JM; excellent posts, very clearly evaluated.
And of course a reference to one of my posts always raises my opinion of the poster!! :wink:
and Satt; good point "why two not three?". I guess the third option, atrophied from lack of neccessity (or lack of "fun"
)
And in that mode; one of my favourite comments on evolution would be the allusion to bilatteral symetry; if there had been a "designer" involved, what idiot would have given us two of everything, arms, legs, eyes, etc., when three would be so much more practical!!!
I could add; if s/he made us in her image, she's got some serious bitching to do to her "maker"!! :wink: