The semantic argument about “Darwinism” continues

February 11, 2009 • 2:21 pm

John Kwok has called my attention to the appearance of a special “Darwin” issue of the journal Evolution: Education and Outreach. It’s free, and you can find it here. Lots of interesting stuff, including an article by the late Mike Majerus on industrial melanism in the peppered moth (as you may know, Mike died–way too young–about two weeks ago).

Eugenie Scott and Glenn Branch from The National Center for Science Education also have a piece called “Don’t call it Darwinism,” which I must say makes some strong arguments for replacing the term with “evolutionary biology.” They give examples of how creationists have used “Darwinism” as a perjorative for the field, includng replacing “evolutionary biologist” with “Darwinist” in their writings. Good points, but I’m still not convinced. I doubt that creationism would retreat an inch if we all started saying “evolutionary biology” instead. I think it’s far more important to teach people what “Darwinism” is than to quibble endlessly about the term (Olivia Judson also argued against “Darwinism” in the NYT last year). Still, do read Genie and Glenn’s article and see what you think.

Richard Dawkins reviews WEIT

February 11, 2009 • 1:30 pm

Well, I have to admit that I’m thrilled (or “chuffed”, as the Brits say). Richard Dawkins has reviewed Why Evolution is True in the Times Literary Supplement (here), and it’s a rave (and long–ca. 3000 words). I didn’t expect Richard to do a review at all (he rarely reviews books), much less to like the book so much. It’s really nice. And, as a bonus, Richard characteristically gives a discussion of what “truth” is in science, and how it is distorted by creationists and relativists.

Richard has now posted his review on  his website, and the comments are accumulating.   Nice original drawings there of the “bee ball” I talk about on WEIT and an amusing rendition of “God’s balls,” one of the more amusing parts of Richard’s review.

Darwinism must die????

February 10, 2009 • 9:00 pm

The science section of today’s New York Times is a celebration of evolution, including several articles that are excellent.  Unfortunately, the one by Carl Safina, an ecologist, is not.  Called “Darwinism Must Die so that Evolution May Live.”  He gives the usual misguided reasons for abandoning the term, to wit:

By propounding “Darwinism,” even scientists and science writers perpetuate an impression that evolution is about one man, one book, one “theory.” The ninth-century Buddhist master Lin Chi said, “If you meet the Buddha on the road, kill him.” The point is that making a master teacher into a sacred fetish misses the essence of his teaching. So let us now kill Darwin. . . . .

Using phrases like “Darwinian selection” or “Darwinian evolution” implies there must be another kind of evolution at work, a process that can be described with another adjective. For instance, “Newtonian physics” distinguishes the mechanical physics Newton explored from subatomic quantum physics. So “Darwinian evolution” raises a question: What’s the other evolution? .. . .

Charles Darwin didn’t invent a belief system. He had an idea, not an ideology. The idea spawned a discipline, not disciples. He spent 20-plus years amassing and assessing the evidence and implications of similar, yet differing, creatures separated in time (fossils) or in space (islands). That’s science.

Well, how much confusion has really been caused by using the term “Darwinism”?   How many people have been made to think that we biologists adhere to an ideology rather than a strongly supported theory?  Would creationism and its country cousin, intelligent design, suddenly vanish if we started using the terms “modern evolutionary theory” (ugh!) or the insidious-sounding “neoDarwinism”?  I don’t think so.  “Darwinism” is a compact, four-syllable term for “modern evolutionary theory,” which is ten syllables long.  And, of course, Darwin had far more influence on modern evolutionary research than Newton has on work in modern physics. In fact, in no other area of science has a research program suggested by one person lasted for a century and a half.  As I write in my own homage to the term (to be published in Current Biology):

. . . . True, Darwin wasn’t always correct: he got genetics wrong, and his views on species and speciation are pretty wonky.  And of course evolutionary theory has advanced: systematics, continental drift, and population genetics are all areas untouched by his looming shadow.

Still, these advances amount to refinements of Darwinism rather than its Kuhnian overthrow. Evolutionary biology hasn’t suffered the equivalent of quantum mechanics. But some biologists, chafing in their Darwinian straitjacket, periodically announce new worldviews that, they claim, will overturn our view of evolution, or at least force its drastic revision.  During my career I have heard this said about punctuated equilibrium, molecular drive, the idea of symbiosis as an evolutionary force, evo-devo, and the notion that evolution is driven by the self-organization of molecules.  Some of these ideas are worthwhile, others simply silly; but none do more than add a room or two to the Darwinian manse.  Often declared dead, Darwinism still refuses to lie down. So by all means let’s retain the term.  It is less of a jawbreaker than “modern evolutionary biology,” and has not, as was feared, misled people into thinking that our field has remained static since 1859. What better honorific than “Darwinism” to fête the greatest biologist in history?

As Nicholas Wade notes in his essay on Darwin in the same section as Safina’s:

Not only was Darwin correct on the central premises of his theory, but in several other still open issues his views also seem quite likely to prevail. His idea of how new species form was long eclipsed by Ernst Mayr’s view that a reproductive barrier like a mountain forces a species to split. But a number of biologists are now returning to Darwin’s idea that speciation occurs most often through competition in open spaces, Dr. Richards says.. . . It is somewhat remarkable that a man who died in 1882 should still be influencing discussion among biologists.

Finally, as my colleague Steve Pinker points out:

Linguistically, the point is moot – once a name sticks, only massive forces toward political correctness can change it
(African American, Native American, etc.). Voltaire noted that the Holy Roman Empire is neither Holy, Roman, nor an Empire, but that’s what we still
call it. Even if Darwinism had outgrown Darwin, it would be impossible to rechristen it.

Just noticed that over on Pharyngula, P.Z. agrees with me.

Speciation celebrated in the NYT

February 10, 2009 • 2:06 pm

One of the good pieces in today’s New York Times is the article by Carol Yoon on speciation, “Genes offer new clues in old debate on species’ origin.”  Maybe I’m biased, since speciation is my own area of research, but I think it’s nice that such an important area of evolutionary biology (after all, biodiversity requires both changes within lineages and the generation of new lineages) is singled out during Darwin Week.  Carol’s article was inspired by my grand-student Daven Presgraves’s and his colleague Shanwu Tang’s new paper in Science describing a gene causing inviability in species hybrids.  Tang and Presgraves found that two genes producing nucleoporins (proteins involved in transport of substances across the nuclear membrane) caused the death of hybrids between two species of fruit flies (Drosophila).  Apparently the genes had diverged so much between the species that they do not work together when present together in the genome of a hybrid.

It is a surprise that nuceloporins would be involved in the death of species hybrids, and we have no idea why this happens.  One of the areas of speciation that we know almost nothing about is which genes have diverged to produce the reproductive barriers between species.  We know of only nine at present, all producing either the death or sterility of hybrids.  And all of these genes bear, in their DNA, the traces of natural selection, so we can at least say that natural selection—as opposed to other evolutionary forces—was involved in this case of evolutionary divergence. My only quibble with this discussion is that Yoon repeatedly calls genes like this “speciation genes.”   But we don’t know if these genes were actually involved in speciation: their divergence may have occurred after the reproductive barriers between species (which, after all, can be caused by divergence in mating behavior or ecological preference) had already evolved. That is, the sterility or death of hybrids may represent examples of POST-speciation evolution.  Nevertheless, they are still quite interesting, because they can explain some of the regularities of evolution, such as “Haldane’s rule,” (the preferential death or sterility of those hybrids having sex chromosomes that are not alike—males in most species but females in birds and butterflies).

Kudos to Ms. Yoon for adhering to the biological species concept (BSC) in her article: the view that a “species” is a group of interbreeding organisms separated from other such groups by genetically enoded barriers to reproduction.  There are many other species concepts, but none that has yielded a productive research program on speciation. As far as I know, every single paper studying the process of speciation in real organisms is concerned with studying the origin of reproductive barriers.

The plural of “octopus”

February 10, 2009 • 12:57 pm

An alert reader, distressed that I used the word “octopi” in my New Republic article, has clipped out the proper term and mailed it to me.  Here is the answer:

Octopus.  Because this word is actually of Greek origin—not Latin—the classical plural is octopodes.  But the standard plural in American English and British English alike is octopuses.  Still, some writers [like me!] mistakenly use the supposed Latin plural.

A weird early arthropod from Germany

February 8, 2009 • 9:00 pm

As I’ve said, the latest issue of Science is chock-full of great articles on speciation and evolution.  In one of them, Gabriele Kühl, Derek Briggs, and Jes Rust describe a new 390-million-year-old fossil from the Hunsrück Slate beds in Germany.  This species, named Schinderhannes bartelsi, has what is called a “great appendage” in front of the mouth, consisting of two large protrusions, each of which has spines as well as leglike filaments on it.  (This appendage was probably a device to grab prey and convey them to the radial mouth behind.)  It also has two “winglike” protrusions that were used for locomotion, and a tail spike. The reconstruction by Elke Groening is below:12100-reconstruction

This weird animal is similar to Anomalocaris, one of the mysteries of the Burgess Shale fauna (see Steve Gould’s Wonderful Life for an overview): both have the “great appendage”.  The new fossil, however, is 100 million years younger than those of the Burgess Shale.  Kühl et al.’s work shows, however,  that the “great appendage” animals were “paraphyletic” (that is, they don’t form a group of species more closely related to each other than to any other species), and that Schinderhannes bartelsi is actually an arthropod more closely related to the chelicerates, the group including horseshoe crabs and scorpions. Indeed, the front claws of scorpions and horseshoe crabs are probably derived from this great appendage.

More than 99% of all species that existed over life’s history are thought to have gone extinct without leaving descendants, and fewer than 1% of these are known as fossils.  How many weird and wonderful species like this will never be known to science? A sad sidelight on this is that the Hunsrück Slate beds have since been closed, so there is no chance to see what other fossils lie in this amazing formation.

Fossil and X-ray of Scinderhannes bartelsi, as well as interpretive drawing and reconstruction. From the Science paper.
Fossil and X-ray of Scinderhannes bartelsi, as well as interpretive drawing and reconstruction. From the Science paper.

Gabriele Kühl, D. E. G. Briggs, and J. Rust.  2009.  A great-appendage arthropod with a radial mouth from the Lower Devonian Hunsrück Slate, Germany.  Science 323:771-773.

Darwin the prude, sexual selection, and sperm competition

February 8, 2009 • 10:16 am

Last Thursday’s Times Higher Education Supplement (the UK one) has a series of short pieces on Darwin and his legacy.  Perhaps the most interesting is by Tim Birkhead, the noted evolutionist who works on sperm competition in birds and has written a number of academic and popular books on the topic.  Birkhead claims that Darwin was reluctant to publish work on sexual selection—and missed entirely the topics of sperm competition between males as well as the relative promiscuity of females—because of the prudishness of his Victorian milieu as well as of his daughter Henrietta.  I’m not a historian of science and so can’t evaluate these claims, but Birkhead’s piece is provocative and well worth reading, as are the other pieces in this supplement.