Here’s a detailed article — let’s call it Everything You Always Wanted To Know About Kissing But Were Afraid To Ask — from the How Stuff Works people. One thing I didn’t know:

Ancient Romans also used kissing as part of political campaigns. However, several “kisses for votes” scandals in 18th century England led — in theory — to candidates kissing only the very young and very old.

Kisses for votes? How did that work, exactly? I can see it now, George Clooney and Halle Berry, they could flip a coin to see who’s at the top of the ticket, a runaway “Kisses For America” campaign.

Link via Sexoteric.