Researchers examined 7,200-year-old DNA, revealing previously unknown early humans in Southeast Asia.
The findings shed light on the prehistoric Toaleans, who mysteriously disappeared 1,500 years ago.
The remains of a 17- to 18-year-old girl who died about 7,200 years ago have revealed a prehistoric lineage of humans previously unknown to science.
The Leang Panninge remains, named after the cave in Sulawesi, Indonesia, where they were found, were likely of a person of the Toalean culture, an elusive group of hunter-gatherers who disappeared about 1,500 years ago.
The findings, published in the peer-reviewed journal Nature on Wednesday, provide insight into the geographical movements of early modern humans.
The 'enigmatic' Toaleans
The Toalean culture is "enigmatic" for archeologists, Adam Brumm, a professor of archaeology at Australia's Griffith University and an author on the study, told Insider in an email.
Toalean culture "seems to come out of nowhere ... apparently having no or limited contact with other early foraging cultures elsewhere in the island," he said.
The Toaleans kept to one small part of Sulawesi's southwestern peninsula, Brumm said.
That is particularly interesting to paleontologists because Sulawesi is part of the Wallacea region, a collection of Indonesian islands that were used by the first modern humans as "stepping stones" between Eurasia and Oceania as early as 50,000 years ago, the scientists said in a news release.
The Toalean culture left behind tools and intricate arrowheads but very few fossils and no workable DNA before the Leang Panninge remains.
'We cannot say who this population was'
The process of extracting the DNA from the 7,200-year-old bones was painstaking, but it was worth it, the study's authors said in their statement.
The genetic material revealed that the teenager shared ancestors with the modern-day Papua New Guineans and Indigenous Australians who arrived in Wallacea as early as 50,000 years ago, they said.
The generally held hypothesis before these findings was that Asian populations entered Wallacea only about 3,500 years ago, Brumm told CNN.
But the DNA also revealed genes that didn't fit with any other known population, the scientists said, suggesting that a distinct group - previously unknown to science - must have emerged from Asia in Wallacea earlier than previously thought, and left no modern-day descendants.
"We cannot say who this population was. But it formed a unique profile in this 'genetic fossil' never seen before in any present-day or ancient individual," Cosimo Posth, a professor of paleogenetics at Germany's Eberhard Karls University of Tübingen and an author on the study, told Insider in an email.
The authors also found traces of Denisovan DNA, an extinct group of archaic humans related to the Neanderthals most commonly found in Siberia and Tibet, suggesting that they traveled much farther than previously thought.
The Toalean culture didn't fare well in the long run, though, Posth said.
"It seems to be replaced by later human movements and admixture in the region, leaving us with the question: 'What happened to the bearers of the Toalean culture?'" he said.
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