Denisovans and Neanderthals went extinct thousands of years ago. But scientists have found fragments of Neanderthal and Denisovan DNA in the genomes of modern residents of Melanesia. In fact, Melanesians have the highest degree of ancient DNA ever documented. Researchers at Binghamton University in New York sequenced the genomes of 1,523 people from across the globe, including 35 Melanesians. Then they compared them to DNA extracted from the remains of Denisovans and Neanderthals.
How did Denisovans reach Melanesia?
Findings of the study were published in the journal Science. Andrew Merriwether, the co-author of the study, said it was quite surprising that these Neanderthal and Denisovan genomes made it out to such a remote place. Melanesia region includes Fiji, Papua New Guinea, Maluku Islands, the Solomon Islands, West Caledonia and Vanuatu.
Human remains dating back to 48,000 years have been recovered from the region. What’s puzzling is that no one has been able to connect them with any other place. When you compare their genomes, they don’t cluster with any other group, said Merriwether. They have been living there, isolated, for a very long time. These places are volcanic islands with mountains, making it extremely challenging for ancient humans to reach these places.
Melanesia is also the most linguistically diverse place on the planet. Melanesians speak more than 800 languages. The question that intrigues researchers is how Denisovans made their way to the faraway, tiny islands.
No Neanderthal or Denisovan ancestry among Africans
The new study confirmed prior findings that all non-African people had 1.5-4% Neanderthal genomes. Melanesians were the only population that also had a Denisovan ancestry.
The study found that Melanesians are about 1.9% Neanderthal and 3.4% Denisovan. The latest evidence suggests that modern humans and their early relatives had interbred on at least three separate occasions. Neanderthals were first discovered in Germany, while Denisovan remains were found in Siberia. Past studies have showed about 2% genetic overlap between non-African populations and Neanderthals. But there is no Denisovan or Neanderthal ancestry among Africans.