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<\/div>An excavation at Laili cave in East Timor in 2019<\/p>\n
Mike Morley<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A cave on the island of Timor has given archaeologists a vital clue to the route taken by ancient humans when they first made their way to the Australian continent.<\/p>\n
It is known from archaeological evidence in Australia\u2019s Northern Territory that people were there at least 65,000 years ago. At this time, when sea levels were lower, Australia and New Guinea were part of a larger landmass known as Sahul.<\/p>\n
Researchers believe there are two likely routes people could have taken from South-East Asia to Sahul. One is a southern route via Timor. Alternatively, Homo sapiens<\/em> could have travelled via Sulawesi, an island to the north of Timor.<\/p>\n Now, Sue O\u2019Connor<\/a> at the Australian National University in Canberra and her colleagues believe they have found evidence ruling out the possibility that the first arrivals came through Timor.<\/p>\n In other locations on Timor, the oldest evidence of human occupation was less than 50,000 years old. Archaeologists were unable to look for older artefacts as, at all the other sites they studied, they hit bedrock rather than sediment layers that could potentially contain evidence of an earlier presence, says O\u2019Connor.<\/p>\n <\/p>\n In 2019, her team dug a new pit at a cave called Laili, on the north coast of East Timor, and discovered a rich deposit of archaeological evidence including tens of thousands of stone tools, proving that humans had occupied the island for 44,000 years.<\/p>\n Crucially, however, this layer of occupation was underlain by sediments with no evidence of humans. This means it is likely that before 44,000 years ago, people were absent, says O\u2019Connor.<\/p>\n \u201cThis is the first time in Timor that we have sterile, non-occupation layers below evidence of people\u2019s presence,\u201d she says.<\/p>\n O\u2019Connor says such a clear boundary between no evidence of humans followed by tens of thousands of years of artefacts is called an \u201carrival signature\u201d.<\/p>\n The cave\u2019s prominent location and access to resources gives the researchers confidence that it is unlikely to have been missed by any early humans travelling through the area.<\/p>\n \u201cIt\u2019s a really, really big cave with a big flowing river in a braided floodplain and very close to the coast,\u201d says O\u2019Connor. \u201cIt\u2019s a perfect place for people to establish an occupation base camp. You couldn\u2019t find a more ideal setting.\u201d<\/p>\n Because of the evidence that people were in Australia 65,000 years ago but not in Timor until 44,000 years ago, it means humans most likely migrated via the islands to the north, says O\u2019Connor.<\/p>\n \u201cLooking at the layers in Laili cave, it\u2019s like \u2018bang\u2019 \u2013 you can really see clearly when the people arrive,\u201d she says. \u201cIt was like a line had been drawn between the two layers \u2013 before people and after people. It was so clear.\u201d<\/p>\n