All  
Ancient DNA Sample From Indonesia Is From An Extinct Human Lineage

Ancient DNA Sample From Indonesia Is From An Extinct Human Lineage

Print

Genetic researchers have confirmed what archaeologists had previously suspected. A 7,200-year-old fossilized skeleton found in a cave on the Indonesian island of Sulawesi in 2015  cannot be linked  to any previously discovered type of modern human. Through the sequencing of a recovered DNA sample, the researchers proved the skeletal remains belonged to a young woman from an extinct human lineage known as the Toaleans, who lived exclusively in southern Sulawesi for tens of thousands of years before finally going extinct in the fifth century AD. 

An international team of specialists with expertise in archaeogenetics (the recovery of and study of ancient DNA from fossils) completed the sequencing of the DNA, which was recovered from the inner ear bone of the female’s badly decayed fossilized skeleton. In  an article  discussing their findings in the journal  Nature, they scientists reveal that the young woman, who has been given the nickname Bessé’, was approximately 18 years old at the time of her death. 

"This was an exciting discovery, as it was the first time a relatively complete set of human skeletal remains had been found in association with artifacts of the 'Toalean' culture, enigmatic hunter-gatherers who inhabited the southwestern peninsula of Sulawesi between around 8,000 to 1,500 years ago," study author Adam Brumm, professor of archaeology at Griffith University in Australia,  told Live Science via email .

The Leang Panninge Cave in Sulawesi, Indonesia where the DNA of an extinct human lineage was discovered. (Leang Panninge research team /  Nature)

Rare Evidence: Extinct Human Lineage DNA In Sulawesi Cave

The skeleton was recovered originally by archaeologists from the University of Hasanuddin in Makassar, Indonesia, who were performing excavations at Leang Panninge Cave in southern  Sulawesi. This is one of several caves in the area that have produced artifacts associated with the Toalean people, whose ancestors arrived on the island sometime between 50,000 and 65,000 years ago.

The Toaleans are believed by most researchers to have been the original inhabitants of the island of Sulawesi (although  that has been disputed ). Modern Indonesians, including those who reside on Sulawesi, are descended from Asian Neolithic-era  hunter-gatherers who arrived just 3,500 years ago. Since the Toaleans survived to the fifth century AD, it seems the two groups must have peacefully co-existed on Sulawesi for quite some time.

Excavations at Leang Panninge Cave in Sulawesi, where the DNA evidence of an extinct human lineage was discovered. (Leang Panninge research team /  Nature)

The Surprising Genetics of an Extinct Human Species

Since the young woman is the first authenticated Toalean ever found, her DNA sample has revealed important and fascinating details about the genetic history of her people. 

Unsurprisingly, her DNA proved that the Toaleans came from the same ancient ancestors as modern-day  Australian Aborigines  and the indigenous people of the island of  New Guinea . This ancestral group migrated by sea from continental Asia, at least 50,000 years ago, in search of new lands to occupy.

Most settled in New Guinea and Australia, which during that time were part of one large Oceanic supercontinent known as  Sahul. Ice Age conditions in that era had dramatically lowered sea levels, and it was only after the Ice Age ended and sea levels rose that flooding turned Sahul into a series of separate islands.

While most of these ancient seafarers ended up on Sahul, it seems a small contingent chose to stay behind on Sulawesi, where they created their own unique culture (along with a separate genetic lineage).

The Toaleans shared about half of their DNA with their Australian and New Guinean cousins, and the nature of that relationship was a predictable result that emerged from the DNA testing on Bessé’. But the genetic researchers were shocked to discover that a good portion of Toalean DNA had come from an entirely different source. Specifically, from an ancient ancestral group that had never before been detected in any ancient DNA sample taken from the region.

Fragmentary remains of the Toalean female human pelvis. (University of Hasanuddin /  Nature)

“Our analyses also revealed a deep ancestral signature from an early modern human population that originated somewhere in continental Asia,” the genetic researchers wrote in the online publication  The Conversation . “These ancestors of Bessé’ did not intermix with the forebears of Aboriginal Australians and Papuans, suggesting they may have entered the region after the initial peopling of Sahul.”

Who were these ancestors, exactly? Right now, it is too soon to say. Scientists will need to collect more DNA samples from more skeletal remains before they can learn more about this new and previously unknown extinct human lineage of  ancient Pacific migrants . Further excavations at other Toalean sites may produce such discoveries, but for now information about these ancient Asian travelers will remain frustratingly scarce.

Handprint paintings attributed to the Toaleans found at Pettakere Cave at the Leang-Leang prehistoric site in south Sulawesi, Indonesia. (Cahyo /  CC BY-SA 3.0 )

The Elusive Toaleans Revealed

In just a single study, one sample of Toalean DNA has revealed some amazing details about the genetic history of that ancient people, who up to now had only been known through their artifacts. 

The existence of the Toaleans was first discovered in 1902, when Swiss naturalists Paul and Fritz Sarasin completed the first successful excavations of Toalean-occupied caves in southern Sulawesi. Over the decades, many details have emerged from the study of Toalean artifacts, including the fact that these opportunistic hunter-gatherers survived by  hunting wild pigs  and harvesting shellfish from the island’s creeks and estuaries.

The archaeological record makes it clear they lived side-by-side for many centuries with descendants of modern humans, who first arrived 3,500 years ago. But it seems that there was no interbreeding between the two groups, since no traces of Toalean DNA have been found in the genomes of modern Indonesians.

Excavations at various Toalean sites in southern Sulawesi are continuing. It remains to be seen if more skeletal remains are found, but for now the DNA of one young woman who lived 7,200 years ago is the only resources available to researchers who are eager to unlock the genetic secrets of this  extinct human lineage  of Sulawesi.

Top image: Fragmentary remains of the human skull of a female  Toalean. DNA found in her ear proved she was from an extinct human lineage .              Source: University of Hasanuddin /  Nature

By Nathan Falde

Next article