Ever stopped to consider how gross kissing with tongue is? You'd never go up to a stranger at a bar and ask to borrow their toothbrush, so why do we think it’s totally normal to swap spit with them instead?
As it turns out, our predisposition to snog is all tied up in the primal urge to find the perfect mate.
“Kissing - like touching and smelling – is an emotion-driven act that allows us to identify the most compatible and ‘evolutionary advantageous’ partner,” Fulvio D’Acquisto, professor of immunology at Roehampton University tells The Independent.
On a subconscious level, it also provides us with a chance to (not so subtly) suss out the other person’s immune system.
“We tend to feel more attracted to someone with a different immune response,” adds Dr Sarah Johns, an expert in human reproduction at the University of Kent.
“The major histocompatibility complex is detectable in body odour, so by kissing and tasting someone it gives the opportunity to assess how similar or different that individual is to you biochemically.”
Back in the caveman days, this was key in ensuring the tribe produced strong offspring.
“From an immunological perspective, this has the advantage of ‘favouring’ the reproduction of individuals that carry very little risk of incompatibility – and hence reducing the risk of miscarriages – ultimately supporting the survival of the species.”
Consider this your science-backed permission to pucker up.