Prehistory of Australia - Arrival

Arrival

See also Early human migrations#South Asia and Australia

The minimum widely-accepted timeframe for the arrival of humans in Australia is placed at least 40,000 years ago. Many sites dating from this time period have been excavated.

In Arnhem Land the Malakunanja II rock shelter "has been dated to around 55,000 years old".

Archaeological evidence indicates human habitation at the upper Swan River, Western Australia by about 40,000 years ago. Tasmania, which was connected to the continent by a land bridge, was inhabited at least 30,000 years ago. Others have claimed that some sites are up to 60,000 years old, but these claims are not universally accepted.

Palynological evidence from South Eastern Australia suggests an increase in fire activity dating from around 120,000 years ago. This has been interpreted as representing human activity, but the dating of the evidence has been strongly challenged.

Charles Dortch has identified chert and calcrete flake stone tools, found at Rottnest Island in Western Australia, as possibly dating to at least 50,000 years ago. This seems to tie in accurately with U/Th and 14C results of a flint tool found embedded in Tamala limestone (Aminozone C) as well as both mtDNA and Y chromosome studies on the genetic distance of Australian Aboriginal genomes from African and other Eurasian ones.

Migration was achieved during the closing stages of the Pleistocene, when sea levels were much lower than they are today. Repeated episodes of extended glaciation during the Pleistocene epoch, resulted in decreases of sea levels by more than 100 metres in Australasia.

The continental coastline extended much further out into the Timor Sea, and Australia and New Guinea formed a single landmass (known as Sahul), connected by an extensive land bridge across the Arafura Sea, Gulf of Carpentaria and Torres Strait. Nevertheless, the sea still presented a major obstacle so it is theorised that these ancestral people reached Australia by island hopping. Two routes have been proposed. One follows an island chain between Sulawesi and New Guinea and the other reaches North Western Australia via Timor. However, an alternative theory, involving accidental colonisation as a result of tsunamis, has recently been proposed.

The sharing of animal and plant species between Australia-New Guinea and nearby Indonesian islands is another consequence of the early land bridges, which closed when sea levels rose with the end of the last glacial period. The sea level stabilised to near its present levels about 6000 years ago, flooding the land bridge between Australia and New Guinea.

It is unknown how many populations settled in Australia prior to European colonisation. Both "trihybrid" and single-origin hypotheses have received extensive discussion; however, the issue has become politicised, with the assumption of a single origin tied in to ethnic solidarity, and multiple entry used to justify white seizure of Aboriginal lands. There is little objective data to settle the issue one way or the other.

Human genomic differences are being studied to find possible answers, but there is still insufficient evidence to distinguish a "wave invasion model" from a "single settlement" one. Some Y chromosomal studies indicate a recent influx of Y chromosomes from the Indian subcontinent.