Walkabout

A couple of days ago, a long-time reader of (and frequent contributor of topics for) Skeptophilia sent me an email saying "Time to get your Archaeo-Geek excited!", with a link to a study about archaeological finds in Australia.  I was really confused at first because I read "Geek" as "Greek" and was puzzled about how there could be an ancient Greek settlement in Australia. 

I need new glasses.

Anyhow, once I got that sorted, I found that the actual research was pretty amazing.  A team of archaeologists led by Kasih Norman of Griffith University has discovered artifacts dating back to the Late Pleistocene Epoch -- on the order of twenty thousand years ago -- indicating a large human population living in a thriving ecosystem, with rolling hills and a large freshwater lake, all of which are now at the bottom of the Gulf of Carpentaria.

The authors write:

The submerged Northwest Shelf of Sahul (the combined landmass of Australia and New Guinea at times of lower sea level) was a vast area of land in the Late Pleistocene that connected the Australian regions of the Kimberley and western Arnhem Land during times of lower sea level than today.  The shelf extends >500 km northwest from the modern-day shoreline with a now-submerged landmass of ∼400,000 km2, an area more than 1.6 times larger than the United Kingdom.  The region might have been an area of initial entry for the peopling of Sahul.  Irrespective of the precise locations people used to disperse into Sahul, the Northwest Shelf is adjacent to the oldest known archaeological sites in Australia , and might have been one of the first inhabited landscapes on the continent.  Archaeological evidence for Late Pleistocene use of the continental shelves of Sahul by the First Australians is demonstrated on multiple large islands that are remnant portions of the continental margin, including Barrow Island, Kangaroo Island, Hunter Island, and Minjiwarra (Stradbroke Island).

The distribution of artifacts, which include stone axes, flint tools, and arrowheads, indicate at east two major pulses of settlement, which is cool because it lines up with what we know about the linguistics of the region.  The majority of the indigenous languages of northern and central Australia -- 306 of the 400 recorded native languages -- belong to the Pama-Nyungan family, which is (as a group) a linguistic isolate, related to no other known language group.  The rest are scattered clusters of unrelated languages, indicative of arrivals at different times or from different places, apparently when the Gulf of Carpentaria was mostly dry land and you could walk from New Guinea to Australia without getting your feet wet.

Eventually, of course, as we were coming out of the last ice age, the sea level rose and gradually that block of lowlands filled in from both sides, isolating Australia from the islands to the north and halting the walkabout that allowed for easy settlement.  But at its height, the archaeologists believe the now-submerged region could have been home to between fifty and five hundred thousand people.

"[Sea level rise] likely caused a retreat of human populations, registering as peaks in occupational intensity at archaeological sites," the authors write.  "Those who funneled into an archipelago on the shelf would go on to become the first maritime explorers from Wallacea [what is now the islands of eastern Indonesia], creating a familiar environment for their maritime economies to adapt to the vast terrestrial continent of Sahul."

Further research into the archaeology, topography, and paleoecology of the region is sure to turn up more information about a landscape that has altered dramatically in the last fifteen-thousand-odd years.  It also spurs researchers to look at other regions flooded by sea level rise -- like Doggerland, now beneath the turbulent waters of the North Sea -- perhaps to recover more clues about where and how our distant ancestors lived.

"Now submerged continental margins clearly played an important role in early human expansions across the world," the researchers write.  "The rise in undersea archaeology in Australia will contribute to a growing worldwide picture of early human migration and the impact of climate change on Late Pleistocene human populations."

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