Evolution of the heart

[Mikel]

Hi! I ran across your forums today trying to find someone who could help me. I'm debating with a guy on another site with forums who appearently has absolutely no idea what evolution is about and one of the things he said was "They can’t explain how that cell evolved into a mulit-celled organism or how that multi-celled organism grew a back bone slowly or how animals went from having 2 to 3 to 4 chamber in their heart….it’s sorta hard to have 2 and a half chambers in your heart, is it not? And supposedly evolution is extremely slow so you’d have one guy with 2 chambers, the next with 2.00001 chambers, the next with 2.00002 chambers….it doesn’t really work…you have 2 or you have 3. You die if you have anything in between." I'm afraid I don't exactly know much at all about the evolution of the heart. I tried researching and couldn't find anything on it. Can you help me? What exactly would you say to him?

[Skye]

Here's a fairly good site. Between 2 and 3 chambers you have lungfish, in all their slimy glory, with a partial interatrical septum.

 

http://www.auburn.edu/academic/classes/zy/0301/Topic12/Topic12.html

[aommaster]

Its pretty amazing to me. The evolution of the heart. You hacn't have 1 and a hlaf heart. Its either single, double or no circulation at all. That means that the evolution behind it must have been very big!

[Mikel]

Thanks alot. I'll come here for any more questions I have.

[apathy]

also, during evolution, things don't change by themselves. the whole organism is a sophisticated concert of mechanisms. change one thing by a little, and you might change something else a lot.

 

by breeding foxes for tameness, a few other things started to change, as the foxes got more and more tame, generation by generation, they started to look differently, and act differently besides the tameness, they started barking like dogs!

http://www.exn.ca/Templates/Story.cfm?ID=1999033055

http://home.wlu.edu/~blackmerh/jsk/canid.htm

eh, just google "fox breeding tameness"

 

You can't just argue, how did this small piece evolve step by step?

[Mikel]

I gave that first link in a different debate entitled "evolution vs. creationism". A fellow believer of evolution was the first to respond. He said

I remember seeing a progamme about those Silver Foxes. They choose deliberatly for tameness and now they act like domestic puppies and dogs. I didn't know the information about the physiological changes though, that was rather interesting. Obviously the domestic dog wasn't so intensively bred like this and other traits were selected as well as tameness (speed, size, herding or tracking abilites as well as asethetic purposes). I wonder if when choosing for tameness the humans accidently choose slightly "cuter" animals - which might explain the more appealing appearance of the foxes, or whether those traits are part of a set of genes which promote less aggression.

I think the difficulty is, playing devil's advocate, artificial or natural selection does not necessarily prove evolution, as natural selection is only one componant of it.

 

I would question the wisdom of taming another animal. Especially since they are now having to sell some off to the fur trade.

 

"Men have forgotten this truth," said the fox. "But you must not forget it. You become responsible, forever, for what you have tamed." Antoine de Saint-Exupéry.

How would you respond?

[apathy]

Oh, well, i would point out that he didn't address the point at all. (The foxes started looking like something else, not so much like foxes anymore, when bred for tameness alone.) You can't just talk about one little piece "evolving" on its own.

 

If our ancestors were simpler beings they wouldn't have half a heart, or half an eye. They would have a more rudimentary organ. One that preforms the function, but maybe not as well as the later, more sophisticated versions. Or, more precisely, it performed the function to the requirements of the organism, which was to our perception, simpler.

 

Tell, him to google: "planaria eyespot" to see simpler eyes, "insect ganglia" to see simpler brains, "insect heart" to see simpler circulatory systems

[Mikel]

Ummm... well... i'm a dumbass (I haven't even gone into biology yet) so, I'm not quite sure what your talking about. It may be better, since you know what your talking about, for you to argue it. http://www.giveupalready.com/showthread.php?s=&threadid=59146&pagenumber=2

First you must register. Beware of the moderators. Btw, i'm Mikel on there too.