Today is International Kissing Day or World Kiss Day. As the author of The Science of Kissing, what better way to celebrate than to share some fascinating facts about kissing:































































• The earliest literary evidence for kissing comes from India’s Vedic Sanskrit texts, dating back 3,500 years.































• A passionate kiss can make our pupils dilate – probably one reason so many of us close our eyes.































• Two-thirds of us tilt our heads to the right when we kiss, and it’s not correlated with right-handedness.































• A man is far more likely to prefer sloppy tongue kisses than a woman. The added testosterone from his saliva may serve to enhance her libido over time.































• We are not the only species to engage in kissing-like behaviors. Great apes press their lips together to express excitement, affection, or reconciliation.































• In studies, people remember more of the details about a first kiss than first sexual experience.































• Kissing works like a drug in our bodies, and can promote dopamine – the same neurotransmitter stimulated from addictive drugs like cocaine.































• Our lips are packed with sensitive nerve endings so even a slight brush can send a cascade of pleasurable signals to the brain encouraging us to continue under the right circumstances.