A new study finds that most interbreeding between modern humans and Neanderthals occurred between Neanderthal males and Homo sapiens females.
Neanderthal men were short, powerful and lively, while our ancient women seem to have preferred these traits, researchers say.
It has been known for centuries that humans and Neanderthals had intimate relationships, as many people today carry traces of their DNA. But how this happened has remained unknown – until now.
Analysis of the genes of Neanderthals and modern humans showed that Neanderthal DNA is less abundant on the human X chromosome, suggesting that little DNA from Neanderthal females entered the human genome.
At the same time, Neanderthals had more human DNA on their X chromosomes than in the rest of the genome, reinforcing the idea that most interbreeding was between Neanderthal males and human females.
This discovery challenges the long-held assumption that natural selection "cleaned out" Neanderthal genes on the X chromosome due to biological toxicity.
According to the researchers, social preferences and attraction between the sexes offer a simpler explanation. “The interactions were partial and driven by physical attraction,” says Dr. Alexander Platt, one of the researchers.
Recent studies also suggest that Neanderthals and humans may have been kissing around 50,000 years ago. Analysis of primate species that kiss, such as chimpanzees and orangutans, and the use of statistical models showed that Neanderthals may have engaged in kissing during intimate relationships.
Combining this data with the traces of the crosses suggests that kissing may have been part of their intimacy.
Researchers believe that interbreeding occurred largely by agreement, but in the harsh prehistoric world there may not have always been equal choice. Thus, males and females may have been involved in different ways, leaving behind a complex social and biological history. /GazetaExpress/
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