Australia: The Land Where Time Began

A biography of the Australian continent 

Mixed Australian Ancestry – Genetic Basis

Attempts to extract ancient DNA from WLH 50, and it suggested by current technology that it will never be possible. Genetic analysis, including palaeogenetics, has confirmed many of the earlier hypotheses concerning the pattern of migrations to Sahul, as well s the sources from which the migrants came. Analysis of the nuclear genome (nDNA) from a 100-year-old sample from an Aboriginal man, that was chosen to minimise any European admixture (Rasmussen et al., 2011), concluded that the ancestors of this individual, and possibly of many other Australian Aboriginals were part of an Asian lineage that separated from the gene pool of all other contemporary populations that were non-African approximately 70 ka. Mixture for this, as well as other lineages, has been demonstrated by other genetic evidence that is now available;

“it is becoming increasingly difficult to imagine a structure model that can fully explain the complex pattern of archaic ancestry in non-Africans without invoking any restructure events with archaic humans” Skoglund & Jacobsson, 2011: 18305).

Explanations of human prehistory that assume the Eve replacement theory can no longer be considered.

“The recent finding that significant interbreeding occurred between Neanderthals and modern populations refutes the long-standing model that proposes all living humans trace their ancestry exclusively back to a small African population and completely replaced archaic human species, without any interbreeding (d’Errico & Stringer, 2011: 1060).

This is compatible with the conclusion reached by Wolpoff & Hee in this monograph.

It is suggested independently here based on comparisons of anatomy that a mixed ancestry an interpretation that is well supported by Aboriginal Australian anatomical variation, in the same sense that mixed ancestry is an explanation that is well supported for recent European variation (Wolpoff et al., 2001). The dispersal of hunter/gatherers into Europe at the close of the ice age, and later of farmers migrating into Europe from western Asia, is largely a reflection of the recent genetic history of Europe. The indigenous European hunter/gatherers of the Late Pleistocene had relatively little input into the gene pool of Neolithic Europeans. The recent genetic history in southern and southeastern Asia also reflects mixture with Late Pleistocene and Holocene dispersals across Asia. At this time agriculture did not reach Australia, though domestic dogs did, minimally by 3,450 BP ± 95 (Milham & Thompson, 1976).

Europe is also a good analogy for Australia early in the history of these regions, in the sense that the populations of the Late Pleistocene of these regions are a consequence of mixture. There is a historic confusion of geographic source with evolutionary status in both regions. This has meant confusing an Indonesian source with “robust” and “archaic” cranial anatomy in Australia; in Europe it has meant an indigenous European source with introgression from what had been thought of as a different Neanderthal species. It is now understood that many interbreeding events took place across Eurasia during the Late Pleistocene, from Europe to Australia (Wolpoff et al., 2001; Wolpoff & Lee, 2012), which means that adaptive genes were able to disperse widely, under selection, between populations (Hawks, 2013). Many of these adaptive genes, and possibly most of them, originated in populations of Africans, as the majority of genes in the human gene pool of the present are of African origin.

It has seemed to be important in some discussions of the prehistory of Australia that the earliest crania that were dated were recognised as gracile (i.e., “modern”) and not robust (i.e., “archaic”).  This had been taken as an evolutionary sequence from a robust condition into a more gracile (“modern”) one, which was similar to other parts of the world, and it would have indeed been a disproof! Though the robust crania in Australia were not more “archaic,” and they did not evolve into more gracile (=”modern”) populations. The reason the robust crania were different was because they included some ancestors from different places; Wolpoff & Lee have argued here from skeletal evidence that Pleistocene Indonesia was very likely one of these places. Every known fossil sample from Australia that included more than 1 or 2 individual has combinations of anatomical features indicating ancestors from several geographic regions. This is a reflection of a history of mixture of populations from different sources.

One implication of this has been noted early on (Howells, 1967: 339), the sequence of dispersals from different source populations does not matter. The differences between populations that entered Australia, contra Webb and others, are not of evolutionary grade (“modern” or “archaic species) but from source areas (such as China or Indonesia (27)). And this reason, of which region the earliest migrants are from (28) is not pertinent; this is entirely an archaeological and historical issue.  The question that was important in earlier discussions  - which migrants were first – is not relevant in the evolutionary processes described in this way.

Sources & Further reading

Habgood, P. J. (2016). "WLH 50: How Australia Informs the Worldwide Pattern of Pleistocene Human Evolution By Milford H. Wolpoff and Sang-Hee Lee PB - PaleoAnthropology 2014: 505−564. DOI:10.4207/PA.2014.ART88." Archaeology in Oceania 51(1): 77-79.