Tuesday, December 4, 2007

Keeping Half an Eye on Behe

Decidedly unintelligent intelligent-design proponent Michael Behe has long been one of the loudest voices in the shouting match that the attempt to get supernaturalism into public schools often becomes. Behe, a biochemist at the Lehigh University, is the man responsible for first coining the term "irreducible complexity," which refers to the supposed property of some biological features (both on a micro and macro level) which, Behe thinks, are far too complicated to have evolved by natural selection. Ignoring for the moment that this is a piss-poor argument that amounts to little more than "Well I can't imagine how it could have happened; therefore, God did it!", I'm happy to report that Behe's been dealt a bit of a blow today.

One of Behe's favorite macro examples of an irreducibly complex feature is the human eye which, he claims, is such a marvel of adaptation that it couldn't possibly have come about over time (he likes to point to a quote attributed to Darwin, in which the scientist laments "the difficulty of believing that a perfect and complex eye could be formed by natural selection"); after all, Behe asks, "what good is half an eye?" Now, it seems that scientists have answer that question, and the answer is "better than no eye at all." Researchers at Australian National University, the University of Queensland, and the University of Pennsylvania have, through a cooperative effort, proposed a way in which the vertebrate "camera eye" could plausibly have evolved.

Their research paper is long and full of biological jargon (it's here if you want to read it anyway), but the first paragraph more or less sums up their point:

More than 600 million years ago (Mya), early organisms evolved photoreceptors that were capable of signalling light, and that presumably mediated phototaxis, predator evasion by shadow detection or vertical migration, and the entrainment of circadian rhythms. However, it was not until the Cambrian explosion, beginning around 540 Mya, that animal body plans began evolving very rapidly2, 3, 4 and image-forming eyes and visual systems emerged. The possession of advantageous capabilities or attributes, such as sight, rapid movement and armour, might have become crucial to survival, and might have led to an 'arms race' in the development of defensive and offensive mechanisms5. In the various phyla eyes evolved with diverse forms, but apparently based on certain common underlying features of patterning and development, as exemplified by genes such as PAX6 and RAX (also known as RX), which have critical roles during neurulation and brain regionalization.
So what good is half an eye? Well, just having a light-sensitive organ (as opposed to the camera-like eye of modern vertebrates) could let you avoid predators (fast moving shadow approaching? Better scoot back under cover!), navigate (Remember, the sun and moon are up!), or know when to go out and feed (No more light outside the shelter? Time to party!).

There's a lot more to this discovery that, while interesting, is beyond the scope (and readership) of this blog. If you want to read more about it, check the study itself! For now, though, suck it, IDers.


Anonymous said...

Happy fail; you seem to not be able to read.

Your scientists' paper is made irrelevant in its first sentence, which you seem not to have caught: "early organisms evolved photoreceptors that were capable of signalling light".

Mmm? This sentence is not elaborated on. This is the phenomenon Behe writes about. Behe doesn't say that an eye couldn't have 'evolved' from photoreceptors (this is in fact one of Darwin's favorite 'examples' of 'evolution') but says that the photoreceptors could not have 'evolved' from nothing.

Reading your bio, you seem to be a student of philosophy. Philosophy is certainly a 'big picture' science, and therefore one of the most interesting and rewarding ones. However, you, as many, seem to have a tendency to miss the small picture; to ignore the detailed.

See that sentence? You seem to have, as most, brushed it off, ignored it. Photoreceptors, one might think, are tiny, primitive cells.

But they are intensely complicated. Behe shows that the network of proteins leading to the reception and translation of a single photon is ridiculously complicated, and would not work even if one step was omitted. 'Half an eye', in the allegorical/metaphorical sense, as Behe uses it, refers, as one who had read Behe would know, to 'half a photoreceptor'. And indeed, half a photoreceptor would be useless.

Anonymous said...

One must sacrifice one's intellect (and intellectual integrity) in order to believe (and argue) that metabolic, Von Neumann-type machines could arise by only random, natural processes in the first place, and in the second, that after the first miraculous cell(s) arose, random mutations resulted in newer, more complex genetic program, structure, and function.