posted on Jul, 9 2009 @ 10:23 AM
reply to post by Desolate Cancer
The best explanation is a combination of several factors.
For starters, two eyes are better than one because you get depth perception. One eye can be handy over no eyes, but without at least two you can not
judge depth very well.
More than than two eyes then starts to stress out the brain. All the information coming in form eyes has to be processed and interpreted by the brain.
If you add more eyes, that is more processing.
As for them being on the head, this makes them very close to the brain for faster transmission. For tall humans, it can take up to a tenth of a second
for nerve signals to get there. Well when something is lunging at you with the desire to eat you, you can as much reaction time as possible.
So in terms of evolution, two eyes would be the ideal. Things with many eyes all over the body would struggle to sync up the information in their
head. It would mean the brain requires much more energy and thus food, oxygen, and other nutrients.
Flounder, which over the last few million years saw the lopsided group win out and become the norm with both eyes on one side of the head, show that
even when the eyes are better off some where else, it is still two near the brain that win the game of natural selection.
I hope this helps.
BTW, you can find mutants in most animals species that have more or less than two eyes. They don't survive well, even the ones with more.