In the eye of the beholder

A  short science news piece in the New York Times (“ In a Marine Worm’s Eyes, the Theory of Evolution,” March 1st) reported that scientists have found in the embryos of marine worms what may be one of the precursors of the eye, long a favourite bugaboo of intelligent design (ID) opponents of the evolution creation story.

Even if the modern eye has developed from more primitive eyes, the critics challenge, how did such a complex mechanism ever develop in the first place in simple, sightless creatures? The current researchers found significant light-sensing capability in the few hundred cells of the embryos of worms that have been around for half a billion years:

Four-day-old lamp shell larvae, for example, have puzzling dark spots on either side of the front end of their bodies. Recently, Carsten Lüter, a biologist at the Berlin Museum of Natural History, and his colleagues dissected the eyespots of some lamp shell larvae. They discovered that each spot was actually a pair of neurons, one for capturing light and one containing pigment. The neurons connected to a brainlike clump of neurons inside the larva.

More surprising, the researchers found that the light-sensitive genes were active in embryos as young as thirty-six hours old, before neurons had begun to form. What could be the purpose of photoreceptors at such a young stage of development? The researchers addressed this question by placing a light on one side only of a dish of embryos, with a clear result:

The lamp shell embryo is covered with tiny beating hairs, which it uses to swim in a spiral pattern. . . . after 20 minutes, twice as many embryos would end up on the illuminated side of the dish as on the dark side. . . . [Researchers] hypothesize that the cells can detect the direction of light because it is blocked in some directions by the embryo’s yolk. It can then use this information to change the rhythm of its hair.

Later, they speculate, this photosensitivity became concentrated in a specific group of cells, leading after millions upon millions of generations to the first recognizable eye.

This is, of course, neither the first nor the only evidence for the natural development of highly sophisticated physical systems like the eye. But it continues the assault on the pseudo-science that is ID theory. There are crucial differences between this kind of science and the science-like “evidence” of ID. For one thing, real science doesn’t dismiss existing data. ID evidence is always highly selective. Richard Dawkins, for one, concedes that evolutionary theory would fall if there were even one truly irrefutable piece of contrary evidence. Find one human toe bone in a bed of ancient dinosaur fossils, for example, and the whole theoretical edifice crumbles. That’s how science works.

ID pseudo-science has different criteria. The goal for the ID scientist is to find among mountains of confirmatory data just one piece of ambiguous evidence which can be re- or mis-interpreted to support a divine origin or young earth scenario, then to use that creative leap — in spite of or ignoring all the other evidence and all the other explanations of almost all of his or her colleagues — to challenge the enormous weight of physical evidence and theoretical probability that argues for the other side. The process looks like the scientific method, but its conclusions are always rigidly predetermined, so the search for proof is always narrow and prejudicial.

Postmodernist critics of scientific rationalism argue that science is always conducted like this — that theory leads to expectation, leads to a certain type of investigation, leads to a favoured conclusion. Perhaps. But in real science the favoured theory falls when enough contrary evidence emerges. No evidence ever refutes the presuppositions of creation science. To claim that the rigour and discipline of real science is like the preconceptions and selectively of ID pseudo-science is disingenuous at best and often intentionally deceptive.

Besides, as I’ve noted elsewhere, the anti-evolution offensive of the fundamentalists is misguided from the start. What would disproving evolution prove? Certainly not that their belief in God is justified. Even if all of the evidence and all of the results of all of the studies of all of the theories and all of those theories themselves were proved absolutely wrong, of no more rational validity than astrology, that disproof would not in the least lend proof to the existence of a supernatural creator. It just doesn’t work that way. I’m wrong that the moon is made of green cheese, therefore God exists? Hardly! My example may be silly, but the point is fundamental — and something which too many believers fail to grasp.

So let the ID supporters cherish their “cherry-picked” evidence and “just so” stories. Let them continue to search for that one piece of sufficiently ambiguous material that lets them concoct their hugely improbable (and often simply wrong) interpretations. Let them misrepresent, misapprehend, mistake, and misconstrue the weight of evidence. Let them dismiss and ignore the judgement of everyone else in the field.

It’s not going to do them any good.