Our ears once breathed [evolution of ears]

Nature Magazine ^ | 18 January 2006 | Helen Pearson

[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."

---

Footnote 1: Brazeau M. D.& Ahlberg P. E. Nature, 439. 318 - 321 (2006).

[Coyoteman]

All these "discoveries" and "facts" seem to be set 370 million years ago. I think they do that so that not as many people will laugh at them.

Here's one a bit more recent. Happy now?

---

Fossil: KNM-ER 3733 Site: Koobi Fora (Upper KBS tuff, area 104), Lake Turkana, Kenya (4, 1)

Discovered By: B. Ngeneo, 1975 (1)

Estimated Age of Fossil: 1.75 mya * determined by Stratigraphic, faunal, paleomagnetic & radiometric data (1, 4)

Species Name: Homo ergaster (1, 7, 8), Homo erectus (3, 4, 7), Homo erectus ergaster (25)

Gender: Female (species presumed to be sexually dimorphic) (1, 8)

Cranial Capacity: 850 cc (1, 3, 4)

Information: Tools found in same layer (8, 9). Found with KNM-ER 406- A. boisei (effectively eliminating single species hypothesis) (1)

Interpretation: Adult (based on cranial sutures, molar eruption and dental wear) (1)

See original source for notes:
Source: http://www.mos.org/evolution/fossils/fossilview.php?fid=33

[wyattearp]

To be ignorant is curable.

On crevo threads? You're kidding, right?

[Ichneumon]

Let me translate the article for you: I don't want there to be a God. I don't want to be responsible to a God. I don't want to think that maybe I'm not the highest thing in the Universe. But more than anything, I don't want you to think that their is a God who is smarter than we scientists because in our little world, WE ARE GOD.

You really need to work on your reading comprehension. That's not at all what it says.

[crghill]

I'll get over myself the moment that people who are scared to death of religion get over themselves trying to prove there is no God.

[shuckmaster]

Let me translate the article for you:

That's not exactly how I would translate the article about fish ears but, I basically agree with your statement.

[crghill]

That's exactly what it says!

[Emmett McCarthy]

And it proves exactly what?

[phantomworker]

Of course there is a God! And evolution exists as well.

[Rudder]

The article got me to thinking about the evolution of the neural connections for the ear and I went searching for some old articles I'd read in college. To wit:

" In the head region, large neuromasts in groves are present besides small pit organs (Fig. 10-4). These large sense organs seem to correspond to the 'head canal organs'. Five series of the large groove organs can be seen: (1) supraorbital, (2) occipital, (3) preorbital, (4) infraorbital, and (5) postorbital besides many pit organs. The small pit organ system of the head consists of four rows: (1) rostral (supra-maxillary), (2) mandibular, (3) periorbital, and (4) opercular. The structure of the head pit organs is essentially similar to those in the trunk. Each neuromast in the groove organs bears a large transparent jelly-like cupula (170 micron height) on its surface (Fig. 10-4). The cupula cannot be seen in intact living fish because it is transparent. Presence of the cupula can be demonstrated by immersing living fish in 0.004 percent solution of Wasserblau (Grubler) for two days. The surface of the cupula is stained blue by this dye. The cupula is stiff and flexible. The structure is homologous with the crista ampullaris of the inner ear. Gerard (1936) inferred that the inner ear of vertebrates has phylogenetically derived from a primitive lateral line system."

[Oztrich Boy]

Sleazy strawman alert

[Mamzelle]

Is "Nature" magazine peer-reviewed?

[Ichneumon]

I'll get over myself the moment that people who are scared to death of religion get over themselves trying to prove there is no God.

If I ever meet anyone like that, I'll be sure to let them know. Now, what relevance does that have to the current study?

[OrioleFan]

Amazing what we have been able to learn from the comet dust that just returned...

[crghill]

If people want to knock religous thought, let them do that. Just don't try to mislead the whole world into believing that a microbe tripped on the sand, grew into a snail, which fell off a ledge and became a snake that became a monkey that metamorphed into a human being. That's just stupid!

[Coyoteman]

The challenge from you was "All these "discoveries" and "facts" seem to be set 370 million years ago. I think they do that so that not as many people will laugh at them."

I posted a "discovery" and "fact" much younger. I figured you would be happy that not everything was 370 million years old.

Just no pleasin' some folks!

[microgood]

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."

This statement puts into doubt any objectivity on the part of the researcher. It appears the motive behind the work is not related to advancing scientific knowledge, but sticking a hot poker in the eye of those he detests.

[Ichneumon]

Is "Nature" magazine peer-reviewed?

Yes it is.

[CarolinaGuitarman]

"If people want to knock religous thought, let them do that. Just don't try to mislead the whole world into believing that a microbe tripped on the sand, grew into a snail, which fell off a ledge and became a snake that became a monkey that metamorphed into a human being. That's just stupid!"

I agree. Your post is stupid.

[wyattearp]

I'll get over myself the moment that people who are scared to death of religion get over themselves trying to prove there is no God.

You are making some rather asinine assumptions here:

1) that people here are scared to death of religion.
2) that people here are trying to prove that there is no God.

1 assumes facts not in evidence (got any?), and 2 is the fallacy of proving a negative. Other than that, you're... um... well, you're 0 for 2.

[crghill]

Exactly!