More than 50,000 years ago, a 13-year-old girl died. He was very special, because his skull fragments revealed that this girl was the first generation of marriage between two different hominin species.
His mother was a Neanderthal while his father was a Denisova. Both species are the closest relatives of modern humans who have become extinct.
Researchers also showed at least the girl was 13 years old when she died, while radiocarbon dating put her death time more than 50,000 years ago.
Next, they take DNA samples from bones and sort them. They found that his mother was a Neanderthal and his father was Denisovan.
"The interesting aspect of this genome is that it allows us to study things from two populations," said Fabrizio Mafessoni, geneticist at the Max Planck Institute for Evolutionary Anthropology.
Denny's DNA also revealed that his mother was genetically closer to the Neanderthal population living in Western Europe than those who lived in the Denisova Cave in the East about 20,000 years ago.
This shows that Neanderthals immigrated throughout Europe tens of thousands of years before disappearing.
Another interesting thing, so far only four Denisova humans have been identified through DNA analysis. Denny is the fifth.
"It is surprising that we found children from Neanderthals and Denisovas among a handful of ancient individuals whose genomes have been sequenced," said Svante Pääbo, an evolutionary geneticist with Max Planck Institute for Evolutionary Anthropology.
"Neanderthals and Denisovans may not have many opportunities to meet. But when they meet, they will often mate, far more than we thought before," Pääbo added.