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.