"Bilateral symmetry is predictable from evolution-it makes sense for a mobile
organism to specialize so as to have a front and a back end. Sense organs
are most useful up front, to see/smell/taste/feel/hear/etc. where you are
going, so having eyes symmetrically distributed on the front end makes sense.
Two eyes rather than one medial eye allows better vision to
each side, and if the eye is good enough, can allow binocular vision. Since
we're usually going forwards, extra eyes in back have not been a particular
advantage, and the pineal "eye" is reduced or lost in many vertebrate
lineages. Additionally, there's the "other mammals have two eyes so we are
likely to maintain this pattern" line of reasoning, which is less a priori.
Directionality is probably important in the presence of more than one eye-we
also have two ears, but one nose and one mouth-light and sound have more
direction to them than smell or taste."
I find it difficult to understand why bilateral symmetry, as you so ably
outlined it, is predictable from evolution. The only argument you give in
support of your assertion is that "it makes sense." I don't see how you can
justify evolution with this argument? You offer no mechanism as to how
evolution brought bilateral symmetry about. Natural selection?
Non-selective evolution? Did it all occur by myriads of unguided
happenstances? I would like to see you support your "makes sense" with some
substantial arguments about just how evolution brings about bilateral
Apparently you have not given serious consideration to the alternative
hypothesis that all examples of bilateral symmetry provide evidence of the
work of an intelligent designer. As Moorad wrote, "It all smells like a
Designer with a purpose to me."