What is the evolutionairy theory on the Giraffe?

I've been watching this thread with interest.Question to evolutionists: If the giraffe's neck would have required many random mutations without the advantage of selection, do you agree this would make the evolution of the giraffe's neck highly implausible?Gotta run. I should be back sometime tomorrow.

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Actually a good question, my first answer would be yes, it would be implausable.

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Well, here is the dilemma you face. Did you know that a full grown giraffe's heart weighs over 24 pounds and pumps 16 gallons a minute? Because the giraffe's heart is much larger than his head, a series of special one-way, back-flow preventer valves are needed in the neck to regulate the flow of blood to the head, especially when the giraffe is bending down to get that much needed drink of water. Without these valves, the immense blood pressure coupled with gravity would make for one nasty headache and other such repercussions. Elastic blood vessels in the giraffe's head allow harboring of enough blood to prevent the giraffe from passing out when bent in this position.Now, how do you propose these valves evolved? Natural selection cannot help because the valves are useless until functional. So you need a bunch of lucky mutations for this scenario to play out. The odds of this happening by pure chance is pretty much impossible. You admitted above that without selection, its an implausible scnario. Its time to listen to yourself, let go of your fairytale, and come to your senses. (If you would like to see what happens to the poor Giraffe, go here: http://www.evolutionfairytale.com/giraffe1.htm)BTW, genetic drift is a problem for evolution. Many evolutionists realize this and reject the small population model of upward evolution. Why? Because if selection is rendered powerless, deleterious mutations will surely outpace beneficial ones since there are so many more of them.

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Firstly, a valve is anything that can restricts flow in one or both directions. A small flap which bends one way & less so in another would have the ability to restrict flow in one direction. This is true REGARDLESS OF HOW SMALL it is. If it proved to be an advantage then nat. sel. takes over. Lucky mutations, yup. But then Ive got a lot to choose from.

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This is a story, Mark. You admitted that without selection this would be implausible. Selection cannot do much until there is a functioning valve. Even if I grant you a partially functioning valve, how many lucky mutations would be needed to produce this primitive valve? Would you agree that 10 mutations would be too few? What about 100? How many are you willing to commit to as the worst case number of mutations needed before selection can recognize the valve as useful? (note that there are actually many valves involved, not just one, but I'm keeping it simple for now)

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[This message has been edited by Fred Williams, 12-20-2001]

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The appearance of these valves in arteries in the giraffe's neck only required a minor mutation moving a valve gene from a leg vein to a neck artery.

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I realize you are trying to invoke homeobox mutation. It’s a nice try, but it won’t cut it. For one, the pressure gradients would be dissimilar. If you are familiar with fluid mechanics, the pressure required to pump something upward increases an amount that is more than proportional to the increase in height. Ie it’s logarithmic. You can’t expect the correct pressure valve to just pop into place. Another problem is the fact that there exists a labyrinth of these valves in the Giraffe’s neck. There is no way to conceive of all these valves being recognized independently by selection, which is what you are implying. I’m trying to determine how much luck is needed. How many mutations are you willing to grant that are not going to be recognized by selection? You know you are grasping at straws when you try to say one.