Blood Clotting: How did it evolve, if it did (Humans)

by David Turell , Thursday, December 03, 2015, 00:49 (3278 days ago) @ David Turell


> David: First problem with considering evolution inventing this is the mechanism obviously must have a controlled start and a controlled stop. This cannot be invented by hunt and peck; it must work from the beginning. After this stage the clotting factors appear and there are over 17 of them, all in beautiful coordination. I can't think of anything but design. In organisms with a blood/circulatory system this is a 'must' for life to survive.- Another article further describing the mechanism. It is this sort of complex arrangement that leads to my belief in God:-http://www.evolutionnews.org/2015/11/clotting_contro101231.html-"To prevent serious injury or death, the body had to come up with a mechanism that could apply a substance strong enough to stop the blood loss. -"This innovation is called hemostasis and involves three actions; vasoconstriction, platelet aggregation, and activation of the clotting factors. Hemostasis ultimately forms a fibrin clot, stops the bleeding, and allows healing to take place. However, since heart attacks and strokes occur due to clotting, the body must be able to control hemostasis so that it only turns on when it's needed and turns off and stays off when it's not. In other words, controlled hemostasis is a delicate balance between the forces that promote and prevent clotting. -***-"So, in summary, the clottingfactors in the blood remain inactive until blood vessel injury takes place to turn on the coagulation cascade. Meanwhile, the liver and the endothelium combine to produce anti-clotting factors that together work to turn off hemostasis and allow it to stay off when it's not needed. It is this delicate balance of clotting and anti-clotting factors that allows the body to normally be able to stop bleeding when injured, while at the same time allowing blood to flow freely to the tissues. Moreover, the total absence of fibrinogen, or prothrombin, or Tissue Factor, or Factor V, or Factor VII, or Factor VIII, or Factor IX, or Factor X, or Factor XI, or Factor XIII, or antithrombin, or protein C or TFPI would have made it impossible for our earliest ancestors to live long enough to reproduce. -"Michael Behe has described a system where the absence of any one part renders it non-functional as being irreducibly complex. It certainly looks like hemostasis is irreducibly complex, because if any one of the many clotting or anti-clotting factors were absent life would be impossible."-Comment: If you kept count there are 17 or so various factors acting to promote and to stop clotting. I can't think of a Darwinian just-so story to make this happen by chance or by itty-bitty steps by innovation.