Among all the chocolates sold today are Hershey’s Kisses. They date to 1907. Actual kisses are considerably older. How much older is anyone’s guess. Bonobo apes like to French kiss, which is a disturbing mental image I’ll pass along to the reader. References to kisses turn up in some of the earliest ancient writings, including Vedic texts from India dating to 1500 BC. In Greek New Comedy of the 300s BC and later, comic playwrights sometimes would name a sexy female character Philematium (Kissy). The Romans, methodical as always, had a separate word for each of three categories of kisses: 1) Osculum, a kiss on the cheek appropriate for friends and family members; 2) Basium, a kiss on the lips for more intimate connections; and 3) Savolium, what we today call a French kiss. (That last Latin word sounds wet, doesn’t it?)
Kisses aren’t quite universal, but they are nearly so. Some 90% of human culture groups kiss as part of common romantic behavior. A LiveScience article notes the remaining 10% do something similar to kissing “such as face blowing.” (But do they face blow on a first date?) The same article says that the area around the mouth is rich in an oily substance called sebum, which contains a lot of chemical information about a person. Ah, that explains it; we kiss because we want to sniff out clues from the sebum. What other reason could there be?
Incidentally, if you’re looking for a Valentine’s Day movie, let me suggest Don Juan (1927). It still holds the record for the number of kisses in a film. John Barrymore divvies up 127 of them between Mary Astor and Estelle Taylor.