Ojuice5001

I used to think the entire case for creationism was flawed, but then I learned some details about the transitional-fossil debate. I think it is actually a good argument for old-earth creationism . Darwin on Trial by Phillip Johnson did a good job of presenting the facts about how there are a lot of missing transitional fossils. Here are three examples:

1. Fish to Amphibians There are few fish that have much potential to evolve into amphibians. The main candidates are the rhipidistians. But they are close relatives of the living coelecanth. And the coelecanth has been dissected, and showed little sign of being related to amphibians. Which leaves us with no good candidates.

2. The Various Orders of Mammals There are no fossils that are closely related to the common ancestor of all placental mammals (not that we even know what that ancestor is!). Whales, rodents, ungulates, bats, and edentates all appeared in primitive but recognizable forms, with no links to the common ancestor. Why should that be, if each took millions of years to evolve? Minerva isn't the only thing that sprang fully formed from the brain of Jove! (Sorry, couldn't resist putting that joke in somewhere.)
Unlike the other two examples, this is not just one missing transitional fossil, but half a dozen.

3. Insect Wings The first insects had no wings, like modern silverfish. But later insects had wings, which supposedly evolved from an otherwise unknown structure. Why don't we have any fossils of insects with this unknown structure? Or halfway evolved wings? Also, what good would it do an insect to have halfway evolved wings? They could easily keep a vertebrate from breaking its neck, as Dawkins correctly argues. But insects are tougher, and therefore a wingless insect is highly unlikely to die by falling from the top of a tree.

The only good theory of how macroevolution occurs is that microevolution adds up to macroevolution. Johnson makes some other points against this theory--blind watchmaker evolution--that seem good, but the only one I really find convincing is the one about transitional fossils. It may be possible, but not without creating many animals that are mysteriously absent.

So either evolution or creation could be true, but as blind watchmaker evolution is too slow to operate without leaving behind numerous fossils that we don't find, both must invoke a mystery rather than an explanation of how large changes occur.

I feel a need to clarify two things. First, I am not rejecting common ancestry. I am merely saying that the gods caused the large changes involved in macroevolution--it's more of an intelligent design idea. And second, I am not saying that some monotheistic Supreme God caused the changes--after all, finite gods are perfectly capable of doing the trick. The Roman (Olympian) gods have not been in power much longer than humans existed so they were not involved in pre-Quaternary evolution, though Jupiter and Prometheus were the ones behind the evolution of humans. Other gods, who are now dead or absent, caused pre-Quaternary macroevolution.

tgamble

[quote]Originally posted by Ojuice5001:
[QB]<a href="http://members.aol.com/ps418/tran.htm" target="_blank">http://members.aol.com/ps418/tran.htm</a>

<a href="http://www.gcssepm.org/special/cuffey_05.htm" target="_blank">http://www.gcssepm.org/special/cuffey_05.htm</a>

also see <a href="http://www.talkorigins.org/faqs/faq-transitional.html" target="_blank">http://www.talkorigins.org/faqs/faq-transitional.html</a>

Johnson is hardly a reliable source of information on evolution.
<a href="http://www.talkorigins.org/faqs/johnson.html" target="_blank">http://www.talkorigins.org/faqs/johnson.html</a>

probably because the fossil record isn't perfect.
<a href="http://www.fossilmuseum.net/Tree_of_Life/Phylum%20Arthropoda/Subphylum_insecta/subphylum_insecta_fossils.htm" target="_blank">http://www.fossilmuseum.net/Tree_of_Life/Phylum%20Arthropoda/Subphylum_insecta/subphylum_insecta_fossils.htm</a>

What is a half evolved wing anyway?

I don't think anyone expected that....

btw, old earth creationism denies common descent which you apparently accept. So why would you claim a case for old earth creationism if you reject it?

Ojuice5001

Tgamble,

I can see that talkorigins is right about fish-to-amphibian evolution. Also the general unreliability of Johnson--he seemed different from other creationists, but maybe he's not. I called my position "old-earth creationism" because Johnson would call this position creationism--I hadn't realized OEC necessarily denies common descent. The stuff about mammals and insects, I still think are good points.

ps418

Ojuice,

You may be interested in reading a book called <a href="http://www.amazon.com/exec/obidos/ASIN/1573831336/qid=1027729190/sr=8-1/ref=sr_8_1/103-1152123-5290209" target="_blank">Darwinism Defeated?</a> This is a debate between Phil Johnson and another evangelical Christian, Denis O. Lamoureux. There is an archived thread on the book too:
<a href="http://iidb.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001286&p=" target="_blank">Johnson takes a beating.</a>

Regarding the common ancestor of the placental mammals. There are in fact forms that are very close to that which would be expected from a stem group, such as the recently discovered <a href="http://www.nature.com/nsu/020422/020422-15.html" target="_blank">Eomaia</a> from the early Cretaceous northeast China. Granted, this genus in particular was not known until recently.

Ji, Q. et al. The earliest eutherian mammal. Nature, 416, 816 - 822, (2002).

Abstract:The skeleton of a eutherian (placental) mammal has been discovered from the Lower Cretaceous Yixian Formation of northeastern China. We estimate its age to be about 125 million years (Myr), extending the date of the oldest eutherian records with skull and skeleton by about 40–50 Myr. Our analyses place the new fossil at the root of the eutherian tree and among the four other known Early Cretaceous eutherians, and suggest an earlier and greater diversification of stem eutherians that occurred well before the molecular estimate for the diversification of extant placental superorders (104–64 Myr). The new eutherian has limb and foot features that are known only from scansorial (climbing) and arboreal (tree-living) extant mammals, in contrast to the terrestrial or cursorial (running) features of other Cretaceous eutherians. This suggests that the earliest eutherian lineages developed different locomotory adaptations, facilitating their spread to diverse niches in the Cretaceous.

Cheers,

Patrick

MrDarwin

There has been lots of research in recent decades on the evolution of insects, and the evolution of insects wings. Things are looking good for the wings being derived from gill pads, as are still found on the aquatic nymphs of mayflies (order Ephemeroptera). This theory was developed by Jarmila Kukalova-Peck at least 20 years ago, and she has found some really fascinating fossils to back it up.

One of the problems with insect wing evolutio is that nobody could figure out where the wings came from in the first place; modern insects have uniramous (i.e., unbranched) appendages, unlike most other arthropods, e.g., crustaceans, which have branched (biramous) legs, with one of the branches usually being a gill. So the wings were a complex, articulated organ without antecedents, that seeingly sprouted from nowhere; in this context, it's very difficult to conceive of any possible use or function for the incipient or proto-wings.

But as it turns out, the oldest insect fossils do have branched appendages, so that's one objection gone; and the wings of early insects (and some of them had 3 pairs of wings, unlike modern insects) were very similar to the gills of aquatic insect nymphs. So there was never "half a wing"; there were articulated appendages that functioned as gills in the aquatic nymphs, but were modified to act as wings in the terrestrial adults.

This is very, very cool stuff and I wish it were more accessible on the web (I just did some searching but don't have all night) but plug in keywords like "insect wing evolution Kukalova-Peck" and you'll come up with a few summaries of her research and theories.

Edited to add a footnote: recent molecular studies are showing that insects are most closely related to crustaceans, which makes perfect sense in light of the biramous legs of early insects. In other words, winged insects are flying crustaceans.

[ July 26, 2002: Message edited by: MrDarwin ]</p>

pz

Oh, dear. Have you even looked at the literature on this subject? This is one of those areas that has recently seen a great influx of new data. Jenny Clack just recently published a very good book, _Gaining Ground_, that covers all the fossils in wonderful detail. You might also want to check out a more popular work, Zimmer's _At the River's Edge_.

Bottom line: your claim is wrong.

Look up Kukolova-Peck.

There are some great fossils of early insects with intermediate wings. There are a couple of competing hypotheses, but the most likely one to me is that they evolved from respiratory structures.

You've made a couple of claims about what is known that are patently bogus, and which you should have known were untrue if you had even the most casual acquaintance with accounts of this subject from the popular press. Aren't you a bit embarrassed? If not, you should be.

Albion

Here's a link to the transcript of a BBC Horizon programme about the fish-amphibian transition:

<a href="http://www.bbc.co.uk/science/horizon/2000/missinglink_transcript.shtml" target="_blank">http://www.bbc.co.uk/science/horizon/2000/missinglink_transcript.shtml</a>

Ojuice5001

Hmmm. So there are insects with intermediate wings. I guess creationism is as silly as I'd always thought.

Richiyaado

One must never underestimate Johnson's ability to misdirect readers with his rhetoric. He's a master at this.

Philip Kitcher has written that, like other creationists, Johnson would have his readers believe there's a huge problem relating to the lack of transitionals, but he creates the impression that a great many more organisms fossilize than actually do. If you tie your claim to a hugely overoptimistic estimate of organisms fossilizing, it might well seem persuasive to readers who don't understand how rare fossilization actually is.

Secondly, he's very good at the ol' bait and switch. He'll begin with a grudging acknowledgement that the transition from reptiles to mammal-like reptiles is a point in evolution's favor. But then he creates the impression that this is trivial and demands evidence showing how one sort of digestive system for reptiles can change over time to produce an extremely different sort of system for mammals. Of course, he makes no mention of the fact that fossils of soft tissues are exceedingly rare.

Johnson is nothing if not a clever lawyer. Wrong, but clever.

Oolon Colluphid

It’s a creationist myth. It’s also a straw man: “such a thing couldn’t work, so evolution’s crap!” But ‘such a thing’ isn’t being proposed, so the argument’s crap.

And anyway, to paraphrase Dawkins, to the question ‘What good is 50% of a wing?’, the correct response is: precisely 1% better than a 49% wing in breaking your fall if you drop out of a tree by accident.

That works fine for things like surface area of wings/gliding membranes, but it doesn’t mention the other element: that the thing now called a ‘wing’ may not have been used as a wing when it started.

Having just visited (on Saturday) the <a href="http://www.nhm.ac.uk/museum/tempexhib/dinobirds/" target="_blank">London Natural History Museum’s marvallous Dino-bird Exhibition</a> and seen many of the fossils for myself (inc ‘fuzzy raptor’, both the slab and the counterslab!), I can state categorically that there were no half-wings on display. There were however many forelimbs, with increasingly birdwing-like hands, and with feathers. It’s what Gould termed exaption, adapting and developing some pre-existing structure to a new function. Birds didn’t start without those limbs at all, and grew wings de novo. They had the standard tetrapod set of limbs, walked on their back legs, then redefined the function of the front ones.

With insects, the physics of flight is a bit different. They’re much smaller than birds, so a bit of wind has a tendency to get them airborne anyway, perhaps whether they like it or not. Hence something like gill pads could become used as aerofoils. Move ’em, and you’ve got wings. The rest is simply refinements.

A 1/16th, 1/8th, even a 1/4 wing, probably wasn’t used as a wing. At some point, the new function becomes the primary one. Eventually, the new function may be very far removed from the original one -- as with pectoral fins of osteolepiform fish becoming legs, wings or hands.

So to answer your question tgamble, a half evolved wing would be a structure that’s balanced 50/50 between the old and the new functions.

Oolon