Why Do We Kiss?

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Kissing is not universal among human beings and, even today, there are some cultures that have no place for it. This suggests that the behaviour is not innate or intuitive, as it so often seems to us.

It could be that kissing is a learnt behaviour that developed from ‘kiss feeding’, the process by which mothers in some cultures feed their infants by passing masticated food from mouth to mouth. Yet, there are some present-day indigenous cultures that practise kiss feeding but not social kissing.

Another possibility is that kissing is a culturally determined form of grooming behaviour, or, at least in the case of deep or erotic kissing, a representation, substitute for, and complement to penetrative intercourse.

Whatever the case, kissing behaviour is not specific or unique to human beings. Primates such as Bonobo apes frequently kiss one another; dogs and cats lick and nuzzle one another and members of other species; even snails and insects engage 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 behaviour implies and strengthens trust and bonding.

Vedic texts from ancient India seem to talk about kissing, and the Kama Sutra, which probably dates back to the second century CE, devotes an entire chapter to modes of kissing. Certain anthropologists have suggested that the Greeks learnt about erotic kissing from the Indians after Alexander the Great invaded India in 326 BCE. But even if true, this need not mean that erotic kissing originated in India, or that it does not predate the oral roots of the Vedas.

In Homer, which dates back to the ninth century BCE, King Priam of Troy memorably kisses the hand of Achilles in pleading for the return of Hector’s defiled corpse:

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 the Histories, which date back to the fifth century BCE, 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 reports that, because the Greeks ate of the cow, which was sacred to the Egyptians, the Egyptians objected to kissing them on the mouth.

Kissing also features in the Old Testament. Disguised as Esau, Jacob steals his brother’s blessing by kissing their blind father, Isaac. In the Song of Songs, which celebrates 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 commonplace. 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 (d. 43 BCE) and Catullus (d. 54 BCE) celebrated kissing, as, for example, in Catullus 8.

Roman kisses fulfilled a range of purposes from the political and legal to the social and sexual. The status of a Roman citizen determined the part of the body, from cheek to foot, on which he or she would be expected or allowed to kiss the emperor. In an age of widespread illiteracy, kisses served to seal agreements—hence the ‘X’ on the dotted line, and the expression ‘to seal with a kiss’. Couples got married by kissing before a gathering, a Roman practice that continues today.

Customs changed with the decline of Rome. Early Christians often greeted one another with a ‘holy kiss’, which was believed to lead to a transfer of spirit. The Latin anima means both ‘breath of air’ and ‘soul’, and, like animus [mind], comes down from the Proto-Indo-European root ane- [to breathe, blow]. Although St Peter had spoken of the ‘kiss of charity’, and St Paul of the ‘holy kiss’, early Christian sects omitted kissing on Maundy Thursday, the day of the year on which Judas betrayed Jesus with a kiss. Outside of the Church, kissing was used to cement rank and social order, for instance, subjects and vassals kissed the robe of the king, or the slippers or ring of the pope.

After the fall of Rome, the romantic kiss (as opposed to the social kiss) seems to have disappeared for several hundred years, only to re-emerge at the end of the eleventh century with the rise of courtly love. The kiss of Romeo and Juliet is emblematic of this slow movement, which sought to remove courtship from the purview of family and broader society and celebrate romantic love as a liberating, self-determining, and potentially subversive force.

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The fate of the star-crossed lovers reminds us that such carefree abandon is not without risks, and it could be that vampirism evolved as a representation of the dangers—to health, rank, reputation, prospects, and happiness—of kissing the wrong person.

Read more in Heaven and Hell: The Psychology of the Emotions.