Monday, March 26, 2007

Organisms, Groups, and Memes: Vehicles or Replicators? Part 2

I have never understood Punctuated Equilibrium in the manner that Dawkins, in his chapter, spends considerable time refuting. Evolution is gradualist, as Dawkins says, in the sense that there is no such thing as half an animal. A "transitional fossil" can be a confusing concept, giving one the idea that certain animals are "transitional" as opposed to being "normal" (when in fact every living thing is "transitional"). This misunderstanding is exploited by creationists in their tiresome demand for "transitional" fossils.

P.E. is, essentially, a reinterpretation of the fossil record which turns out not to be as radical or revolutionary as Gould portrayed it to be. Dawkins likens the difference between previous interpretations and the Gould-Eldredge proposal as the difference between walking up a hillside and ascending a staircase. There are no "gaps" in the fossil record, only steps.

Dawkins explores Gould and Eldredge's equation: P.E. + Wright's Rule = Species Selection

Wright's Rule: "The proposition that a set of morphologies produced by speciation events is essentially random with respect to the direction of evolutionary trends within a clade." In other words, in an apparent analogy with mutational randomness, if a species of horse shows marked progression toward larger body size, a new species of horse would not necessarily follow this trend, if Wright's Rule is preserved. As many new species would be smaller than the clade as larger. Therefore, Wright's Rule must be tested.

However, Dawkins points out (quoting Gould): "'If Wright's Rule be valid, and new species of horses arise equally often at sizes smaller and larger than their ancestors, then the trend is powered by species selection. But if new species arise preferentially at sizes larger than their ancestors, then we don't require species selection at all, since random extinction would still yield the trend.' Gould here simultaneously sticks his neck out and hands Occam's Razor to his opponents!" Dawkins adds that he can imagine some major speciational trends of the type described by Cope's Rule,* but points out that this is quite different that the original question, that of individual sacrifice behavior or adaptations "for the good of the species." The difference is between the concept of the group as replicator versus the group as a vehicle for replicators.

Palaeontological major trends, such as the length of horses' legs, are simple, requiring only a few replicator replacements, whether we mean genes or species at this point. However, many more replicator replacements are required for the evolution of a complex adaptation such as those that allowed a land mammal to evolve into whales, for example. Even if such a complex phenomenon could be broken down into smaller evolutionary events, the adaptation involves an interrelated web of changes that group-selectionism just could not produce them without yielding, over and over again, a highly unlikely barrage of parallel beneficial trends. (Indeed, this mistaken idea of group-selectionism could be what some creationists imagine evolution to be, leading them to dismiss evolution as improbable.)

Dawkins writes:

The theory of species selection, growing out of that of punctuated equilibria, is a stimulating idea which may well explain some single dimensions of quantitative change in macroevolution. I would be very surprised if it could be used to explain the sort of complex multidimensional adaptation that I find interesting, the 'Paley watch," or 'Organs of extreme Perfection and Complication' kind of adaptation that seems to demand a shaping agent at least as powerful as a deity. Replicator selection, where the replicators are alternative allels, may well be powerful enough. If the replicators are alternative species, however, I doubt if it is powerful enough, because it is too slow. Eldredge and Cracraft (1980, p. 269) appear to agree.

Part 3: Memes

16 comments:

johnadavison said...

http://www.iscid.org/ubb/ultimatebb.php?ubb=get_topic;f=6;t=000370;p=34

Consider my message April 9, 2007, 10:45

Enjoy!

"A past evolution is undeniable, a present evolution undemonstrable."
John A. Davison

johnadavison said...

Kristine

If you can't handle that URL just go to "brainstorms" and my Manifesto thread and message April 9, 2007, 10:45

Cheers.

I love it so!

I would like to hear your response.

"A PAST EVOLUTION IS UNDENIABLE, A PRESENT EVOLUTION UNDEMONSTRABLE."
John A. Davison

Kristine said...

John, I can't even open your blog.

Some ass is posting as "Charles Darwin" and the comment seems to go on for pages!

It's crashing my computer. If you think I'm doing it, I'm not! I would not do that to you. Okay?

So, anyway, Dembski is out of ideas and stealing yours? Is that the gist? Sorry, I'm in grad school with finals coming up - I've been neglecting Crandaddy at my blog as well - hanging around AtBC too much and I can't keep track of everything.

Didn't you say that Dembski would be out of UD soon, or that UD would fold, or both? You're probably right.

johnadavison said...

Kristine

My blog has been sabotaged by some creep posting as charles darwin. That is not the point.

I have no idea what Dembski or Springer is up to. It looks like they are trying to discredit me whatever the cost. I have no respect for either of them or for the denizens of Panda's Thumb either for that matter.

I think you should reconsider your loyalties and your convictions. That is the only reason I contacted you. When you lie down with dogs you may get up with rabies.

Do me a favor and call the attention of the troops over at ATBC to my recent comment at "brainstorms." I would think they would love it!

Good luck with your exams.

"A past evolution is undeniable, a present evolution undemonstrable.
John A. Davison

Kristine said...

(I thought it was "fleas.") Why, thank you for your kind wishes. I need all the help I can get.

Okay, I'll tell the people at AtBC if you really want me to...

Alan Fox said...

I think you should reconsider your loyalties and your convictions. That is the only reason I contacted you.

I doubt that loyalty has as much to do with scientific understanding as evidence, theories based on evidence and convincing explanation based on theories and evidence.

Oh, and there is the thirst for ultimate truth and knowledge.

Your inability to discus your own hypothesis rationally with anyone who expresses the least scepticism is a major handicap to your being taken seriously.

PS someone appears to have posted "Origin of Species" several times on your blog. A case of being overwhelmed by the evidence? You can easily delete the offending comments or indeed the whole thread using your dashboard controls.

Alan Fox said...

Kristine

Sow the wind...

I can't post at ISCID as a certain Dr (Ph D in engineering) David L. Hagen banned me!

John is a saltationist, an advocate of Goldschmidt and his "hopeful monsters", so I am surprised he did not comment about puntuated equilibria as this has been linked to saltation.

Kristine said...

Sorry to hear that, Alan. I don't mean to brag, but Richard Dawkins e-mailed me personally last night to complement my work here on Phenotype.

Alan Fox said...

Oooh, I am SO jealous. I expect you'll be framing a copy :)

Did you listen to John's "interview", BTW? I was, frankly, quite impressed with his lucidity of expression, (not of content, however), though Jason did give him an easy ride. I was toying with blogging about it, but I struggle to find time these days, and one comment leads to another...

Kristine said...

I shall be meeting Dawkins on my trip to the Galapagos, so eat your heart out! ;-)

I have not been able to listen to the show yet, since I final projects due next week and my job has been hectic, but I plan to today, at the library where I can get a faster connection. I am in the home stretch with school and pretty exhausted.

Lui said...

Hey Kristine, that's awesome! On that, could you do me an enormous favour if you're able to: will you please send Dawkins my kindest regards? Could you also, if you're able and willing, ask him what advice he would give to an aspiring evolutionary biologist who started off studying in the field a little later than most other people due to conflicting interests and indecisiveness? I'd ask him myself, except that I don't know if the e-mail address I used was the right one (because of no response, though that could be due to the enormous amount of mail he must get every day. Or perhaps my messages were too banal to respond to).

Alan Fox said...

I shall be meeting Dawkins on my trip to the Galapagos, so eat your heart out! ;-)

I shall take vicarious pleasure in the reports you will be posting. Look forward to reading your commentaries and seeing the pics. Have a fantastic time and give my regards to the great man.

Kristine said...

Thanks, Lui and Alan, I'm off!

Take care!

Lui said...

No more posts?

Kristine said...

Sorry. I do intend to take this up again.

I've been inundated with work, school, and moving, but hopefully things will settle down for me soon.

And JAD and I had a kind of falling out. (I managed to scare VMartin, though.) ;-)

Jay Rogers said...

"I would be very surprised if [punctuated equilibria] could be used to explain the sort of complex multidimensional adaptation that I find interesting, the 'Paley watch," or 'Organs of extreme Perfection and Complication' kind of adaptation that seems to demand a shaping agent at least as powerful as a deity."

Kind of an amazing statement!

Micro-evolutionary steps betweeen species can be explained by random molecular drift working in tandem with Darwinian natural selection -- but those big jumps can only be explainable by something like a deity just as long as we don't think of it as a deity.

Is that a fair paraphrase?

I liked Dawkins most recent blog where he complained about the comparison between Darwinism and the Nazi eugenics movement. He didn't deny the logical association, he just claimed to be an inconsistent Darwinist!

"As I have often said before, as a scientist I am a passionate Darwinian. But as a citizen and a human being, I want to construct a society which is about as un-Darwinian as we can make it. I approve of looking after the poor (very un-Darwinian). I approve of universal medical care (very un-Darwinian). It is one of the classic philosophical fallacies to derive an 'ought' from an 'is'."

I could comment ad nauseum on this, but I'll leave it as food for thought.