Why do humans kiss?

Beware the 'Kiss Of Death'. How do you know when you've received it? A good indication is that the person kissing you is a big, fat man called 'Don' who smells of cigars and Grappa. If, while kissing you on the lips, Don squeezes your cheeks and sends 'the boys' out with you. You've had it - run like hell. If you don't, it is likely that death will follow.

Let's put kidding away, I'm serious about it, We do people kiss? and why it's the most pleasurable thing that you may experience on earth ? If you are doing it with the right company :p
is it just something embedded to our minds so we do it whenever we have the chance ? let's have a look at some theories of How people started to kiss

This one seems to be silly and yes it is silly but romantic, it's like every story that appear after the existence of something just to make it look good or romantic

As was custom, the young man gave the young lady a token of engagement, similar to today's engagement ring. While she was out in the fields, she was attacked, and to keep the token safe, she put it in her mouth. Her lover heard of her attack and ran out to her, where she was alone, but shaking. He took her in his arms, and tried to console her over the loss of the token, as he could not see it anywhere. She opened her mouth to show him where it was, and he was very pleased. He wanted to take it from her mouth, but also did not want to let go of her. He leaned down and took it from her mouth using his lips, and this was the first kiss. Realizing the pleasure of the kiss, the token was removed, the kissing resumed, and kissing is now embedded in our culture.

Some people call it The hunger of passion but I don't get it because if you are hungry many dishes will fly around your head wishing to get one of them if not all, so DO YOU wish to kiss lots of people?

On the other hand why kiss are so adorable while human mouth is full of bacteria and it might sound funny but it could be safer to kiss a dog (if he got the proper food) than kissing a human

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