Why do we wink?

Yes, I’ve spelt that correctly.
Why do we wink? And why do we wink less these days? Is it the dying fad of a cad? You’ve a smiley that winks :wally but I don’t see many people winking these days… I can even remember the last time I was winked at - on a ski slope in Austria 6 years ago (I was told at the time that it means that the person is ‘up for it’).
Winking and shooting your finger at the same time - that’s what I want to see more of.

P.S. I never did find out if the person was, indeed, up for it.

P.S. I never did find out if the person was, indeed, up for it.