AsianScientist (Aug. 18, 2021) – Carrying clues to human history in their DNA, a Philippine indigenous group called the Ayta Magbukon have the highest amounts of Denisovan ancestry in the world. These findings were published in Current Biology.
Before the airplanes and ferries of today, early humans were already routinely on the move, migrating to new lands and interbreeding among diverse populations. Ancient hominins known as the Denisovans, for example, had admixed with Australasian ancestors—a group encompassing Australians, Papuan Highlanders and Philippine Negritos.
However, much of this intertwined history has yet to be uncovered. Traces of ancestral DNA in modern humans hold evidence of past admixing events, but it is only recently that researchers have mapped and analyzed genomic data of underrepresented populations, particularly among Philippine indigenous groups.
To understand the complex interactions between Denisovans and Australasians, an international team investigated over two million genotypes from 118 ethnic groups in the Philippines, detecting significant levels of Denisovan DNA among the Negrito populations.
Led by Dr. Maximilian Larena and Prof. Mattias Jakobsson from Sweden’s Uppsala University, the huge collaborative effort involved various local institutions in the Philippines such as cultural communities, universities and government units, including the National Commission on Indigenous Peoples and the National Commission for Culture and the Arts.
While the data supported the known admixing between ancestral Negritos and Denisovans, the team’s surprising discovery was finding the significant Denisovan genetic imprint left on the Ayta Magbukon Negrito people. Aytas inherited about five percent of their DNA from Denisovans—a striking 30 to 40 percent more than present-day Papuan Highlanders, who were previously regarded as the group with the most Denisovan ancestry.
As they ran simulations of possible interbreeding patterns, the researchers also uncovered how such variability in archaic DNA levels arose despite the intertwined ancestry. Separate Denisovan lineages may have entered the evolutionary picture only after the Negrito-Papuan groups had already diverged, leading to independent mixing events and greater Denisovan imprints among Negrito peoples.
Not only did the study rewrite the prevailing narrative around Australasians’ shared history, but it also lends insight into evolutionary differences between Ayta Magbukon and other Negrito ethnic groups.
According to researchers, Negritos more recently mated with East Asian migrants, who carry very little Denisovan DNA. By introducing East Asian lineages, this admixing sharply diluted the archaic ancestry of the Negrito populations, masking the Denisovan traces with other genetic tracts.
But since their Denisovan ancestry remained intact, the Ayta Magbukon group likely had minimal admixing with East Asian populations compared to other Philippine indigenous peoples.
Alongside the 2019 discovery of a hominin fossil dubbed Homo luzonensis, these emerging lines of evidence are shedding light on archaic Philippines, with several possibly genetically linked ancestral species inhabiting the islands before modern humans arrived.
“Altogether, our findings unveil a complex intertwined history of modern and archaic humans in the Asia-Pacific region, where distinct Islander Denisovan populations differentially admixed with incoming Australasians across multiple locations and at various points in time,” the authors concluded.
The article can be found at: Larena et al. (2021) Philippine Ayta possess the highest level of Denisovan ancestry in the world.
Source: Uppsala University. Photo: Shutterstock.
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