Gregory said...

I don't think one needs an analogy to the content of any physical theory, only to the use of terminology to describe them.

Anonymous said...

Larry, I'm honored! I thought I might provoke some kind of a reply in the comments section, but not a whole post.

As for your response to my way of putting your position, I know I didn't use your exact words - just my impression of you. Likewise for your version of my position.

"Pete's position is that "Darwinist" refers to evolutionary biologists who no longer exist. He seems to think that everyone has become a pluralist these days. I beg to differ."

I know; it's a matter of emphasis and proportion for both of us, and you think emphasis matters a lot. My impression of your view is that only a special few rate as pluralists, and there is a benighted ultraadaptationist under every bed. [aside to newcomers: this impression dates to before blogging existed. and I knew Larry could quote Dawkins and old Mayr at length on this].

Pete Dunkelberg is one of those people who emphasize natural selection in their discussion of evolution....

Of course. It's important, or at least more fun, to emphasize selection when you are in the conversion since you work so hard to knock it. You will sometimes say something like "Natural selection is an important mechanism of evolution." but preferably in the context of criticizing others who agree. They may even be called "deniers of chance" i.e. Darwinists or panadaptationists although Darwin introduced chance into biology.

Regarding what I called your "official ruling" on Darwin, I have inveigled you to deny it, so that Darwin is not a Darwinist in your terms. But perhaps you'll stretch him in.

On variable usage of terms:

"Darwin's theory of natural selection has been a perennial candidate for burial. Tom Bethel held the most recent wake in a piece called "Darwin's Mistake" (Harper's, February 1976): "Darwin's theory, I believe, is on the verge of collapse .... Natural selection was quietly abandoned, even by his most ardent supporters, some years ago." News to me, and I, although I wear the Darwinian label with some pride, am not among the most ardent defenders of natural selection. I recall Mark Twain's famous response to a premature obituary: "The reports of my death are greatly exaggerated."

Gould, Ever Since Darwin, Chapter 4: Darwin's Untimely Burial p 39.

So far as evolution itself goes, I do think that everyone who is with the program at all knows that a ceaseless interplay of random and nonrandom factors makes life what it is. I don't agree on dividing people up into good guys and bad guys based on, for instance, whether they are personally interested in neutral theory.

The Newtonian analogy:
Well, I like it. Newton was the Darwin of physics. Newton and Darwin both laid out crucial basic principles that enabled others to see much farther than before. Selection and F = mA are still fundamental. Neither knew of atoms (in Darwin's case, the 'atoms' of inheritance). Physicists still talk sometimes of Newtonian physics, but without this bad habit of calling others Newtonists as a put down. Good for them.

Pete Dunkelberg

Torbjörn Larsson said...


"I don't think one needs an analogy to the content of any physical theory"

Said a biologist. :-P

Agreed, really. This is why I labeled it "philosophical".


"Newton was the Darwin of physics."

I didn't mean to imply that Newton has any different stature than Darwin - they were both seminal persons of wast new fields. But while I haven't yet found much of the creationists implications of philosophical choice in Darwin's theories, ironically Newton has some.

It is more complicated than I thought and described above, though. The Stanford Encyclopedia of Philosophy mentions his need to both distinguish between clocks and time and previous conflation of them, and material time & space and previous views of "arealism".

Isaac Newton founded classical mechanics on the view that space is something distinct from body and that time is something that passes uniformly without regard to whatever happens in the world. For this reason he spoke of absolute space and absolute time, so as to distinguish these entities from the various ways by which we measure them (which he called relative spaces and relative times).

In the light of Newton's difficulties, it seems that his choice was virtually nonexistent. It was up to later physicists to realize that there was a choice and change the assumptions.

Larry Moran said...

Pete Dunkelberg says,

So far as evolution itself goes, I do think that everyone who is with the program at all knows that a ceaseless interplay of random and nonrandom factors makes life what it is. I don't agree on dividing people up into good guys and bad guys based on, for instance, whether they are personally interested in neutral theory.

I think we've moved way beyond the point where things are as black and white as you make out. Yes, it's true that (almost) every biologist recognizes the interplay between selection and drift (and other things). That's not really the point. It isn't the point today and it wasn't the point back in 1977.

The issue is broader than that. It's about how you view the big picture of evolution. I like to call this their "worldview" after Dawkins but some people (paging John Wilkins) really object to this term. Gould and Lewontin referred to it as the adaptationist program.

The adaptationists, or ultra-Darwinians tend to see everything as an adaptation unless there's evidence to the contrary. They tend to favor some form of progress in evolution based on climbing adaptive landscapes. Most of them think that evolution is mostly stimulated by environmental change. They tend to be skeptical of things like junk DNA because it doesn't fit comfortably into their worldview. They tend to be sympathetic to evolutionary psychology because it exploits the (presumed) power of natural selection as an explanation. They tend to be dismissive of punctuated equilibria because it conflicts with gradualism. They mostly believe that macroevolution is just a lot of microevolution spread out over a long period of time. They see nature as "designed" and they're not afraid to proclaim that natural selection is behind the "design" of all lving organisms. As a general rule, they conflate the terms "evolution" and "natural selection."

The pluralists take a sharply different view of life. They often think of random genetic drift as the default mode of evolution and proof of selection requires evidence, not just plausible stories. They usually don't like the idea of progress in evolution. They tend not to think of environmental change being the major stimulus to evolution. They keep concepts like founder effect and population bottlenecks in the active portion of their minds when thinking about evolutionary explanations. They are comfortable with junk DNA because it poses no threat to their worldview. They tend to dismiss evolutionary psychology because they are skeptical of claims for the power of natural selection. They are sympathetic towards higher levels of evolution and distinct roles for macroevolution. They usually retain an active awareness of the faults and foibles of evolution so they shy away from talking about life as "designed."

There are few evolutionary biologists who fit exactly into either of these molds but there are enough who share the differing worldviews to justify making a distinction between adaptationists and pluralists. The easiest way to recognize which camp you fall into is to ask yourself what you thought of Daniel Dennett's book Darwin's Dangerous Idea. I find that's the best way of identifying a real pluralist—most of them are so angry at Dennett that they had a hard time finishing the book! Adaptationists, on the other hand don't see what all the fuss is about. Dennet's book seems perfectly normal to them.

Anonymous said...

Larry, that's a good clear statement of your position. I agree there is value in staking out these polarities as long as you don't put everyone in one end or the other. And perhaps being clearly at one end helps one become a famous author.

But for many others there is a third way, exemplified in some recent threads here by p-ter. He would simply respond to your subpoints on either side with "It's an empirical question".

Pete Dunkelberg

Larry Moran said...

Pete Dunkelberg says,

But for many others there is a third way, exemplified in some recent threads here by p-ter. He would simply respond to your subpoints on either side with "It's an empirical question".

Yes, that's what p-ter would say. But he's wrong. It's not only an empirical question. It's also a theoretical question. It's about how you formulate hypotheses and address the data.

If you don't ask the right questions about evolution then you have no hope of getting the right answers no matter how much data you accumulate.

It's all very well and good to dismiss the debate by saying that the issue will be answered empirically but that misses the entire point. It's the adaptationist program that's being criticized. That's a program that directs the sorts of questions you ask and the data you collect. If there's something wrong with the way you do science—and I'm one of those who think there is—then collecting more data by the wrong method isn't going to help.

If you're convinced that everything is an adaptation then you spend all your time looking for evidence of adaptation and you tend to stop looking whenever you find some, no matter how weak it might be. That's because you've stopped being skeptical. Your worldview doesn't accommodate any other explanation, like accident or chance, so you don't seriously consider other possibilities.

This is what's happening with junk DNA. Many scientists are latching on to some very questionable data that shows a possible function for some of the DNA that we characterized as junk. Because they desperately want this DNA to be functional they aren't being very skeptical of their data. They aren't considering the possibility that their data is an artifact and they don't do the proper controls.

Because their reviewers share the same bias, the papers are being published in prestigious journals. This is the danger of not having a proper theoretical understanding of the issues before you pick up a Pipetman.

A. Vargas said...

Saying "it's empirical" is pretty cheap. We all want that. What you need to say is what kind of empirical evidence would settle these questions, and present it.
Then again, empiricism, believe it or no, can also be supplemented by logic and reasoning. Selection keeps phenotypic evolution within limits, but phenotypic variation is truly not random and lacking direction, but is constrained and/or facilitated by development. Therefore selection is not alone in determining the direction of phenotypic evolution. Variation will follow preferred pathways of structural transformation according to the nature of the developmental mechanisms in place. This is what Gould meant by considering structural constraints and possibilities play an importante role,according to the phylogenetic group and previous evolutionary history of an organism.

Elevight said...

Everyday, I see an overwhelming abundance of ingenuity in nature, all of which Darwinians prefer to believe just came into being on its own, with no intelligence involved. In my experience as a human being, there is no aspect in my life that has impressed me that isn't governed by intelligence. From the clothes I wear, to the music I listen to, to the toothpick I use, everything that has a sensical utility is always governed by some kind of intelligence behind it. These things I marvel at daily do not even compare to the ingenuity and complexity of so many natural mechanisms that exists in nature, and yet there are people who prefer to think everything just evolved naturally without intelligent guidance. These people are either blind, or insist on being blind. I'm sorry, but my respect dwindles down to a negative towards pseudo-intellectuals who love to harp over implausible theories that only super-gullible people or non-thinking people could buy. Tell me why nature has a predominant preference for bi-pedal and quadri-pedal appendages as a means of locomotion. You cannot convince me two legs or four legs are the most efficient, and yet, it has been a persistent pattern since time immemorial. If everything evolved naturally, we would have a hell of a greater number of variations in all living species. I may have 2 hands, another may have 3, another may have 4 (which, by the way, is 2 necessarily the best configuration natural selection can come up with)? When there is a persistent pattern and glaring specificity, there has to be intelligence involved. That's why we make cars with round wheels, tables with flat tops, toothpicks not the size of baseball bats, and whatever else you can think of. To say that the most impressive, intelligent, awesome things in life came from the total absence of intelligence is the most idiotic thing I have heard in my life.

Unknown said...

I'm not sure I agree with you here.

"If everything evolved naturally, we would have a hell of a greater number of variations in all living species. I may have 2 hands, another may have 3, another may have 4 (which, by the way, is 2 necessarily the best configuration natural selection can come up with)?"

This isn't true. Perhaps 3 legs might be 'better' than two, but in order for a bipedal population to evolve to that state, there is almost always a non-functioning intermediate which is actually deleterious to the population. There must be a lot of selective pressure for the third leg that the species actually go through and evolve that third leg. The point here is that natural selection doesn't just create variation in a snap (i.e. go from 3 legs to four); natural selection implies a cost-benefit analysis of whether a trait is important (or not important) enough to homogenize throughout a population. This is perhaps why the 'perfect' species will ever evolve, we are not 'perfect', and why there is not as much variation as you are hoping for.

Overall, I think your approach to discrediting evolution is a weak one.