Ancient Women Preferred Interbreeding with Neanderthals More than Men
Jakarta, CNBC Indonesia - Researchers have discovered new evidence regarding interbreeding between modern humans (Homo sapiens) and Neanderthals. Female humans appear to have interbred far more frequently with Neanderthals than did male humans.
Interbreeding between ancient human ancestors and Neanderthals occurred tens of thousands of years ago, when both species inhabited the same geographical areas.
Unlike modern humans, who evolved in Africa, Neanderthals were a hominin species that evolved in Europe and Asia before ultimately going extinct.
In a genetic study, scientists uncovered new evidence about admixture between the two species. Pairings of human females with Neanderthal males proved far more common than pairings of human males with Neanderthal females.
The study, published in the journal Science, states that “whenever Neanderthals and modern humans interbred, there was a preference for Neanderthal males and human females, not the reverse,” according to Alexander Platt from the University of Pennsylvania, one of the study’s authors.
This conclusion is based on analysis of Neanderthal DNA found in modern humans outside sub-Saharan Africa. Neanderthal DNA is not evenly distributed throughout the human genome.
Neanderthal DNA is extremely rare on the human X chromosome, a phenomenon researchers have termed the “Neanderthal desert.”
“For years, we suspected this ‘desert’ existed because some Neanderthal genes were ‘toxic’ to humans, as often occurs when species interbreed. We thought these genes caused health problems that eventually disappeared through natural selection,” said Platt.
The research analysed modern human DNA preserved in three Neanderthal fossils: Altai, Chagyrskaya and Vindija. The results were then compared with genetic data from humans from sub-Saharan Africa.
Interestingly, a reverse phenomenon occurred in Neanderthals. The presence of modern human DNA on Neanderthal X chromosomes was 62 percent more common than its appearance on other chromosomes.
Females have two X chromosomes, whilst males have only one. If Neanderthal males interbred more frequently with human females, the number of Neanderthal X chromosomes appearing in human genes would decrease. Conversely, more human X chromosomes would be found in the Neanderthal population.
“The simple explanation is that there was a preference in partner selection,” said Platt.
Platt stressed that this finding does not suggest that Neanderthal males appeared physically attractive to Homo sapiens females.
“It’s possible everyone found interspecies mating repugnant, or perhaps attractive. However, it appears that one type of mating may have been viewed as preferable or less desirable than another,” he noted.