Thursday, April 5, 2007

Eel sperm and Irreducible Complexity

Although it seems outlandish, there is still a heated debate over evolution in some circles. I don't support the dichotomy it produces between science and spirituality/religion, I think that view is too extreme on both sides. Supposedly from the folks engaged in this debate, you have to be either an atheist scientist or a biblical literalist -- there is no in-between.

Anyway, one of the most compelling and popular arguments for the anti-Darwin camp has come from Michael J. Behe, and hinges upon "irreducible complexity."

To keep an explanation of irreducible complexity short, lets use the example of a mousetrap -- but think of it as an organism. If it developed (evolved) in bits and starts over an enormous amount of time, it would have spent the grand majority of its existence inoperable. You would have a hinge running around without a trigger, or a hinge and a trigger without a platform upon which to operate. It wouldn't be able to catch it's prey, the mouse. Irreducible complexity says, in a nutshell, that massively intricate creations in nature couldn't possibly develop gradually, because they can't function in the intermediate states. The thing doesn't work til the very end of its evolution. Therefore, it was made all at once, bang.

Sperm comes up not only because it's a big crowd pleaser, but because the flagella in sperm (the whippy tail-thing) is one of the linchpins in this argument. The way flagella work is mind-bogglingly complex -- you can click on the picture heading this post to get a peek inside that mechanism. So, if scientists could find an intermediate form -- one that didn't have all the elements of modern flagella but worked anyway -- they'd be able to refute this piece of evidence.

They have found this evidence, in Eel Sperm. The link I provided there is to a long and relatively dull article explaining the situation in more detail. Point being, intelligent design folks who are trying to shoot down the current understanding of evolution and bring our understanding back to the world-view popular in the 1800's don't have many legs to stand on, and this one just got cut off.

Now although I don't prescribe to either of the extremist camps of this argument, I do take umbrage at the "results" of the modern creationist movement in society: reduction in federal funding for scientific research involving anything "evolutionary," and weakened science curricula in schools (U.S. teens in the lowest 25% of scientific understanding; over 1/2 the U.S. population believes that humans were formed as we are now ~10,000 years ago).

[Many thanks to Professor Estes at Portland State University for the ideas contained in the current RBT posts, as well as some text and images. This post is essentially a synopsis of one portion of her last lecture. Since she is teaching the one Bio class I have this term, I expect her work to figure prominently in the RBT's for the next 2 1/2 months]


Quotidian said...

Leave it to me to comment on sperm...

Anyway, dredging into the back of my mind, I seem to remember something about eel being able to change their gender in response to a decline in the population of the opposite gender.

Less reproduction mates = go **** yourself... with results.

So with my extremely limited knowledge, it wouldn't surprise me to find that the eel contains the different stages of sperm development. It would seem that the sperm only really need to travel when they are moving in search of eggs - something that would be more common in evolutionarily higher organisms. (Don't most fish and such use a smegma that kinda glues itself to the free floating eggs?) As a link between fish and whatever evolved to walk on land, the eel seems like it would be perfectly suited to develop things that land-dwellers would need - like mobile sperm.

(Am I completely wrong in this notion?)

Bpaul said...

I see from a brief flurry of research that some eels can change sex -- but the fact that they do in response to environmental cues I'm ignorant of at this point.

As for mobile sperm -- that predates vertebrates bigtime. They've been wiggling a loooong time, even in plants.

But a connection between the sex changing and a lesser or more primitive sperm seems quite plausible. I'll dig around a bit, I'm curious now.