Buzz Off! Can't You See I'm Up to My Ears in the Organic Chemistry of El Sidrón's Dental Calculus???

Hmmm. I've been struggling with Stephen Bradley's comments on my recent post about Neanderthal oral hygiene at El Sidrón. Throughout he has maintained that the most likely source for the chemical constituents revealed by sophisticated mass spectrometry is wood smoke and cooked food. I have tried to suggest alternative natural sources of some of the compounds that he and his co-authors have identified.
     I would be dead in the water after his protracted comments on my earlier efforts were it not for my determination both to overcome my substantial ignorance of organic chemistry and to extend my argument beyond Stephen's assertions and, indeed, his conclusions. I'm having some success, I think. Take, for example, his insistence that alkenes and alkanes are plant waxes: 

The thermal desorption-GC-MS (TIC) (Fig. 1 inset) is dominated by a series of n-alkanes (carbon numbers C22 to C35), suggesting a higher plant source (Eglinton et al. 1962), most probably derived from plant waxes in the original food consumed.

I'll ask Stephen or some other organic chemist to adjudicate whether or not I've discovered another natural source of these chemicals--insects. Here is a snippet regarding the Dufour gland of a wasp, Habrobracon hebetor (Say) (Hymenoptera: Braconidae). 

The hydrocarbons consist of a homologous series of n-alkanes (n-C21 to n-C31), a trace amount of 3-methyl C23, a homologous series of internally methyl-branched alkanes (11-methyl C23 to 13-methyl C35), one dimethylalkane (13,17-dimethyl C33), a homologous series of monoenes (C(25:1) to C(37:1)) with the double bonds located at Delta9, Delta13 and Delta15 for alkenes of carbon number 25 to 31 and at Delta13 and Delta15 for carbon numbers 33 to 37 and three homologous dienes in very low amounts with carbon numbers of 31, 32, and 33. [emphasis added]*

I realize that eating insects isn't as sexy as eating cooked plants, specially not wasps. But it's not just wasps. A quick check suggests that hydrocarbons of all kinds are naturally occurring substances in insects. And it wouldn't be the first time that a primate was 'caught' eating insects. I've eaten crickets many times at sushi bars.
     I don't think I'll continue in this vein, trying to ferret out alternatives to Hardy et al.'s inferences. At this point I'd just like to chill on my veranda with a cold one.
     But not quite yet. This business with the El Sidrón Neanderthals' dental calculus has made me think about the assumptions that Stephen Bradley owned up to--that as far as he knows the Neanderthals made fires and cooked food and did numerous other things that you and I might do. I think otherwise.

     I don't know which is worse: me, having lived with the Middle Palaeolithic archaeological record for going-on 30 years and spending all my time trying to pierce the inferential balloons that my colleagues set free to ascend to the scholarly firmament, or earnest peers like Stephen Buckley having taken breath from those same balloons as a matter of course in their intellectual upbringing, spending all their time inadvertently adding to the cloud of colourful spheres floating above our heads. Whadda you think? I know what I think. I think this calls for me to touch on a subject near and dear to my heart in the near future--the context of discovery versus the context of justification (or verification). I've often been accused of being 'unscientific' because I start from the assumption that the Neanderthals were dummkopfs. So, stay tuned.

* Arch Insect Biochem Physiol. 2003 Nov;54(3):95-109. Novel diterpenoids and hydrocarbons in the Dufour gland of the ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae). Howard RW, Baker JE, Morgan ED.

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Prometheus Unfounded: Contradictions and Conundrums at Wonderwerk Cave

Wonderwerk Cave profile (Photo by M. Chazan)

I've previously opined on aspects of the claim for very early fire use at Wonderwerk Cave, South Africa here, here, here, and here. In brief, it's Swiss cheese. Today I'm beginning to look at Peter Beaumont's 2011 synthesis of the 'evidence' for hearths in the cave, published in Current Anthropology. Forgive me if this comes across as unusually pedantic--I find the author's descriptions to be less-than rigorously scientific, and thus less-than helpful if one's hoping to cast a critical eye on what amounts to his life's work. I've found it all very difficult to wrap my brain around. See what you think.   
     Beaumont begins his discussion of what he calls 'hearths' by mentioning that in places he observed 'poorly defined ash lenses' and in other places 'ash-rich' deposits, which he thought had been 'single hearths ... largely destroyed (perhaps by trampling).' It's unfortunate that there could be so much ambiguity entailed in such a short paragraph.
     First of all, what really is the difference between a 'poorly defined lens' and an 'ash-rich deposit'? Aren't they both 'ash rich' if you can recognize the ash in profile? And what about the other sequelae of burning, charcoal and the reddened substrate. I would have expected any fire that could turn plant fuel to ash would have been sufficiently hot and of such a duration that it would also have reddened the sediments beneath the fire. Moreover, in many cases where reddened sediments and ash are visible in a stratigraphic sequence there is a higher than average chance that there will be a layer of charcoal-enriched or blackened sediment between the reddened substrate and the ash. Trampled or not, Beaumont's inference that these ash lenses were hearths is hardly to be believed on the face of it.
     Presumably Beaumont wants us to believe that, in the case of the 'ash-rich' places, any vertical distinction that at one time would have been evident between the ash and the reddened sediments had been obliterated by treadage. Yet, if that were the case, how is it that he's able to discern anything that might be called discrete (albeit poorly defined) ash lenses? For Beaumont to be able to observe 'lenses' comprising ash, those lenses must have escaped, in large part, the destructive results of trampling. And surely, if the ash 'lenses' had escaped the ravages of time and trampling such that they were visible in profile, the underlying reddened sediments would also have retained enough integrity to be visible, too! Yet, the author mentions nothing about the substrate, reddened or otherwise. Odd. On the other hand, one has to agree that in all likelihood it was trampling that transformed what had once been intact ash deposits elsewhere in the cave into something the author calls (merely) 'ash-rich.'

[My recognizing problems with Beaumont's after-the-fact verbal descriptions doesn't ensure that the his inferences are incorrect. However, one does have to wonder. Doesn't one? One would have thought that a perspicacious referee or editor would have noticed these vague and incongruous descriptions. Wouldn't one?] 

     Alas, the abovementioned 'hearths' aren't the only curiosities to be found in Beaumont's treatment of putative fire use at 1+ Ma. In another example he describes stratum MU2, in excavation 5, where as much as 45 cm (!) of the stratigraphic column 'is very largely composed of white ash with many burned bones and fire-damaged Middle Stone Age artifacts.' This ash apparently 'accumulated slowly' and continuously between about 1,155,000 and about 70,000 years ago. [Get out your calculators!] 
     Depending on what Beaumont means by 'very largely composed of' [and it's not at all clear], it sounds as if he's suggesting that for 1,085,000 years a very wide area of the cave received little other sedimentary input than that of completely combusted plant material. That's a prodigiously long time for a single depositional process to have endured, and a phenomenally long time for a large surface comprising a substance as mobile as ash to have survived without either blowing away or being adulterated by larger [especially inorganic], autochthonous clastic input. 
     Even more mysterious: Beaumont claims that the ash was the result of thousands of fires fueled by above 15 tons of fuel. It's really hard for me to imagine that such a focus of hominid activity could have escaped the inevitable, and destructive, treadage that would have accompanied that use of that part of the cave for what amounts to a single activity--that of making and keeping fire--over such a vast expanse of time. I suppose it's not impossible. But, probable? I really don't think so. Plausible? Barely.
     Beaumont's description of MU 2 in excavation 5 just makes no sense. If his account of its clastic composition is accurate, nothing but a long-lived colony of fire-loving faeries could have produced it! There must be alternative explanations. And, indeed there are, provided by an unlikely source--the latter-day excavators of Wonderwerk Cave, the very ones who have recently reprised Beaumont's long-standing claim of fire use by Acheulean hominids.
     Here's what Matmon, Chazan, Porat and Horwitz conclude in 'Reconstructing the history of sediment deposition in caves: A case study from Wonderwerk Cave, South Africa' published in the Geological Society of America Bulletin (First published online October 14, 2011, doi: 10.1130/​B30410.1).

The cave sediments comprise a sequence of fine sands and silts that were transported naturally by wind to the environs of the cave and later into the cave by water. Transport within the cave occurred by low-energy water sheetflow, which distributed and deposited the sediment in its final location. Field observations and grain-size distribution analysis of the sediments inside and outside of the cave imply the following sediment transport scenario: eolian transport of Kalahari sand to the Kuruman Hills, slope wash of the eolian sediment into the intermontane valleys, fluvial transport of the sediment from the intermontane valleys to the entrance of the cave, and final deposition of the sediment inside the cave by low-energy water action.

 These are the verbatim conclusions. Unfortunately for the authors, this sequence of transport processes leading to the input of allochthonous sands and silts at Wonderwerk Cave can equally explain the presence of anything that would be as easily transported as sands and silts. Indeed, anything lighter than fine sand--if it shows up at the doorstep--would have been subsequently transported into the cave by sheetwash. Sheesh! They've done my work for me! 
     Their conclusions also solve a riddle that I found while wandering through the images from Wonderwerk. This one shows non-conformable and curiously wavy strata. I've drawn yellow rectangles where I see evidence of what appear to be erosional events overlain by non-conformable strata. These observations support the conclusions of Matmon et al. It appears that there have been numerous erosional episodes during the build-up of sediments in Wonderwerk Cave. The wavy contacts suggest an agent even more energetic than sheetwash. If these observations are borne out it's clear that at times the input of material and liquid from outside the cave was considerable.     

After Berna et al. 2011

Make of it what you will. 
     Beaumont describes 'grass mats' in various stages of combustion that occur here and there in the cave. Regardless of how they arrived at the cave's doorstep, in they went--wind-whipped dry grass, partly combusted grass, grass ash [try saying that five times really fast without saying something unfit for polite company], small bits of burned bone made as light as fine sand by partial combustion. You name it! Matmon et al.'s conclusion opens the door to serious questioning of Wonderwerk's depositional history. How can they claim, unequivocally, that any wind-transportable allochthonous sediments came to rest in the cave by the hands of hominids?
     Seriously! They are way past the bounds of logical inference when they claim that any of the tiny particles that Berna et al. describe in exquisite micromorphological detail were left there as a result of hominid behaviour. Somebody's gotta tell them. I'm trying me best. But they appear not to be listening.
     So, get out there to the meetings and to your classrooms and call out the litany of overwrought inferences of hominid behaviour that keep emanating from Wonderwerk Cave!     

     

One thing's for sure: the excavations at Wonderwerk Cave are looking more and more like job security for this Subversive Archaeologist.

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"We Didn't Start The Fire" (Billy Joel, Storm Front, 1989)

You already know what I might be gonna say. Don't you?
     I've much more to say about the Beaumont Current Anthropology article that I began blurting about earlier this week. His field and post-excavation observations are, to my ear and eye, Byzantine. And I'm enjoying poking holes in and fun at his meandering piece on Wonderwerk Cave.
But, you'll have to wait, I'm afraid, because at the moment I'm having a very pleasant conversation with a not-inexpensive 2010 Sonoma County Chalk Hill Chardonnay produced by the Rodney Strong Estate Vineyards. The label describes it as 'displaying yellow apple and pie spice with a hint of minerality on a long finish.' I couldn't agree more. I don't have much of an olfactory due to chronic rhinitis, but even I can add to that description 'hints of butter and butterscotch.' This is not a cheap wine. And, in contrast to the manner in which I drink my Crane Lake vinifera, I'm savoring every moment of this one.
     Don't panic! I haven't lost what's left of my left-side brain. It was a gift from someone who appreciates the work I do in my lowly day job. In defense of my lowly position, I at least share something with all of the other pay grades at my university--a very comfortable package of benefits that means I needn't worry about health care, or much else, and which also includes a pension. I'd gladly take the poor pay in exchange for the extremely and unusually good total compensation package!

     TTFN!

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Updated: 20th Century Fertilizer Mining in Wonderwerk Cave!

 I'm working furiously on the rabbit hole that Wonderwerk Cave is rapidly showing itself to be. Last year, long-time worker at Wonderwerk publishes this:

…the cave was exploited for “agricultural fertilizer” between 1940 and 1944, when the cave interior was largely dug out to a depth of up to 2.5 m (Current Anthropology, 52, 585-595, 2011).

WTF? I can assure you its wasn't owl poop they were mining. It was, yes, bat guano.

     No bat guano in Wonderwerk Cave just became 'Whatever happened to the bat guano in Wonderwerk Cave?'

     This isn't over.


Oops! Almost forgot. This just in. Nature, yesterday, publishes an article titled Evolutionary anthropology: Homo 'incendius', by Bert Roberts and Michael Bird. Fire at 1 Ma is not just big news, it's as big as it gets. And it's all gonna fall.
     Next up: Prometheus unfounded.

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It's Not Monday! It's Fry-Day.

I just pressed send on an email to Francesco Berna and Paul Goldberg, asking them to respond to my argument just the other day that they shouldn't have expected to see Berlinite in the fire-affected sediments at Wonderwerk Cave. Viz.

Berna, et al. 2012. Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. PNAS April 2, 2012. Published online before print April 2, 2012, doi:10.1073/pnas.1117620109

Remember? They argued that the fire had to have been deliberately introduced to the cave by hominids because they found nothing that would suggest that spontaneous combustion of bat guano was responsible. They erroneously believe that bat guano spontaneous combustion necessarily produces Berlinite. But they are tripped up by an empirical bump in the road. They report finding the effects of heat, but only up to 550 degrees Celsius. Unbeknownst to them, Berlinite forms at 583. Thus, their claim for fire use at 1 Ma is baseless. 
     I'm hoping that the direct approach will coax them either to overcome the shortcomings of their empirical findings or publish a retraction of their huge claim that at 1 Ma hominids were using fire.

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I MUST BE BAT-GUANO CRAZY!

All right. I'm working on the dregs of a halfway decent boxed chardonnay. I'm waiting for the washing machine to be free. I'm ready. It's time to turn up the heat on the claims emanating from Wonderwerk Cave, Northern Cape Province, South Africa. There's a fatal flaw in the argument that there's evidence for the controlled use of fire in the Acheulean (i.e. Lower Palaeolithic) levels, at about 1,000,000 years BCE [and I'm not talkin' 'bout Brigitte Bardot].
     Wonderwerk Cave's located where there's a diamond labelled WK in the heart of the photomap below.

After Henshilwood and Dubreuil. 2011. The Still Bay and Howiesons Poort, 77–59 ka: Symbolic Material Culture and the Evolution of the Mind during the African Middle Stone Age. Current Anthropology, 52, 361-400.

I'm seeing all these news reports! This story is everywhere you look. If you watch the news ticker up top for a few minutes, you'll see not only the English-speaking media reports, but also those from areas where they speak Spanish, French, Portuguese, German, Scandihoovian and some I don't even recognize. In words of one syllable this is big news to a lot of folks. And well it should be, if it were true. As you now know, I have have reason to counter the claim.
     I may not be a geochemist or a micromorphologist, but I am sentient. And when I see an extraordinary claim... Well, you know how it goes. I do what I can to learn enough to achieve a minimal level of critical ability and then assess the extent to which the claimants attempt--successfully--to rule out natural processes. In the case of this Lower Palaeolithic Prometheus, the chemistry and the technology are my stretch domains. However, logical argumentation is my comfort zone. So, with a little Googling and some gumption, that's where I'm headed today. 
     I'm talking about a paper, recently published in PNAS.

Berna, et al. 2012. Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. PNAS April 2, 2012.

 Published online before print April 2, 2012, doi: 10.1073/pnas.1117620109

[Hey Rocky! Watch me pull a(nother) rabbit outa my hat!]

The authors contend that their findings provide 'the earliest secure evidence for burning in an archaeological context.' [At this point all of you readers will, automaton-like, voice the pre-eminent subversive question: 'Did they rule out natural causes before imputing their discoveries to humans or other hominids?' Pat, pat. Good little Subversive! Here's a biscuit.]

Paul Goldberg and Francesco Berna

I've been seeing similar claims from Middle Palaeolithic contexts since the late 80s, almost always accompanied by Paul Goldberg's micromorphological analysis and Steve Weiner's or Francesco Berna's Fourier Transform Infrared Spectrometry of the phosphate minerals. I've been skeptical all along, which is my proclivity, nevertheless I've been reluctant to mount a critique. Until now. The stakes have finally grown too great to remain silent. 
     I've known Paul since the mid 80s. We spent time together at Keatley Creek, in B.C. Then after a month-long stint at Kebara Cave in '89 he toured me around the south of Israel, at which time I met Arlene Rosen, and during which I got hotter than I can remember ever being before or since, in the Dead Sea Depression. 
     I had a job once when I was at SFU. I was to impregnate a bunch of micromorphology samples from the Keatley Creek site with fibreglass resin. Unfortunately the vacuum chamber I was using was a little short of breath and some of the samples turned out crap. But that's beside the point. [Really, Rob? What IS the point of all this reminiscing?] The point is that I know Paul. I know his work. He [quite literally] wrote the book on the micromorphological study of archaeological sediments. I accept his findings. Nevertheless, when all's said and done in the authors' analysis of Wonderwerk Cave, it's not Paul's micro-study that's at fault. Nor is it Francesco Berna's FTIS results. It's the way they argue on the basis of their findings at which I baulk.

Wonderwerk Cave [er, the entrance, at any rate]

In case there are one or two of you who're wondering what's so special about fire, I would just remind you that the controlled use of fire has always been considered one of the hallmarks of human achievement [remember Prometheus?]. It's the same in human evolution. Making and using fire is as human as it gets. That there are numerous articles propounding its use in the Middle Palaeolithic is at odds with other evidence of cognitive evolution [there's much subversion yet to be done there]. That's bad enough for this subversive; the claim from Wonderwerk Cave could set back empirical enquiry into the true first use of fire by a hundred years. 

     At Wonderwerk a deeply stratified deposit contains an abundance of what are referred to as 'rubefied' [or reddened] sediments. This should come as no surprise, since the deposits are made up almost exclusively of aeolian sand that's encrusted with iron oxide [=rust]. However, there are also places where the excavators recovered floral ash and burned faunal fragments. Bat caves are capable of building up prodigious deposits of guano--they've been mined, historically, for fertilizer--and those deposits are known to burst into flame spontaneously. So, why couldn't the fire-affected traces be the result of naturally occurring fire(s)? After all, the authors report no features at the site that might be construed as hearths.
     To their credit, Berna et al. have succeeded in mounting a convincing argument that enough heat was generated here and there in the deposits to have altered the chemistry of plant and animal remains, leaving ash and burned bone and plant remains. They infer that temperatures higher than 550 °C were not in evidence. 
     They base their refutation of the spontaneous combustion argument on the work of one geologist from one cave in Romania, Cioclovina. The authors conclude that natural, spontaneous combustion of bat guano had not occurred in Wonderwerk Cave. 
     This is the shape their argument takes

a) When bat guano spontaneously combusts it transforms some of the guano's aluminum phosphates into two very rare forms: Berlinite and hydroxylellestadite.

 b) FTIS found no Berlinite or hydroxylellestadite in the samples from Wonderwerk cave.

c) Therefore no spontaneous combustion of bat guano can explain the fire-affected flora and fauna in the cave.

Here are some brutal facts up against which this argument cannot stand.

1. The discovery of Berlinite in unconsolidated sediments at Cioclovina Cave is unique. All the rest of the Berlinite known in the world occurs in the form of ore. At Cioclovina the Berlinite formed during one or more episodes of very high temperature combustion of bat guano--so hot, in fact, that a stratum of sediment was fused solid (Onac, Effenberger and Breban, High-temperature and “exotic” minerals from the Cioclovina Cave, Romania: a review, Studia Universitatis Babeş-Bolyai, Geologia, 52, 3- 10, 2007).

2. The discovery of hydroxylellestadite at Cioclovina Cave is equally unique. 

3. Berlinite forms at 583 °C (http://www.mindat.org/min-633.html) [I was able to find no empirical data on the temperature at which hydroxylellestadite forms].

4. Bat guano degrades normally to form phosphate minerals including, but not limited to Brushite, ardealite, monetite, Taranakite, variscite, crandalite, sasaite, hydroxylapatite, whitlockite, vivianite, Hopite, sampleite, and churchite (Encyclopedia of Caves, 2nd Edition, by W.B. White and D.C. Culver, Academic Press, 2012).

5. Under great pressure and very high temperatures bat guano will form Arnemhite, Berlinite, and Pyrocoproite [and is now known to form hydroxylellestadite] (Encyclopedia of Caves, 2nd Edition, by W.B. White and D.C. Culver, Academic Press, 2012).

Berna et al. have argued that because no Berlinite was found at Wonderwerk Cave they were able to rule out spontaneous combustion of bat guano at the source of the heat that altered the floral and faunal remains they examined. However, the same authors have determined that at Wonderwerk Cave combustion occurred at temperatures below 550 °C. Mineral science teaches us that Berlinite and hydroxylellestadite form at temperatures at or above 583 °C. No such temperature was reached in Wonderwerk Cave. Ipso facto, prest-o change-o, Berna et al. have erred in presuming that Berlinite would have formed at Wonderwerk Cave.
     Berna et al. state the following

Moreover, micromorphology and mFTIR did not show evidence for remains of guano and/or high-temperature phosphate mineral phases (i.e., berlinite and hydroxylellestadite); these minerals characteristically form during spontaneous combustion of bat guano—a rare event but one documented inside caves. 

I would be verrry interested to see the complete results of the FTIS analysis of the Wonderwerk sediments. Given that there are Chiroptera remains in the sequence it's likely that there would have been at least some guano lying around at some time during the hominid use of the the cave. And, as you prolly know, bats are known to aggregate in the gabillions in some caves. I'd be surprised to find NO evidence of the phosphate minerals that would belie the earlier presence of bat guano--burned or not.
     So, there you have it, Paul and Francesco [we've never actually met, Francesco, but I hope you won't mind me using your first name--they always told me I should act like a grown-up once I got my Ph.D., and so I try now and again to follow their advice]. 
     The gauntlet is thrown down. 
     Gentlemen! Show me the monetite!