Why Do We Kiss?

[Article revised on 3 May 2020.]

Source: Pixabay

Kissing is not universal among human beings. Even today, there are some cultures from which it is completely absent. This suggests that it is not innate or intuitive, as it so often seems to us.

One possibility is that it is a learned behavior that evolved from "kiss feeding," the process by which mothers in some cultures feed their babies by passing masticated food from mouth-to-mouth. However, there are some contemporary indigenous cultures which still practice kiss feeding, but not social or erotic kissing. Another possibility is that kissing is a culturally-determined form of grooming behavior, or, at least in the case of erotic or deep kissing, a representation, substitute for, and complement to, penetrative intercourse.

Whatever the case, kissing behavior is not unique to human beings: Primates such as Bonobo apes frequently kiss one another, and dogs and cats lick and nuzzle one another, as well as members of other species; even snails and insects take part in antennal play. It could be that, rather than kissing, these animals are in fact grooming, smelling, or communicating with one another, but, even so, their behavior implies and furthers trust and bonding.

Vedic texts from ancient India seem to refer to kissing, and the Kama Sutra, which probably dates back to the 2nd century, devotes an entire chapter to modes of kissing. Some anthropologists have suggested that the Greeks learned about erotic kissing from the Indians when Alexander the Great entered India in 326 BC. However, this need not mean that kissing originated in India, nor that it does not predate the oral roots of the Vedic texts. In Homer, which dates back to the 9th century BC, King Priam memorably kisses Achilles’ hand to plead for the return of his son’s cadaver:

Fear, O Achilles, the wrath of heaven; think on your own father and have compassion upon me, who am the more pitiable, for I have steeled myself as no man yet has ever steeled himself before me, and have raised to my lips the hand of him who slew my son.

In his Histories, which date back to the 5th century BC, Herodotus speaks of kissing among the Persians, who greeted men of equal rank with a kiss on the mouth and those of slightly lower rank with a kiss on the cheek. He also reports that, because Greeks ate of the cow, which was sacred in Egypt, the Egyptians would not kiss them on the mouth.

Kisses also feature in the Old Testament. Disguised as Esau, Jacob kisses the blind Isaac and thereby steals his brother’s blessing. In the Song of Songs, which seems to celebrate sexual love, one of the lovers implores, “Let him kiss me with the kisses of his mouth, for thy love is better than wine.”

Under the Romans, kissing became much more widespread. The Romans kissed their partners or lovers, family and friends, and rulers. They distinguished a kiss on the hand or cheek (osculum) from a kiss on the lips (basium) and a deep or passionate kiss (savolium). Roman poets such as Ovid and Catullus celebrated kissing, as, for example, in Catallus 8.

Roman kisses fulfilled purposes from the social and political to the sexual. In an age of illiteracy, kisses served to seal agreements—whence the expression "to seal with a kiss," and the "X" on the dotted line. The social status of a Roman citizen determined the part of the body on which he or she could kiss the emperor, from cheek down to foot. Couples got married by kissing in front of a gathered assembly, a practice which, of course, has been carried into modern times.

Practices changed with the decline of Rome and the rise of Christianity. Early Christians often greeted one another with a "holy kiss," which they believed led to a transfer of spirit. The Latin anima means both "breath of air" and "soul," and, like animus ("mind"), derives from the Proto-Indo-European root ane- (to breathe or blow). Although St. Peter had spoken of the "kiss of charity," and St. Paul of the "holy kiss," early church sects omitted kissing on Maundy Thursday, which marks the date on which Judas betrayed Jesus with a kiss ("But Jesus said unto him, "Judas, betrayest thou the Son of man with a kiss?""). Outside the Church, kissing was used to consolidate rank and social order, with, for example, subjects and vassals kissing the robe of the king or the ring or slippers of the pope.

If you think about it, the concept of romantic love barely features among the 66 books of the Bible. In the Bible, all love is directed at God, and the love for the spouse and more generally for the other is subsumed under the love of God. The two greatest love stories in the Bible are not of husband and wife, nor even of man and woman, but of man and man, and woman and woman.

After the fall of Rome, the romantic kiss seems to have disappeared for several centuries, only to re-emerge at the end of the 11th century with courtly love. The kiss of Romeo and Juliet is emblematic of this movement, which sought to remove courtship from the purview of family and society, and to celebrate love no longer as a dutiful act but a liberating and potentially subversive force. Yet, the fate of the star-crossed lovers reminds us that such careless freedom is not without risks, and it could be that the concept of vampirism evolved as a representation of the dangers—to health, rank, reputation, prospects, and happiness—of kissing the wrong person. 

Neel Burton is author of Heaven and Hell: The Psychology of the Emotions and other books.