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Author Topic:   Peppered Moths and Natural Selection
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Joined: 05-02-2006
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Message 341 of 350 (670912)
08-21-2012 2:00 AM
Reply to: Message 338 by barnes
08-20-2012 6:31 PM

Re: Evolution activity
Mike? Is that you? The "real Mike Barnes"? What were you in 1990, SK2 or SK1?

Is your "impossible question" and challenge supposed to be akin to the problem of evolving a four-chambered heart from a three-chambered job? After all, you would argue that while converting the 3-chambered model to the 4, the whole thing would have be shut down, right?

Well, crocodiles do it all the time. They're born with three-chambered hearts and as they grow larger to where they need more efficient oxygen transport which requires a more efficient circulatory system, they switch from three chambers to four without skipping a heart-beat.

You see, a three-chambered heart has two atria and one ventricle, whereas a four-chambered heart has the same two atria and two ventricles. The only physical difference between the two is a muscular septum that separates the ventricle into two chambers. In a three-chambered heart, the oxygenated blood from the lungs gets intermixed with the de-oxygenated blood from the body, which is good enough for an animal with a low metabolism, such as amphibians and most reptiles. But in a three-chambered heart, there is not such intermixing, so the body gets the oxygenated blood from the lungs.

You see, Mike, the secret to coming up with a valid analogy is for the processes involved to be the same or very close to the same. Your engine "analogy" is a false analogy which has nothing to do with how evolution works.

Here's the key to creating a valid analogy: evolution is the result of life doing what life does, so your analogy needs to emulate what life does. Car engines do not fit that bill.

This message is a reply to:
 Message 338 by barnes, posted 08-20-2012 6:31 PM barnes has not yet responded

Replies to this message:
 Message 342 by RAZD, posted 08-21-2012 5:14 AM dwise1 has not yet responded

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