MrDarwin

"Relative stasis"? I have to wonder just what you mean by that. Over the long term, the fossil record shows nothing of the kind, and the fossil record is "overflowing with fossils of transitional animals". I will try to find more links to the Chinese fossils (I'm thinking more of the fossils of early animals, particularly early arthropods, although the dinosaur-to-bird fossils are illustrative as well).

Moreover, the earth is still overflowing with transitional animals (and plants)--or more correctly, with the descendants of species transitional between major groups, which still retain characteristics of both groups (picture the duck-billed platypus, an egg-laying mammal with some other reptilian characteristics). Just because they are "transitional" doesn't mean they stopped evolving. I believe there was a discussion here just a few weeks ago about "transitional animals" that are alive today.

The point is that there are transitional forms still alive, but their status (and the status of fossil transitionals) as such is obscured by our classification system, which tends to pigeonhole species into existing groups rather than creating a multitude of new groups for the many that don't quite fit. Thus the platypus is pigeonholed as a "mammal" even though it lacks many of the characteristics of virtually everything we call a mammal (in fact the taxonomic category of "mammal" had to be redefined following the discovery of the platypus).

Similarly, I'm currently working on a group of plants in which the traditional classifications have turned out to obscure a huge evolutionary transition, but with molecular systematics suggesting new phylogenetic relationships more objectively (i.e., without the preconceptions of existing classifications) many of the problems in this large and taxonomically confusing group are starting to make sense. One enormous advantage of molecular systematics is that analyses deal with individual species, rather than groups that may or may not be monophyletic, and may or may not be defined correctly.

MrDarwin

The short answer is no, natural selection is not a sufficient explanation, which is why there is a lot more to evolutionary theory than natural selection. Does Johnson really suggest that evolutionary biologists haven't asked this very question?

But this question is somewhat misleading because it leaves out two major (as well as numerous minor) components of evolutionary theory: mutation and extinction. Without mutation (and here I use the term quite broadly) to generate variation, and extinction to separate potentially breeding populations, there could be no such thing as evolution.

MrDarwin

Before this gets bumped down too far, here are just a few websites for luvluv that I found after a quick google search:

http://www.sas.upenn.edu/earth/geol125/CambLife02.ppt
http://www.peripatus.gen.nz/paleonto...hengjiang.html
http://www.nmnh.si.edu/paleo/shale/index

For more information on the Chinese fossils search on "Chengjiang fossils" or "Chengjiang fauna".

luvluv, a few quick questions about your own impression of "Darwin on Trial": first, did you come away from the book feeling like Johnson had a good grasp of evolutionary theory (at least as it is promoted by evolutionary biologists)? Second, do you feel that he fairly presented the work and conclusions of evolutionary biologists? And third, did you come away with any sense of how he would interpret the same evidence that biologists use to support evolution?

luvluv

I'm sorry folks, I've been on kind of a weird schedule lately (It's 2 in the morning right now!) and it's been hard for me to post. It's gonna get worse before it gets any better, as I'm out of time and without computer access for the weekend.

I should be able to catch up Monday.

Lobstrosity

I hope luvluv hasn't forgotten about this thread--I was looking forward to some discussion...

Doubting Didymus

You could always PM him. Speaking of which, do you know how to check your own PMs, lob?

faust

Ok, I'll toss my uninformed two cents into this b/c i'm kinda bored, and a little buzzed and i kept seeing that silly book on the shelf at barnes and nobles in the "Science" section.

I'll quote and beef with posters I agree with. I'm sure i'll make some mistakes so feel free to call me on them.

Doubting Didymus:
Ok, I agree with that, I just quoted it b/c it is such an eloquent blunt way to put it, i like it.

etc etc....

Not only is this a good explanation of what probably happened, but it appears to have happened at least 3 times from scratch. Unless you want to argue that mollusks, vertibrates, and insects didn't develop eyes until they were already diverged. Insects have eyes do they not? Yet they are completely different from vertibrate eyes and mollusk eyes and still work. Even more annoying is the recent discovery of some species of starfish that have eyes damned near everywhere. They're like compound eyes but distributed. Silica sheets over light-sensitive photocells. Very clever, even their nervous system is geared towards it. We call this "convergent evolution." Several approaches to solving the same problem.

Lobstrosity:
That's been proven a wrong definition of insects vs other arthropods. It's a close save, but molecular evidence has shown closer relation between some arthropods with less or more than 6 legs to insects, as well as the interestingly close relation of crabs to arthropods (I don't care, I still like lobster.) The whole arthropodia is such a blur of diversity it's insane. You've got millipedes, convergent evolution of venom (not even counting reptiles), crabs, shrimp, crawfish, lobster, all with damned close molecular biological and genetic matches, some with chitin and calcium carbate, some with just chitin and other organics. Hox genes multiplication, morpohology, molecular biology, genetic matches for lung/gill function across the whole range.
Just as a note, apparently one of the only specific methods to identify fruit fly species is by penis morphology. I'm not kidding. It seems that they are so similar in other regards that that is the "gold standard." I'm glad i'm not a fly.
This true and I'm going to beat it to death.

1st: There are several versions of the Universal Genetic Code. The one used in prokayotes is different from eukaryotes slightly, and in some species of archaea as well. The evilutionists say that eukaryotes incorporated prokayotes as organelles back when god was a boy, if this were the case, the organelle genomes would require different translation rna, i.e. ribosomes and tRNA that were specific for the prokaryote-standard code. Oddly enough this is precisely what we see. This underlies 18s and 16s ribosomal sequence as a major split, and allows them to be used as molecular clocks. (As a side note, ribosomes are interesting b/c they are made of amino acid chains -and- RNA, constituting a molecular "transitional fossil" and that doesn't even count ribozymes.)

2nd: The "relatively few" schemes of R/DNA that would work encompasses a truly HUGE VAST UNIMAGINABLE variety of protein shapes. Protiens could function with similar tertiary properties that would be formed chemically by a staggeringly enormous number of primary sequences. In other words, the coverage of sequence-space of known proteins is absolutely miniscule compared to the available sequence-space. All extant protein sequences are so similar, in such a tiny corner, (of very coherent similarity) of the total possible sequence-space they could adapt, that the idea that they have no common ancestor is laughable. Let me know when you luvluv, can comprehend what the number of permutations of a chain of 10 letters could take. It is 10^26. There are as of yet only 23 or so amino acids used in nature, so let's be fair and say any given sequence of 10 amino acids (a polypeptide) would be 1/10^23 possibilities. And that's just 10 letters. Imagine that most proteins are waaay longer than that, and the ones we've sequenced all have way more in common with each other than any random selection of x numbers of chains of similar length in that possible set.

Please some creationist tell me how my math is wrong here.

That, and insect eyes, and starfish eyes, etc. Convergent evolution solves a good question of natural selection once again.
Those damned HOX genes. They even determine body plans for non-vertebrates like insects too.
Sounds like a good idea, lets apply it to lungs. Snakes start off with two, then one develops and the other doesn't, it's vestigal. Your example was such a good idea that it's seen in several organ systems besides gill/aortic systems.



Ok, I've got to stop this post now. I've carried on far too long. I didn't get a chance to dive into plant genetics with my favorites arabodopsis, and ferns, and woody ferns, and pines, and flowers, and polyploidy, and horses and donkeys... well I need to sleep eventually.

If something I said didn't make sense, then read up on it. If it still doesn't make sense, ask me about it. If it still doesn't make sense, then buy me a drink or something cause i'll need it.

Also, defn of species.. are we talking BSC or some other defn? There is much to species concept, subspecies, allopatric vs sympatric, relative types, genotype frequency, ad infinitum.

"Go to sleep faust!!!"



ok

MrDarwin

In a nutshell, my own take on this is that the fossil record is much, much better than creationists make it out to be (and it's getting better all the time), and there are multitudes of "transitional forms", both in the fossil record, and living today.

If evolutionary theory were really as flawed as creationists say it is, then every biologist who studies the history and relationships of living organisms would immediately reject it. But in the course of my own research (and I dare say in the course of the research of virtually all biologists) there is simply no other way to interpret the things I observe, because evolutionary theory is built upon observations and every biologist who deals even peripherally with evolution makes observations that are consistent with evolution. The theory does not exist in a vacuum, it is not speculation or abstract philosophy, it is an explanation that makes sense of the fossil record and genetics and morphology and biochemistry and biogeography and any number of other biological disciplines. Evolutionary theory is based on evidence and creationists have offered no credible alternative explanations for that evidence. The fact that some biologists disagree over some details of the theory, or that vanishingly fewer than 1% of all biologists reject evolutionary theory entirely, does not make evolutionary theory any less sound.

Critics of evolution like Phillip Johnson seem to think that if they can only find enough little flaws in evolutionary theory, the whole thing will fall apart. Sorry, but science doesn't work that way. Evolutionary theory is robust enough that even if some small parts turn out to be misunderstood or even erroneous, the whole structure still stands. And until somebody can effectively falsify evolutionary theory (I don't recall any suggestions by Johnson as to how it could be falsified) and offer an alternative theory that explains our observations of life and its record in the earth's history even better than evolutionary theory does, evolutionary theory will stand because biologists make enough observations of their own to convince them that the theory as a whole is sound. The problem, apparently, is in relaying that conviction to those people who do not personally study biology.

luvluv

I'm back!

Doubting Didymus:

But am I right in saying that what Intelligent Designers mostly dispute is the ability of Darwinian mechanisms to create genetic information? If evolution is defined solely as change, then it is undeniable. If it is defined as speciation, then it has some support (in that scientists have succesfully produced in laboratory settings animals which cannot interbreed... they used intelligent design in the form of purposeful breeding to do so... but why quibble?).

But is there any evidence that Darwinian mechanisms can create information? Aren't I right in thinking that even when species of bacteria becomes immune to poisons, it is because they LACK a critical enzyme or catalyst that there fellow bacteria have (and which the resistant bacteria SHOULD have)? It is not that new genetic information has been produced that has allowed the bacteria to survive, it is that old genetic information has been LOST and this allows the bacteria to survive.

It hardly explains how bacteria came to exist in the first place.

Let's start with the first step. How did the organism go from having no photocell to having a photocell? Let's produce a model of what a photocell is exactly and explain how this came to be.

Don't simplify it, present it here in all it's complexity and lets go from it not existing to it existing in it's fully fleshed out form, as it exists in functioning organisms.

Lobstrosity:

That's not true. Let's elevate the discourse, shall we?

There is the problem of information creation, the problem of stasis in the fossil record, and the problem of irreducible complexity, for instance.

If people disbelieved it simply because it contradicted the Bible they would never bother to bring up actual problems with the theory.

I don't understand what this is supposed to prove. Are you saying a vertabrate with four arms and two legs would falsify evolution?

If not then why are you offering it as a proof?

Unless I am mistaken, there are animals, humans even, born with extra appendages all the time. Mostly fingers, but occasionally arms, feet, even HEADS. What would be so spectacular about an animal with six appendages? That would be a relatively easy mutation compared with something like the brain, for example, and it would have an obvious advantage. So what is so spectacular about the fact that we only have four appendages? Six, eight, or ten appendages would be just as explicable under evolution. It would be a lot easier to explain a few extra arms via Darwinian mechanisms than it would be to explain first person conciousness or the sense of humor, for instance.

I would say that I have just as much of a right to expect extra limbs SOMEWHERE DOWN THE LINE OF VERTABRATES given evolution as I would given creationism. Are extra limbs supposed to be more difficult to come by than feathers? Higher-conciousness? Tails (and why don't the prehensile versions count as extra appendages, btw?)?

If I already believed in evolution, this might be a good reason for continuing to believe it. But assuming I don't, why should the fact that animals have four appendages convince me of anything?

You act as if the only alternative to evolution is literal Genesis creationism, and suggesting that one is false proves the other true. I accept no such dichotomy. They could both be false as literal explanations (and I personally think they are.)

Mr. Darwin:

Good questions:

1) I've read 2 more of Johnson's books since I started this thread (and I'm halfway through a third) so in surveying all these books I would have to say that he has a good grasp of the basics.

2) If by fair you meant thorough, I would have to say no.

3) No. But in fairness, I thought the question the book was asking was not so much whether or not Darwinism has any support, but whether the support is so overwhelming that it must be unassailably true. He was simply asking whether it is so completely unproblematic as to be doubted only by imbecilles.

Okay, well then what is it that biologists have observed that convinces them that Darwinian mechanisms can create information?

Coragyps

One example, hot off the press, is in Lev-Maor et al, Science, 300, 1288-91 (23 May 2003) The abstract:
and part of the conclusion:
To this non-biologist, that means that these exceedingly common DNA bits can acquire functions (read "code for new proteins") withour foolin' with the proteins we already have. One of the real biologists here may help us out with a deeper analysis, but it looks to me like this is yet another mechanism, to add to things like gene duplication + mutation of the copy, that does indeed add information to a genome.