'X' became symbolic for a kiss because in the middle ages when alot of people were illiterate and they used to sign documents with an X and then kiss it for sincerity.
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Kissing actually has the biological purpose of passing on biological information and chemical signals to assess mating possibilities and status.
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In medieval Italy, if a man was caught kissing a woman in public, he had to marry her whether he liked it or not.
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When you kiss someone for the first time, you get a spike in the neurotransmitter dopamine, making you crave more.
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On average, a human being will have sex more than 3,000 times and spend two weeks kissing in their lifetime.
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Kissing releases masses of oxytocin, a "love potion" that helps couples bond and feel more attracted to each other.
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The average person in their lifetime will spend an estimated 20,160 minutes kissing!
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Men who kiss their wives in the morning live five years longer than those who don't.
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