
Kissing at the conclusion of a wedding ceremony can be traced to ancient Roman tradition where a kiss was used to sign contract. Source
While a quick pucker kiss uses just two muscles, a full on French kiss involves all 34 muscles in the face.
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The first on screen French kiss was in the 1961 film Splendor in the Grass, with Natalie Wood and Warren Beatty.
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On average, two-thirds of people tip their heads to the right when they pucker up.
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The first time two men kissed on screen was in 1927.
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