Kissing is a form of bonding and recognizing kin. Apes and birds feed their young by passing on chewed up food mouth to mouth.
Sexual kissing could have been a way that was passed down from gestures that were used to recognize those who aren’t kin.
The term for it is relic gesture.
https://www.irishtimes.com/life-and-style/health-family/scie...
[..] What are the origins of kissing?
In early human societies, it is believed mothers weaned their babies by chewing up their food and then passing it to their babies by lip-to-lip contact. Evolutionary biologists suggest that erotic kissing is a so-called relic gesture, passed down through cultures from these early practices of the mother’s deep kissing and the infant’s searching tongue movements.
“If young lovers exploring each other’s mouths with their tongues feel the ancient comfort of parental mouth feeding, this may help them to increase their mutual trust and thereby their pair-bonding,” writes Desmond Morris in his classic book on human behaviour, Manwatching.[..]
Desmond Morris’ Manwatching is an excellent read.
Sexual kissing could have been a way that was passed down from gestures that were used to recognize those who aren’t kin.
The term for it is relic gesture.
https://www.irishtimes.com/life-and-style/health-family/scie...
[..] What are the origins of kissing?
In early human societies, it is believed mothers weaned their babies by chewing up their food and then passing it to their babies by lip-to-lip contact. Evolutionary biologists suggest that erotic kissing is a so-called relic gesture, passed down through cultures from these early practices of the mother’s deep kissing and the infant’s searching tongue movements.
“If young lovers exploring each other’s mouths with their tongues feel the ancient comfort of parental mouth feeding, this may help them to increase their mutual trust and thereby their pair-bonding,” writes Desmond Morris in his classic book on human behaviour, Manwatching.[..]
Desmond Morris’ Manwatching is an excellent read.