Friday, December 6, 2013

Die, selfish gene, die!

"Die, selfish gene, die!" is the provocative title of an article by science writer David Dobbs [Die, selfish gene die!].

Dobbs begins with ....
The selfish gene is one of the most successful science metaphors ever invented. Unfortunately, it’s wrong.
The article attracted the attention of Jerry Coyne who effectively dismantles the strange ideas promoted by Dobbs. Read all about it at: David Dobbs mucks up evolution, part I and David Dobbs mucks up evolution, part II.

As it turns out, this is just another example of a science writer who has been mesmerized by the latest effort to overthrow modern evolutionary theory by some scientist promoting their own work. In this case it's Mary Jane West-Eberhard.

But there's a more serious issue here and I'm not sure that Jerry Coyne recognizes it. The selfish gene metaphor can be interpreted in several different ways. Here's how Richard Dawkins describes it in the preface to the 1989 edition of The Selfish Gene.
The selfish gene theory is Darwin's theory, expressed in a way that Darwin did not choose but whose aptness, I should like to think, he would instantly have recognized and delighted in. It is in fact a logical outgrowth of orthodox neo-Darwinism, but expressed as a novel image. Rather than focus on the individual organism, it takes a gene's-eye view of nature.
Lot's of people misunderstand the selfish gene metaphor. They think it means that organisms behave selfishly but that's not what Dawkins meant at all.

Jerry Coyne explains this in his book Why Evolution Is True (p. 226) ....
As Dawkins shows clearly, the "selfish" gene is a metaphor for how natural selection works. Genes act as if they're selfish molecules: those that produce better adaptations act as if they're elbowing out other genes in the battle for future existence. And, to be sure, selfish genes can produce selfish behaviors. But there is also a huge scientific literature on how evolution can favor genes that lead to cooperation, altruism, and even morality.
There are two main criticisms of the selfish gene metaphor and both of them are quite valid. It's the reason why Dawkin's view hasn't caught on the the evolutionary biology textbooks. It usually merits nothing more than a footnote.

The most damning criticism comes from evolutionary biologists who point out that the primary unit of selection is the individual and not the gene. Stephen Jay Gould and Richard Lewontin are prominent opponents of what they see as an unnecessary reductionism in Dawkins' writing. Clearly, hierarchical theory (Gould) is inconsistent with the selfish gene metaphor because evolution can also operate at the level of groups and species (according to Gould and others). There are plenty of other evolutionary biologists who object to selfish genes for these reasons.

The second objection comes from the focus on natural selection and "Darwinism" (or neo-Darwinism). Many evolutionary biologists have a pluralistic view of modern evolutionary theory. That view includes random genetic drift where the appropriate metaphor might be "lucky gene" or "accidental gene." The problem with the Dawkins' metaphor, according to these critiques, is not that "selfish genes" don't exist, it's that the metaphor is not appropriate for evolution in general.

While I admire Jerry's take-down of Dobbs, I'm not sure that he (Jerry Coyne) fully appreciates these other criticisms of the selfish gene. Here's what Coyne wrote ...
Let me add one thing, though. I’m constantly puzzled these days by how often people argue that the neo-Darwinian synthesis is wrong, and that we need a new paradigm. Genetic assimilation, epigenetics, horizontal gene transfer—all of these buzzwords are evoked as reasons to jettison our “conventional” view of evolution. But always, when you look at the data, the evidence that these phenomena will overturn neo-Darwinism is nonexistent.

I’ve already written a lot on the epigenetics hype, and have shown that there’s no evidence that a single adaptation in nature involves the fixation in the DNA of an epigenetic alteration of the genome that isn’t initially inherited. Yet people keep banging on about epigenetics.

I’m not sure why the hype continues, but perhaps it has to do with the fact that the main paradigm of evolution—the neo-Darwinian synthesis—is largely consolidated, and is correct. Sure, there are surprises to come, and interesting new phenomena, but there’s no “quantum mechanics” of evolution on the horizon. Some theories don’t need to be overthrown because they’re generally right. Perhaps people don’t like working in a field where there’s no new “paradigm” to forge, and Kuhn has ruined us all!

The "neo-Darwinism is dead" trend may have to do with ambition, or perhaps with boredom. I don’t know. What I do know is that the many recent challenges to neo-Darwinism have all failed to hold water, but people keep pouring liquid into that sieve.
The problem here is that Jerry doesn't really say what he means by "neo-Darwinism." Most of his writing suggests that he's talking about natural selection, albeit updated by a knowledge of genetics. He does mention, from time to time, random genetic drift and other aspects of modern evolutionary theory but I'm not sure if he appreciates the fact that some legitimate evolutionary biologists really do think that neo-Darwinism is dead.

Here's the Wikipedia description of neo-Darwinism. It illustrates the problem.
Neo-Darwinism is the 'modern synthesis' of Darwinian evolution through natural selection with Mendelian genetics, the latter being a set of primary tenets specifying that evolution involves the transmission of characteristics from parent to child through the mechanism of genetic transfer, rather than the 'blending process' of pre-Mendelian evolutionary science. Neo-Darwinism can also designate Darwin's ideas of natural selection separated from his hypothesis of Pangenesis as a Lamarckian source of variation involving blending inheritance.
I think we should refer to modern evolutionary theory as "modern evolutionary theory" in order to make sure we're not talking about "Darwinism," "neo-Darwinism," or the hardened version of the "Modern Synthesis." Modern evolutionary theory includes an important role for random genetic drift, Neutral Theory, and population genetics.

We could clarify a lot of discussion if we stopped talking about extending "Darwinism" or extending the Modern Synthesis or proclaiming once again that the selfish gene has died. In fact, the selfish gene has died, it died almost thirty years ago but most people don't know that. RIP.