Young Kissing Girls

Nature and history of the kiss
The origins of the kiss were studied in the early 20th century by natural historian Ernest Crawley. He wrote that kissing was "a universal expression in the social life of the higher civilizations of the feelings of affection, love (sexual, parental, and filial), and veneration." According to Crawley, touch is 'the mother of the senses,' and the kiss was a tactile and specialized form of intimate contact. However, he notes that the act of kissing was very rare among the "lower and semi-civilized races," but was "fully established as instinctive in the higher societies." Yet even among higher civilizations Crawley saw differences: while the kiss seems to have been unknown to ancient Egypt, it was well established in early Greece, Assyria, and India.
The kiss of lovers, according to 19th century anthropologist Cesare Lombroso, originated and evolved from the maternal kiss. Crawley supports this view by noting that Japanese society, before the 20th century, was "ignorant of the kiss except as applied by a mother to her infant," while in Africa and "other uncivilized regions," it was commonly observed that neither husbands and wives, or lovers, kissed one another. However, kissing was common among the Greeks and Romans as when parents kissed their children, or when lovers and married persons kissed. The kiss in Western societies was also used in various religious and ceremonial acts, as where the kiss had a sacramental value. Crawley concludes that generally, although kissing was prevalent in some form since primitive times, it "received its chief development in Western culture."
In modern times, scientists have done brain scans on people when a romantic relationship progresses. Some studies found that after that "first magical meeting or perfect first date," a complex system in the brain is activated that is essentially "the same thing that happens when a person takes cocaine." In studies of affection between lovers, when participants viewed images of their partners, their brains' ventral tegmental area, which houses the reward and motivation systems, was flooded with dopamine, an internal chemical that is "released when you're doing something highly pleasurable ..."