A new scientific study delves into that most important of questions: Why do humans kiss? It's a practice carried out by almost no other animals, especially not with the same level of intensity, Time notes. But researchers found locking lips may actually serve an evolutionary purpose: It helps us assess potential mates and weed out the lesser options, LiveScience reports. That explains why women (who are pickier than men when it comes to mating) and people who rate themselves as attractive (who are also pickier) said they found kissing more enjoyable and important than their male and/or less attractive counterparts, Science Daily reports.
It also explains why women find kissing especially important when they're at their most fertile. One theory: Kissing might transmit pheromones or chemical information—some of which can be transmitted through smell—about a partner's health, fertility, or genetic and immune compatibility. As one researcher says, "It's just an excuse to get two people who are interested in each other close enough to have a sniff." Says another, "Mate choice and courtship in humans ... involves a series of periods of assessments where people ask themselves, 'Shall I carry on deeper into this relationship?'" Kissing can help answer that question. (And once a partner is found, one writer suggests applying the principles of software code to the relationship.)