The Acheulean in Arizona: More Bizarre News From the Dark Side of Archaeology

It really doesn't get any better than this. And mind, I wouldn't normally expend much energy dispelling incipient myths like this one, were it not that in this case there's a real danger of it sprouting legs and moving under its own power thanks to a daft academic archaeologist in Boston.

We won't be so crass as to point out the misspellings, 
erroneous capitalization and poor punctuation. Will we?

My dad used to say 'A little knowledge is a dangerous thing.' The only serious danger in the field of archaeology [aside from liver disease and arthritic knees] is that a patently false claim--however well-intentioned--becomes received knowledge. In other words, an erroneous claim that becomes an archaeological myth. In this instance, the danger to archaeology is being multiplied by a gullible Phoenix media hungry for an interesting story and, in an unusual turn of events, a truly credulous and misinformed 'professional' archaeologist, Curtis Runnells, from Boston University.

A putative Acheulean site in Pheonix, Arizona (Photo credit)

      The story goes like this. Mr. Ken Stanton, Amateur Archaeologist, thinks he's found an Acheulean archaeological site. The Acheulean, previously known only from Europe, Africa and southern Asia began about 1.5 Ma. This isn't the first time that such objects have come to light in the southwestern United States. Indeed, the Arizona story is virtually identical to that of the Calico Hills site, famed for having fooled Louis B. Leakey into thinking that Homo erectus had somehow made it to the Americas in the Early to Middle Pleistocene. His attention was drawn to the site  in the late 1950s after broken rocks similar to those Mr. Stanton has lately found compelled archaeologist Ruth DeEtte Simpson to announce her interpretation--that the site contained very old, very crude, stone tools like those that had been known in Europe and Africa for nearly a century. The Calico Hills' proponents are still making those same claims fifty years on, even though they've been thoroughly and rigorously refuted by archaeologists who know a great deal about the geological processes and their expectable outcomes in the production of a desert alluvial fan--C. Vance Haynes, for one.

Ruth 'Dee' Simpson and L.S.B. Leakey at the Calico Hills Early Man site.
(Photo credit)

     But what are the claims, Rob? We wanna see!
Behold and be dismayed. First, photos of Stanton's finds and a cross-section of the sedimentary context, all kindly provided by Mr. Stanton, himself.

An amorphous lump of 
angular vein quartz

A pointy lump of angular vein quartz.

A tiny piece of angular quartz

As one can plainly see from these illustrations, this is vein quartz, which while being very hard, is also quite brittle. And, while some forms of quartz fracture conchoidally, this type does not. Its material nature aside, the geological context is most important in this instance. That these artifacts are found in a desert alluvial fan should be a red flag for any archaeologist, especially one who's geomorphologically aware or is in fact a geoarchaeologist. Alluvial fans develops as a result of the intense, but infrequent, rainstorms that are characteristic of desert climates. The rain falls upslope and quickly entrains every loose bit of rock and dirt that has, through colluvial action, come to rest in the dry course of the newly active ephemeral stream since its last activation. Depending on the energy level of the flow and the nature of the rock being carried along, the overall result is what you see in the profile below.

A cut through the alluvial fan, with quartz geofact visible in the centre.

This high-energy alluvial phenomenon is more appropriately called a debris flow, rather than an ephemeral stream, because the water represents just one component of the stream, the majority consists of sedimentary clasts of various sizes that collide forcefully with one another to produce what in some cases may be seen to resemble chipped stone artifacts that humans or human ancestors have made. This kind of object is called a geofact because it was created by geological processes, but nonetheless fools a naive observer because they appear to have been chipped in a manner that broadly resembles early hominin stone technology. And Rule #1 states that if something that you think is made by people, but that could just as well be made by other natural processes, you can not give priority to people, but must instead show cause as to why we should think anything other than that these are geofacts! 

     The kind of deposit shown in the profile is a diamicton--comprising an unsorted (or at best poorly sorted) mélange of newly angular bits of rock as well as sand, silt and clay, not all of which are clast supported. Such deposits are very UNlike the ones that a permanent stream produces in its path. In the Arizona case the quartz stands out from the rest of the material in the fan because it happens to be of a type that's analogous to that of the finer-grained rock that makes good stone artifacts. I wonder how many bits of vein quartz Mr Stanton passed up because they didn't look like 'good' artifacts!

     Aside from the attention that Stanton's claims received in the Phoenix media, news of his 'discovery' reached an academic archaeologist who is, unfortunately, credulous and is giving these naturally broken rocks more attention than they warrant. The following three passages are messages that archaeologist Dr. Curtis Runnels of Boston University has sent to Mr. Stanton, which have given the Arizona man no reason to suspect that his claims are theoretically unsound.

 These are extremely interesting artifacts and the context is very interesting too. I am not an expert in Arizona desert geology, but the the [sic] deposit looks like a cemented debris flow or perhaps a lake-margin deposit. It could very well be Pleistocene in age. It should certainly be possible to date that context if you can get a knowledgeable regional geologist to look it over; for instance by a technique like Infrared Stimulated Optical Luminescence on the sand grains I can see in the surround [sic] matrix.

We can only guess about the nature of Pleistocene humans: our own species, Homo sapiens, is dated securely at sites like Herto (Ethiopia) to 200,000 years ago and would certainly be a candidate, as well as Homo heidelbergensis (a hominin grade that dates to ca. 400,000 years ago). Without fossils there is no way to tell because these kinds of tools were probably made by more than one hominin grade, perhaps by as many as four or five! 

My summary is that you have early looking artifacts in a definite geologic context that might help pin down their age.

and

Dear KC,

Thank you for showing me the photographs of the lithic artifacts and their findspot from the site that you have discovered near Phoenix.

My specialty is the Palaeolithic of the Old World in the eastern Mediterranean and SE Europe, and not the American SW, but the artifacts that you have shown me would be considered as Lower or Middle Palaeolithic if they were foud [sic] in my area.

They are definitely artifacts [emphasis added], and the typological and technical characteristics that I see in the photographs are consistent with their identification with Pleistocene industries (modes or technocomplexes).  Similar artifacts are widely distributed in the Old World, and have been reported also in the United States over the past century or so. Unfortunately they are rather hard to date: in the Old World such industries have a wide chronological span, ranging from 1.6 myr to ca. 0.175 myr (and some similar forms occur in the Middle Palaeolithic or Middle Stone Age in Europe and Africa much later, down to ca. 50 kyr). Therefore, it is of particular importance that your finds appear to be in a datable geologic context. The photographs you showed me appear to show artifacts in situ (geologically speaking) in a cemented breccia or debris flow. This suggests two things to my mind. The original sites, in the sense of living floors or occupation areas, have no doubt been destroyed by erosion and the artifacts have been redeposited downslope.  Dating the breccia/debris flow would, therefore, give a minimum age for the artifacts, but that would be an important start. My geological training is in the Mediterranean in regions (e.g. Greece, Albania, and Turkey) with similar arid conditions to the American SW, and from what I can see in your photographs I would consider the artifact-bearing deposit to have considerable age, probably Pleistocene.

A more precise estimate In short, I would accept as a working hypothesis to be tested by further research in the field that these artifacts are of Pleistocene age and likely to pre-date, perhaps by a considerable margin, the earliest accepted industries such as Clovis and Folsom in the SWof their age or the affinities with other industries would not be possible at this stage of research.

Good luck! Sincerely yours, Curtis

Curtis Runnels, MA, PhD, FSA, Professor of Archaeology, Archaeology Department, Boston University, 675 Commonwealth Avenue, Boston MA 02215

Editor, Journal of Field Archaeology

and later on

Here is a longer message than I could manage yesterday on my phone in the train. No need to send me the Washington Artifacts; let's not risk getting them lost in the mail. I want to concentrate on the Arizona stuff for the moment. My plan is to discuss the artifacts you already sent me with a geoarchaeologist who is familiar with Arizona geology and get his opinion on the context.

My other plan is to write an essay in the Journal of Field Archaeology as Editor-in-Chief (co authored with my contributing editor Professor Norman Hammond, who is also the Archaeology Correspondent for the Times of London and the editor of the Times Literary Supplement). He is a New World specialist and we have already talked about how the Pre-Clovis picture is becoming clearer. We will call for a total reexamination of the old sites (e.g., George Carter's Texas Street Site and Calico among others) and a new open minded approach to the Pre-Clovis question and invite contributions of manuscripts on the subject for publication. I think the timing is right. The Stanford and Bradley book, Across Atlantic Ice, will be published in January and in it they make their case for the movement of Solutrean people by boat across the Atlantic in the Palaeolithic to the east coast. If one group of Palaeoliths could make the trip, then anything is possible and a complete restudy of the archaeological record is warranted.

All this takes time and don't worry about your priority (i.e. credit for your discovery). I have the evidence before me that you found this stuff first and am willing to say so whenever and wherever necessary.

Best wishes,

Curtis

I ask you, 'How lame can this guy Runnels be?' He recognizes that this is a debris flow, but somehow fails to make the connection between the nature of an active debris flow and the concomitant and expectable damage to, in this case, vein quartz. I will be very surprised if, when Runnels approaches the 'geoarchaeologist who is familiar with Arizona geology' he is told anything other than that these are perfectly good geofacts and not, as Runnels proclaims, 'definitely artifacts.' [By the way, I'm guessing that the above-mentioned geoarchaeologist is none other than Paul Goldberg, whose academic appointment is also at BU. Paulie, you still haven't responded to my Wonderwerk Cave take-down. Clock's ticking...]

     Nitey, nite!

Thanks for dropping by! If you like what you see, follow me on Twitter, or friend me on Facebook. You can also subscribe to receive new posts by email or RSS [scroll to the top and look on the left]. I get a small commission for anything you purchase from Amazon.com if you go there using any link on this site. There's a donate button, too. Your generous gift will always be used to augment the site and its contents.

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.

Please show your support for this blog. Remember that when you purchase from Amazon by clicking any of the links on the right, you'll be getting great discounts and supporting the Subversive Archaeologist's field activities at the same time!

Why No 14C Dates for Blombos Cave's MSA? Not Lobbing Aspersions. Just Sayin' ...

If I were a chess player I probably wouldn't be trying this gambit. But I'm not. So, bear with me.

Worked bone, stone and ochre from Blombos Cave (Wikipedia)

I need help with a question that's been nagging me for years. I'm curious to know if any of the bone artifacts from the Middle Stone Age (MSA) layers at Blombos Cave have been directly dated using AMS 14C. From my reading it appears not. In fact, it looks as if 14C was abandoned in favour of luminescence techniques once they had excavated deeper than those layers identified as Late Stone Age, the earliest of which were dated to give-or-take 39 ka BP. Everything below that is deemed to be MSA, and organic materials such as charcoal and bone were passed over in favour of grains of sand or burned flints in those strata. 
     Remember that, for most of us, MSA is synonymous with the Middle Palaeolithic in the rest of the world, and, for better or worse, it's exclusively associated with the Neanderthals and their ilk, for which the jury is still out as to their cognitive equivalency with us modern types. Finding what are clearly modern human artifacts at Blombas Cave and elsewhere on the order of 30 to 50 ka earlier than anywhere else in the world has stunned and amazed scientists from Barrow to Burbank. But it's never sat well with me. 

Location of Blombos Cave, South Africa (Credit)

     You and I know that 14C is perfectly capable of accurately gauging the age of organic materials until at least 50 ka, notwithstanding the need for calibration that corrects for environmental  and other effects. Why then do we have only luminescence age determinations for the sediments in which the Blombos Cave bone artifacts and charcoal were deposited? Henshilwood et al. (2002) provide some insight, although I'm not certain they realize that by doing so they've left themselves exposed to (at a minimum) questions about their decision.
     That (to me) curious decision is explained in what amounts to a throwaway comment, which I will quote here

In radiocarbon terms, the MSA at BBC is of infinite age (Vogel, personal communication).

The MSA levels are being dated using luminescence techniques: single-grain laser luminescence (SGLL), single aliquot optically stimulated luminescence (OSL and IRSL), multiple aliquot OSL on sediments and also TL of burnt lithics and electron spin resonance (ESR) of teeth (Henshilwood et al. 2002:638). 

Being the skeptical type, I was intrigued by what seemed to me to be such a weak citation as to the inefficacy of 14C beyond 39 ka--the date of the oldest LSA at Blombos. Just a 'Vogel pers. comm.' No reams of empirical evidence. No other justification. So I endeavoured to discover by what authority Vogel had made such a pronouncement.
     No doubt some among you will think it naïve of me, or worse, that I'm poorly informed and ill-prepared to be taken seriously by the palaeoanthropological establishment. Nevertheless, I had no prior knowledge of Vogel's reputation in the radiocarbon world and in the South African archaeological community. His work includes a 1997 paper in Radiocarbon in which he attempted to calibrate 14C dates with U/Th dates within the same stalagmite from a South African cave. That work was superseded a few years later by the more widely cited Fairbanks et al. (2005), who honed the 14C calibration curve back to 50 ka using pristine corals from around the globe. Their findings are that 14C underestimates calendar years such that 45 RCYBP works out to 48,934 calendar years (give or take 500). By this means the calendar date of 39,200 BP from the lowest LSA level at Blombos would have been produced by a radiocarbon age of about 34 ka RCYBP (try it yourself by clicking here to go to Fairbanks's calibration calculator).
     It would seem, therefore, that despite Vogel's pronouncement, cited in Henshilwood et al. (2002), there is no physical limitation on dating organic material that is older than 39 ka (i.e 34,000 RCYBP), as long as its age doesn't exceed 45 RCYBP. That would, theoretically, allow the excavator of Blombos Cave to extend use of 14C for at least a further 11,000 RCY beyond the earliest LSA from Blombos Cave. Surely some of the MSA materials could be presumed to date from this 11,000-year window.
     Directly dating the bone and charcoal from the upper MSA strata may prove nothing. However, knowing that there's no theoretical limit on the use of 14C for that 11,000 year period leaves wide open the question as to why Chris Henshilwood hasn't attempted to date, directly, some of his bone artifacts or charcoal from the MSA layers. It's just possible that they would yield dates far younger than those produced by luminescence techniques (about which I've had a certain amount to say in previous efforts here at the Subversive Archaeologist).

From Henshilwood et al. (2002)

     After all, the MSA levels in Blombos (at least those illustrated in Henshilwood et al. [2002], shown above) appear to be quite shallow--the sort of depth that you could imagine accumulating in far less than the 35 ka that the luminescence dates would have you believe it took for them to accumulate--and it's within reason to suspect that they could easily have been deposited in the 11 RCY or so before 39,200 BP.
     And so. For what it's worth, I'm issuing a challenge from this lofty perch of mine. Chris, try dating some of your MSA bone using good, old-fashioned, AMS 14C and see what you get. A fair few of us are curious to know the result. 

Let Me 'splain Somethin' to You 'bout John Hawks, Svante Pääbo, and You, Lucy

I suppose I should just come out and say it, since there's no point in being coy. The now-irrefutable evidence that you and I share varying amounts of apomorphic genetic material with the Neanderthals does nothing to settle the question of whether or not the Neanderthals and we might have, could have, would have, or should have had offspring together. 
     No good. 
     Whatsoever. 
     And here's why.
     For a moment, put aside whatever 'feelings' you may have about the Neanderthals' cognitive abilities compared with those of you and me. 
     About 100,000 years ago, at Qafzeh Cave, there are skeletally modern humans. A geological minute later there are Neanderthals a few km down the road at Kebara Cave. These two morphotypes may never have set eyes on one another. But the overlap in their territories, whatever the reason, means that there's at least a good chance they bumped into one another. Which means that if they recognized each other as potential mates the strong likelihood is that they did the wild thing and had families.
     You can slice it and dice it, split hairs, and argue 'til you're blue in the face, but the archaeological traces associated with each of these two species leads to the  robust inference that they behaved in the same manner. They produced Mousterian assemblages at each site, with a Levallois facies. If we had never found the skeletal remains at Kebara or Qafzeh, we archaeologists would no doubt have reached the same consensus--that those traces were left by hominids that were, more or less, behaviorally and cognitively identical.
     As you're no doubt painfully aware by now, I have strong reservations as to the abilities of the Neanderthals, based on my 'reading' of the archaeological record. And, those of you familiar with my three (Yep, 3) solo publications will know that, when I speak of the cognitive abilities of the Neanderthals I'm also speaking of morphologically modern, but archaeologically identical, penecontemporaneous hominids such as those at Qafzeh. What many of you don't know is that, if asked, I would also include Homo sapiens idaltu, at 160,000 kya and any other shape of hominid that left a similar archaeological record, regardless of their epoch. 
     I'm an archaeologist with a deep knowledge of evolution, human and otherwise. I'm also equipped with a modicum of knowledge in comparative vertebrate paleontology, geomorphology, pedology, animal bone identification, interpreting animal bone from archaeological sites, vertebrate taphonomy, site formation processes, lithic analysis, and informal logic. But I'm still just an archaeologist when it comes to the Middle Palaeolithic. 
     And, until such time as it's possible to say that Broca's Area unequivocally demonstrates that the owner possesses the ability to read this blog, or that we're able to say that the FOXP2 gene unequivocally demonstrates that its owner possesses a similar ability, all that remains for anyone to use in understanding the abilities of those ancient hominids is the archaeological record. 
     Archaeologists are uniquely placed to interpret ancient behaviours from archaeological traces. Anatomists cannot. Vertebrate palaeontologists cannot. Geomorphologists cannot. Sometimes I really wonder if lithic analysts can. I am profoundly aware that my expectations and presuppositions of Neanderthal behaviour can clutter and colour my perceptions. That's why I concentrate so heavily on the physical evidence and its context, because that's the only way to move past my expectations in understanding the cognitive abilities of Middle Palaeolithic hominids.
     Along the way, if I find knowledge claims that don't stand up, or represent, merely, one alternative explanation for the archaeological traces under examination, I'm compelled to point that out. There are so many extraordinary claims in the literature of the Middle Palaeolithic that it would takes decades of work like mine to really put the feet to the fire of those who've come before. I simply can't stand by while the real howlers are allowed to remain in the archaeological corpus. 
     And you're here to observe me at it. 
     So, to get back to the genome data. I'm in awe of the biochemical wizardry that John Hawks, Svante Pääbo, and their extremely adept colleagues are demonstrating. Yet, their documentation of the degree of relatedness between modern humans and the Neanderthals, or the Denisovans, means only that we share a common ancestor with the ancestors of those groups. 
     I'm very proud to say that it's still up to the archaeologists, and they alone, to decide which Middle to Late-Pleistocene hominid morphotype or population gave rise to people like us, and when that occurred. As it was before the 1000 genome data became available, when it comes to Middle Palaeolithic hominid behaviour we have a lot of work to do before we've investigated every alternative explanation for each and every extraordinary claim that's made about that distant time.
     I'm gonna go back to that task now.

Of Birch-Tar Hafts and Caribou-Tibia Fleshers: Campitello Quarry and Old Crow Flats

All would-be subversives take note, regardless of your area or epoch of specialization. This article is about sedimentary context--association--and only nominally about the Middle Palaeolithic. Even if you're not someone who gets a kick out of interpreting site sediments, and prefers to leave that to the 'experts,' you'd be far better off sticking with this post because one day, sure as shootin', you'll need to have these skills under your belt lest you fall for the oldest geomorphological trick in Mother Nature's book.

     In 2001 Mazza et al. (2004) discovered some very interesting lithic artifacts in a galaxy far, far away the Campitello sand and gravel quarry, near Bucine, in Italy. One was half encased in birch tar, and bore the unmistakable negative impressions of the haft. Cool enough, you might say. Trouble is, the claim is that it's Middle to early-Late Pleistocene in age. More Neanderthal chemical engineering? Wait and see. 

[May I say that Marco Langbroek has been very kind in directing my attention to this find. The trouble with my having been inactive for so many years is that I've been unable to keep up with the primary literature. It means, simply, that I am reliant on my friends and friendly acquaintances to bring such material to my attention. In this case, Marco has set me something of a challenge, and has goaded me into trying to, as he puts it, 'explain this one away.' All I can say in response is, 'With pleasure!']

A tip of the hat to Marco Langbroek for making this image available to us.

Thus, the gauntlet is thrown down (a lot like the gloves in a hockey game, in actual fact, which is, as you know, the national sport of my home and native land, but which I never played). This'll be most difficult trial in the short tenure of the Subversive Archaeologist. 

     After sowing the seeds of doubt with respect to claims of Middle- to Late-Pleistocene birch tar from Inden-Altdorf, Germany (Pawlik and Thissen 2011), I should say at the outset that I've no quarrel whatsoever with the chemical characterization of the Campitello Quarry mastic as being that of birch tar. Mostly it's because the same chemist that organized the real chemical characterization of birch tar is a co-author on the Campitello Quarry paper. So, where does that leave the subversive? If ya can't fault the evidence, you might be able ta find fault with the context.

[In fact, the contrast between this claim from Italy and the one from Inden-Altdorf has made me realize that there are really only two primary ways that archaeologists can 'get it wrong.' First is in the interpretation of their observations, as I've argued was the case at Inden-Altdorf. The other is the context of the evidence. In the Campitello case, it's the context--the association of the artifacts with the surrounding sediments--with which I have a problem.] 

     I think the Italians were expecting a little flak on the matter of context. In the following quote from their introduction, you'll notice that they are quick to point out their biostratigraphic evidence, which they aver will corroborate the putative age of these objects.  

Elephant and rodent remains were exposed in November 2001 in a clay pit, Campitello Quarry, in the outskirts of Bucine, a small village in the southern part of the Upper Valdarno basin, on the left hydrographic side of the Arno River. … The bones were entombed in fluvial gravels and sands stratigraphically dated to the Middle Pleistocene. A more clear-cut chronological indication is given by the rodents which prove that the finds date back to a moment of the late Middle Pleistocene [emphasis added].

As I was reading along, as I'm sure you will, too, I noticed that the artifacts and Elephas remains were found in sediments first described as a 'clay pit,' then as 'fluvial gravels and sands,' and finally as the fluviatile, 'massive, grey-green sand' of the latest stratigraphic unit, the Monticello Succession of the Valdarno Basin. Here's a schematic cross-section of the Arno River Valley from the article.

I want to go here. Look at the name of the mountain range in the south!

This sedimentary context is one in which chronostratigraphic 'mixing' is not just possible, but likely. In this case, the most recent sediments are identified as 'flood-plain' and these form a terrace, capping the older sediments in a recently formed, deeply dissected valley system. These recent erosional features are illustrated by the narrow U-shaped voids that have exposed the stratigraphic sequence to varying depths across the Valdarno Basin.

     Such erosional gulleys and valleys are notorious in  archaeological lore because they're places where younger clasts can easily be introduced into older sediments, and be unrecognized as such by the excavators. In this case, the excavators arrived after some of the Elephas bones were discovered (presumably by workers quarrying for sand and gravel--a common enough occurrence in such geological formations), which means that, at least for those objects discovered during quarrying, ALL of the overburden had already been removed. The authors do not say whether or not the portion they actually excavated was taken from beneath 15 or so metres of more recent sediments. But you'd think they might have mentioned it if they did. 

     So, there's at least a possibility that the sand in which they excavated was not the sand that had lain undisturbed for upwards of several hundreds of thousands of years. Take a closer look at the Valdarno cross-section, which I've pumped up in the illustration below. Here you can see these U-shaped erosional gulleys, and you don't need much of an imagination to see how it's possible for items of any age to be introduced into what are much older sediments as these features evolve. Couple that possibility with the absence of any real contextual evidence (or published description) for what lay stratigraphically superior to the bone and stone remains, and you have a recipe for, at a minimum, serious questions about their true provenience(s).

By the way. The notation with respect to the Acheulean is only meant to convey the presumed age of the oldest artifacts found terrace-top. Everything up to and including yesterday is up there, too. 

     Luckily for us, the Mazza et al. article provides several clues that the bones and lithics were indeed introduced from younger sediments. The first of these is the grain size of the enclosing sediments, which is described as fluviatile sand in a point bar context. Any stream that is depositing nothing but sand at some point in its journey has long since lost the energy to transport larger and heavier clasts, such as Elephas bones and the relatively massive lumps of stone and tar. That said, a river laying down sand at a point bar still has considerable speed and transport capacity, even if it's bedload is well-sorted sand, which leads me to the second observation.

     The second clue that the tar-wrapped artifact may have been introduced from more-recent times involves its   preservation condition. According to Mazza et al. the bones and stones do not appear to have been entrained for long (i.e. no signs of rounding that would rapidly occur in an ongoing point bar context). How is it possible, then, that they were buried without any signs of having been entrained in such a fluvial context? Not very possible is the definitive answer. [I would hasten to add that it's just possible that they were purposefully buried in a river point bar by some obsessive-compulsive Mid- to Late-Pleistocene hominid. But I doubt it.]

     The third clue given in Mazza et al. is that the lithic artifacts are patinated. This implies a considerable time spent in the open (ask anyone). Again, this isn't what you'd expect on a point bar.

     The fourth clue that all is not as it should be is the context of the microtine fauna, described in this way.

[the microfauna were found] in a layer of fine sand, silty clay and thin laminae of organic debris, that coated the sand bed which contained the stone implements and the elephant skeleton [emphasis added].

Such sediments could NOT have been deposited in a point bar. Full stop. Unless, that is, the river suddenly turned into a basin in which water stood still long enough for the fines (i.e. clay and silt-sized particles) to settle out. Something just isn't right about the archaeologists' interpretation of the sedimentary context of these objects. There can be no doubt of that.

     Notwithstanding the fine work done by the faunal specialists in identifying the Mid-Pleistocene microfauna, or the chemical characterization of the birch tar, or the taphonomic study of the Elephas bones, there is nothing coherent about the archaeological context of these finds. Every aspect of the archaeologists' description contributes to the strong suspicion that the substantive finds are not all from the same time.

     To give you an example of how easy it is to get fooled by the complex depositional processes in geomorphic contexts like the Valdarno Basin, one need only recall the famous 'Old Crow Flats caribou flesher' that caused a big stir amongst Paleo-Indian archaeologists in North America and abroad in the late 1960s and on into the 80s. Discovered in a point bar of the Old Crow River, this caribou bone artifact was found associated with 25,000 year old animal bones. 

The same type of caribou tibia artifact as that found at Old Crow Flats (Illustration credit).

The following is a snippet of a synopsis of North American archaeology that appeared in Archaeology magazine in 1999.

In the summer of 1966, a paleontologist collecting fossils from along the Old Crow River in arctic Canada found amidst a jumble of bones from now-extinct Pleistocene animals a caribou tibia, its end carved into a toothed spatula. The mammoth remains found with the flesher appeared to have been flaked and fractured, like artifacts. The specimens were more than 25,000 years old, far older than anything then known from the western hemisphere. ...redated in the 1980s the caribou tibia flesher proved to be only 1,350 years old.

from David J. Meltzer, 'North America's Vast Legacy,' Archaeology 52(1), January/February 1999.

Those with long enough memories will bear me out on this matter.

     In closing, I'd like to offer a challenge of my own: that Mazza et al. subject a minute sample of the birch tar for radiometric dating--specifically radiocarbon. I'll bet my well-worn Marshalltown that it doesn't exceed the limit of radiocarbon dating, which, as most of you know, is (at the extreme end of extreme) not above 75,000 years, and is normally cited as give or take 50,000. Definitely not Middle Pleistocene, but could be Late. My guess is that it's no more than terminal Pleistocene or Holocene in age.

     *puff of smoke*