The truth about lying

I have a very close friend who frequently reminds me (and others) that the one thing she cannot abide is being lied to; and that she herself never lies.  But isn't lying an essential part of what it is to be a sentient being.  When a moth unfolds its wings to reveal two very large roundels that look just like predator's eyes, isn't that moth lying, by pretending to be what it is not and thereby avoiding being eaten?  The plant and animal kingdoms are also full of examples of far more intricate and deadly intentional falsehoods, such as the Angler fish that appears to dangle a tasty morsel on a spine in front of its mouth, so that it catches and eats any smaller fish tempted by the lure, or the Venus fly trap that lures insects with an irresistible scent, only to snap its leaves shut on the hapless insect, which it then digests.
Humans are also animals - very sophisticated animals, but animals nonetheless.  So it is no surprise to learn from a study written in August 2007 that
"In any conversation lasting ten minutes or longer, 20% of adults will lie"
In fact, we become so used to doing it that often we do not even notice that we are doing it. 
And yet as a child I was taught that lying was always wrong, and I would be punished either in this world or the next if I told a lie.
I guess there are lies, and then then are lies.  If I steal something and then deny that I have done so, that sort of behaviour is harmful to society and is not tolerated.  Whereas if my girlfriend asks that proverbial trap for the unwary: "Does my bum look big in this?", it is perhaps more understandable that I should not want to be pointlessly cruel by agreeing that it is.  So instead I tell her that she looks just great the way she is, and of course her bum does not look big in that dress.  Is that really such a bad lie?
Must go to bed.  To be continued.....