No, we don't, but here is what we do know:
1) No Neanderthal mtDNA lineage has been found to date among several thousands of Europeans.
2) No Neanderthal mtDNA lineage has been found to date in fossils of early modern Europeans.
3) Models of intra- and inter-specific craniofacial variation support a clear morphologocal distinction between Neanderthals and Cro-Magnon.
4) The considerably shortened period of Neanderthal somatic development points strongly toward a clear distinction between Neanderthals and Cro-Magnon.
5) The clear divergence and monophyly of Neanderthal mtDNA suggests a long separation of Neanderthal and Cro-Magnon female lineages, four times greater than that of the most recent common ancestor of human mtDNAs. IOW, the most recent common ancestor of Neandertal and modern human mtDNAs is indicated to have been roughly 550,000 years ago.
6) Intermediate hominid forms stand between their most recent common ancestor and each respective lineage of Neanderthal and of Cro-Magnon.
7) We find no evidence of the contribution of Neanderthals to modern human genetics in haplotype tree analyses and performed phylogeographic analyses.
8) Neanderthal fossils cease to occur in a region almost immediately following the advent of modern human fossils into that region.
9) We find no mixed communities of Neanderthal and Cro-Magnon.
10) We find no hybrid intermediate forms signifying Neanderthal/Cro-Magnon admixture.
11) Cro-Magnons were the first to produce arrowlike projectiles tipped with ivory and amber, while Neanderthal weapons were only wooden spears sometimes tipped with stone points.
12) Cro-Magnons also made figurines and created objects of bone, an ability the Neanderthals apparently largely lacked.
13) Cro-Magnons learned to build the first true houses; there is only one known instance where a Neanderthal appears to have built a crude dwelling, quite possibly by imitation of Cro-Magnons.
14) It is almost certain that the FOXP2 gene that is critical in modern human speech and language was absent in Neanderthal. Silent polymorphisms in the gene date the critical mutations in the FOXP2 gene to the last 100,000 years, long after the last common ancestor of Neanderthal and Cro-Magnon.
I meant to ping the two of you also to my post #175, that you may find of interest!
http://cogweb.ucla.edu/Abstracts/Wilford_98.html
I have read that Neanderthals had speech. Did they or not?
In any contest where one side has long-range weapons (arrows, atlatls, slings) and the other side doesn't, the side that has only short-range weapons is in deep trouble
This point looks wrong to me. Lagar Velho Child for one controversial data point, various Skuhl specimens for others that come to mind at once.
European Neanderthals seem to be the most extremely divergent from us, espically in the West. In the Near East especially, there are more ambiguous and intergrading specimens. The story there is complicated. Note the caption to the Skuhl 5 specimen on that page.
Your post is anexcellent summary of the reasons for your position.
Unfortunately it does not address some concerns of mine regarding phenotypic features observable in some modern humans and H. nea skeletons. One can see short forearms, receeding chins, sloping foreheads and elongated skulls on any busy downtown street.
In addition, the information I got from this website (geared to the educated lay person):
http://www.appliedbiosystems.com/biobeat/index.jsp?articleId=113672dd-653c-ea97-69147147026d8325&type=0
leads me to suspect a degree of over interpretation of the data. The data I'd like to see would be from the earliest H. nea and the earliest H. sap in the middle east.
Some of your points regarding differences, while correct, do not seem to me to be a bar to breeding oreven necessarily indicative of a difference in intelligence. Little to no evidence of representational art might mean they painted their bodies, not their walls. Lack of technological development to me argues for lack of competition or environmental stress rewarding experimentation, not necessarily intellectual deficit. As a matter of fact, the neanderthal flute I've read about highlights an artistic and intellectual skill I, for one, totally lack.
Arguments from morphology alone are as silly as phrenology, and would lead to hundreds of ridiculous inferences if applied to modern humans. Arguments from absence are only as strong as the evidence suggests exhaustiveness, and here is does not remotely do so. N. sites have been found at recent as 30,000 years ago (subject to some error in the dating, to be sure - maybe 35ky bp really), some in regions long since passed by H. settlement (e.g. in the Balkans). As for the idea that N. couldn't talk, it is extremely implausible on its face. There are no significant anatomical differences detectable in anything connected to speech.
Moreover, the supposedly so rapid spread of H. through the range of N. is a time scale of 7,000 years. 7000 years ago, a few farmers had evolved villages in the fertile crescent, and not a single human grouping on the globe today existed. In other words, 7000 years in the tiny cockpit of Europe is forever, for all purposes of ordinary history and diffusion of peoples. It is rather like saying the Germans displaced the Babylonians, and there is no evidence they interbred. Except the time scale is twice as long. There is no reason to expect a subset of mankind to last 7000 years unaltered in the first place.