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 In response to my opening statements my friend referenced some very popular arguments from a book entitled Darwin Black Box by Michael J. Behe. My friend: You should sit down and talk to my brother one of these days though. He's reading a book called Darwin's Black Box. I don't know if you've read it but you should give it a gander. One of the things my brother explained is about the blood in the human body. He can explain it better but it says something about how if evolution were to have occurred by Darwinism then EVERYTHING would have evolved. For example (taking various quotes from the book): the blood, which is irreducibly complex. If you take away one protein in blood that promotes clot formation, localization or removal of blood clots (there are about 30 proteins) then the irreducibly complex system would fail. For example: the body commonly stores enzymes (proteins that catalyze a chemical reaction, like the cleavage of fibrinogens) in the inactive form for later later use. The inactive forms are called pro enzymes. When a signal is received that a certain enzyme is needed, the corresponding pro enzyme is activated to give the mature enzyme. As with the conversion of fibrinogens to fibrin, pro enzymes are often activated by cutting off a piece of the pro enzyme that is blocking the critical area. The strategy is commonly used with digestive enzymes. Large quantities can be stored as inactive pro enzymes, then quickly activated when the next good meal comes along. Thromdin (which is a blood clotting protein) initially exists as the inactive form, prothromdin. Because it is inactive, prothromdin can't cleave fibrinogens, and the animal is saved from death by massive, inappropriate clotting. Still, dilemma of control remains, if fibrinogen and prothromdin were the only proteins in the blood clotting pathway, our animal would be in bad shape. When the animal was cut, prothromdin would just float helplessly by the fibrinogen as the animal bled to death. Because prothromdin cannot cleave fibrinogen to fibrin, something is needed to activate prothromdin. The blood clotting system is called a cascade - a system where one component activates another component, which activates a third component, and so on. Another protein called Stuart factor cleaves prothromdin, turning it into active thromdin that can then cleave fibrinogen to fibrin to form the blood clot. Unfortunately, as you may have guessed, if Stuart factor, prothromdin and fibrinogens were the only blood clotting proteins, the Stuart factor would rapidly trigger the cascade, congealing all the blood of the organism. So Stuart factor also exists in an inactive form that must first be activated. This is just an example of SOME of the blood clotting proteins, and we could go on and on for quite a while still. Alright if you skipped over most of that or failed to understand what Behe was talking about that's fine. It is meant to be confusing. In order to rebuttal Behe's points I had to learn what he was talking about or basically I read up on blood. My response: You brought up some wonderful arguments typically put forth by creationists. Let's break down some of these arguments. Let me start, however, by stating that just because something is complex does not mean that it is designed by a creator. In the book Darwin's Black Box, Behe is able to present things in a way that may seem plausible to an uninformed reader. I.e. it sounds sciencey. First he presents a bad argument, such as: intermediates are impossible in the development of a complex system. No one scientifically trained would accept this, but a member of the general public might find it convincing. “If you take away one protein in blood that promotes clot formation, localization or removal of blood clots (there are about 30 proteins) then the irreducibly complex system would fail.” -Behe Behe is saying that complex protein structures contain up to 5 -7 positions that must work in this sort of chain. Also known as an “cascading effect” this is where one protein activates another protein, which causes another protein to activate, and so on and so on. Basically Behe is arguing that this would simply be too complex a process to evolve on it’s own. An immense body of research, some of which I sight at the end, refutes this. ... See More A recent paper, for instance, by Krem and Di Gera have found numerous biochemical similarities in protein structures between horseshoe crabs, fruit flies, and humans. Let me remind you Behe believe in evolution for non-vertebrates. Seems a bit hypocritical to me. Furthermore these similarities suggest that these cascades were built by adding enzymes from the bottom of the cascade up and from similar macromolecular building blocks. In other words this provides evidence that we not only share a common ancestor with these species but we also have evidence for how these so called too complex protein structures could have evolved. Second Behe only discusses one type of protein structure typical of antibodies. There are many other types of protein structures (kinases, phosphatases, proteases, adaptor proteins, sumoylation enzymes, etc) that use only 2 to 3 positions of amino acids. If you randomly take 400 amino acids divided equally into 4 types of acids and watched the amino acids couple, then triple, and so on and calculated the amount of random combination it actually would be quite possible. Also much work has come out demonstrating that new protein interactions and protein networks can evolve fairly rapidly and within the limits of evolution. Conversely there are many other aspects of blood that scientists have figured out the evolutionary path of. Hemoglobin, for example, is a wonderful protein that picks up oxygen in the lungs and delivers it to that rest of the cells. There is so much work on the evolutionary processes behind hemoglobin (see Krem & Ceri for example) I will also mention that in Behe book he discusses hemoglobin only briefly (pp. 206-207) and states that it makes a poor example of design.Great job Behe leave out the stuff that disproves your theory/religion. http://www.talkorigins.org/origins/postmonth/feb97.html Krem MM, Di Cera E. (2002). Evolution of enzyme cascades from embryonic development to blood coagulation. Trends in Biochemical Sciences 27(2):67-74. Miller K. Finding Darwin's God: A Scientist's Search for Common Ground Between God and Evolution Cliff Street Books, 1999. Hardison, R. 1998. Hemoglobins from bacteria to man: Evolution of different patterns of gene expression. Journal of Experimental Biology 201:1099-1117. Leave Comment:
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