The absolutely disgusting reason why humans started kissing — and it has nothing to do with love

Kiss your assumptions goodbye.

You may think you know why humans enjoy smooching with one another, but a new study published this month has revealed the real history behind why we lock lips.

Research conducted by Adriano R. Lameira, an associate professor of psychology at England’s University of Warwick, concludes that kissing was once an evolutionary instinct, something done to groom another being.

“Evidence supports that kissing isn’t a derived signal of affection in humans,” Lameira, who believes that kissing was once part of a lice-removal method, told Daily Mail.

“It instead represents a surviving devolved, vestigial form of primate grooming that conserved its ancestral form, context and function.”

According to the study of ape behavior, “kissing is likely the conserved final mouth-contact stage of a grooming bout when the groomer sucks with protruded lips the fur or skin of the groomed to latch on debris or a parasite.”

“This made grooming important for hygienic purposes given the high parasitic load on the ground,” Lameira said.

But as humans evolved with less body hair, grooming became less necessary and, ultimately, only what we know today as kissing remained.

Lameira estimates that humans “became a kissing ape” approximately 2 million to 4 million years ago, and the earliest record of humans kissing, per Daily Mail, occurs in Mesopotamian texts circa 2500 BC.

How it got it became an act of sexual nature, however, “remains more speculative,” he noted, adding that kissing with “sexual intent” is “a special case” of such behavior and further research is needed to identify how kissing and sex became so intertwined.

“Only once kissing was used as a general convention for showing affection, could kissing become a mutual mouth-to-mouth act,” he explained.

Kissing, now, is “a crystalized symbol of trust and affiliation,” Lameira added,

“Few natural human signals carry the symbolism and social sanctions of kissing,” Lameira said, adding that kissing is now “a crystalized symbol of trust and affiliation.”