Posted on 01/10/2002 10:11:55 AM PST by Junior
BOZEMAN, MONT. -- It's not often that a presentation given to the Society of Vertebrate Paleontology elicits coos and clucks of sympathy. These are, after all, the scientists who study Tyrannosaurus rex and other fearsome beasts of the past. But that's exactly the reaction Kenneth Dial got when, at the group's annual meeting last October, he showed video footage of a fuzzy little partridge chick with its wings taped to its sides trying to climb a tree -- only to tumble down into Dial's waiting hands. Unfettered, however, the chick flapped its tiny wings while climbing and steadily made its way up. After teasing the audience for its sentimental display, the University of Montana biologist returned to the matter at hand: explaining how this and other experiments involving ground-dwelling birds led him to hatch a new hypothesis regarding the origin of avian flight.
Traditionally, scholars have advanced two theories for how bird flight evolved. One of these, dubbed the arboreal model, holds that it developed in a tree-dwelling ancestor that was built for gliding but started flapping to extend its air time. The other, known as the cursorial theory, posits that flight arose in small, bipedal terrestrial theropod dinosaurs that sped along the ground with arms outstretched and leaped into the air while pursuing prey or evading predators. Feathers on their forelimbs enhanced lift, thereby allowing the creatures to take wing.
As the idea that birds descended from dinosaurs gained acceptance by all but a few paleontologists, so too did the cursorial hypothesis. But both the arboreal and cursorial scenarios have explanatory gaps. As far as tree dwellers go, of the hundreds of nonavian gliding vertebrates around today, not one flaps its appendages. And why would natural selection have favored the development of little protowings in a theropod equipped with heavily muscled legs for running across the ground? Neither theory, Dial asserts, adequately addresses the step-by-step adaptations that led to fully developed flight mechanics.
Dial's eureka moment came after learning that partridges and their fellow ground birds routinely abandon terra firma in favor of trees and other elevated spots for safety. Although these animals appear to fly up into trees, he found on closer inspection that in many cases they were actually running up -- legs bent and body pitched toward the tree -- while flapping their wings. Subsequent research revealed that wing flapping assists in this vertical running by sticking the bird to the side of the tree, much as a spoiler helps to press a race car to a track.
Although the adult ground birds are generally perfectly capable of flying up trees, their preference for running may stem from a time early in life when the couldn't yet fly: before a baby ground bird has the ability to launch itself into the air, the only means it has for getting off the ground is vertical running. And as Dial's experiments show, when a juvenile is trying to evade a predator this way, the aid of even a partially formed wing can mean the difference between life and death.
Perhaps a bird ancestor's protowing conferred the same benefit, he suggests, and therefore natural selection favored its development. Over time, wings evolved to the point of enabling not only vertical running but, when employed by an animal running across the ground, flight.
So far Dial's model has ruffled few feathers. Living animals do not necessarily make good models of extinct ones, however. "Is that the way bird ancestors did it? Well, maybe, maybe not," comments Kevin Padian of the University of California at Berkeley. "But [Dial] is showing that it's possible." For his part, Dial is leaving it to the paleontologists to figure out whether his theory of the genesis of avian flight jibes with future fossil finds -- or whether it's for the birds.
The current run of crevo threads this year:
(2002-01-01) Conservatives, Darwin & Design: An Exchange
(2002-01-01) Design Yes, Intelligent No
(2002-01-01) Intelligent Design As a Theory of Technological Evolution
(2002-01-07) Genetic Marker Tells Squash Domestication Story
(2002-01-07) SNPs as Windows on Evolution
(2002-01-07) Supreme Court Won't Hear Case on Teaching Evolution
(2002-01-07) Universe Of Life: Maybe Not, A
(2002-01-07) What Every Theologian Should Know about Creation, Evolution, and Design
(2002-01-08) Universe Might Last Forever, Astronomers Say, but Life Might Not, The
(2002-01-09) Life On Other Planets? Vatican Aide Ponders The Possibility
(2002-01-10) Study: Neanderthals, Modern Humans Same Species
42 posted on 1/10/02 12:22 PM Pacific by WRhine
You'd need wings, flight feathers, a specialized light bone structure, specialized flow-through design heart and lungs, specialized tail, specialized general balance parameters etc.
For starters, every one of these things would be antifunctional until the day on which the whole thing came together, so that the chances of evolving any of these things by any process resembling evolution (mutations plus selection) would amount to an infinitessimal, i.e. one divided by some gigantic number.
In probability theory, to compute the probability of two things happening at once, you multiply the probabilities together. That says that the likelihood of all these things ever happening, best case, is ten or twelve such infinitessimals multiplied together, i.e. a tenth or twelth-order infinitessimal. The whole history of the universe isn't long enough for that to happen once.
All of that was the best case. In real life, it's even worse than that. In real life, natural selection could not plausibly select for hoped-for functionality, which is what would be required in order to evolve flight feathers on something which could not fly apriori. In real life, all you'd ever get would some sort of a random walk around some starting point, rather than the unidircetional march towards a future requirement which evolution requires.
And the real killer, i.e. the thing which simply kills evolutionism dead, is the following consideration: In real life, assuming you were to somehow miraculously evolve the first feature you'd need to become a flying bird, then by the time another 10,000 generations rolled around and you evolved the second such reature, the first, having been disfunctional/antifunctional all the while, would have DE-EVOLVED and either disappeared altogether or become vestigial.
Birds, of course, are simply the easiest case to visualize. Every other complex creature which ever walked the Earth involves the same kind of zero-probability event sequence holding good.
Basically, if a theory requires one or two probabilistic miracles or zero-probability events in the entire history of the world, you might could still listen. But evolution just stands everything we know about probability on its head.
Gee, it had to be revised 14 times and you want me to believe it is "the ulitmate"?
Me, I'll stick with Jesus as my Resource - the same yesterday, today, and forever.
<];^)
You must read James Hogan .... good author :)
You have proven that flying squirrels do not exist.
What does that prove?
And as Dial's experiments show, when a juvenile is trying to evade a predator this way, the aid of even a partially formed wing can mean the difference between life and death.
From your post:
I'll say it again: to be a flying bird, you'll need a baker's dozen highly specialized systems, any one of which would be anti-functional and a severe impediment until the day it all arrived.
Either you did not read the article, or you simply give knee-jerk responses whenever the subject of creation vs. evolution comes up. Pavlov would've have loved you (and gore3000, but that's another story).
Not bad if you consider that decimal places, log's, and powers-of-ten couldn't have been used since they weren't invented yet.
Anyway. Notice that the "birds" (reptiles according to this theory) were created BEFORE the current (domesticated) farm animals that the Hebrews were familar with.
Also: Life (fish - other sea creatures) before land animals, just as evolution now claims.
More evidence? God created the land and the seas, and divided the SINGLE original ocean into its current "seas" by moving the land on tectonic plates ... a theory laughed at by the world's "professors" until the mid-sixties.
"Waters" (the original plasma gasses were present BEFORE "light" (the stars) that came from them. The (firmament) planets after light. Creation did NOT start with "Let there be light!"
And, true to new theories about the moon coming FROM a collision between a solidified earth (after the earliest life!) and a glancing asteroid, the moon is clearly said to be made (by God!) much, much later than the earth!
Not bad for a bunch of "ignorant" sheepherders who were living thousands of years BEFORE tectonic plates were discovered, the moon's craters were found to be from asteroid collisions, and birds were found to be evolving (created/designed!) from their dinosaur ancesters.
Re-re-re-re-reposting an article he probably wrote back when he was still the resident nut at Talk.Origins would be the definition of "knee-jerk."
BTW, let me add another dino-bird link:
Fundamendalism-creationism, topsoil, stratosphere, underarm, dental floss.
I'd have to add to all that the hypothesis presented here does not make much sense. If wings were evlved to help a critter run up a tree in acting like spoilers, they would change so as to continually get better at holding the creature onto the tree, not allowing them to fly up in the opposite direction.
Don't have time to argue this thread today though. A pity, it'd be delicious.
I would hope that not even diehards like my esteemed sparring partners Vade and Junior would give this idea much credence. I realize that discrediting this idea is not the same thing as discrediting the evolution of birds. Still, if evolution is true, if all of those alleged 'transitionals' check out, then it had to happen SOME way. And all ways proposed to date seem very unlikely, as Medved notes.
I had forgotten that phrase would include bugs.
I don't poo-poo evolutionary ideas automatically since I think quite a bit of adaptability was built into the prototypes of each family introduced into the biosphere. If bird wings evolved, I thought the 'started as stabilizers used while they lept after hopping insects' was the least absurd hypothesis. That does not explain the origin of feathers themselves though. They seem to spring up with the hook and barbule system already in place- except for fossils with down feathers which birds have today. How did the small biped dinos know they were going to need flight feathers?
That is a minor problem compared to proposing intermediates between the bird's continuous-throughput respiritory system and the in-out system of all other vertabrates.
Wouldn't you agree that this is an unlikely scenario, and for the exact reason I mentioned?
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