Thursday, 16 February 2012

More Birch Tar From Germany: Königsaue

I won't spend very much time on this last (effectively) claim for the Neanderthals' ability haft lithic artifacts to reach-extending tools, inferred on the basis of their putative ability to dry-distill birch tar. Apparently Dietrich Mania found some birch tar in a what he inferred from the geology was a Middle Palaeolithic context at Königsaue, a lignite quarry in Germany that had once been a lakeside context. One of the lumps has a fingerprint in it. According to Mania it must be a Neanderthal fingerprint. It's not discernible in this image, but we can fairly safely accept its identification as a fingerprint and proceed from there.
One of the birch-tar lumps from Königsaue (from Koller, Baumer and Mania 2001).
I haven't sourced the original German site reports, but I'm happy to shelve that task. That's because the hardened lumps of birch tar that were recovered at Königsaue have been chemically characterized, and I'm satisfied that they are what, first Mania, and now others consider them to be. 
     However, I was struck by an interesting datum in the 2001 article by Koller, Baumer and Mania in the Journal of European Archaeology titled 'High-Tech in the Middle Palaeolithic: Neandertal-Manufactured Pitch Identified.' It's hard to figure out why they bothered to date the birch tar if it was presumed to be from a Middle Palaeolithic context. According to them, 
To ascertain whether these pieces were indeed prehistoric remains, direct AMS radio-carbon dating ... was applied to both pieces ... . The [lab] attributed 43,800 BP to the older sample Königsaue A (OxA-7124) and 48,400 BP to the younger sample Königsaue B (OxA-7125). However, these dates are in contradiction to the assigned geological age of 80,000 years or more. But since the C-14 concentrations after 14 half-lives are too small, both resin finds must be considered outside the reasonable range of application for C-14 dating, and the AMS dates may merely be accepted as a minimum value [emphasis added].
I'm a little bemused by this reasoning, and by the absence of a statement of the error associated with these dates. It's quite possible they overlapped, in which case it makes no difference which was uppermost in the Königsaue sequence. Crucial to the question is the knowledge that the dated samples were recovered in the context of a lignite quarry. Lignite is a carboniferous material that is somewhere between peat and coal. It is mined as a low-grade fuel for power plants. It was formed in the Tertiary period, much later than the true coals. Yet, its age is still such that one would be tempted to call it 'old carbon.' As every undergraduate archaeology student knows, the proximity of archaeological materials to deposits of old carbon have been the subject of protracted debates about the age of, for example, Meadowcroft Rockshelter, the putative late glacial-aged Paleo-Indian site in Pennsylvania.
     I raise this point because the authors of the Königsaue birch-tar paper are careful to argue that their lumps of birch tar are beyond the range of radiocarbon dating. I'm surprised that they state that 48 kyr is near the theoretical or practical limit of radiocarbon--according to Earl Nelson, one of the developers of the AMS technique, any age up to about 75,000 years is theoretically possible, and 50 kyr is a commonplace result in geology. Regardless, why should we accept the conclusion that these lumps are at least 48 kyr old, and most likley far older? It's well known that a very small amount of old carbon is capable of skewing the scintillation counts on which the radiocarbon technique relies in the direction of 'older.' Thus, it's entirely possible that the samples are much, much younger. Perhaps they're from the Mesolithic or Neolithic, where there is well-documented manufacture of birch tar. 
     For the time being I'm going to decline to examine further the underpinnings of this claim for birch tar manufacture in the Middle Palaeolithic. While the unequivocal documentation of birch-tar manufacture in the Middle Palaeolithic would indeed be an extraordinary finding, I'm satisfied that the other presumed evidence for hafting in the MP is so tenuous as to obviate a more strenuous examination of the Königsaue claim.
     Touchstone Thursday tomorrow. See you then!