Wombat Pouch

One of the best creationist arguments I have heard concerns the "backward" pouch of the wombat. Opposite to most marsupial pouches, the wombat's opens to the rear, which is valuable to it, as a burrowing animal, for keeping dirt out of the pouch. But how could the pouch turn around by natural selction?When I first heard about this problem, I thought that the answer that would satisfy natural selection would be that the wobat evolved its pouch seperatly from marsupials that evolved front-opening pouches. But I just saw a TV show that said all of the world's marsupials have a common ancestor: a rat-like animal that lived in China.So is there a well known solution to this probalem that I have missed? I searched the web and the EVC forums for discussion on it, but found none. Could the pouch have flipped around in one fell swoop, with a single genetic mutation? If so, wouldn't other simultateous mutations have had to occur to make the new pouch work? And if the pouch transitioned in a series of small steps, what would that have looked like?IGIT

Well, if the koala has a pouch that does not open on an end, but opens somewhere in between the ends, this pretty much kills the creationist argument, I have to admit. When confronted with features or behaviors of a particular animal that were hard to fathom being the result of natural selection, we know that Darwin often pointed out some other creature that seemed to show an intermediate step, such as the species of bees that did not build perfectly hexagonal chambers in their hives, but was approaching it. The koala pouch might fit that bill.It still seems weird, though, that a pouch that opened in the middle would be superior to one opening on the end, and give the animal an advantage. I guess when the offspring were tiny, it wouldn't make a differnce to them; any pouch arrangement would keep them warm and covered. But when they grew bigger, it seems like a center-opening pouch would be less secure. But even to an animal that didn't burrow, but just moved through heavy brush, a center-opening pouch might be better that a front opener.Like Percy discribed, I at first envisioned a pouch as a four-sided flap that was attached on three sides, so that if the opening reversed orientation by steps, it would "rotate." So if it rotated 90 degrees, the opening might aim right at a hind leg. This way of turning the pouch around doesn't make much sense; if one genetic mutation caused the pouch to rotate say 10 degrees, it's hard to imagine a benefit.And if one genetic mutation turned the pouch 180, wouldn't other simultaneous mutations be needed to make the new arrangment go. For example, would the new borns have the instict to find their way into the pouch, if it were suddenly reversed?So a lateral opening moving in steps from one end of the pouch to the other (no matter which direction) seems to fit best with natural selection.Thanks people. I'll come back when I find something that I think might cast some doubt on the TOE.IGIT Edited by InGodITrust, : No reason given.Edited by InGodITrust, : No reason given.Edited by InGodITrust, : spelling

Good point, WK. You've given a clearer picture of how natural selection could work to shape the various marsupial pouches. Thanks.
IGIT