13. What expensive ingredient was needed for the cities to expand upward?
1 answer:
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As part of the "Great Coastal Migration," the progenitors of the first Australians were among the first modern people to depart from Africa. Debatable, but generally speaking, the Great Coastal Migration left between 50 and 60,000 years ago. As the name suggests, this migration made its way from Africa via Arabia to India and Southeast Asia along the shore of the Indian Ocean. Sea levels were substantially lower back then. The huge islands off the coast of western Indonesia were really a massive peninsula known as Sunda. Australia, Tasmania, and Papua were all part of a one continuous landmass known as Sahul (in both cases "Sunda" and "Sahul" are modern names for these ancient landmasses, rather than ancient names that have lingered). However, water levels never decreased to the point that they could immediately connect the smaller Indonesian islands of Sunda and Sahul. (Check attachment for a map - for reference).
The Great Coastal Migration had to island hop their way through these little islands to reach Australia when they reached the eastern tip of Sunda. For this portion of the migration, boats or rafts were required, and they could have been required sooner if the Great Coast Migrants had departed Africa by the Horn rather than the Suez. However, we haven't yet discovered concrete proof of the type of watercraft that may have been created at the period. The oldest trustworthy indication of the existence of humans is found between 45 and 50,000 years ago in both Papua and mainland Australia. Historically speaking there's a wide diversity of small watercraft used by indigenous Australians (Check out the second attachment for another map reference); but 45-50,000 years ago is far to remote a time for this historical data to really be useful in telling us what sort of boats or rafts the first Australians used to make the final leg of their journey into Australia.
