Something Fishy at Answers in Genesis
I don't generally go looking for articles at Answers in Genesis (AiG). I have written about them previously (the most explicit mentions being in I Can't Escape Fundamentalists Even When I'm Researching Pure Science, Creation Museum, Creation Museum/Creationist Rule of Thumb with the 2nd Law of Thermodynamics, AiG's Creation Museum Follow-Up, and Another Creation Museum Review), and I haven't been terribly impressed with anything coming from their organization. It would be a time sink to go looking for articles to debunk from their site, because there are so many bad articles to choose from (it would also be a bit superfluous since so many have already been covered in the Index to Creationist Claims). However, in a recent comment thread on Pharyngula, someone included a link to AiG, and I took the bait.
The introduction starts off simply and accurately enough.
It is well known that creatures which live permanently in water generally breathe through gills, not lungs. The lungfishes, which are able to survive long periods when their watery habitat dries up, are regarded as a peculiar exception.
In then goes on to set up a possible scenario by which lungs could have evolved, and adds the following statement.
For a long time it was believed that this swim-bladder was a logical ‘first step’ towards the later development of lungs as vertebrates conquered the land.
I don't know the full history of scientific thought on how lungs evolved, but I'll grant them that this could be true - that at one time, people believed it probable that lungs evolved from swim-bladders. Just keep in mind that it's not the current consensus.
Next, the article points out a simple fact about the natural world, but one which I don't see why would have any negative repercussions for evolution.
The first awkward fact, usually not mentioned in high school evolutionary texts, is that there are actually many modern species of fish (not mammals, but real fish) which have lungs as well as gills.
The article then points out a fact from the archaeological record that forces one to question the 'swim-bladder to lung story', and rightly so.
An even more bitter blow for evolutionists (again seldom seen in basic texts) is that fossil evidence has come to light forcing a 180-degree reversal in the ‘swim-bladder to lung’ story. Lungs appear to be much more ‘ancient’ than swim-bladders, so by this reasoning, lungs must have evolved into swim-bladders!
In fact, as noted in my other blog entry, this is the current consensus on the relationship between lungs and swim bladders. It's not just the fossil record that demonstrates this, but cladistics as well. Only teleosts have true swim bladders. Just like this article itself noted, there are other groups of fish that have lungs. And there exist other groups with structures intermediate between lungs and swim bladders. The most parsimonious explanation is that lungs evolved first, and only developed into bladders in one lineage. And just for reference, sharks and rays, which diverged from other fish around 450 millions years ago, don't have any type of lung or swim bladder at all.
Next was another statement that seems obvious enough.
Whether endowed with gills, lungs, or a combination of both, all fish, living or extinct, appear to be (or have been) well equipped for the requirements of their way of life.
But with that in mind, read the passage that immediately followed.
The ‘obvious’ evolution of lungs from swim-bladders turns out to be a myth. In addition, a literal evolutionary- chronological reading of the fossil record shows that evolution must have had remarkable foresight. In spite of the fact that lungs are not needed for survival (fish being able to cope well with gills) they appear and are prevalent among fishes at least 100 million years (on the alleged evolutionary time-scale) before their (imaginary) migration to the land. How wonderful of evolution to develop, all by chance of course, such a ‘test pattern’, ready to be taken out of mothballs when required.
It's like the author completely forgot what he had written just one paragraph before. If he acknowledged that living fish with lungs appear to be well adapted to their environments, why would he think it must have been 'foresight' that made lungs appear in the first place. And how could he write that 'lungs are not needed for survival' of fish, when he just listed examples earlier in the article of fish that do require lungs to survive. And the author never even considered fish with swim bladders that have secondarily evolved non-lung means of breathing atmospheric oxygen (such as bettas). It seems that air breathing is a useful adaptation for aquatic life without any consideration at all for life on land (though there are probably multiple reasons for this, as noted in my previous entry, one of the most obvious is that oxygen levels aren't as consistent in water as in the atmosphere, with some bodies of water being nearly completely devoid of oxygen).
I know there's not a whole lot of new information in this entry compared to my previous entry on lungs and swim bladders, but to read an article that no only ignores evidence and sets up a straw man explanation of evolution, but which also contradicts itself so clearly from one paragraph to the next, is just really frustrating. I couldn't read something that bad without venting about it here. It's just one more example of why not to trust AiG.
Added 2011-07-06 - I should add that I only covered the most obvious errors from the AiG article. There were numerous others, such as what's actually in biology textbooks, as well as details of which animals have lungs vs. swim bladders.