Humans kissed Neanderthals – and they liked it, a new study shows.
Researchers at the University of Oxford and Florida Institute of Technology have found evidence that ancient humans were smooching around 50,000 years ago.
Neanderthals (Homo neanderthaliensis) were a close human ancestor that lived in Europe and Western Asia from about 400,000 to 40,000 years ago.
Previously studies have shown that our species, Homo sapeins, had sex with Neanderthals because Neanderthal DNA survives in people today.
However, whether kissing was part of their sexual encounters has been less clear – until now.
‘While kissing may seem like an ordinary or universal behaviour, it is only documented in 46 per cent of human cultures,’ said study author Catherine Talbot, a professor at Florida Institute of Technology.
‘The social norms and context vary widely across societies, raising the question of whether kissing is an evolved behaviour or cultural invention.
‘This is the first step in addressing that question.’
Kissing occurs in a variety of animals such as monkeys, polar bears, wolves and even albatrosses, while other animals have equivalent behaviours like nose-touching and head-tapping.
For modern humans, kissing is usually an integral part of the mating experience that appears to be controlled as much by biological urges as sex itself.
But the researchers call kissing ‘an evolutionary puzzle’ as it appears to carry high risks, such as disease transmission, while offering no obvious reproductive or survival advantages.
Looking at the evolutionary history of kissing is also tricky because it is clearly not a behaviour that can be determined from archaeological remains.
For the study, the researchers collected data from the scientific literature on the modern primate species that have been observed kissing, including chimps, bonobos and orangutans.
The experts defined kissing as non-aggressive, mouth-to-mouth contact that does not involve the transfer of food.
They used a statistical approach (called Bayesian modelling) to simulate different evolution scenarios along the branches of the primate family tree.
The model was run 10 million times to give robust statistical estimates of our different ancestors who also engaged in kissing.
The results indicate that kissing evolved in an ancestor to the Great Apes somewhere between 21.5 million and 16.9 million years ago.
There are four living classifications of great apes or ‘Hominidae’ – Orangutan, Gorilla, Pan (consisting of chimpanzee and the bonobo) and Homo, of which only modern humans remain.
Results also suggested Neanderthals engaged in kissing too during their existence, which was relatively much more recently (about 400,000 to 40,000 years ago).
This finding adds to a previous study that discovered humans and Neanderthals shared oral microbes via saliva transfer.
Combined with evidence of interbreeding, it strongly suggests that humans and Neanderthals kissed one another during their sexual interactions.
Ever since, kissing has been retained over the course of evolution and is still present in most of the large apes – but why it has survived for so long is unclear.
Last year, Professor Adriano Lameira, an evolutionary psychologist at Warwick University, published a paper outlining the evolutionary origin of human kissing.
The act of sucking very slightly with pursed lips was once a technique to remove tics and lice from each other’s fur, he said, before it started to gain sexual connotations and become an act that preceded mating.
Kissing and lovemaking between Homo sapiens and Neanderthals was thought to be widespread and likely not too dissimilar from today.
‘We of course assume that mating was consensual,’ Paul Pettitt, professor of archaeology at the University of Durham, previously told the Daily Mail.
‘But a sad fact of the ancient world may suggest that this was far from the truth and perhaps one “partner” had little choice in the matter.
‘Thus, in the rough and tumble of the prehistoric world perhaps mating just occurred – impromptu, with little thought or intention.
‘If it was consensual then we can certainly assume there was foreplay – even sensual kissing and cuddling.’
The new study, ‘A comparative approach to the evolution of kissing’, has been published in Evolution and Human Behavior.
