Monday, February 1, 2010

304. Aftermath 19: Australia and New Guinea

( . . . continued from previous post.)

3. On second thought these earliest settlers may well have stuck to the coastal regions rather than expanding in all directions. Since their OoA ancestors would most likely have had a coastal culture, there's no reason to assume they would have been any different in this respect. The interior of New Guinea is rugged and mountainous and the interior of Australia is extremely arid when not actually desert, so it's not difficult to see them expanding along the coasts rather than venturing very far into the interior. Even today, the greatest part of the Australian population lives on the coast and most of the archaeological sites are on or near the coast. Lake Mungo, where the oldest fossils have been found [8], is located near the extreme southeast of Australia, at the opposite pole from the point at which the earliest settlers are most likely to have arrived, which makes it likely that the entirety of the Sahul coast (and nearby interior regions) could have been populated within a relatively brief period. So it seems reasonable to think in terms of a fairly rapid expansion along the coasts of the entirety of Sahul, possibly in both directions, followed by a very long period of stability, in which these relatively peaceful and cooperative hunter-gatherer descendants of HBP and HMP could have lived together in harmony for literally tens of thousands of years.

4. We must now return to an earlier era, prior to the settling of the Sahul, when colonies of Out of Africa migrants would have been strewn across the Indian Ocean coast, from the Indus Delta all the way to what is now Myanmar, Thailand, the Malay Peninsula and possibly beyond. Since progress along this coast is generally thought to have been rapid, possibly speeded by the use of rafts or boats, the various populations would have resembled one another in many respects, most likely with an African, if not actually Negrito, morphology and a culture still steeped in the traditions of HMC. I've already written of the necessity for some sort of "fudge" factor (along the lines of Alan Guth's Cosmic Inflation) to reconcile the basic Out of Africa model with the gap we now see in the form of a cultural and genetic discontinuity between the Horn of Africa and greater Southeast Asia (including the Sahul), a gap centered in South Asia. To account for this gap, as I've already argued, we are almost forced to posit a major population bottleneck (or series of bottlenecks) in this region, possibly due to the Toba eruption, at a very early stage of the OoA migration.

5. As a result of the precipitating event, the population of many if not all groups in South Asia and to some extent neighboring Southeast Asia, would have been drastically reduced, to the point that many lineages might not have survived at all, especially those in India. And population bottlenecks produced by such an event could have led to founder effects leading to the emergence, especially in the region to the east of India, of new and distinctive morphologies, which we could refer to as "proto-Mongoloid," "proto-Caucasoid" and "proto-Australoid." If there is, indeed, a relation between Paleosiberians, Mongols, Chinese, etc., such an event would provide us with a reasonable explanation for that relationship, which would have to have been based on a very early founding event, prior to the divergence of these groups from one another. Similarly, if there is more than an accidental relationship between the morphology of the Ainu and European "Caucasoids," such a founding event, at such an early period, and in that particular region, could explain it. Since Australoid morphology is much less far flung, there is less reason to argue that it too must have originated with the same event, and indeed it's possible that this very distinctive type might have emerged as the result of a more localized bottleneck event at some later date. Nevertheless, it seems reasonably safe to assume that Australoid morphology might well have originated in the same disastrous event as that which most likely produced the others.*

6. If Australoid peoples originated to the east of India, some groups could have migrated toward the west and south, where we find so many now (see Oppenheimer's The Real Eve for his theory of how India could have been repopulated in the wake of Toba), while others, or perhaps only one such group, could have slowly migrated east as well. If we can associate this population with Y chromosome haplogroup C*, as suggested by Redd et al [5], we can follow their progress across Southeast Asia, down to Island Southeast Asia and, finally, to either the southern Sahul or Australia, depending on the timing of their arrival.+ It is much too early, however, to claim a clear genetic association (or lack thereof) between Indian and Australian Australoids. However, it is unreasonable, as I see it, to insist that this very clear morphological association is some sort of illusion, simply because all the genetic i's and t's have not yet been dotted and crossed.

7. The most promising clue offered by the Redd et al study [5] is the significant difference they found between the histories of males and females in Australia. The mitochondrial phylogenies for the female line are all consistent with an early migration to the Sahul in the immediate wake of the Out of Africa migration, and little significant change in the population makeup since then, aside from what one might expect from differences produced by drift once New Guinea and Australia had become separated (roughly 10,000 years ago). It is partly due to this deceptively clear picture that Birdsell's "trihybrid" theory has been rejected in favor of the notion that the Sahul was populated by only one single immigration event. But this is a picture of the female line only. When we add the very different sort of evidence for the male line, as formulated by Redd et al, a very different picture of Australian/ New Guinean history emerges.

8. On the basis of this relatively new (though admittedly debatable) evidence, it's possible to suggest a scenario somewhat different from either that of Birdsell or his detractors. Thus, after the initial migration involving "gracile" or perhaps even "Negrito" types exclusively, with a relatively pacifistic HMC culture, we can posit another migration, occurring many thousands of years later, of Australoid hunter-gatherers with a very different, more aggressive and combative, post-bottleneck, culture. To be consistent with the genetic evidence, at least as it currently presents itself, the new immigrants would have to have been either exclusively or mostly male. It's very difficult to speculate as to when this event could have taken place. According to Redd et al,
The divergence times reported here correspond with a series of changes in the Australian anthropological record between 5,000 years ago and 3,000 years ago, including the introduction of the dingo [24]; the spread of the Australian Small Tool tradition [25]; the appearance of plant-processing technologies, especially complex detoxification of cycads [26]; and the expansion of the Pama-Nyungan language over seven-eighths of Australia [27]. Although there is no consensus among anthropologists, the former three changes may have links to India, perhaps the most relevant of which is the introduction of the dingo, whose ocean transit was almost certainly on board a boat. In addition, Dixon [28] noted some similarities between Dravidian languages of southern India and Pama-Nyungan languages of Australia.
While this argument makes sense, it's not definitive, so there's no point in pinning ourselves down to the mid-Holocene immigration (or invasion) date suggested above. Regardless, the notion that an aggressive, largely or completely male group with an Australoid morphology arrived in Sahul/Australia to confront a largely non-aggressive, non-violent population already established in the most favorable places, could go a long way in accounting for the picture we now see in both Australia and New Guinea.

(to be continued . . . )

*Again, I must emphasize that I am not referring to "racial" differences, but morphological ones. There is no such thing as a science of "race" (partly because no one really knows how to define that term as anything other than a social construct) but there is certainly a science of comparative morphology, a far less ambitious, and more clearly circumscribed, mode of anthropological research, which, because of its questionable history, is often confused with "racial science."

+The picture for Australia was "corrected" by Hudjashov et al [14], who discovered two new C haplogroups in Australia, C4a and C4b. But they don't say whether or not this directly contradicts what Redd et al claim to have found, i.e., a significant presence of C* in Australia, and a 2% presence in India, among tribal groups likely to have Australoid morphology. In fact the Hudjashov group's discussion of the Y haplogroups is confined to only a single paragraph and is incomplete and also vague. They claim their evidence is inconsistent with Huxley, who lived in the 19th century, but make no reference to Redd et al, whose study dates from only a few years prior to theirs. Regardless of their discoveries regarding C4a and C4b, the real question is the status of C*. And even if C* has been superseded in Australia by C4a and C4b, that still does not rule out a connection between India and Australia, it just makes it more difficult to prove.

1 comment:

German Dziebel said...

Just an observation (pace Terry Toohill) without an instant implication for this post:

Major haplogroups in Australia (Y-hap C, mtDNA N) are minor haplogroups in India, and that major haplogroups in India (Y-hap F, mtDNA M) are minor haplogroups in Australia.