Huddie William Ledbetter (January 20, 1888 – December 6, 1949)
[Update: Stephen Buckley continues his riposte in the Comments. Just click on the link at the foot of this post. 2012.08.21]
The other day I wrote about fact-checking Hardy et al.‘s recent treatise ‘Neanderthal Medics?‘ I pointed out that there was no substantive reason to accept their claim that the presence of four carbon compounds–flourene, fluoranthene, pyrene and phenanthene–implied that the El Sidrón Neanderthals had inhaled wood smoke.
Tonight I’d like to take up another of their conclusions, that several other chemical compounds indicated the presence, in dental calculus, of bitumen or oil shale. I should remind you that dental calculus largely comprises dead oral bacteria. As the authors put it
Also identified were a series of hopanes (carbon numbers C29 to C33), indicative of an oil shale or bitumen and corroborated by the presence of the isoprenoid hydrocarbon biomarkers phytane and pristane … (p. 620)
Hopanes? Hopanoids. According to my favorite encyclopaedia, Wiki, the main function of hopanoids ‘is to improve plasma membrane strength and rigidity in bacteria.’ Hmm. Bacteria. Arrrr, Jim. Bacteria be the creaturs that make the biofilm that forms dental plaque, first off, and then calculus. Arrrr. It may well be the case that hopanes occur in bitumen or oil shale, but that may well be because both substances are the end-product of organic decomposition, decomposition that would in all likelihood have involved bacteria and other microorganisms.
‘Pristane is a natural saturated terpenoid alkane obtained primarily from shark liver oil, from which its name is derived (Latin pristis, “shark”). … It is also found in mineral oil and some foods. Biosynthetically, pristane is derived from phytol.’ Among other sources of phytol, ‘… [i]n ruminants, the gut fermentation of ingested plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats.’ Phytane is a diterpenoid alkane that’s formed by the breakdown of phytol.
Granted, as Hardy et al. mention, these are all products that might be found in bitumen or oil shale. But, as I’ve pointed out, there’s nothing unambiguous about the source of these compounds in the Neanderthal dental calculus at El Sidrón. And, for all we know, the (stable isotopically characterized) carnivorous Neanderthals, along with the meat and connective tissue, were consuming the contents of the rumen of their prey, much in the way the !Kung men on the hunt once did as a way of acquiring water where none occurred on the landscape.
I find it really hard to believe that the editors of Naturwissenschaften gave more than a second’s thought to the authors’ interpretations, so taken must they have been by the study’s results. After all, it’s not every day that you get to see a report based on sequential thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), such as that of Hardy et al. Only problem is, when an archaeologist fails to rule out natural occurrences before imputing Neanderthal behaviour, it’s like popcorn without butter. It’s indigestible.
For my part, I’ll go back to imagining the Neanderthals occasionally inhaling the smoke of wildfires, and waiting for extinction while they fed on whatever they could of the animals they brought down or scavenged.
Do I really need to go on in this manner? Or, have I satisfactorily demonstrated the wrong-headedness of Hardy et al. I don’t see the point. Anyone care to take the wheel?