Is a kiss just a kiss? The art and science of smooching

With Valentine’s Day around the corner, Susan Spencer asked: Is a kiss just a kiss? An evolutionary biologist says kissing is common in the animal kingdom and may date back 21 million years. A certified sex therapist explains why we kiss — and why some smooches linger in our memories for decades. Finally, a panel of editors at InStyle Magazine weigh in on the most iconic kisses in pop culture.