72 Human Devolution: a vedic alternative to Darwin’s theory
In I-cell disease, a flaw in signal tagging disrupts the vesicular transport system. Instead of carrying the protein-degrading enzymes from the ribosomes to the lysosomes, the system carries them to the cell wall, where they are dumped outside of the cell. Meanwhile, damaged proteins flow into the lysosomes, where they are not degraded. Without the proteindegrading enzymes, the lysosomes fill up like overflowing garbage cans. To deal with this, the cell manufactures new lysosomes, which also fill up with garbage proteins. Finally, when there are too many lysosomes filled with garbage proteins, the whole cell breaks down and the person with this disease dies. This shows what happens when one part of a complex system is missing—the whole system breaks down. All the parts of the vesicular transport system have to be in place for it to work effectively.
Behe (1996, pp. 115–116) says: “Vesicular transport is a mind-boggling process, no less complex than the completely automated delivery of vaccine from a storage area to a clinic a thousand miles away. Defects in vesicular transport can have the same deadly consequences as the failure to deliver a needed vaccine to a disease-racked city. An analysis shows that vesicular transport is irreducibly complex, and so its development staunchly resists gradualistic explanations, as Darwinian evolution would have it. A search of the professional biochemical literature shows that no one has ever proposed a detailed route by which such a system could have come to be. In the face of the enormous complexity of vesicular transport, Darwinian theory is mute.”
The Blood Clotting mechanism
The human blood clotting mechanism is another puzzle for evolutionists. Behe (1996, p. 78) says: “Blood clotting is a very complex, intricately woven system consisting of scores of interdependent protein parts. The absence of, or significant defects in, any one of a number of the components causes the system to faiclass="underline" blood does not clot at the proper time or at the proper place.” The system is thus one of irreducible complexity, not easily explained in terms of Darwinian evolution.
The blood clotting mechanism centers around fibrinogen, a blood protein that forms the fibers that make up the clots. Normally, fibrinogen is dissolved in the blood plasma. When bleeding begins, a protein called thrombin cuts fibrinogen to make strings of a protein called fibrin. The fibrin filaments stick together, forming a network that catches blood cells, thus stopping the flow of blood from a wound (Behe 1996, p. 80). At first, the network is not very strong. It sometimes breaks, allowing the blood to flow out from the wound again. To prevent this, a protein called the fibrin stabilizing factor (FSF), creates cross links between fibrin filaments, strengthening the network (Behe 1996, p. 88).
Meanwhile, thrombin is cutting more fibrinogen into more fibrin, which forms more clots. At a certain point, the thrombin has to stop cutting fibrinogen or else so much fibrin would be produced that it would clot up the whole blood system and the person would die (Behe 1996, p.81).
There is a complex cascade of proteins and enzymes involved in turning the blood clotting system on and off at the proper times. Thrombin originally exists as an inactive form, prothrombin. In this form, it doesn’t cut fibrinogen into the fibrin filaments that make clots. So for the clotting process to start, prothrombin must be converted to thrombin. Otherwise, a person bleeds to death. And once the proper clotting is formed, thrombin has to be turned back into prothrombin. Otherwise, the clotting continues until all the blood stops flowing (Behe 1996, p. 82).
A protein called the Stuart factor is involved in the activation of prothrombin, turning it into thrombin, so that the clotting process can start. So what activates the inactive Stuart factor? There are two cascades of interactions, which begin with transformations at the wound site. Let’s consider just one of them. Behe (1996, p. 84) says: “When an animal is cut, a protein called Hageman factor is then cleaved by a protein called HMK to yield activated Hageman factor. Immediately the activated Hageman factor converts another protein, called prekallikrein, to its active form, kallikrein. Kallikrein helps HMK speed up the conversion of more Hageman factor to its active form. Activated Hageman factor and HMK then together transform another protein, called PTA, to its active form. Activated PTA in turn, together with the activated form of another protein called convertin, switch a protein called Christmas factor to its active form. Finally, activated Christmas factor, together with antihemophilic factor . . . changes Stuart to its active form.” The second cascade is equally complicated, and in some places merges with the first.
So now we have the activated Stuart factor. But even that is not enough to start the clotting process. Before the Stuart factor can act on prothrombin, prothrombin has to be modified by having ten of its amino acid subunits changed. After these changes, prothrombin can stick to a cell wall. Only when the prothrombin is adhering to a cell wall can it be converted (by the Stuart factor) into thrombin, which initiates clotting. The sticking of the prothrombin to the cell wall near a cut helps localize the clotting action in the exact region of the cut. But activated Stuart factor protein turns prothrombin into thrombin at a very slow rate. The organism would die before enough thrombin is produced to start any effective clotting. So another protein, called accelerin, must be present to increase the speed of the Stuart factor protein’s action on prothrombin (Behe 1996, pp. 81–83).
So now the prothrombin is converted into thrombin. The thrombin cuts fibrinogen, forming fibrin, which actually forms clots. Now we can turn to the question of how to stop this clotting process once it starts. Runaway clotting would clog up the organism’s blood vessels, with life threatening results. After thrombin molecules have formed, a protein called antithrombin binds to them, thus inactivating them. But antithrombin binds only when in contact with another protein called heparin, which is found in uninjured blood vessels. So this means that the antithrombin binds to the activated thrombin molecules only when they enter undamaged blood vessels, thus inactivating them and stopping the clotting. In an injured blood vessel the clotting can continue. In this way, the clotting goes on only at the site of the wound, and not in other uninjured blood vessels. Once the injured vessel is repaired the clotting will also stop there. This is accomplished by a process just as complex as the one that stops blood from clotting in uninjured blood vessels (Behe 1996 pp.87–88).
After some time, when the wound has healed, the clot itself must be removed. A protein called plasmin cuts the fibrin network that makes up the clot. As one might guess, plasmin first exists in its unactive form, plasminogen, and must be activated at the proper time to remove the clot. Its activation, of course, involves complex interactions with other proteins (Behe 1996, p. 88).
Behe (1996, p. 86) says, “The blood-clotting system fits the definition of irreducible complexity. That is, it is a single system composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system effectively to cease functioning . . . In the absence of any one of the components, blood does not clot, and the system fails.” Evolutionists have not offered any satisfactory explanation for how this complex chemical repair system, involving many unique proteins with very specific functions, came into existence.