Wednesday, August 12, 2009

Do Nerve Cells "Look Like They Evolved?"

In debate tournaments you can see smart people make a dubious proposition seem compelling. It reminds me of evolutionists who, while generally quite intelligent, are dogmatic that evolution is a fact. Though such a proposition is dubious, they can make it sound good. The reasonings that evolutionists weave, however, ultimately fail. No matter how sweet sounding is their coaxing, it falls apart under a little probing. One evolutionist, for instance, has responded to my point that evolution is based on religious premises.

I pointed out that Jerry Coyne's arguments for evolution rely on theological committments. Coyne's explanations for why the recurrent laryngeal nerve and the biogeographical distribution of the species, for example, rely on assumptions that what we observe would not have been designed or created. Hence they must have evolved.

In his response the evolutionist states that "if God designed the laryngeal nerve in this way, it sure looks a hell of a lot like evolution." This is the height of absurdity. This evolutionist (a palaeoanthropologist) apparently does not understand nerve cells very well. Let's have a look at the basics of nerve cells.

Nerve cells have a long tail which carries an electronic impulse. The tail can be several feet long and its signal might stimulate a muscle to action, control a gland, or report a sensation to the brain.

Like a cable containing thousands of different telephone wires, nerve cells are often bundled together to form a nerve. Early researchers considered that perhaps the electronic impulse traveled along the nerve cell tail like electricity in a wire. But they soon realized that the signal in nerve cells is too weak to travel very far. The nerve cell would need to boost the signal along the way for it to travel along the tail.

After years of research it was discovered that the signal is boosted by membrane proteins. First, there is a membrane protein that simultaneously pumps potassium ions into the cell and sodium ions out of the cell. This sets up a chemical gradient across the membrane. There is more potassium inside the cell than outside, and there is more sodium outside than inside. Also, there are more negatively charged ions inside the cell so there is a voltage drop (50-100 millivolt) across the membrane.

In addition to the sodium-potassium pump, there are also sodium channels and potassium channels. These membrane proteins allow sodium and potassium, respectively, to pass through the membrane. They are normally closed, but when the electronic impulse travels along the nerve cell tail, it causes the sodium channels to quickly open. Sodium ions outside the cell then come streaming into the cell down the electro-chemical gradient. As a result the voltage drop is reversed and the decaying electronic impulse, which caused the sodium channels to open, is boosted as it continues on its way along the nerve cell tail.

When the voltage goes from negative to positive inside the cell, the sodium channels slowly close and the potassium channels open. Hence the sodium channels are open only momentarily, and now with the potassium channels open, the potassium ions concentrated inside the cell come streaming out down their electro-chemical gradient. As a result the original voltage drop is reestablished.

This process repeats itself until the impulse finally reaches the end of the nerve cell tail. Although we’ve left out many details, it should be obvious that the process depends on the intricate workings of the three membrane proteins. The sodium-potassium pump helps set up the electro-chemical gradient, the electronic impulse is strong enough to activate the sodium channel, and then the sodium and potassium channels open and close with precise timing.

How, for example, are the channels designed to be ion-selective? Sodium is about 40% smaller than potassium so the sodium channel can exclude potassium if it is just big enough for sodium. Random mutations must have struck on an amino acid sequence that would fold up just right to provide the right channel size.

The potassium channel, on the other hand is large enough for both potassium, and sodium, yet it is highly efficient. It somehow excludes sodium almost perfectly (the potassium to sodium ratio is about 10000), yet allows potassium to pass through almost as if there were nothing in the way. The solution seems to be in the particular amino acids that line the channel and their precise orientation. For potassium, moving through the channel is as easy as moving through water, but sodium rattles around—it fits in the channel but it makes less favorable interactions with the amino acids.

Nerve cells are constantly firing off in your body. They control your eyes as you read these words, and they send back the images you see on this page to your brain. They, along with chemical signals, control a multitude of processes in our bodies. And no, they most certainly do not look as though they evolved.

The idea that nerve cells, such as the recurrent laryngeal nerve, "look like they evolved" is an unfortunate example of how religion has corrupted science. To an evolutionist, everything "looks" like it evolved, no matter how unlikely. We may as well say my bad day yesterday "looks" like it was caused by the stars.

My evolutionist critic, however, concludes that "It doesn't look like evolution if you refuse to accept that evolution happened." Huh? Apparently sensing a problem, the evolutionist resorts to attributing an extreme position to me. The irony is rich as it is the evolutionists who refuse to to accept design or creation. My critique of evolution is based on the theory, as presented by evolutionists, compared with the empirical evidence. I would be happy to accept evolution if it made sense.

The evolutionist next makes the usual appeal to "the MOUNTAINOUS amount of evidence for evolution." But this is precisely what Coyne's book is about. It presents that "MOUNTAINOUS amount of evidence" and the reasoning is metaphysical. Evolutionists give their reasons why they think evolution is a fact, and when you point out the flaws they are unmoved. "So what!? You're ignoring all the other evidence I didn't mention." Incredible.

Coyne also made an appeal to a famous paper by evolutionist Theodosius Dobzhansky. Dobzhansky was one of the twentieth century's leading evolutionists and he wrote a paper entitled "Nothing in biology makes sense except in the light of evolution."

I pointed out that the paper, including the title itself, is one long metaphysical argument for evolution, to which the evolutionist responds:

This is absurd. There is nothing metaphysical about the title of Dobzhansky's paper [...] As far as Dobzhansky's paper is concerned, the title is an observational statement. [...] Is his reasoning, as Hunter states, theological? No, quite the opposite. It is empirical.

How does one explain the obvious to those in denial? Dobzhansky's paper contains more theological claims than most church sermons. Here are some of Dobzhansky's theological pronouncements from the paper:

What a senseless operation it would have been, on God’s part, to fabricate a multitude of species ex nihilo and then let most of them die out!

They fancy that all existing species were generated by supernatural fiat a few thousand years ago, pretty much as we find them today. But what is the sense of having as many as 2 or 3 million species living on earth?



These are typical of the religious arguments in evolution dating back to Darwin and before. Evolutionists make religious declarations and then turn around and claim to be doing "just science." And the title of Dobzhansky's paper is unequivocally metaphysical. It is the logical equivalent of saying that nothing can explain biology except evolution. That is a truth claim unavailable to science.

Finally, the evolutionist finishes with a circular argument from authority, complaining that I have "no respect for scientists who, for the last 150 years have produced some of the finest scientific work in trying to understand how modern organisms are connected to each other and how they are connected to those which came before."

Here the evolutionist presupposes that evolution is true. If that were the case then, yes, the work should be acknowledged. But that is the point in question. Indeed, we have seen little evidence that evolution is a fact as evolutionists dogmatically mandate. And nothing that Coyne has written suggests otherwise.

Evolutionists are smart people, but no amount of brilliance can turn a frog into a prince. What is fascinating is the degree of denial that evolutionists exhibit. Religion drives science and it matters.