[Update: Please have a look at the four-part response from the biologist who undertook the chemical composition study of the El Sidrón Neanderthal’s dental calculus. It’s in the comments, at the foot of this post. 2012.08.21]
You may be wondering why I didn’t jump on this when it was first announced. Published online on July 18 Hardy et al. claim to have extracted *cough* hard evidence of Neanderthal behaviours akin to those of modern humans from the dental calculus that formed on the teeth of 5 individuals from the Iberian Peninsula.
I’ve been waiting for the time to look in detail at their claims, and although I haven’t finished the fact-checking, I can say that Hardy et al.’s inferences are looking awfully shaky. As before when Very Serious Archaeologists have published chemical analyses, my focus is the authors’ interpretation of their findings. I’ll give but one example of this from their paper.
They claim the following:
The additional presence [in the calculus] of the main combustion markers, fluorathene [sic], and pyrene, along with smaller amounts of fluorene and phenanthrene, strongly supports the evidence for cooking/smoke inhalation in this sample (621).
Pyrene and fluoranthene are the products of combustion, it’s true. However, they are characteristic of incomplete combustion, i.e. combustion in a reducing atmosphere–one in which there is insufficient oxygen for complete combustion to occur. That describes perfectly the ‘cooking’ environment only if you’re producing charcoal or, indeed, smoked salmon. Phenanthrene is found in tobacco smoke and that of coal-burning appliances. Fluorene occurs naturally, and according to the EPA, ‘[f]umes from vehicle exhaust, coal, coal tar, asphalt, wildfires, agricultural burning and hazardous waste sites are all sources of exposure.’
Now, remember that it was the authors’ intention to produce evidence for cooking, fire, and plant use. Their inference here–that the Neanderthals were inhaling smoke– depends entirely on the erroneous claim that the four compounds are present in the Neanderthal’s dental calculus because of smoke inhalation. I have to ask, ‘How likely is it that this group of Neanderthals inhaled smoke from charcoal production or salmon smoking in a reducing environment, tobacco smoke, vehicle exhaust, or hazardous waste?
I think you can guess the answer to my rhetorical question. But that doesn’t address the possibility that the Neanderthals in question weren’t dry-distilling birch or coal tar, and sniffing asphalt. After all, as the authors remind us others have made claims that Neanderthals were capable of dry-distilling birch tar and using asphaltum to haft points on wooden shafts. Why couldn’t these Neanderthals have been doing just that?
I suppose they could have been dry-distilling birch or coal tar (if either Betula or coal were components of the El Sidrón environment–an open question at the moment). Except, if so, they’d have been inhaling the smoke from the wood fires used to ‘cook’ the two substances, rather than inhaling any of the compounds given off while the birch or coal were ‘cooking,’ because it’s necessary to keep the substances being ‘cooked’ in hermetically sealed vessels throughout the process! Likewise, they might have been inhaling asphaltum while they were gluing a rock to a stick. But…well, I think you get the point.
And the point is this. The authors have done nothing, not a thing, to rule out the natural sources of the chemicals they report on. And that is a subversive’s take on but one of the claims made by Hardy et al. I’ll have more on this cockamamy paper in a subsequent post.