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04-07-2011, 04:25 PM
RE: Evolution
(04-07-2011 02:20 PM)TheBeardedDude Wrote:  I am afraid I do not know of any "specialized pumping system" that is required for pumping blood in giraffes. I would assume that it has a large heart for its body size and higher blood pressure in order to keep the blood pumping. I also believe they have some sort of retention system in their brain for storing blood but I could be wrong. The most interesting part of the giraffe to me is the vocal nerve. This is the nerve that only needs to go from the brain to the vocal box near the upper portion of the neck....instead it travels ALL the way down the neck, past the heart and then all the way back UP the neck to the vocal box. Why? Ours and every other vertebrates does the same thing. Start with the fish. The vocal nerve travels from the brain PAST the heart to the vocal box (or the equivalent structure). The heart is on the way to the vocal box. As the head began to elongate and necks began to develop in amphibians, reptiles and mammals the vocal nerve continued along its traditional path past the heart first. Why? It is simpler and easier to simply lengthen the vocal nerve rather than evolving a completely new pathway for the nerve to travel. As for the blood problem I would be willing to bet that there is probably an increased number of blood vessels in the brain and that the diameter of the main artery is different than expected in order to increase the efficiency of the entire system. I am sure that the necks of the giraffe represent an example of stabilizing selection where the most efficient longer necks were slowly selected for over generations such that those whose necks were too long were selected against and those who were too short were selected against. This type of selection would prevent the length of the neck from increasing too dramatically over generations because it would allow for time to improve the efficiency of the heart and artery system.

I am no vertebrate expert so perhaps I can find a book on them to confirm. I will keep you up to date if I find anything new or interesting. And sorry it took so long to reply...I was in the middle of nowhere WY for a month!

Thanks for the reply, that answers my question very well. And don't worry about taking a while to reply, I'm just glad that I've got someone so knowledgeable who's happy to answer my question Smile.

Best and worst of Ferdinand .....
Ferdinand: We don't really say 'theist' in Alabama. Here, you're either a Christian, or you're from Afghanistan and we fucking hate you.
Ferdinand: Everyone from British is so, like, fucking retarded.
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04-07-2011, 04:28 PM
RE: Evolution
No problem!


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04-07-2011, 09:14 PM
RE: Evolution
OH OH!!! I got it, god did it. High five your dad for me.


Laryngeal nerve, encase anyone wanted to do a little research.
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