Australia: The Land Where Time Began |
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WLH 50 ancestry - mtDNA
Current archaeological reconstructions of the peopling of Australia and
lands nearby indicate there were many complex events (Balme, 2013;
Bednarik, 2003, Bellwood et al.,
1995; Davidson, 2010; Flood, 2006; Hiscock, 2008; O’Connell and Allen,
2004, 2012; Webb, 2006). The “huge sea-level rises that flooded much of
Greater Australia, reducing it to the present day archipelago” (Hill et
al., 2007: 40), was no doubt
one driving factor. According to Wolpoff & Lee complexity is also
indicated in mtDNA studies. The strongest signals from the post-glacial
world “appear to result from the movement of indigenous, rather than
introgressive, DNA lineages (op.
cit.)” The region, as well as the rest of the world, was also
subjected to both earlier and ongoing dispersions of populations as the
population of the world increased. To evaluate these reconstructions
based on current genetic activity palaeogenetics is a useful approach.
A generally Asian source for Australian and New Guinean populations is
supported by mt DNA as well as Y haplotype analysis, though it does not
indicate a single source population (Jinam et
al., 2012; van Holst
Pellekaan, 2012). Early migration to New Guinea, which was followed by a
second migration form Southeast Asia (van Holst Pellekaan & Harding,
2006) prior to compacting, followed by reduced habitable areas of land
as the sea level rose at the close of the ice age, is one possibility.
In Australia and New Guinea some of the oldest haplotypes are shared,
with others being specific to each place (Friedlander et
al., 2007), which is a
consequence of the most recent period of isolation by the higher sea
levels. The problem is the difficulty is distinguishing the different
models of migration source or sources from mtDNA alone. McEvoy and
colleagues used a suite of genome-wide SNPs to argue:
The Australians and other Near Oceania samples, from New Guinea and
Melanesia favours the common origin hypothesis
for the original settlement of the Pleistocene Sahul continent …
followed by differentiation into subregional populations. However, we
cannot formally distinguish between this and an initial separation and
isolation of the proto-Sahul population in mainland Eurasia followed by
multiple ancient migrations to various locations in the Sahul” (McEvoy
et al., 2010), emphasis
added.
There is evidence of a high level of diversity of mtDNA lineages across
the region (Smith et al.,
2007), and much as the reconstructions of Australian habitation have
converged on the models of numerous migrations, mtDNA shows the history
of the entire region to be far more complex than first thought (Hill et
al., 2007; van Holst
Pellekaan, 2012; Xu et al.,
2012). Multiple geographic sources and several migrations are suggested
by a complex genetic history.
“Collectively, these [archaeological and genetic] data suggest the
cultural and genetic history of Australia is more complex than a single
dispersal model such as “out-of-Africa” allows” (Smith et
al., 2997: 298).
The pattern of Australian migrations in a broad regional context is
reflected in the mtDNA of living Australian Aboriginal people. It has
been suggested (Bellwood, 1997) that island Southeast Asia (Indonesia,
East Malaysia, and the Philippines) was colonised at a similar time to
that of the first Australian migrations by peoples “related to the
indigenous people of Australia and New Guinea … in the mid-Holocene
immigration of the ancestors of the present-day inhabitants” (Hill et
al., 2007: 29). Some of the
migrants to the Australasian region came in migrations that were 10-30
kyr earlier from the Asian mainland (Jinam et
al., 2012).
It was shown (Reich et al.,
2010) that mtDNA also addresses issues in Australian and Asian
prehistory. The Denisovan mtDNA recovered from Siberian finds differs
markedly from Neanderthal and recent human mtDNA. Susan Sawyer from
Pääbo’s lab has shown that within the Denisovan mtDNA the mtDNA from 1
of the teeth indicates greater mtDNA variation than is known from either
Neanderthal or living humans (Pennisi, 2013). mtDNA that was even older
on the Denisovan clade was recovered (Meyer et
al., 2014) in specimens from
the 430 ka Spanish site of Sima de los Huesos (SH).
The comparisons of WLH 50 by Wolpoff & Lee with some of the earlier
inhabitants of Indonesia, described above, suggests that Australia of
the present is a reflection of a mix of sources, just as is done by the
genetic evidence (this is a conservative interpretation of the mtDNA [Huopenen
et al., 2001]). The pattern
of nDNA variation is a direct reflection of the mixed ancestry.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |