Are There Bats In Beaumont's Belfry? Once More Down the Wonderwerk Cave Rabbit Hole.

Okay! Ready for another visit down the Wonderwerk Cave rabbit hole? Keep in mind the main points of Berna et al.'s paper claiming million-year-old fire use at Wonderwerk. First, lots of burnt stuff--animal bone, grass, ash. Second, no bat guano 'cause there wasn't any Berlinite in the deposits [long story, that]. Their conclusion: no spontaneous combustion. That leaves Homo erectus [or a reasonable facsimile] as the only actor that could have been responsible for the fires in the cave. And Berna et al. report that the senior archaeologist, Beaumont, 'reported macroscopic evidence for burning.' 
     I had to see what he had to say. So I've collected the pertinent portions of 

'The Edge: More on Fire-Making by about 1.7 Million Years Ago at Wonderwerk Cave in South Africa,' by Peter B. Beaumont (Current Anthropology, 52, 585-595, 2011). 

I call Wonderwerk Cave a rabbit hole mostly because the logic of what's been claimed can be a little hard to follow [to say nothing of 'swallow']. 

     One of the first bits we learn is that

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     

Here's a link to the full-sized version on my Flickr account. 

A back-of-a-napkin estimate of the volume of cave earth removed by the 'diggers' yields a figure of 375 cubic metres. I know that most of you know what a cubic metre is, since most of you have had the experience of digging a 1 by 1 to a depth of a metre. But, really, how much Wonderwerk dirt was bagged for fertilizer? 
     A 40 lb (~22 kg) bag of fertilizer works out to about 40 litres. A cubic metre contains 1000 litres (doh!). So, those 375 cubic metres removed from Wonderwerk would have yielded about 9,375 bags of fertilizer. That's a lot of dirt! That's a lot of labour, too. Yet, as you'll discover a little further down, Beaumont surmises that there can't have been much in the way of effective fertilizer in the dirt the diggers removed. Keep that in mind as we work through the rest of Beaumont's 'observations' on Wonderwerk Cave.

     Next Beaumont muses on the likelihood that there was ever a significant number of bats 'hanging' around in the cave. He turns first to a modern observation     

Zoological studies at regional bat caves show that all have dark interiors, little or no air movement, and relatively high humidity levels; the only place in Wonderwerk that partly matches those conditions is a deep roof cavity at its rear, where a small number of bats were seen in 1988, briefly replacing the barn owls that usually reside there...

My guess is that we're to assume nothing has changed during the time that the upper 2.5 metres of the stratigraphic column had built up--i.e. that dirt removed for the presumed phosphate-depauperate fertilizer. I find this to be an astonishing assertion. But, there's more. 

As for bat dung/guano, this was originally linked to the red sand strata ..., a claim not supported by a study of the sediments ..., which showed that all levels are mainly (>90%) made up of sand and roof fragments, or by the finding that the microfauna indicates a preponderant avian occupation of the cave by barn owls..., with only modest amounts of bat guano likely confined to lenses below the roof cavity near the back wall.

Here the author tips his hand. Of course! There never were bats in the cave in any number! The presence of rodent remains convinces him that the major avian residents had been barn owls--for a million bloody years! 

     This strikes me as an odd conclusion to make for three reasons. First, the rodent remains wouldn't have been in the cave had it not been for the owls. But that's not germane to this question, since bats don't eat small furry creatures and therefore would have left nothing other than dead bats, which are in evidence in the cave sediments.   

     Second, does he think that bat guano fossilizes? Well, if he does, he's very wrong. It decomposes like any excrement, leaving phosphate minerals. Thus, if at present it's invisible in the cave sediments we should expect nothing less. And until Berna et al. publish the complete list of phosphate minerals they did find in the cave, we're left in the dark as to the likelihood that bats ever left much behind in the cave [that wasn't mined by 'diggers' that is].  
     Lastly, it's laughable when the author asserts that bat guano would have accumulated only where bats have been observed to roost in the cave in the past hundred years. We're talking about a MILLION years, fer gawd' sake! Beaumont must be the most extreme proponent of uniformitarianism that ever set foot in a palaeontological locality! 

     His conclusion, which appears below, is a case of special pleading, if ever I heard one.

From these data it is evident that the 1940–1944 diggers were marketing a product that contained little in the way of fertilizer

If so, they must have been running a con. And, if it was a con, this might be the only time in criminal history that such a gambit involved hard labour on the part of the grifter! Hey. Maybe not! Maybe the cons were so good at their game that they did a Tom Sawyer on some unsuspecting yokels, and had them dig out half the cave! 

Please, make your own conclusions. I'm happy to hear your reasons why anyone should accept Beaumont's assertions at face value.  


















   

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Still Waiting For Some Response From Francesco and Paul...

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

I'm starting to feel slighted. Tell me why I shouldn't.
     Either Francesco Berna and Paul Goldberg are so far out in the field that they're incommunicado and have been for a while, or they're too embarrassed by their fireplace faux pas at Wonderwerk Cave that they're playing it cool. 
     Paul is someone I've known for decades. I've never met Francesco. When my recent blurt on the matter called into question their claims, I expected an immediate response--so devastating is the overlooked evidence. Yet, crickets chirping was all I heard. Then I emailed Don Grayson, well-known to most of you, who was the National Academy member who acted as the editor for the paper in PNAS. He was intrigued, and thought I ought to pursue the publication route. But I thought it better to email Francesco and Paul instead, a week or so ago, hoping to stir them into some sort of response to my contention, i.e. that finding no Fourier Transform Infrared Spectrographic evidence of Berlinite in the sediments at Wonderwerk Cave can't be used to rule out spontaneous combustion of bat doo-doo in the 1.0 Myr old deposits. 

Home, Sweet, Homo erectus Home (Source):
Home is Where the Hearth Is.

     Theirs is no small inference. An Acheulian Prometheus is big news. No doubt about it! It's not the sort of thing you want to make a mistake about, especially when the mistake you're making is to ignore or to be, evidently, ignorant of the formation temperature of Berlinite [something you would have thought a geochemist and a geomorphologist might have thought to investigate before they made their claim for the controlled use of fire so long ago by Homo erectus--or H. ergaster, whichever you prefer--a species long since extinct--unless you accept that H. Floresiensis is a dwarf relict population, which I happen to do, but which is beside the point in this discussion, albeit really interesting and kewl].
     Remember that no 'hearths' were recorded at Wonderwerk Cave; the excavators instead base their inferences on the presence of heat-altered sediments across a wide area in the million-year-old cave deposits. Unfortunately, the authors report no evidence for temperatures above 550° C, and Berlinite will not form below 583° C. But then, you already know this, 'cause I've written about it here. 
     So, although I'm repeating myself, I'd like to call on the authors--either, any, or all--to respond to my question about their observations, and to comment on the temperatures required to alter the chemistry of the plant and animal remains they recovered, together with their conclusions that Berlinite would surely have been visible if spontaneous combustion of bat guano (a well-known and well-documented phenomenon) had been responsible for the raised temperatures in the cave sediments. 
     I'm waiting, gentlemen.

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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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