Humans migrated at least 50,000 years ago from mainland Asia through the Wallacea chain of islands, now mainly in Indonesia, into Sahul, which includes modern day Australia and New Guinea [see “From Sunda to Sahul” by Nicholas Thomas, Natural History, June 2021]. By around 37,000 years ago, the people of Sahul—Papuan peoples of New Guinea and Aboriginal Australians—had become distinct from their mainland Hòabìnhian hunter-gatherer ancestors. New analyses of a 7,000-year-old skeleton found at Leang Panninge in Sulawesi, Indonesia, suggests that a previously unknown population may have also split off from these groups at a similar time.
The remains were found and analyzed by an international team led by biochemists Selina Carlhoff and Johannes Krause of the Max Planck Institute for the Science of Human History, geneticist Cosimo Posth of the University of Tübingen, Germany, and archaeologists Akin Duli of Hasanuddin University in Indonesia and Adam Brumm of Griffith University in Queensland, Australia.
Morphological analyses of the nearly complete skeleton determined that the remains belonged to a seventeen– or eighteen-year-old female. Genetic material was collected from the petrous bone, a part of the skull that houses the inner ear. The researchers found that this individual was genetically similar to Papuans and Aboriginal Australians. However, while the genomes of individuals of those two lineages include about 2.9 percent Denisovan ancestry, the individual found at Leang Panninge had less; only an estimated 2.2 percent.
Denisovans were a group of archaic humans who mixed with ancestors of modern humans, though the exact timing and location of this interaction is unknown. The results of this study suggest that Denisovans mixed with the Leang Panninge lineage at the same time as the Papuan and Aboriginal lineages. Thus, genetic exchange between these groups could have occurred in the area where the remains were found, a group of islands between Borneo and Australia known as Wallacea.
Because the Leang Panninge genome included less Denisovan ancestry than its closest relations, the researchers hypothesize that the Leang Panninge peoples also mixed with other groups from eastern Asia after splitting off from Papuan and Aboriginal Australians. Further discoveries of humans from this time period are needed to better understand the genetic history of the hunter-gatherers and their migrations. (Nature)