Bones of a teenage girl, presumed to be a hunter-gatherer, from approximately 7000 years ago of the Sulawesi Islands in Indonesia unveiled an entirely different group of humans known to man.
Researchers revealed their recently discovered information gathered from the Leang Panninge cave, where they had uncovered the girl's remains, in a new study published Wednesday in the journal Nature.
"We have discovered the first ancient human DNA in the island region between Asia and Australia, known as 'Wallacea', providing new insight into the genetic diversity and population history of early modern humans in this little-understood part of the world," said study co-author Adam Brumm, a professor of archaeology at Griffith University's Australian Research Centre for Human Evolution, via email to CNN.
Despite the absence of concrete evidence of the actual route and the ways they navigated their journey, researchers believe that the first group of modem humans traveled through Wallacea islands, mainly Indonesian islands that consist of Lombok, Flores, and Sulawesi, as they made their way from Eurasia to Australia 50,000 years ago.
In tropical climates, DNA tends to degrade more rapidly and the fossil record is sparse. However, researchers have found tools and cave paintings which is a clear indication that humans lived on these islands 47,000 years ago.
"They must have done so using relatively sophisticated watercraft of some kind, as there were no land bridges between the islands, even during the glacial peaks of the last ice age, when global sea levels were up to 140 meters (459 feet) lower than they are today," Brumm said.
The skeleton of the girl, believed to be between the ages of 17 and 18, was uncovered in a cave on Sulawesi where she lived 7200 years ago. According to research, she belonged to the Toalean culture, found in a pocket of Sulawesi's southwestern peninsula. The cave is located within an archaeological site called Leang Panninge, reports CNN.
"The 'Toaleans' is the name archaeologists have given to a rather enigmatic culture of prehistoric hunter-gatherers that lived in the forested plains and mountains of South Sulawesi between around 8,000 years ago until roughly the fifth century AD," Brumm continued through the email. "They made highly distinctive stone tools (including tiny, finely crafted arrowheads known as 'Maros points') that are not found anywhere else on the island or in wider Indonesia."
The teen's skeleton is the first largely complete and well-preserved associated with the Toalean culture, Brumm said. For the research, lead study author Selina Carlhoff was able to retrieve DNA from the wedge-shaped petrous bone at the base of the skull.
"It was a major challenge, as the remains had been strongly degraded by the tropical climate," said Carlhoff, also a doctoral candidate at the Max Planck Institute for the Science of Human History in Jena, Germany.
The DNA revealed that she descended from the first wave of modern humans that entered Wallacea 50,000 years ago which was known as a part of the initial colonization of " Greater Australia." These are the knowns ancestors of the present-day Indigenous Australians and Papuans, explained Brumm.
The oldest genome which traced back to the Wallacea islands also revealed something rather groundbreaking: an entirely unknown group of ancient humans.
The results which helped the researchers arrive at this conclusion showed that the teen girl shared ancestry with a separate and distinct group from Asia. These humans most likely arrived after the colonization of Greater Australia and do not share any ancestry with Indigenous Australians and Papuans.
"Previously, it was thought that the first time people with Asian genes entered Wallacea was around 3,500 years ago when Austronesian-speaking farmers from Neolithic Taiwan swept down through the Philippines and into Indonesia," he said.
"It suggests that there might have been a distinct group of modern humans in this region that we really had no idea about up until now, as archaeological sites are so scarce in Wallacea and ancient skeletal remains are rare."
Unfortunately, no descendants of this lineage remain.
The DNA also found a trace of another extinct group of humans known as Denisovans. Based on prior research, they were largely from Siberia and Tibet.
"The fact that their genes are found in the hunter-gatherers of Leang Panninge supports our earlier hypothesis that the Denisovans occupied a far larger geographical area than previously understood", said study co-author Johannes Krause, a professor of archaeogenetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Surprisingly, when her DNA was brought in to compare with that of the other hunter-gatherers from the same time period, the results showed zero traces of Denisovan DNA in the others.
"The geographic distribution of Denisovans and modern humans may have overlapped in the Wallacea region. It may well be the key place where Denisova people and the ancestors of indigenous Australians and Papuans interbred," said study coauthor Cosimo Posth, a professor at the University of Tübingen's Senckenberg Centre for Human Evolution and Palaeoenvironment in Frankfurt, Germany.
This new discovery is only one piece of a larger puzzle to the Toalean culture. With time and more discoveries, Brumm wishes to unveil the whole ancestral story of the ancient humans in southeast Asia.