VOX DEI BAIT #3

First of all, I added some stuff to the prior post.

Second of all, if you were expecting me to reply to any comments on Vox's site today, that's not going to happen during business hours. Don't have the time, and even if I did, I'd have to run an end-around the district's firewall to leave comments from my computer at school. Leave comments for me on my site, and I'll make a good-faith effort to always provide the appropriate context to which my response is based, as well as a link to Vox's latest offering.

Vox writes:

A change in the frequency of alleles within a population is the genetic definition of evolution. What is the genetic definition of speciation?

I'm not really sure we could define speciation in genetic terms without it being very awkward and disjointed. Speciation is usually defined in functional terms, according to the reproductive (or biological) species concept popularized by Mayr. That is, a species is defined as a population or populations which are only able to bear fertile offspring with one another in nature. You could, if you wanted to, express that genetically but why go to all that trouble? We know that there is a genetic basis for whom we are able to have fertile offspring with, and that should be enough for our purposes.

Note that species concepts are just that, concepts. If you're really interested in learning about some of the other ways of conceptualizing the elusive notion of 'species' you should really check out Wilkins's archive, especially this.

Are nucleotide substitutions to be regarded as the genetic equivalent to darwins?

Definitely not. Darwins are scalar quantities that represent measurable changes in traits, in the phenotype. Many nucleotide substitutions have absolutely no effect on the phenotype. Evolution as defined genetically can occur without speciation, without any sort of observable phenotypic trend in the population.

If not, what would be a reasonable definition of a "mendel" that would allow us to track the average rate of genetic evolution as one species transforms into another?

Nucleotide substitutions allow us to estimate rates in which new mutations become fixed in the population, but this has no direct correspondence with speciation. In fact, the higher the rate, the less likely the locus in question is under direct selection, and (as far as I know) the less likely it would contribute to any speciation event---based on what we know today. I add that caveat because the regulatory role of non-coding DNA is an active area of research, and it is always possible that we may find that certain introns might have a role in, say, stabilizing the genome if it is undergoing an episode of reorganization.

VOX DEI BAIT #2

Vox raises some interesting questions. I'm going to beg off on at least one:

3. Is the acceptable margin of error greater for economics or evolution? (It's much larger for both than people realize.) What margin of error is too great to allow a discipline to be reasonably considered a science?

This was prompted by unflattering comparisons between the two, some of which was aimed at tweaking Vox, who thinks he has some credentials in the former area. I don't want to get sidetracked by something like a turf war. I'm not sure that the margin of error is the issue in either case; it's just that both fields study complex phenomena that are more difficult to model than, say, perfectly round billiard balls moving on a frictionless surface. On with the show....

Do you understand the difference between a historical model and a predictive model? If you don't mind, would you quickly explain to those having problems understanding the difference why this is relevant to a discussion of evolution?

This is reminiscent of Charles Thaxton's distinction between origins science and operations science, which Sonleitner discusses here. (More vulgarly, Ken Ham is fond of asking his audiences "Were you there?") In general, historical models are based upon inference, rather than direct experimental test. There is nothing inherently unscientific about the former, as long as you are willing to accept that a higher burden of proof exists. Which is fine: extraordinary claims require extraordinary evidence. It might be added that claims that can be falsified by a single experiment are, often as not, trivial or (as in my above example with a frictionless surface) artificial.

And which type of model, in your opinion, is a better description of the current state of Neo-Darwinian theory?

I don't care for the term 'Neo-Darwinism'; to many Americans, it implies something like religious belief. I prefer the term 'modern synthesis' or 'modern synthetic theory' because this gives the real flavor of the enterprise as I know it. I think the question as posed is a false dichotomy. Simply put, as a synthesis the modern theory contains both historical and predictive elements, inference and observation, speculation and rigorous test.

Now, having said that, it's pretty important that evolutionary biologists (EB) should be at pains to distinguish between inference and experiment, etc. In general, the scientific literature itself is very good at making these distinctions in the discussion of results and their interpretation and popularizations of science are not. And that's a big part of the problem!

Here's an excellent article from the ASA (American Scientific Affiliation) website by Keith Miller that discusses this question. The author, a paleontologist and a Christian, concludes that the differences between the historical and 'hard' sciences in terms of testability are greatly exagerrated.

Is Talk Origins a reliable source? I seem to have come under an amount of criticism for relying on it. If it is unreliable, can you suggest an acceptable one?

The technical articles at Talk Origins seem pretty solid to me, and I don't hesitate to refer to them. I don't pay any attention to the other stuff that goes there, and I suspect that's what bothers some creationists. TO is assertively pro-evolution, and some of the legendary kerfuffles in its forums show partisanship (on all sides) at its worst, but that has no bearing on the scholarship in the technical articles, some of which is outstanding. There are few people who have considered more creationist arguments in more detail than Mark Issak, and I admire Doug Theobald's work, as well.

I conclude that pro-evo types should not, in my opinion, have any problem with Vox basing his arguments on anything at TO, but they certainly have a right to rake him over the coals if they think he's misrepresenting or misunderstanding the material he refers to.

Creationists who don't like TO because of its perceived partisanship might want to look at the ASA site. They have a searchable archive of their journal (Perspectives on Science and Faith) going back nearly 50 years, with lots of scholarship, that's a tremendous resource. Most of the authors are Christians, and they run the gamut between YEC's and full-blown evolutionary biologists. (Disclaimer: I'm a member myself)

Another good source for those who are wary of TO is the archives of the National Center for Science Education. It's a p'm a member of this organization, as well as ASA. There's a lot of detailed criticism of the leaders of the ID movement here. (Disclaimer: I belong to this outfit, too)

Well, I have to go earn a living now, I'll be back for some of Vox's other questions later!

NOT IN KANSAS, AGAIN...

Whenever I see someone asking for a 'trail' of transitional forms (and there are plenty), I know those who make this demand will never be satisfied. No matter how many fossils we find, they will always complain that there are some 'missing links'.

It is as if we have tens of thousands of movie stills showing July Garland in various locations in Oz, which can be arranged to tell a story of her arrival, quest and ultimate return to Kansas---and yet some of us insist that we have not 'proven' that there is any actual film called 'The Wizard of Oz'.

Instead (they claim) each and every frame must have been deliberately crafted by the still photographer, and the idea that they can be arranged to tell a moving story is just some fantasy we've all agreed to promote in order to deny the still photographer's existence.