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." |
Whatever feminine silliness you ascribe, notice that I don't attempt to psych-anal you--
But, I am not in this article, it's about a primitive fish and there's nothing in the article about that fish's manner of olfaction. Yet you said (But our ears could smell--until we evolved. That's according to the peers who pitch their wares here--) there was and used that false statement to criticize the article.
It would seem you're more motivated to hurl false claims that to honestly debate the substance.
It's always sad when people stick to their opinion and don't take into account that someone else, with differing views, might actually have knowledge that might have merit. People should be open to learning and possibly expanding their knowledge and horizons.
New answer to the immortal question:
How does a fish smell?
(drumroll)
Awful!
(budum-chhh)
(crickets)
That's what you think.
Every time that I quote The Book, I am told that that's the Wrong Book, and I need to read a different Version of The Book, which says something totally different, and then somebody else pipes in with their Version of The Book, which says something totally different, and then somebody mentions differing Hebrew and Greek versions of The Book, which are the Only True Versions of The Book, which nobody actually has access to, assuming that they could read it if they did, so we have to rely on Translations of The Only True Versions of The Book, of which There Are Many, but only One True Translation, and the debate rages for days, sometimes weeks, and when it is all over nobody has any idea what actually happened.
A scientist is as good or bad as any other person--this is the basic assertion I make. They can discover a great medicine--or they can feed you hokum and jeer at you when you doubt them.
When it comes to metaphysical questions, I look to philosophy, literature and religion to ask questions and to sometimes provide some approximation of answers. Let science discover a cure for common cold and fully explain how aspirin works (another mystery of aspirin was reported by scientists this morning) before tackling questions that rightly belong to other disciplines.
Which is why I read. A lot.
Actually the UK House of Lords has enough expertise under it's belt to blow any Paleyist organiation out of the water.
And then there is the practice of granting a peerage to emminant scienists - even the Creationist heroes Lord Kelvin and Lord Zuckerman got a guernsey (although I hold ouu hope for a Lord Dawkins as a successor to Lord Medawar)
And, unlike religionists, scientists never speak in absolutes because there is always the potential that tomorrow something could turn up that would obviate any given statement.
And some people's asses still talk.
Honest, you don't have to think in metaphors or even catch a pun. That's not for evos. Just let it all whiz by.
(thanks, though, that was interesting)
Especially after a large meal of legumes.
If you check out my post 29, it seems that the distal strucures of the ear (tympanum, ossicles, etc.) and their evolution coincide nicely with the evolutionary development of the proximal, neural structures of the vertebrate ear (and the data I posted were reported in the 1930's and '40's.)
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