No one knows for sure, but researchers believe that people have been locking lips for thousands of years. There are a number of theories out there about how the kiss got its origin, such as cave mothers chewing their babies’ food and passing it to them by mouth, and “cave couples” kissing to smell each others’ breath as a test of compatibility. Today, about 90 percent of people in the world engage in kissing in some form — from goodnight smooches to nice-to-see-you kisses.
Here’s a quick look at the many different meanings of the kiss.
What’s your favorite type?