Wednesday, March 01, 2006

Some Reflections on Stent's Lecture

As noted in my previous post, there was a lecture at UNLV tonight entitled "Intelligent Design: A Unique View of Globalization and Science" by Dr. Gunther Stent. Here are my reflections on the lecture.

The lecture hall was packed--standing room only. Dr. Stent is a recognized expert in molecular genetics, having written an important textbook on the subject. He seemed quite amiable, though because of his age--he's probably in his 70s or 80s--he was hard to hear.

Anyway, I was rather disappointed in the lecture because it hardly engaged with intelligent design at all. Dr. Stent did describe ID as "bizarre", but no explanation or justification was given for that claim. A couple times he lumped it in the same category as "creationism", evincing no clear awareness that the two movements, while overlapping in some respects, are quite distinct.

Most of the talk wandered over a wide array of issues, from comparing C.H. Waddington's and Herbert Spencer's views on the grounding of moral values in Darwinian theory to an extended discussion of Kimura's theory of 'neutral evolution' to speculations on cultural evolution and the possible role that differences in the ratio of brain size to body size might have on rates of "organismal" (or phenotypic as opposed to "genetic" or genotypic) evolution.

His central concern seemed not to be ID at all but contrasting Kimura's neutral evolution with neo-Darwinian natural selectionist orthodoxy. This part of the talk was quite interesting. The basic idea behind neutral evolution is that most of the genetic variation that occurs in a population has little or no direct relation to the "fitness" of an organism. Accordingly, such changes are invisible to natural selection. Nevertheless, if these "neutral" changes proliferate sufficiently throughout a population then they may become "fixed" in the gene pool. Hence, genetic change can occur in species over time even though that change has not been selected for.

According to Dr. Stent, the rate of evolution due to neutral evolution is a factor of (1) the rate of occurrance of a given neutral mutation, and (2) its rate of fixation in a population's gene pool. A given mutation is more likely to occur in a larger population, but fixation is more likely to occur in a smaller population, so (1) and (2) tend to balance each other out. What this means, according to Dr. Stent, is that the rate of neutral evolution is relatively invariant across factors like size of population, rate of reproduction, life-span, and so forth. Instead, the rate of neutral evolution is a more-or-less linear function of time because the other factors balance each other out. Hence, there is a relatively constant "evolutionary-molecular clock".

Dr. Stent seems to think that neutral evolution is the primary source of changes in a population's gene frequencies over time, with natural selection playing only an occassionaly and largely conservation role by weeding out the most unfit. He did suggest that neutral evolution might pose a challenge for ID because random point mutations and genetic drift seem to point away from any sort of telic directedness.

One question I have about this is that if most genetic changes are really selectively neutral, and most of evolution consists in such neutral changes, then it seems to me that it's going to be somewhat hard to account for the occassional rapidity of phenotypic evolution, as in the Cambrian explosion. The problem is that neutral genetic changes have no positive tendency to distribute themselves throughout a population because they are invisible to selection pressure. So in any halfway decent-sized population it could take hundreds or thousands of generations for even one neutral point mutation to become fixed in the gene pool. Given that some creatures have relatively low birth rates, if most of evolution occurs this way, then I'm rather skeptical that there's been anywhere close to enough time for the whole Darwinian tree of life to emerge.

One final remark: Early on in his talk, Dr. Stent admitted quite frankly that the origin or life is utterly "mysterious". He said that no credible naturalistic theory exists to explain how life emerged from non-life. He even went so far as to say that the very quest for a plausible naturalistic origin of life scenario "seems hopeless" and that researchers in that field were quite "discouraged". Later in the talk he referred to Francis Crick's notorious idea of "directed panspermia", basically the notion that life of Earth was engineered by extraterrestrial aliens and then seeded on the Earth. Dr. Stent obviously regarded Crick's suggestion as silly, but by his own admission neither he nor origin-of-life researchers have anything much better to offer. It seems to me that this admission on his part shows that whatever the merits of his views on neutral evolution, ID is still in the game. The most obvious cases of intelligent design are those that stubbornly resist reductive explanation in terms of natural law, chance, or some combination thereof. The origin of life is increasingly looking like just a case.


At 3/02/2006 10:43 PM, Blogger Heather VFG said...

I also saw this talk given by Dr. Stent and asked him a couple of questions after most people had left. I don't think he gave any strong argument from the field of molecular biology against I.D. I don't think he really intended to either. He conceded to me in private that "this area [I'm assuming related to I.D.] is really not my specialty, but they asked me to come and give a talk, so how could I refuse?". I'm glad he was honest about that. He was also very openly honest about how scientists don't even have a workable hypothesis regarding how life began.

One question I asked had to do with the issue of frogs. Apparently, mammals evolve at a much higher rate than frogs; frogs are pretty much the same as they were 19 million years ago according to fossil records. They even have their own genus, which is a unique trait only to frogs (if I understood him correctly). Dr. Stent's colleague Allen Wilson (sp?) So why do mammals evolve faster than frogs? Brain size to body size ratio. (I think that's what Alan mentioned) So I asked about the flu virus. We know that "evolves" at a very quick rate (we need new strains of vaccine every year). He basically said that it has to do with the organismic status of the thing. Frogs are an organism and viruses are not organisms so that accounts for the difference of evolution rates between frogs and viruses. But I still think that attributing evolution to brain/body size ratio is quite a stretch. How does brain size cause a gene to mutate more quickly?

At the beginning of his talk, Dr. Stent also argued that Darwinism has morality as well, which sure, perhaps it does. Survival of the fittest. (He spent a couple of minutes on this issue in his talk, so this gave me an opportunity to prod deeper into this issue, which I'm very curious about.) Stable home life, economics, monogamy, etc. seems to give a society more stability and ability to be stronger than the society without those things. However, I asked him this:"What would the Darwinist say about things such as euthanasia and getting rid of those society deems as 'useless'?" He replied, "That's a very complicated issue. It depends on if one values life, etc." So that answer seems to mean, "it's up to each person to decide." So that's interesting that he said that considering that he and his family escaped from the Holocaust in Germany. I don't think he truly understood the weight of my question. If a Darwinist society deems you as a hinderance to the rate of their progress (even if they might be wrong, but who is to judge that ultimately?), and decides that it is best to eliminate your existence, would they be justified? That's a very important issue that I think most proponents of Darwinism have been avoiding.

Anyway, thanks for letting me comment here!

At 3/04/2006 4:22 PM, Blogger Doug Rigby said...

I was at Dr. Stent’s lecture as well. It was a little hard to decipher, but to me his talking points played out as follows: (1) It is paradoxical and surprising that modern America, almost alone, is leading the denial of the evolutionary origin-of-life via the Intelligent Design movement. (2) It is possible to challenge the orthodox beliefs of evolution and the recent neutral theory of evolution has done so, and now plays an important role in evolutionary theory. Even though the neutral theory of evolution was anti-natural selection (against one of evolutionary theory’s sacred principles) the challenge has succeeded because of successful predictions and true merit in the scientific court. (3) The unfolding story of evolutionary theory continues to progress, explain more, and points towards a greater role of true random chance not design. (4) In contrast, the intelligent design movement fails as a hypothesis since it explains nothing new, has not contributed to any scientific understanding, and rests ultimately on a literal reading of the Bible that all modernists should reject.

I agree that Dr. Stent is likely not aware of the modest tenets of ID that posit a design hypothesis for only certain specific observations of the world. Yet while proponents of ID see certain kinds of complexity as inferring a designer, Dr. Stent’s sees natural complexity as a reason for the lack of scientific progress – his faith in naturalism is apparently still strong. So his acknowledgement of the “mysterious” origin of life and the current stalemate in science to understand the origin of life clearly doesn’t shake his faith in an ultimate naturalist answer.

My personal view is that because of the many complexities involved and stark human limitations in empirically discovering how animate matter could arise from inanimate matter, it would be pure blind luck if a chemical pathway was found. In many areas of scientific discovery, intuitional empirical (try this, try that) research efforts are being replaced by much more fruitful theoretical simulations on powerful computers. As far as we can discern animate and inanimate matter obey the same natural laws. Given this, once the ongoing explosion of knowledge plays out in molecular evolution and related areas, I expect new theoretical pathways will open up and simulation of theoretical possibilities will lead to breakthroughs. Also searching “origin of animate matter” “origin of life” “chemical evolution” and “autocatalysis” shows that current research is far from dead. Only empirical research into origins of life has hit rough times.

Regarding the neutral theory of evolution I’ve been reading about it the past couple days. Genetic or random drift via the neutral mutations of “junk” DNA is now accepted as noncontroversal; “most evolutionary biologists today maintain that the two theories are compatible” (“Neutral theory of molecular evolution,” Wikipedia). Both natural selection and genetic drift occur, the issue and scientific battles are over which is the active evolutionary mechanism under what circumstances (or whether both are active and how they complement each other). Increasing support is falling behind the idea of “nearly neutral” (neutral but somewhat deleterious) mutations being important (proposed by Ohta, a student of Kimura). These mutations may constitute a significant pathway for building molecular complexity in gene interactions; they also may accumulate over time and emerge in the “fits and starts” of punctuated equilibrium. Scientists are finding that although individual nucleotides are nonfunctional, collectively, genetic drift in portions of “junk” DNA provide the raw material for significant functional novelty in either gene structure or regulation. Information in “junk” DNA is now considered to play important useful and functional evolutionary roles.


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