Humans didn't start kissing on the lips for romantic reasons at all?

It turns out that humans didn't start kissing on the lips for romantic reasons at all. A study by Adriano R. Lameira, an associate professor of psychology at the University of Warwick in England, has concluded that kissing was once an evolutionary instinct.

"The evidence supports that kissing is not a derived signal of affection in humans," Lameira, who believes that kissing was once part of a method of removing lice, told The Daily Mail. "Kissing represents a surviving, degenerate, vestigial form of primate grooming that has retained its original form, context, and function."

According to a study of monkey behavior, "kissing is likely a retained final stage of oral contact during grooming, when a primate extends its lips and sucks on fur or skin (of its partner) to latch on to debris or parasites."

But as humans evolved with less body hair, grooming became less necessary, and eventually all that was left was what we know today as kissing.