A physically modern human
was unearthed at Lake Mungo
, in the south-west of New South Wales
, in 1974. Probably male, the skeleton has usually been dated to somewhere around 25 000 or 30 000 years ago, and a presumed ancestor
of modern Aboriginal
people. But recent studies have reevaluated the date to about 60 000 years BP; and now researchers have claimed to have extracted identifiable DNA
from it. Moreover, this DNA is strikingly different from that of modern
humans, suggesting an earlier migration
of a line that is now extinct
Starting in 1995, Alan Thorne, Gregory Adcock, and Simon Easteal, working at ANU in Canberra, isolated a single gene to get its mitochondrial DNA, and compared its sequence with other ancient Australian skeletons, with other modern humans, and with Neanderthals, bonobos, and chimpanzees, and found that though closer to Homo sapiens than to Neanderthal, it was considerably more divergent from what would be expected if the individual had arisen from the single recent African genesis of the "Out of Africa" theory.
They suggest it supports the "multiregional" theory, by which the spread of pre-modern humans occurred before they speciated into modern sapiens. But this interpretation has been disputed. Because of the remoteness of the site, at the far end of the continent compared to Australia's point of contact with the rest of the world, it would seem unlikely that gene flow could sustain a single wave of speciation among all forms of H. erectus to extend this far.
Also, though the dating (in 1999) was an improvement on previous efforts, some scientists think it unlikely that DNA could be preserved that old in such conditions, since the oldest so far extracted was 30 000 years old from cool, dry conditions.