Human-Neanderthal Hybridization (here we go again ... again)

A day or so back, I posted on an AP article which declared that "skull found in a cave in Romania includes features of both modern humans and Neanderthals, possibly suggesting that the two may have interbred thousands of years ago." The original research article is now online. Let's look at the abstract, shall we?

Between 2003 and 2005, the Pestera cu Oase, Romania yielded a largely complete early modern human cranium, Oase 2, scattered on the surface of a Late Pleistocene hydraulically displaced bone bed containing principally the remains of Ursus spelaeus. Multiple lines of evidence indicate an age of {approx}40.5 thousand calendar years before the present ({approx}35 ka 14C B.P.). Morphological comparison of the adolescent Oase 2 cranium to relevant Late Pleistocene human samples documents a suite of derived
modern human and/or non-Neandertal features, including absence of a supraorbital torus, subrectangular orbits, prominent canine fossae, narrow nasal aperture, level nasal floor, angled and anteriorly oriented zygomatic bones, a high neurocranium with prominent parietal bosses and marked sagittal parietal curvature, superiorly positioned temporal zygomatic root, vertical auditory porous, laterally bulbous mastoid processes, superiorly positioned posterior semicircular canal, absence of a nuchal torus and a suprainiac
fossa, and a small occipital bun. However, these features are associated with an exceptionally flat frontal arc, a moderately large juxtamastoid eminence, extremely large molars that become progressively larger distally, complex occlusal morphology of the upper third molar, and relatively anteriorly positioned zygomatic arches. Moreover, the featureless occipital region and small mastoid process are at variance with the large facial skeleton and dentition. This unusual mosaic in Oase 2, some of which is paralleled
in the Oase 1 mandible, indicates both complex population dynamics as modern humans dispersed into Europe and significant ongoing human evolution once modern humans were established within Europe.

Umm. No mention of hybridization. So what does the main text say?

The potential phylogenetic scenarios could involve evolutionary reversals relative to the presumably ancestral MPMH [Middle Paleolithic Modern Humans], the appearance of a uniquely derived set of traits in the lineage leading to the Oase remains, and/or reflect incomplete paleontological sampling of Middle Paleolithic human diversity. In this case, Oase 2 could indicate only descent from earlier MPMH. Alternatively, it could reflect admixture with Neandertal populations as oxygen isotope stage
3 modern humans spread through western Eurasia, as suggested elsewhere (1, 10, 28-32). This mixture would have resulted in both archaic traits retained from the Neandertals and unique combinations of traits resulting from the blending of previously divergent gene pools. The ultimate resolution of these issues must await considerations oflarger samples of MPMH, European early modern humans, and chronologically intervening specimens.

Draw your own conclusions.

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Off the top of my head, being a complete novice to this topic (I can barely parse what you've quoted from the research article), I can think of half a dozen other explanations.

I believe this is the journal article the New Scientist article is based on:

http://www.pnas.org/cgi/content/abstract/0606966103v1

EvolGen is also discussing it. Given that you are skeptical of this hybridization, I'm curious about your reaction to this. One thing I don't understand -- we share lots of genes with closely related ancestors. Why does this gene suggest hybridization rather than simply being related species with a common ancestor?