At www.eurekalert.org/pub_releases/2013-01/m-gf011413.php … the story compares gene flow between India and Australia on at least two occasions. However, bearing in mind Aborigines and the peoples of New Guinea may have earlier origins as there is considerable evidence to suggest they were living in the region over 50,000 years ago, this will hardly be the last word on the subject. The study concerns more recent connections. The consensus, until now, is that Aborigines and the people of New Guinea were largely isolated from other human groups for at least 50,000 years ago. Right up until the arrival of European voyagers in the 17th and 18th centuries – although a good case has been made that Chinese voyages of exploration in the 14th century may have reached Australia. Now, we have evidence that people with genes shared with India, the Dravidians of the southern part of the continent, reached Australia as recently as 4230 years ago – and in all likelihood they brought the dingo with them as they appear to have links in common with Indian village dogs. The origin of dingos has always been problematic and it is generally assumed they arrived with some people from SE Asia blown off course in a storm, or something like that. The interesting point about this discovery is that it coincides with a series of widespread migrations in other parts of the world, set in motion by environmental factors of some kind. Moe Mandelkehr, in a series of articles in SIS Review has described an Earthwide Event that occurred, in his view, at 2300BC. However, in order to encompass all the changes and upsets the event is best seen as lasting from 2300 to 2000BC, culminating in a major drought episode that brought an end to dynasty 11 in Egypt and Ur III in Sumeria. Mandelkehr described a series of major migrations around 2300, across the top of Canada for example, and in Asia, movements of people across the top of the steppe zone ending up in NE Europe, movements by horse mounted nomads from the steppes south into the Balkans, and eastern Europe, in one direction, and south via the Caucasus into northern Mesopotamia, and Iran, or further east via Afghanistan and the Khyber Pass to end up in northern India, and even further east, movements that impinged on China. In Europe itself there were major migrations taking place – the Beaker folk movements for example. Therefore, a migration by sea across the Indian Ocean fits snugly into the model of global movements of people, and is supported by a welter of evidence collected by Mandelkehr. It also coincided with archaeological evidence of introductions into Australia of new plant processing techniques and stone tool technology (such as the appearance for the first time of microliths).
The other, earlier migration, also washed up against India and all points east as negrito people are found in the subcontinent, on the Andaman Islands, in SE Asia and Malaya, and in various parts of Indonesia and the Philippines (the Mamanwa people) as well as New Guinea and Australia. This movement may go back as far as 36,000 years ago as genetic evidence seems to suggest they divided from each other at about this time. Again, this was a period of great upheaval, including major die-offs of mammal species. So, it might be useful to think in terms of a major migration at this time, in response to environmental factors of some kind, which led to their dispersal over a wide area SE Asia. As most of Indonesia was actually part of the continental land mass during the last Ice Age, it means they didn't necessarily have to island hop by boat. They could have travelled by boat along river systems or hugged the coast.