australia Colonisation – the Demographic Context

Australia: The Land Where Time Began

Australia Colonisation – the Demographic Context

It is demonstrated by genetic and archaeological evidence that modern humans descended from anatomically modern humans who had evolved in Africa and then spread across the world colonising any vacant land and then eventually replacing other hominids where the land was occupied (Lahr & Foley, 1994, 1998; Chen et al., 1995; Watson et al., 1997; Relethford, 1998, 2001; Quintana-Murci, 1999; Ingman et al., 2000; Cooper et al., 2001; Forster et al., 2001; Henshilwood et al., 2002; Macauley et al., 2005; Rose, 2006).

Hiscock suggests the spread of anatomically modern humans (AMH) probably occurred between 100,000 BP and 50,000 BP (Watson et al., 1997; Forster, 2004; Palanichamy et al., 2004; Forster & Matsumura, 2005; Merriwether et al., 2005), when India and Asia were occupied by AMH, which were regions adjacent to Australia.

The colonisation of Australia may have occurred shortly after the arrival of AMH in Southeast Asia, possibly an extension of the dispersal of a species with language who could solve many problems, which included the technical difficulties involved in large water crossings (David & Noble, 1992). The arrival of anatomically modern humans in southeast Asia has, however, not been dated accurately (Barker et al., 2007); their movement to Australia possibly being delayed by the difficulty of the maritime crossing or by regional environmental events.

The Toba eruption that occurred between 75,000 BP and 71,000 BP was one such event which was of catastrophic proportions that occurred in Sumatra (Chesner et al., 1991; Zielinski et al., 1996). Lava flows, dust and tephra from this eruption of the supervolcano partially or completely deforested large areas of southeast Asia (Rampino et al., 2008; Rose & Chesner, 1990; Rampino & Self, 1992, 1993; Flenley, 1996). Foragers that were migrating to the east may have found the region had at this time no food or raw materials for tools available.

It was suggested by some researchers that populations around the world were killed, which would have allowed the colonisation of an Asia, that was mostly empty, by anatomically modern humans that were moving out of refuge areas such as Africa (Rampino & Self, 1992; Ambrose, 1998, 2003; Rampino & Ambrose, 2000; Rampino, 2002). According to Hiscock the evidence does not support mass extinctions in other parts of the world (Oppenheimer, 2002; Gathorne-Hardy & Harcourt-Smith, 2003). Though the devastation of the Toba eruption was regional, it is still possible it influenced the movement of AMH to Australia.

Hiscock suggests that if humans had passed the area of Toba before the eruption they may have travelled towards Australia in order to search for areas that were less affected by the devastation. If humans had not yet reached the vicinity of Toba at the time of the eruption they may have been presented with a barrier of ecosystem destruction. There is a suggestion that following the eruption population growth may have caused groups to move away from the recovering region, towards Australia, in the period between 65,000 BP and 45,000 BP (Lahr & Foley, 1994; Lahr, 1996). By linking the environmental change in southeast Asia and the spread of foragers to Australia, this suggestion possibly explains the reason the estimated antiquity of common maternal genetic ancestors of all living Aboriginals is similar to the date of the Toba eruption, about 74,000 ka.

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