Saturday, February 6, 2016

Impossibility Theory, An Advance over Mere Indeterminacy: By Werner Fredsenberg (Fred Reed)

Previously I have proved that life cannot have evolved. Today I will prove that life cannot exist.
Let us begin with Samuel Johnson’s response when asked whether we have free will. He replied that all theory holds that we do not, all experience that we do. A similar paradox occurs in the realm of Impossibility Theory. Many things occur in biology that all science says are possible, while all common sense says that they are not.
Consider the development of a barely-existent zygote into seven pounds of puzzled and alarmed baby. (“Where the hell is this?”) Anyone familiar with Murphy’s Law knows that it isn’t possible. Half an hour with a textbook of embryology will confirm this judgement. It is a case of phenomenal complexity following phenomenal complexity building on phenomenal complexity with, almost always, no errors of consequence.
The resulting little science project enters wherever we are with a squall, the ductus arteriosus closes, the nursing instinct kicks in, and the interloper eventually grows into, God help us, a teenager (arguably the only flaw in the process)….

Suspensory ligaments, connecting the lens of the eye to the ciliary body. Do you really believe these delicate ropes can form perfectly all by themselves ? If so, I figure somebody must have put something in your drugs.
Common sense says that it can’t work. The sciences say that it can, and the fact that it does lends a certain weight to their argument. Each step in this impossible process can be shown to follow the laws of chemistry and physics. It all works. There is no need for spirits or poltergeists to explain it. Except that it obviously can’t happen.
Sez me, Something Else has to be involved. You tell me what, and we will split the Nobel money……

The following simplified description of the biochemical functioning of the retina is fromDarwin’s Black Box: The Biochemical Challenge to Evolutionby Michael Behe. The book, which I recommend, is accessible to the intelligent laymen, for whom it is written. The author includes the following techno globe on the biochemistry of the retina to give a flavor of the complexity of things. The sensible reader will skip  most of it.
When light first strikes the retina a photon interacts with a molecule called 11-cis-retinal, which rearranges within picoseconds to trans-retinal. (A picosecond is about the time it takes light to travel the breadth of a single human hair.) The change in the shape of the retinal molecule forces a change in the shape of the protein, rhodopsin, to which the retinal is tightly bound. The protein’s metamorphosis alters its behavior. Now called metarhodopsin II, the protein sticks to another protein, called transducin. Before bumping into metarhodopsin II, transducin had tightly bound a small molecule called GDP. But when transducin interacts with metarhodopsin II, the GDP falls off, and a molecule called GTP binds to transducin. (GTP is closely related to, but critically different from, GDP.)
GTP-transducin-metarhodopsin II now binds to a protein called phosphodiesterase, located in the inner membrane of the cell. When attached to metarhodopsin II and its entourage, the phosphodiesterase acquires the chemical ability to “cut” a molecule called cGMP (a chemical relative of both GDP and GTP). Initially there are a lot of cGMP molecules in the cell, but the phosphodiesterase lowers its concentration, just as a pulled plug lowers the water level in a bathtub. Another membrane protein that binds cGMP is called an ion channel. It acts as a gateway that regulates the number of sodium ions in the cell. Normally the ion channel allows sodium ions to flow into the cell, while a separate protein actively pumps them out again. The dual action of the ion channel and pump keeps the level of sodium ions in the cell within a narrow range. When the amount of cGMP is reduced because of cleavage by the phosphodiesterase, the ion channel closes, causing the cellular concentration of positively charged sodium ions to be reduced. This causes an imbalance of charge across the cell membrane that, finally, causes a current to be transmitted down the optic nerve to the brain. The result, when interpreted by the brain, is vision. If the reactions mentioned above were the only ones that operated in the cell, the supply of 11-cis-retinal, cGMP, and sodium ions would quickly be depleted. Something has to turn off the proteins that were turned on and restore the cell to its original state. Several mechanisms do this. First, in the dark the ion channel (in addition to sodium ions) also lets calcium ions into the cell. The calcium is pumped back out by a different protein so that a constant calcium concentration is maintained. When cGMP levels fall, shutting down the ion channel, calcium ion concentration decreases, too. The posphodiesterase enzyme, which destroys cGMP, slows down at lower calcium concentration. Second, a protein called guanylate cyclase begins to resynthesize cGMP when calcium levels start to fall. Third, while all of this is going on, metarhodopsin II is chemically modified by an enzyme called rhodopsin kinase. The modified rhodopsin then binds to a protein known as arrestin, which prevents the rhodopsin from activating more transducin. So the cell contains mechanisms to limit the amplified signal started by a single photon. Trans-retinal eventually falls off of rhodopsin and must be reconverted to 11-cis-retinal and again bound by rhodopsin to get back to the starting point for another visual cycle. To accomplish this, trans-retinal is first chemically modified by an enzyme to trans-retinol— a form containing two more hydrogen atoms. A second enzyme then converts the molecule to 11-cis-retinol. Finally, a third enzyme removes the previously added hydrogen atoms to form 11-cis-retinal, a cycle is complete.
The biochemistry is way over my head, but the complexity is clear. The idea that this came about by accident requires powers of belief beyond mine, and the idea that it functions flawlessly for seventy years is more so. Ask a biochemist whether he can construct this system in the laboratory. Ask him whether he can construct any system of similar complexity that will work, maintaining itself, for seventy years.
From all of which I conclude that we are more puzzled than we believe we are. These thoughts will not be well-received by those more inclined to protect the paradigm than to examine it. Oh well.