The authors propose two different scenaria: one that the archaic specimen from Longlin is derived from a morphologically variable African population; the other that it represents an indigenous archaic remnant.
From the paper:
One widely discussed candidate for the oldest modern human in East Asia is the skeleton from Liujiang, southern China . Yet, the geological age of this individual has “been an everlasting dispute since the discovery of the fossils in 1958” as “there is no documentation on the exact stratigraphic position of the human remains” [4, p. 62]. As a result, its estimated age lies within the broad range of >153-30 ka , . The age of the Upper Cave (Zhoukoudian) remains is similarly problematic and has been a major source of uncertainty since their discovery in the 1930s, with estimates ranging from ~33-10 ka , . Furthermore, the Niah Cave child from East Malaysia possesses uncertain provenience . However, a recent field and lab program aiming to assess the stratigraphy and dating of the deposits at the site has proposed an age of ~45-39 ka for this cranium .The evidence is slowly mounting for the place of origin of fully modern H. sapiens, as region after region strikes out by having archaic humans present when they are not supposed to be there. Both Sub-Saharan Africa and East Asia have struck out, and Europe had already struck out because of its documented Neandertal population. Australasia is not a valid option due to the lack of precursors, and the Americas because of the their late settlement.
That leaves two options: northernmost Africa (what is now desert) and Arabia/the Gulf Oasis/Indian subcontinent. I'd say that things are looking good for my two deserts theory.
UPDATE: From the New Scientist:
And so it begins. For years, evolutionary biologists have predicted that new human species would start popping up in Asia as we begin to look closely at fossilised bones found there. A new analysis of bones from south-west China suggests there's truth to the forecast.
The distinctive skull (pictured, right) was unearthed in 1979 in Longlin cave, Guangxi Province, but has only now been fully analysed. It has thick bones, prominent brow ridges, a short flat face and lacks a typically human chin. "In short, it is anatomically unique among all members of the human evolutionary tree," says Darren Curnoe at the University of New South Wales in Sydney, Australia.
Exactly where the Red Deer Cave people belong in our family tree is unclear. Curnoe says they could be related to some of the earliest members of our species (Homo sapiens), which evolved in Africa around 200,000 years ago and then spread across Asia to reach China. He prefers the idea that they represent a new evolutionary line that evolved in East Asia in parallel with our species, just as Neanderthals did – primarily because they look very different to early African members of our species.
Curnoe says an initial attempt to extract good DNA from the fossils failed. "We are doing more work now involving three of the world's major ancient DNA laboratories," he says. "We'll just have to wait and see if we're successful."
PLoS ONE 7(3): e31918. doi:10.1371/journal.pone.0031918
Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians
Darren Curnoe et al.
Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site.
We undertook a detailed comparison of cranial, including a virtual endocast for the Maludong calotte, mandibular and dental remains from these two localities. Both samples probably derive from the same population, exhibiting an unusual mixture of modern human traits, characters probably plesiomorphic for later Homo, and some unusual features. We dated charcoal with AMS radiocarbon dating and speleothem with the Uranium-series technique and the results show both samples to be from the Pleistocene-Holocene transition: ~14.3-11.5 ka.
Our analysis suggests two plausible explanations for the morphology sampled at Longlin Cave and Maludong. First, it may represent a late-surviving archaic population, perhaps paralleling the situation seen in North Africa as indicated by remains from Dar-es-Soltane and Temara, and maybe also in southern China at Zhirendong. Alternatively, East Asia may have been colonised during multiple waves during the Pleistocene, with the Longlin-Maludong morphology possibly reflecting deep population substructure in Africa prior to modern humans dispersing into Eurasia.