LEIPZIG, Germany, Feb. 17 (UPI) -- New data suggests Neanderthals and humans mated 100,000 years ago, much earlier than previously thought.
Researchers at the Max Planck Institute for Evolutionary Anthropology discovered the earlier interbreeding event using a variety of DNA analysis techniques. The study's results were published this week in the journal Nature.
"We knew from Neanderthal DNA found in the genomes of humans outside Africa that Neanderthals and humans have interbred," study co-author Sergi Castellano, said in a press release.
"This interbreeding is estimated to have happened less than 65,000 years ago, around the time that modern human populations spread across Eurasia from Africa," Castellano continued. "We now find evidence for a modern human contribution to the Neanderthal genome. This is likely the result of much earlier interbreeding."
Researchers compared the genomes of a Neanderthal specimen -- recovered from the Atlai Mountains of Siberia, near the Russia-Mongolia border -- with modern human genomes recovered from fossils collected across Africa. The analysis revealed several shared genetic mutations, suggesting interbreeding.
Researchers also analyzed the genome of a Denisovan specimen and the genomes of two Neanderthal specimens unearthed in Europe -- one from Croatia and one from Spain. Their genomes showed no evidence of the DNA of modern humans, but the new data doesn't prove modern humans never mated with European Neanderthals or Denisovans.
"The signal we are seeing in the Altai Neanderthal probably comes from an interbreeding event that occurred after this Neanderthal lineage diverged from its European cousins, a little more than 100,000 years ago," said lead researcher Adam Siepel.
The human DNA found in the Siberian specimen suggests a group of modern humans left Africa much earlier than the ancestors of modern Europeans and Asians, whose ancestors left Africa some 65,000 years ago.
The group of humans split from the two main modern human populations in Africa some 200,000 years ago. After lending their genetic diversity to Siberia's Neanderthals 100,000 years ago they became extinct.