The First Australians were among the world's earliest ocean explorers, undertaking a 2,000 kilometre migration through Indonesia at least 65,000 years ago. Research published earlier this year highlights the most likely route by mapping the region over time through changing sea levels.
     Some archaeologists have argued for an initial human migration into Australia through New Guinea, because islands across northern Indonesia are relatively close together, and people could easily see to the next island. First landfall on Australia has been argued to be both more difficult and less likely than first landfall at New Guinea, as the final crossing distance from was more than 80 kilometres. It was also thought that the Australian landmass was not visible from any Indonesian island. Despite that it was proposed that now submerged islands off the Australian continental shelf were visible from Timor, but until recently ocean floor data sets were not adequate to test this.
     During an ice age lasting from around 71,000 to 59,000 years ago, western Indonesia formed part of the Pleistocene continent of Sunda, while Australia and New Guinea were joined to form Sahul. Using surface height data, the new study ran more than 10,000 computer analyses of visibility between islands and continents in the whole of Island South East Asia. The results show that between 70,000 to 60,000 years ago - and potentially for much longer - people could see from the Indonesian islands of Timor and Rote to a now submerged island chain in the Timor Sea at the midpoint between southern Indonesia and Australia. From there it was possible to sight the Australian continental shelf, which then formed a massive fan of islands extending towards Indonesia - much of it now more than 100 metres below the surface.
     The findings potentially solve another mystery: if people island-hopped from Timor and Rote they would have arrived on the now submerged northwest coastline close to all of Australia's most ancient occupation sites, such as Madjedbebe, Nauwalabila and Boodie Cave.
     While we might be closer to understanding where people first reached Australia, signs of the earliest explorers to reach Indonesia have been more elusive. Another team of researchers have now begun the search on Rote and West Timor for the earliest evidence of the region's first human arrivals, the likely ancestors of the First Australians.

Edited from Australian National University (28 March 2018)