However, there are some homologies that do look positively disadvantageous. One of the cranial nerves goes from the brain to the larynx via a tube near the heart. In fish this is a direct route. But the same nerve in all species follows the same route, and in the giraffe it results in an absurd detour down and up the neck, so that the giraffe has to grow maybe 3-5 meters more nerve than it would with a direct connection. The “recurrent laryngeal nerve,” as it is called, is surely inefficient. It is easy to explain such an efficiency if giraffes have evolved in small stages from a fish-like ancestor; but why giraffes should have such a nerve if they originated independently … well, we can leave that to others to try to explain. [Mark Ridley, Evolution, Blackwell, p. 50, 1993]
It is yet another example of how evolution’s religion harms science. Let’s have a look.
Having it both ways
Evolutionists say that everything in the universe, indeed even the universe itself, just happened to spontaneously arise. And when dramatic differences are discovered in otherwise similar species, evolutionists do not lose a beat. Though evolutionists maintain that evolution is constrained by law, they are always able to imagine new contingencies to explain such dramatic changes.
Yet here, in the example of the giraffe’s recurrent laryngeal nerve, we are told that evolution was simply not able to remedy this gross inefficiency. Now of course there is no falsifying this account. Certainly, it is possible that the evolutionary account occurred as evolutionists imagine. But evolution’s ability to turn on a dime, switching from a new-designs-rapidly-appear narrative to an evolution-is-constrained narrative, depending on the problem at hand, makes the argument not as compelling as evolutionists insist it is.
Furthermore, in spite of the usual bold evolutionary claims, evolution in fact does not explain how the giraffe’s recurrent laryngeal nerve, or any nerve for that matter, evolved. The textbook informs the student that the inefficiency is “easy to explain” as a product of evolution, but in fact evolutionists provide nothing more than vague speculation. That last thing nerve cells look like is a product of evolution.
Nerve cells: More than just a wire
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.
Is the recurrent laryngeal nerve “surely inefficient”?
Evolutionists interpret biology, not surprisingly, according to evolution. They see biology as a series of kludges and flukes that just happened to come together. Naturally, they view the giraffe’s recurrent laryngeal nerve as an evolutionary blind alley. The nerve pointlessly got stretched. But in fact, on its long journey around the giraffe’s heart, the recurrent laryngeal nerve is hard at work. Gray’s Anatomy explains that as it winds around the subclavian artery the nerve sends several filaments to the cardiac plexus. It also sends branches to the mucous membrane, the oesophagus, and trachea. In fact, there is nothing like biology to remedy evolutionary misconceptions. Perhaps the recurrent laryngeal nerve is inefficient, perhaps it isn’t. But let’s try understanding it first before making theory-laden conclusions.
Nonetheless, this is what evolutionists believe. As evolutionist Jerry Coyne explains, the giraffe’s recurrent laryngeal nerve “makes no sense under the idea of special creation ... No form of creationism/intelligent design can explain these imperfections.” As he further explains in his book, Why Evolution is true:
One of nature’s worst designs is shown by the recurrent laryngeal nerve of mammals. Running from the brain to the larynx, this nerve helps us speak and swallow. The curious thing is that it is much longer than it needs to be. ... In giraffes the nerve takes a similar path, but one that runs all the way down that long neck and back up again: a distance fifteen feet longer than the direct route! ... This circuitous path of the recurrent laryngeal nerve is not only poor design, but might even be maladaptive. That extra length makes it more prone to injury. It can, for example, be damaged by a blow to the chest, making it hard to talk or swallow. But the pathway makes sense when we understand how the recurrent laryngeal nerve evolved. ... But the particular bad designs that we see make sense only if they evolved from features of earlier ancestors. If a designer did have discernable motives when creating species, one of them must surely have been to fool biologists by making organisms look as though they evolved. [82-5]
Or again, here is how evolutionist Richard Dawkins puts it:
The recurrent laryngeal nerve is a remarkable piece of unintelligent design. The nerve starts in the head, with the brain, and the end organ is the larynx, the voice box. But instead of going straight there it goes looping past the voice box. In the case of the giraffe, it goes down the full length of the giraffe’s neck, loops down one of the main arteries in the chest and then comes straight back up again to the voice box, having gone within a couple of inches of the voice box on its way down. No intelligent designer would ever have done that.
Some people are not quite sure what to make of this evolutionary metaphysics. In order to understand evolution, one needs to listen to what the evolutionists are saying. You may not agree, but this is what evolutionists believe. What if you believed the things evolutionists insist must be true? It may be difficult, but pretend for a moment that you actually believed as Darwin and the evolutionists do. Then, of course, you would say evolution is a fact. You would have to agree that the details are not well understood, but so what? So what if the theory is bizarre given the science—it must be true, one way or another.
This is rationalism.
When I pointed out this recurrent laryngeal nerve argument in my previous posting, a professor commented that this is not a problem for evolution, but rather a problem for me:
1. Either there is no prediction of what an omnipotent, designer would do,
2. ... or there is a prediction.
In the former case it is then clear that there is no prediction, the assumption of such a Designer makes no predictions about anything, and if so this hypothesis is not science.
In the latter case, there is a prediction and the giraffe’s recurrent laryngeal nerve is evidence against it.
We’ve been over this ground here many times. Cornelius has never explained what, if any predictions the hypothesis of Design makes.
The problem is that opponents of evolutionary biology want to have it both ways. In other cases they try to make predictions that an omnipotent Designer would not make certain kinds of designs. The simplest example is junk DNA. People who argue that there is evidence for Intelligent Design often say that it does make a prediction—that there will not be junk DNA. They never, ever, say where in their theory this prediction comes from, because to do so would be to admit that its origin is in theology. An intelligent, benign Designer would just not do it that way, they are arguing.
Cornelius continues to be caught on this dilemma and continues to try to argue that there is no prediction from Design, but continues to try to maintain that Design is science. He’s stuck. We’ve been over this ground many times here, and he is still stuck. He can get unstuck by disavowing the junk DNA prediction, but then he’s ultimately going to have to admit that his Design hypothesis is not science.
Rationalists place their need to know above limitations of their knowledge. If you point out the limitations they will criticize you for violating science’s intellectual necessity. They will even turn their dilemma onto you, assuming you face the same problem (no, I do not have a “Design hypothesis” as the professor thinks).
But how can we possibly know how the giraffe’s recurrent laryngeal nerve (or DNA that evolutionists label as junk, or a thousand other structures) ought to be designed? We barely understand how it even works. I would be the first to agree, indeed the first to argue, that our ability to judge and predict how an omnipotent designer would and would not make certain kinds of designs is limited. I will be happy when we can simply understand how those designs work.
I will be even happier when evolutionists cease their claims that evolution is a scientific fact based on metaphysical claims. If the professor is sure the design theory fails to qualify as science because it argues nature looks like it was designed, then why does he not also hold that evolution fails to qualify as science because it argues nature looks like it was not designed? Is it OK to argue what a designer would not do, but not OK to argue what a designer would do?
Evolutionists are fond of declaring what is and is not legitimate science, but their arguments are hypocritical. Science must stick to what is testable, they insist, but they then make all manner of untestable, metaphysical claims.
Evolutionists have taken science far afield. They have immersed science in their religious and philosophical concerns. And when you point it out they blame you for causing the problem. Religion drives science and it matters.