Monday, March 21, 2005  Unnatural selection?  Remember the old
rhyme: "I never saw a purple cow, and hope I never see one; but
I can tell you, anyhow, I'd rather see than be one."   H.
halobium may have appeared earlier in the history of life than
organisms that use chlorophyl. It is not unreasonable to imagine
that they might have remained the chemical template for all
successive plant life, in which case even land plants might be
purple.  And if plants were purple, then some animals might have
evolved purple protective coloration. Hence, purple cows. (wink)