Saturday, April 24, 2010

Darwin's Dilemma

My buddy John sent me the DVD by that title, though the title apparently also belongs to a DOS video game from the 1990s. The film summarizes a startling event -- the Cambrian explosion. In Darwin's own words:

There is another and allied difficulty, which is much more serious. I allude to the manner in which species belonging to several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks.
The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained.
Charles Darwin, On the Origin of Species, 6th Edition
(Project Gutenberg EBook #2009), chapter 10
As the film explains, Darwin's theory predicted gradual change over long periods of time, but what the fossil record shows is the sudden appearance of several phyla over a very short period of time.

Now I'm not a biologist and I'm not going to argue for or against intelligent design. What I would like to do is make a few observations that struck me.

First, and this is something I heard some time ago (not in this film) about Chinese biologists conversing with their American counterparts. "We can criticize Darwin but we cannot criticize our government. You can criticize your government but you cannot criticize Darwin." I don't have names, dates, or even the exact wording, but anyone who thinks scientists aren't dogmatic needs to look at the evidence. Some are, some aren't -- just as some Christians are dogmatic and some aren't, and the same for other religious groups and political parties. In connection with this, you might enjoy reading Lewontin's comment on dogmatism in science.

By the way, is censorship is alive and well in the politically-correct scientific establishment even today? I suppose yes; you might want to check out the claims made in this article from an admittedly conservative source.

Second, a few years ago we heard a fascinating recap of the debate over evolution, presented by a venture capitalist who attends our church. He has no axe to grind over evolution, though he's a product of our educational system he believed as most right-thinking Americans do -- that natural selection is how we got to have all these species, Darwinian evolution is established fact, those who disagree are willfully ignorant, etc.

Some years before that, he was at some retreat or something when he discovered that people at our church don't all believe the evolution story. Apparently someone heard him mutter, "What kind of whackos am I getting myself involved with?" He does not remember saying this out loud, but apparently...
His comment was this: Darwin's "tree of life" has remarkable similarity to what geneticists have discovered by analyzing so-called "junk DNA" in various species. These markers seem to be consistent with Darwin's ideas; that is, with no knowledge of DNA, Darwin came to many of the same conclusions that modern biologists have by looking at analyses of the genetic material of many different species. In other words Darwin was spectacularly right about the relationships between species as confirmed by inspecting DNA. But Darwin's theory was also spectacularly wrong in its prediction that various species would appear gradually in the fossil record, whereas the fossil record shows just the opposite: a veritable explosion of life in the Cambrian era. I am not sure what the producers of this particular film would say about the discoveries related to "junk" DNA. To be fair, though, the subject of the film was Darwin's dilemma -- which has nothing to do with DNA, junk or otherwise.

Third, is Darwin's Dilemma actually still a problem for the theory of evolution (or "conjecture" -- but I'll give it the benefit of the doubt)? A search on the topic yields a reference to PNAS June 20, 2000 vol. 97 no. 13 6947-6953, titled "Solution to Darwin's dilemma: Discovery of the missing Precambrian record of life" by J. William Schopf, who writes “those of us who wonder about life's early history can be thankful that what was once “inexplicable” to Darwin is no longer so to us.”

But 8½ years later, Science Daily announced that Darwin's dilemma had been finally solved:

Solution To Darwin's Dilemma Of 1859

ScienceDaily (Jan. 9, 2009) — A solution to the puzzle which has come to be known as ‘Darwin’s Dilemma’ has been uncovered by scientists at the University of Oxford, in a paper to be published in the Journal of the Geological Society.
This article by Jonathan Wells disputes that those scientists solved the dilemma; indeed, Wells concludes:
But this was not Darwin’s dilemma. Darwin’s dilemma was the absence of intermediate fossils showing that the Cambrian phyla diverged from a common ancestor. Callow and Brasier didn’t solve Darwin’s dilemma. Instead, they put one more nail in the coffin of Darwin’s attempt to salvage his theory from it. The truth is that “exceptionally preserved microbes” from the late Precambrian actually deepen Darwin’s dilemma, because they suggest that if there had been ancestors to the Cambrian phyla they would have been preserved.
So just googling around doesn't give me a really good feeling for The Answer. I used to think this was a Really Important Issue; now, though I don't think it's exactly trivial, I'm not nearly as concerned about it. Part of the reason is that I no longer believe Genesis 1 was intended to be a chronological account of creation; rather, I think it was a polemic (more on this here). And if you're interested in some comments from a website that's not quite so conservative or religious, you might enjoy reading the DVD's customer reviews on amazon.

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