Kiss — the most common way of expressing affection (and not just romantic). Perhaps that is why setting world records in relation to kissing on Valentine's day has become as good a tradition as sending "Valentines" to those whom we appreciate and love. The longest kiss to date lasted 33 hours, the largest included 39 897 simultaneous kisses, and the fastest — 112 kisses received in one minute.
Moreover, the kiss can not be said as a purely cultural tradition, common only in a certain part of the globe. It is known that 90% of the World's population has this way of expressing feelings, while the remaining 10% replace this practice with something similar.
The question remains: why are we kissing? Scientists say that it is an assessment tool partner to create strong offspring. But not only.
Smell and pheromones.
A kiss assumes, that people are very close each other. This means that they have the opportunity to evaluate the smell and, in a sense, the "taste" of the partner, determining whether this person is suitable for procreation. Live Science reports that people's breath and saliva contain chemical signals that they are healthy or sick, and in the case of women — information about ovulation, and all this is extremely important for reproduction.
In addition, the skin around the nose and mouth is rich in sebum (sebum), oily substance that performs the function of natural moisture. Studies show that sebum contains pheromones-chemicals that transmit information about the biological composition of a person. When people gather each other's pheromones during a kiss, they subconsciously become more or less sexually interested in each other (depending on whether the proposed composition of pheromones suits them).
In one study, scientists found that we prefer pheromones in humans with a different type of immune system. It is assumed that this is because such a genetic difference improves the health and vitality of the offspring.
Psychology and sex.
Along with the chemical substances, which the two men exchanged while kissing, and important psychological component. Scientists believe that regular kisses help couples increase their sense of affection for each other.
This theory is confirmed by the fact that the level of oxytocin (the hormone responsible for the feeling of affection between people) in the brain during a kiss increases significantly. That could explain why people constantly kiss during sex with a loved one, but almost do not do this during the "casual" sex.
Another common explanation for kissing — the exchange of liquids, stimulating sexual arousal. A number of experiments on the topic showed that men tend to perceive the humidity of the kiss as an indicator of sexual receptivity of the woman they kiss.