Thursday, February 09, 2006

Darwin Day Talk

So the big talk went well yesterday. Around thirty people showed up. If there were any creationists in the audience, they didn't say anything. Here's the Cliff's Notes version of what I said.

I began by showing a few of those cartoons Ken Ham likes so much, in this case drawn from his book Creation Evangelism for the New Millenium. You now the ones I mean. The ones that show evolution as the foundation of a secular worldview that promotes abortion, homosexuality, family breakup and all that other nasty stuff. I then rhetorically asked what kind of scientific theory could possibly provoke a response that irrational.

From here I discussed a few common myths about evolution. Evolution is neither a theory about the origin of the universe, nor about the origin of the Earth, nor about the origin of life. I gave examples from various cable news pundits illustrating each of these fallacies. Likewise, evolution is neither an atheistic theory nor is it a theory of random chance. I pointed out that the claim that humans and lobsters shared a common ancestor does not imply that we should expect to dig up a half-human half-lobster fossil. Finally, I explained why evolution does not say we evolved from apes.

After clearing up what evolution is not, I spent a few moments explaining what evolution is. I identified the hypotheses of common descent and natural selection as the primary shaper of that descent as the core of the theory.

Then I launched into the longest part of the talk, wherein I laid out some of the evidence for common descent and natural selection. The audience consisted primarily of students and I did not want to assume they were familiar with this area. Judging from the comments I got after the talk, this seems to have been the right decision.

I began with the fossil record, and argued that fossils provide three types of evidence for common descent. First, the broad history of life as revealed by the fossil record is perfectly consistent with common descent. No Cambrian rabbits, to use a famous example. Second, creationist protestations notwithstanding, there are droves of transitional forms in the fossil record. Finally, the geographic distribution of fossils supports common descent. For example, armidillos are native to South America, and that is also where you go to find the fossil ancestors of modern armidillos.

Next up was the issue of anatomical homologies. I used the ye olde forelimb example. There's a reason it's a classic. Why do the forelimbs of humans, whales and bats, among others, use the same bones in the same relative positions? This makes no sense from an engineering standpoint, but makes perfect sense if all of these critters evolved from a common ancestor.

Then came embryology. Why do the early developmental stages of very different organisms nonetheless look nearly identical? Why do human embryos form tails and yolk sacs? Why is it that birds possess the genetic information for making teeth when that information is not expressed in modern birds?

Then we talked about vesitigal structures like pelvic bones in whales in snakes. I brought up many others as well. Everyplace else we find pelvic bones they are there for attaching legs to torsoes. If whales and snakes evolved from critters with legs, this is easy to explain. If not, then what are they doing there?

I said a few words about biogeography as well, but I won't belabor that here.

Finally I discussed some of the genetic and molecular evidence for common descent and thisis where things got interesting. I used the example of cytochrome-c. I explained that all organisms possess some form of this protein, but that there is enormous functional redundancy in its structure. In other words, there are many different functional forms of the protein. Human and yeast cytochrome-c differ in over forty precent of the protein, but human cytochrome-c works perfectly well when transplanted into yeast.

How then to explain the fact that human and chimp cytochrome-c is identical? More genearlly, how do we explain the fact that the phylogenetic trees constructed by analyzing cytochrome-c across the animal kingdom perfectly matches the phylogenetic trees constructed by other methods. I argued that this fact alone argues strongly for common descent.

These patterns certainly can't be epxlained funcitonally, after all. And given the sheer variety of functionla cyctochrome-c proteins, we can't explain it as the result of chance either.

At this point an audience member asked how the ID folks explain this fact. I had to confess I didn't know. The only ID proponent I could think of who has addressed this subject was Cornelius Hunter, who did so in his contribution to Dembski's anthology Uncommon Dissent. But his only reply was to hold out the vague hope that there was some functional explanation after all for the patterns. Does anyone know of any other ID reply to this point?

I completed my round-up of the evidence for common descent with a discussion of retroviral scars. For example, the genomes of primates reveal numerous insertions of retroviral DNA. As with the cytochrome-c, the patterns of these insertions matches perfectly with the phylogenetic trees constructed by other means.

Next up was natural selection. I began with Darwin's description of natural selection from The Origin. Then I used Dawkins' “Methinks is like a weasel,” experiment to illustrate how it is possible in principle for natural selection to craft complex structures.

I then provided brief discussions of evolutionary computation, known instances of speciation via artificial selection, field studies of natural selection, laboratory experiments on selection that have shown that new functionalities can evolve, ring species, and artifical life. After this summary I argued that the upshot is that any claim that the adaptations of modern organisms are not the result of natural selection will have to be defended by appeal to specific biological data. There is no sound, armchair argument that can show that natural selection is fundamentally incapable of doing what biologists attribute to it.

I next offered three lines of evidence to show that natural selection really was responsible for crafting the complex systems in nature. I pointed to the fact that many complex systems appear to be cobbled together from parts that were readily available in related organisms. I used the examples of the bee-attracting gizmos of orchids. I also observed that, again, ID protestations notwithstanding, scientists had discovered plausible series of intermediates for a great many complex structures.

Related to this line of evidence are the many “senseless signs of history,” to borrow Gould's phrase, that we find in modern ogranisms. I pointed to the fact that we breathe and swallow through the same tube as an example. This makes perfect sense in the light of evolution (which posits that this system evolved from more primitive systems in ancient lungfish). I pointed to other examples as well, such as the weakness of our lower backs and the backward wiring of our eyes.

The final line of evidence came from the applications of game theory to problems of animal behavior. Mathematical models based on game theory explicitly assume that natural selection is the cause of the behaviors being analyzed. The success of these models is testimony to the correctness of this assumption.

This was the longest section of the talk. I next gave a short biography of Darwin and described what, exactly, his contribution to biology was.

Then came a round-up of various anti-evolution arguments. I treated Behe's claims about irreducible complexity in detail, and also said a few words about the tautology argument and the thermodynamics argument. I chose those three because all of them have been prominent lately, and all of them represent attempts to show that evolution is false while making very little appeal to the actual biological data. I used the following representative statement from the Judge's decision in the big Dover case:

The immune system is the third system to which Professor Behe has applied the definition of irreducible complexity. In Darwin’s Black Box, Professor Behe wrote that not only were there no natural explanations for the immune system at the time, but that natural explanations were impossible regarding its origin. However, Dr. Miller presented peer-reviewed studies refuting Professor Behe’s claim that the immune system was irreducibly complex. Between 1996 and 2002, various studies confirmed each element of the evolutionary hypothesis explaining the origin of the
immune system. In fact, on cross-examination, Professor Behe was questioned concerning his 1996 claim that science would never find an evolutionary explanation for the immune system. He was presented with fifty-eight peer-reviewed publications, nine books, and several immunology textbook chapters about the evolution of the immune system; however, he simply insisted that this was still not sufficient evidence of evolution, and that it was not “good enough.”

Since I was mostly out of time at this point I had to jettison the part where I disucssed that recent Washington Post article about the odious Caroline Crocker. See this post for details on that.

So instead I wrapped it up with Darwin's old “There is grandeur in this view of life” quote, answered questions for another hour and a half, and called it a night. All in all, a successful evening.

Monday, February 06, 2006

Public Presentation II

Just wanted to remind everyone that I wll be giving a public talk about evolution here on the James Madison University campus, Wednesday, Feberuary 8, at 6:00 pm, in Taylor Hall room 305. I am told that cake will be served. I look forward to seeing everyone there.

Replying to Shulevitz

I never got around to blogging about Judith Shulevitz's review, for The New York Times, of Eugenie Scott's book Evolution and Creationism, and Michael Ruse's The Evolution-Creation Struggle. The article wasn't bad enough to merit a frothing at the mouth refutation, but wasn't good enough to really be worth reading. It was the usual pap that you get when a non-scientist has to find something to say about this subject. Those poor, beknighted, pointy-headed, ivory-tower intellectuals, thinking this is about science, she seems to say. Don't they realize that creationism is a cultural and anthropological phenomenon? Yawn.

Her article sure did provoke some good letters though. Paleontologist Niles Eldredge offers these wise words:

Judith Shulevitz's essay (“When Cosmologies Collide,” Jan. 22) contends that scientists often do not acknowledge the broader social implications of “evolutionism,” the mélange of often conflicting philosophical conclusions that have been drawn by disparate people from the very idea that life has evolved. It is this evolutionism, she says, that continues to inspire much of the resistance to evolution. But she gives short shrift to the fact that nearly all of the rhetoric of creationists, including contemporary “intelligent design” proponents, consists of ill-informed attacks on evolutionary biology itself, rather than on the inchoate philosophical ramifications of “evolutionism.”

Beyond the cardboard assertions of “irreducible complexity” in the supposed outboardmotor- like apparatus of bacterial flagella, and a few other oneliners in the current intelligent design canon, lie reams of tired old assertions of the supposed failings of evolutionists to explain natural phenomena. There is every reason for us evolutionary biologists to fight back, especially when the stakes are so high: the further dilution of integrity in science teaching in our nation's secondary schools.

Well said. And here's Skeptic's Society president Michael Shermer offering similarly wise words:

Although it is occasionally true that evolutionism can turn into bad philosophy in the hands of a rabid anti-theist, intelligent design (I.D.) creationism is always bad science and bad theology. We saw in the Dover trial why I.D. is bad science. I.D. is bad theology because it turns God into a mere garage tinkerer, a fumbling watchmaker, a Dr. Frankenstein cobbling together biochemical parts from the primordial soup into complex organisms. Such a God cannot be the omniscient and omnipotent God of Abraham; indeed, the I.D. God would have the same skill sets as an advanced extraterrestrial intelligence capable of genetic engineering and other feats.

Far more nourishing than the original article.

The Metabolism of Evolution Information by the Blgosphere

Moment of Science offers this excellent summary of how evolutoin information is metabolized by the blogosphere. Great stuff!

Hitchens Nails It

Chirstopher Hitchens says all that needs to be said about the riots over those Danish cartoons depicting caricatures of Muhammad:

As well as being a small masterpiece of inarticulacy and self-abnegation, the statement from the State Department about this week's international Muslim pogrom against the free press was also accidentally accurate.

“Anti-Muslim images are as unacceptable as anti-Semitic images, as anti-Christian images, or any other religious belief.”

Thus the hapless Sean McCormack, reading painfully slowly from what was reported as a prepared government statement. How appalling for the country of the First Amendment to be represented by such an administration. What does he mean "unacceptable"? That it should be forbidden? And how abysmal that a “spokesman” cannot distinguish between criticism of a belief system and slander against a people. However, the illiterate McCormack is right in unintentionally comparing racist libels to religious faith. Many people have pointed out that the Arab and Muslim press is replete with anti-Jewish caricature, often of the most lurid and hateful kind. In one way the comparison is hopelessly inexact. These foul items mostly appear in countries where the state decides what is published or broadcast. However, when Muslims republish the Protocols of the Elders of Zion or perpetuate the story of Jewish blood-sacrifice at Passover, they are recycling the fantasies of the Russian Orthodox Christian secret police (in the first instance) and of centuries of Roman Catholic and Lutheran propaganda (in the second). And, when an Israeli politician refers to Palestinians as snakes or pigs or monkeys, it is near to a certainty that he will be a rabbi (most usually Rabbi Ovadia Yosef, the leader of the disgraceful Shas party) and will cite Talmudic authority for his racism. For most of human history, religion and bigotry have been two sides of the same coin, and it still shows.

And later:

I am not asking for the right to slaughter a pig in a synagogue or mosque or to relieve myself on a "holy" book. But I will not be told I can't eat pork, and I will not respect those who burn books on a regular basis. I, too, have strong convictions and beliefs and value the Enlightenment above any priesthood or any sacred fetish-object. It is revolting to me to breathe the same air as wafts from the exhalations of the madrasahs, or the reeking fumes of the suicide-murderers, or the sermons of Billy Graham and Joseph Ratzinger. But these same principles of mine also prevent me from wreaking random violence on the nearest church, or kidnapping a Muslim at random and holding him hostage, or violating diplomatic immunity by attacking the embassy or the envoys of even the most despotic Islamic state, or making a moronic spectacle of myself threatening blood and fire to faraway individuals who may have hurt my feelings. The babyish rumor-fueled tantrums that erupt all the time, especially in the Islamic world, show yet again that faith belongs to the spoiled and selfish childhood of our species.

Exactly right.