Thursday, February 12, 2009

Clearing up misconceptions about evolution on Darwin's birthday

Between site visits at work, I typically listen to progressive talk radio (1310 AM WDET) while I'm driving. Well, today, for some weird reason, my favorite station decided to broadcast NASCAR instead of Thom Hartmann, much to my displeasure, so I changed the band with the intention of listening to NPR, which is my usual fallback. However, the station that came on when I changed the band to FM was 103.5, WMUZ, and it was Bob Dutko, talking about evolution.

Now, I should disclose here that I have been on Bob Dutko's show five times now. I have had conversations with him--as the opposing viewpoint--on evolution, separation of state and church, the notion of dinosaurs and humans coexisting (peacefully?), and the existence of his god (twice). The reason my radio was tuned to his station on the FM band was because the last time I switched to FM was to listen to his show on the way to my appearance on it.

After hearing Bob speak today, it became clear to me that we're going to have to have another conversation about evolution. He brought up several points that I need to address, but one that stuck in my mind was his use of a Stephen Gould quote, followed by a misrepresentations of the idea of punctuated equilibrium. Another notion he tied into his discussion about Gould was the idea of transitional fossils and why they may or may not be in the fossil record.

First, punctuated equilibrium is the idea that mass extinction events leave biological niches to be filled, and species will undergo relatively rapid physiological changes as they fill them, if they have enough genetic variation/adaptations to replace the extinct species' specializations. For example, with a small mammalian scavenger species that could not thrive as a predator in an environment full of them, but is aggressive/fast/strong enough to become a predator after a mass extinction, members of the species with adaptations that enable them to be predators will fill that niche, and the rest of the active genes that go along with those adaptations will be passed on. The ones with the most predatory behavior are likely to separate with those who have a more passive tendency to scavenge, so their physiology will follow a different path from their more passive relatives. Plenty of experiments have demonstrated that certain physiological characteristics go along with certain adaptations; foxes, for example, when bred for submissive behavior similar to that of domesticated dogs, will produce offspring with droopier tails and ears, shorter snouts, and more clownish behavior--traits that are typically found in omega males in wolf packs.

Getting back to Bob: he was talking about transitional fossils, and how he though scientists explained them away. He quoted Gould (he brought this same quote up during our broadcast conversation about evolution). It was something about how Gould was complaining that the lack of transitional fossils in the record is an aggravating problem for biologists. He went on to say that Gould believed in punctuated equilibrium, which Bob represented as species just evolving slowly, then evolving all of a sudden, out of the blue, and that's why there's no fossil record of them.

No, no, a million times, no.

I'm setting the record straight here, and I hope I get the opportunity again to do it on his show (our next show is about the existence of Jesus, which I'm contesting as being nothing but mythology).

Bob expects to find freakish, half-evolved forms in the fossil record if evolution is true. The problem with this expectation is that it ignores that only about ten to fifteen percent of DNA in a given species is active, and that different genes will be active in relation to different manifested adaptations. If the active adaptation is an aggressive nature, a whole set of physiological characteristics will follow. There are only so many viable combinations of active genes, so whatever the result of evolutionary change will be a fully formed specimen, but with different active genes. Plenty of forms have been deemed "transitional", but controversy rages over them because there's no way (currently) to determine with certainty whether a form is an intermediary between two species. Perhaps a DNA simulation will yield the answer someday, but for now, we have comparative anatomy, more or less.

So, half-evolved forms are not what I would expect to find in the fossil record, because the changes that occur at the genetic level must manifest themselves in the form of a viable specimen with the ability to reproduce, not some freakish, half-formed animal with adaptations somewhere between one species and another.

As far as Bob's contention that Gould believed that animals evolved slowly, then suddenly--POOF!--changed into something else is concerned, Gould went on to say in the same literature that as surprising as it is, transitional fossils have been found. Furthermore, punctuated equilibrium would still take a couple million years, which is rapid when compared to the average life cycle of a given warm-blooded species (twenty-six million years). The odds of finding the fossils of a species that has a couple million years of existence and relatively rapid physiological change are more remote than the odds of finding fossilized remains of a species that existed for twenty-six million. Fossilization just doesn't occur that often.

With artificial selection (horse breeds, dog breeds, and Darwin's famous example of pigeon breeds), it is easy to see transitional forms--but if you dug up the skeleton of a Chihuahua and a Great Dane, would you be able to tell that that either of them came from wolves? Would you be able to identify the forms between the wolf and the Great Dane or the wolf and the Chihuahua as transitional forms? If we didn't know already that these dog breeds were the result of human intervention, creationists would argue that any forms you found were separate species that happened to be similar, because comparative anatomy means nothing to them. They would argue that they are separate, specially-created species--and they would be wrong.

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