Posted on 01/18/2006 6:10:34 PM PST by PatrickHenry
Our ears could have started evolutionary life as a tube for breathing, say scientists, after examining the ancestral structure in a 370-million-year-old fossil fish.
Evolutionary biologists are intrigued by how complicated sensory organs evolved from structures that may have had completely different uses in ancestral creatures. The bony structures in ancient fish, which at some point turned into ears, for example, appear to have had mainly a structural function, bracing the cheek and holding up the jaw. How exactly they made the transition to their role in hearing has proved a bit of a mystery.
The ear is a relatively easy organ to study. Its evolving bones have been preserved as fossils, whereas the soft tissues of other specialized features, such as eyes and noses, have long decayed.
So Martin Brazeau and Per Ahlberg of Uppsala University in Sweden decided to take a close look at the ear-like features of an ancient, metre-long monster from the Latvian Natural History Museum in Riga. Panderichthys was a fish, but is thought to be closely related to the earliest four-limbed tetrapods that eventually climbed on to land and gave rise to modern vertebrates.
The researchers examined Panderichthys and found that the bony structures in its head combine features of fish and tetrapods, capturing a snapshot of evolution in action. "It's neat to see that transition," says Hans Thewissen who studies the evolution of the ear and other organs at Northeastern Ohio Universities College of Medicine, Rootstown.
Half-way house
Ancient fish have a narrow channel from the roof of the skull into the mouth, known as a spiracle, which is bounded by a long bone known as the hyomandibula that braces the cheek. In tetrapods, the equivalent bone is stubbier, a step towards the stirrup-like stapes bone that helps to transmit sound waves into our skulls.
The team found that Panderichthys has a wide, straight spiracle rather than a narrow one, and a shortened hyomandibula. They report their findings in Nature1.
Some have previously speculated that our ancient ears may have had a role in breathing.
On the basis of this new fossil evidence, the team speculates that the widened spiracle may have served Panderichthys much like the breathing holes used by modern-day sharks and rays. These allow the fish to inhale water over their gills while lying on the seabed, and avoid gulping in grit through the mouth.
The demonstration of an organ evolving provides tangible evidence against the idea, put forward by some proponents of creationism, that sensory organs are so intricate that they must have been designed by a higher being. Brazeau says: "It's a slap in the face to that kind of thinking." |
Nature 439, 318-321 (19 January 2006) | doi:10.1038/nature04196
Tetrapod-like middle ear architecture in a Devonian fish
Martin D. Brazeau1 and Per E. Ahlberg1
Few fossils show the incipient stages of complex morphological transformations1. For example, the earliest stages in the remodelling of the spiracular tract and suspensorium (jaw suspension) of osteolepiform fishes2, 3, 4 into the middle ear of tetrapods have remained elusive3. The most primitive known tetrapods show a middle ear architecture that is very different from osteolepiforms such as Eusthenopteron3, with little indication of how this transformation took place. Here we present an analysis of tetrapod middle ear origins that is based on a detailed study of Panderichthys, the immediate sister taxon of tetrapods. We show that the spiracular region is radically transformed from osteolepiforms and represents the earliest stages in the origin of the tetrapod middle ear architecture. The posterior palatoquadrate of Panderichthys is completely tetrapod-like and defines a similarly tetrapod-like spiracular tract. The hyomandibula has lost its distal portion, representing a previously unrecognized advance towards a stapes-like morphology. This spiracular specialization suggests that the middle ear of early tetrapods evolved initially as part of a spiracular breathing apparatus5, 6.
Great argument. Google "mathematical science" and tell all those prestigious organizations that they're not using the term "science" correctly.
You were talking about 2+2, son. Would you be less confused if I had used the word "arithmetic" instead of "math"? Read things in context, so that you'll understand them better.
Sorry, Junior's argument was that scientists NEVER speak in absolutes. That's clearly an incorrect argument.
You know what he means, don't be coy. Stop trivially nitpicking semantics and maybe people might start to take you seriously for a change.
On the basis of this new fossil evidence, the team speculates
the widened spiracle may have served
Alas for irreducible complexity.
Alas for irreducible pomposity.
I am a scientist who recognizes evolution...I also am a Christian who believes God created the world...I have no problems Can we just stop the 'science-creationist' war for a moment? Some people try to improperly use science to refute the existence of God. Others try to use Scripture to ignore the science in front of their face -- No one thought the Earth revolved about the Sun until it was scientifically proven...100% Christians now recognize that the Earth moves about the Sun.
Oh, great - another evolutionary fairy tale.
Let's recount the conversation:
Me: Oh? I've never heard a mathematician state that 2 plus 2 might equal 4.
You: That's because math isn't science, son. See post #71 if you're still confused.
So now your position now is that math (mathematics) IS science, but arithmetics (a branch of mathematics) isn't? I guess I am confused.
Oh, and please don't call me "son". I'm not your son and you're obviously not using the term out of affection, but rather to belittle and denigrate.
Sorry, Junior's argument was that scientists NEVER speak in absolutes. That's clearly an incorrect argument.
You know what he means, don't be coy. Stop trivially nitpicking semantics and maybe people might start to take you seriously for a change.
I think I do know what he meant. What he meant was that EVOLUTIONARY scientists don't talk in absolutes. He just happened to lump in all scientists in order to try and validate the uncertainty of evolution. I can come up with many more examples where real scientists speak in absolutes.
Yeah, but I haven't breathed through my ears for some time now. ;^)
The only persons I've ever seen trying to usurp God are christians. Mainly Christian "leaders"; not scientists or "evolutionists"
TBN president Paul Crouch put it, "I am a little god! Critics, be gone!" (Paul Crouch, Praise the Lord program - TBN July 7, 1986).
Kenneth Copeland declares "You dont have a god in you, you are one," (Kenneth Copeland, The Force of Love , 1987, audiotape #02-0028, side 1.)
Benny Hinn pronounces, "I am a little messiah walking on earth,"(Benny Hinn, Praise-a-Thon program on TBN (November 6, 1990).
There you have it. Benny Hinn the messiah. Here's a link to just one of many sites that has documented these yahoos saying the above. Is it true that scientists claim to be God?
I need to go back to the sandbox and learn to do bullets.
In the morning then.
You haven't met these guys then.
Yes they are for real
I saw no common sense in evidence from you.
Probably the best logical deduction for proof of evolution is that things are not reproduced as clones but different.
Thank you for the ping!
Because all of the proofs for or against are using the same, yet different source, and all the while the argument goes unpresented by either side, as perceived by each side, based upon the variable in perfection of the same, yet different source.
I think it's bedtime now. %-)
Not as far fetched as you would think. Elephants use their trunks in a variety of ways. Bathing,throwing dust on their backs, fighting, bending small trees, carrying stuff.
Scientists don't deny this. They just believe that God left evidence for our education.
I didn't provide a full answer. Let me try again:
As a general rule (and there are many journals with exceptions or small variations) the scientific report is structured thusly:
Title, (an accurate, descriptive and useful title), Authors, etc. (all authors, their institutional affiliations, and contact information) Abstract ( a terse summary), Introduction (a general discussion of why this experiment should have been done), Method (what was done and how, usually a very precise description),Apparatus (a tech description of the scientific equipment used and how it was used), Results section (wherein the hard data are presented with virtually no discussion resembling an interpretation, Interpretation of Results (The word interpretation is limited in its meaning here. It means a clarifying instruction manual on how to statistically assign significance to the various data. Here is the section where the authors have to say if they confirmed their hypothesis or not, Discussion (Here is the "speculative" section that disturbs you so.) Here, also, is where peer review can be seriously critical (I've published and served on peer reviews many, many times). The author cannot get away with bizarre or wild speculation, nor can the author speculate beyond positions inconsistent with the data and the known facts about the Topic, Summary (what we did, why we did it,how we did it, what we found, and what we think it means).
So, this is the "standard" protocol for the initial dissemination scientific research.
Your suggestions for improvement...?
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