Aussie Crossing

Apologies for last week's blogging silence, Christmas took me away from my computer, however I am back and here with another installment.

Regardless of whether the original Australians came from Africa in an early wave 75,000 years ago or a later split from an Asian population, they still had to undertake an epic journey across Indonesia and a sea voyage to reach this new home. Looking at a map of Australasia today it is difficult to imagine a group travelling such vast distances using only fairly primitive rafts for transport. However as always seems to be the case with human migration, climate seems to have played a role in enabling this spread south into Australia. The world 55-65,000 ya was experiencing a glacial period, because of this large quantities of water were locked away in the polar regions, the consequence of this was that sea levels in the Australasian area were as much as 200m lower. This meant that instead of chains of islands between Australia and Asia there were land bridges - the Sunda and Sahul shelves, allowing the migrating humans to cross an extensive area by land.

                                                                   

Figure 1 - Migration route of humans in blue

Despite much of their journey being across land there was still Wallacea to contend with. As you can see in Figure 1, Wallacea is an area consisting of small islands separated by deep channels of water, the most extensive section of open water would have been 50 miles, across the Java trench. The most likely method of travel across this expanse was using bamboo rafts, whether this journey was possible at such an early time was a debated topic, however the prominent anthropologist Alan Thorne recreated the journey, constructing a raft from materials which would have been available to the ancient population, and using no modern navigational gadgets, the raft lasted the 50 miles of the journey, illustrating that this transportation was a possible mode for the new colonisers .

The video below is taken from 'The Incredible Human Journey', it shows what travel by bamboo raft would have been like and the difficulties that can be encountered in open water. It also suggests that the discovery of Australia would have occurred by accident, mainly because it was over the horizon and would have therefore been into the unknown.