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Author Topic:   How can evolution explain body symmetry?
Random123
Inactive Member


Message 170 of 284 (220246)
06-27-2005 9:36 PM
Reply to: Message 1 by CrackerJack
05-29-2004 11:59 PM


Actually, we are not symmetric in many different ways
We are not symmetrical internally, it was already said in the forum. But are we symmetrical externally? No, not really.
- We are assymetrical vertically: that reflects one fundamental assymetry of the world surrounding us, gravity pulls in only one direction.
- We are assymetrical front-to-back: we are constrained by gravity, and by other factors, such as the necessity to move. There are many ways of locomotion, ours happen to be this way, efficient movement forward with some limited capability for backward locomotion.
- We are symmetrical side-to-side: the vertical assymetry is a consequence of the environment, and the front-to-back assymetry works well, there is no need for equally efficient locomotion in forward and backwards, thus this assymetric shape is actually efficient. Now, what about lateral assymetry? Once you are moving forward, two spatial axis are already set - the vertical, by gravity, and the front-back, by the forward movement itself. The third axis (sideways) presents no assymetry: the world calls for our attention on both the right and left sides equally. Therefore, with respect to the interactions with the world, sideways symmetry is an advantage: assymetrical individuals would be easy preys on one side. A person with one substantially shorter leg would have problems moving as fast as a laterally symmetrical individual (and when running away from a lion, the symmetrical one will probably live longer and eventually reproduce!)
Sideways symmetry is required only externally, due to the factors explained above. Internally, not much symmetry is really necessary (other than that required for the external functionality).
Notice that such layout doesn't strictly need to be produced by intelligent design, but it is understandable as a consequence of evolutionary pressure, survival-of-the-fittest, a very earthly explanation.
Finally, allow me a very short digression here. At first glance, evolution is unsatisfying, as we would rather be the consequence of a very special design from God. And maybe we are, but on a much more subtle level. Evidence of intelligent design is not necessary available for us even if it exists, since any formal system that is "powerful enough" contains true statements that cannot be proven through any derivation within the formal system itself (for a truly remarkable discussion on this subject, see "Godel, Escher, Bach" by Douglas Hofstadter). Operating only within the rules of the formal system, one cannot always reach the level of understanding that is available to one who works on a higher level, "outside the system". Which means that God might be completely beyond our reach, and this time "by intelligent design".
On a more practical note: by "working outside the system" I don't mean making unscientific explanations, as opposed to scientific theories (which would be "working inside the system"). Merely existing in this universe means that we automatically operate within this formal system, and "working outside the system" is just impossible. If there is a meta-universe, it is inaccessible.

This message is a reply to:
 Message 1 by CrackerJack, posted 05-29-2004 11:59 PM CrackerJack has not replied

Replies to this message:
 Message 171 by AdminJar, posted 06-27-2005 9:44 PM Random123 has not replied
 Message 172 by Brad McFall, posted 06-30-2005 11:35 PM Random123 has not replied

  
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