More Re: Karen Ruebens* and Neanderthal Lithic Cultural Traditions [?]—Part The First

Over the last two years I’ve barked at and bitten the referees and editors of most of the journals we depend on for new knowledge of us and our origins: Science, Nature, Quaternary Research (QR), QR InternationalQR ScienceJournal of Archaeological SciencePNAS, and the hapless PLOS ONE.

Moving right along . . .

The other day I promised more detail as to why I think Karen Ruebens’s arguments in the Journal of Human Evolution (JHE) couldn’t stand up to critical scrutiny. Today, I’m fulfilling that promise. This must be your lucky day!

Go here to access the paper.

I’m finding that I’m spending a lot of time on this critique. I suppose it’s worthwhile to suggest a good reason as to why I should expect you or anyone else to follow me down this path. I think there’s a really, really, important reason for both.

Karen Ruebens is claiming to have achieved what could not be achieved by others in the . . . oh . . . hundred-plus years that archaeologists have been seriously studying the Middle Palaeolithic (MP).

Think about it. It’s akin to a fossil hunter revising the entire bipedal ape taxonomy and phylogeny. It’s no small thing. And the media are already running with it, and in many languages.

It’s for this reason it’s imperative that we take a very close look at the premises, the evidence, and the arguments used in support of Ruebens s claims. If her claims becomes orthodoxy, those of us on this side of the palaeoanthropological fence will be rolling it uphill on an even steeper slope.

Get it?

Got it?

Good!

This paper deals with the “late” MP, about 115,000 ka to about 35,000 ka [i.e. Marine Isotope Stages (MIS) 5d–3, see below]. It was a time during which the Neanderthals had the run of Ice-Age Europe and western Asia—at the same time as the global climate was deteriorating. As you can see from the graphic below, the late MP started off at the height of the last interglacial. Initially the Neanderthals enjoyed a climate much like that of today. But, by the time Neanderthals disappeared from the fossil record, Earth’s climate was on its way to being the coldest it had been for several hundred thousand years. The Last Glacial Maximum (LGM) occurred considerably later, and by that time our direct ancestors had been the sole inhabitant of Europe for some 20,000 years.

Marine Isotope Stages of the last 300,000 years. Dashed yellow line marks the division between warmer and colder global climate. Dashed grey lines delineate the late Middle Palaeolithic period discussed in the Reubens paper.

Actually, as I began reading this paper I had high hopes, because of what motivated the author: to unjumble the tangle of lithic technological terms and local and regional temporal and typological nomenclature used throughout Europe by palaeolithic archaeologists. Ruebens focusses on bifacially flaked stone artifacts from the last 20 kyr or so of the MP [from about 60 ka to about 40 ka], and a broad swath of Europe including France, England, the low countries, and Germany.

Data collection was aimed at acquiring observations on

1. artefact condition [oddly, not defined, nor does it form part of the presentation];
2. technology—raw material, blank, cortex, back, cross section, shaping and edge angles;
3. typology—both bifacial tool concept and bifacial tool type;
4. measurements and ratios. 

I put the terms concept and type in italics for a good reason: those words are a red flag to me. A concept can reside in the mind of the archaeologist; or, its use can bely the presumption or interpretation that a concept was formed in the head of, in this case, a Neanderthal rock knocker. As for the notion of a type, many of the 50 or so MP types defined by François Bordes are now seen as representing a stage in a time-transgressive sequence of flake removals that had no object other than to create and maintain a useful cutting edge. Many of Bordes’s types were erected due to what’s come to be known as the Finished Artifact Fallacy (FAF)—the idea that although we are able to group like with like, the group’s constituents need not result from deliberate action. Harold Dibble’s careful work on lithic reduction sequences gave us the best illustration of the FAF.

From Harold L. Dibble, “The Interpretation of Middle Paleolithic Scraper Morphology,” American Antiquity 52:109-117, 1987.

The Ruebens paper’s major claims are concisely laid out in the abstract, a snippet of which is reproduced below.

     Results indicate a high level of variation among individual bifacial tools and assemblages. Each bifacial tool concept is correlated with various methods of production, resulting in large degrees of morphological variation. Despite such variation, a distinct three-fold, macro-regional pattern was identified: the Mousterian of Acheulean Tradition (MTA) in the southwest dominated by handaxes, the Keilmessergruppen (KMG) in the northeast typified by backed and leaf-shaped bifacial tools, and, finally a new unit, the Mousterian with Bifacial Tools (MBT), geographically situated between these two major entities, and characterised by a wider variety of bifacial tools.
     Differing local conditions, such as raw material or function, are not sufficient to explain this observed macro-regional tripartite [word missing? division?]. Instead, the MTA and KMG can be viewed as two distinct cultural traditions, where the production of a specific bifacial tool concept was passed on over generations. Conversely, the MBT is interpreted as a border zone where highly mobile groups of Neanderthals from both the east (KMG) and west (MTA) interacted. [emphasis added]

This isn’t the first time the author uses the term correlated, and while it’s denotatively correct in this context, the reader’s thoughts instantly presume that some robust statistical analyses will be presented. They never materialize. [Further down, these correlations will figure prominently.] Then the other shoe drops. We learn that the author has found evidence of cultural traditions in her research. I was on pins and needles to see the data! 
But, before getting into the gritty business of typologies, I want to pause and consider what the abstract tells us about the primary finding of Ruebens s work. I don’t know about you, but after I read the abstract and consulted the map at left, my first impression was that what’s identified as “a border zone,” and a third “distinct cultural tradition”—the MBT—appears to be anything but. Seriously, the MBT is not a “border zone,” even if it says so in the paper. The MBT spans the breadth of the MTA, yet it overlaps the KMG only for about half the length of the total overlap between the MTA and KMG. Moreover, this reader is wondering just how the author managed to distinguish between the two ‘cultural traditions,’ MTA and MBT, if the MBT is superposed. I say to author Ruebens: “Do tell!”

As I pored over the text and tables in this paper, it became clear to me that results are squarely based on the a priori presumption that the shiny biface thingies called different names in different places WERE, in fact, the result of concepts in the Neanderthal consciousness—she accepts, holus-bolus, the reality of the various artifact types. Having mentioned the FAF in her introduction, the author completely ignores it for the remainder of this paper. So, she addressed the 25 differently named biface types, lumped like with like, and arrived at five categories, or types, concepts, cultural traditions—you name it. 

Okay. Let’s look at what the author distilled from the plethora of counter-productive local nomenclature and typologies. [Sorry to have to put up the entire table in what follows.]

Ruebens states that the five divisions are 

defined by a diagnostic combination of technological and typological attributes, including the location and extent of the bifacial shaping and/or retouch, the number of cutting and backed edges, the cross section of the piece and its overall outline shape (Table 3). All five concepts can be viewed as rather distinct, with only few transitional forms being present in the archaeological record. Since each concept is based on least common denominators, morphological variation is present within each category, as expressed by differences in size and exact outline shape.”

I know exactly what the term lowest common denominator means in arithmetic. However, I have no idea how I’m to understand its use in this context. I’m guessing it must be used figuratively. Unfortunately, it’s never mentioned again. Table 3 follows. I had to put it sideways to make it legible. Sorry.

After having a look at Table 3, I think I might have a better understanding of what the author is trying to tell us when using the term correlation. I believe it’s that her five concepts share many traits among them, but that each one has a unique ‘signature.’ Let’s look closer at Table 3, although I have to say off the bat that it doesn’t inspire confidence. 

Call me a pedant, if you want. But, I believe we can toss out the category “Location of shaping/retouch.” Why? Because Ruebens has told us she’s undertaking a study of bifaces! So, there’s not much point in using ?bifaciality? as one of the diagnostic criteria. No. Wait! She’s at least partly justified in using this parameter—one of the five type/concept/cultural traditions is bifacial  only some of the time. Hold the phone. What, fer gawd sakes, is a “partial biface?” A lump of rock is either a bifacially flaked something-or-other, or it’s not! More reason to toss out the category.

You are the weakest link! Say goodbye to “Location of shaping/retouch.”

I also think we can toss out the attribute of backedness? I mean, once you’ve recognized a feature of some artifacts, and called it backing, you shouldn’t NEED any other criteria to distinguish backed things from things having no back. “Back” is an especially shaky criterion if three of the types may or may not be backed [which is what I take the term ‘variable’ to mean in this context]. Thus, this category is useful only useful, all of the time, to help distinguish hand axes from backed bifaces. What good is that?

Dave, what parting gifts do we have for “Back”?

Number of cutting edges seems another tosser. ‘Cause, if backed bifaces and bifacial scrapers can have 1 or 2 cutting edges, and the other three can have only 2, then we’re talking about seven types, not five. Fat lot of good that does! “Cutting edge” [which this research isn’t, by the way] is only useful for distinguishing between the three that always have 2 cutting edges and the four other types that can’t seem to make up their minds.

Gong! Get that talentless “Cutting edge” off the stage.

So, where does that leave us? Let’s re-jig Table 3 using the criteria left once the unhelpful ones are tossed out.

Once the array is culled to this point, it’s clear that “outline shape” is capable—all by itself—of uniquely identifying the five concepts that Reubens has proposed.

I guess it’s all right if Ruebens wanted to go to so much trouble to substantiate the five concept type traditions. Problem is: to be usefully critical of this paper, this poor reader was compelled to go through the truly painful process that I’ve just dragged you through. Worse, others might be tempted to ask the question, “Where was the editor when this paper was undergoing review for its publishability? Where were the referees?” I’d never ask such questions. But others might.

So, you’ve just seen the author find a very strenuous way to replace good, old fashioned, typology.

It’s time we saw some of those shiny bifacial thingies.

I extracted these images from each of the three figures in Ruebens’s  paper, resized them to the same scale, and placed ‘like with like.’ Here’s what I got. Look long and hard, but not too. Your head might explode.


As you can see, the objects in the left part of the frame are all termed hand axes. The others fall under what the author refers to as “backed and leaf-shaped bifacial tools,” which comprise the other four concept/type/traditions. Can you see the same things I see? For example, how do you get a leaf shape out of any of those objects on the right? No plant that I know of has such asymmetrical leaves! And, frankly, the whole issue of the so-called backed artifacts gives me hives. I could easily see any of the ‘backed’ artifacts in this array arising from continued flake removals on a ‘hand axe’ such that it ceases to look like a hand axe. [Remember the Dibble diagram up top?]

Logically, the proximal—butt—end of the ‘hand axe’ that’s been whittled down to something resembling the bottom four on the right. That butt would be identified as the backed portion, and the final flake removals on the opposite margin created one final cutting edge before it was dulled beyond usefulness and discarded.

Tell me I’m wrong. Isn’t that what the FAF is all about? Regardless of your position on hand axes, it’s straightforward: if the FAF is in play with hand axes, logically we should be able to see the results of gradual further reduction along the lines that we saw in Dibble’s work with MP scrapers.

Fellow FAFsters, start your engines!

[By the way, no doubt because I’m Anglophone and geographically deprived, I’d never heard of either the Keilmesser or the Faustkeilblatt before today. Live and learn.]

Table 3 isn’t all that this paper is about. If it were, I’d be breathing easier. Instead, Ruebens goes on to consider other parameters of European MP bifaces in an effort, one imagines, to bolster her identification of the five concept/type/traditions and to set the stage for the new map of MP Europe. I’m keeping an open mind. [As if.]

So, we’ve come to the point where I sum up this installment of my remarks on the Ruebens paper.

Here it comes. The summary.

I hope that the referees and editors are squirming by now. This story doesn’t have a happy ending for the JHE crew, and it’s not the fault of the author.

Next time I’m gonna get into the metrics of this revision of the MP of Europe. Hold on to your hat!

* I apologize for spelling the author’s name incorrectly throughout the earlier version of this piece.

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The Little Species that Could: Boivin et al.’s "Human dispersal across diverse environments of Asia during the Upper Pleistocene"


The environmental fluctuations that characterized the Pleistocene meant there were sometimes more- and sometimes less-attractive times for our ancestors and fossil relations to have left Africa for greener pastures. In their Jan. 15, 2013 electronic release, Nicole Boivin and her co-authors leverage their [nearly] unique knowledge of Arabia and southern Asian to try out an argument that they abstract in this way:

Fossil, archaeological and genetic findings are seen to converge around a consensus view that a single population of H. sapiens exited Africa sometime around 60 thousand years ago (ka), and rapidly reached Australia by following a coastal dispersal corridor. … We argue that the fossil and archaeological records are too incomplete, the coastal route too problematic, and recent genomic evidence too incompatible for researchers not to remain fully open to other hypotheses. … Current archaeological, genetic and fossil data … appear to increasingly favour a more complex out of Africa scenario involving multiple exits, varying terrestrial routes, a sub-divided African source population, slower progress to Australia, and a degree of interbreeding with archaic varieties of Homo. (Boivin, N., et al., “Human dispersal across diverse environments of Asia during the Upper Pleistocene.” Quaternary International (2013), http://dx.doi.org/10.1016/j.quaint.2013.01.008)  

So, what can Boivin et al. tell us about our evolution that we didn’t already know? Their paper gives us a possibility, not a likelihood. It accommodates some data. It tells a story.

To the great pleasure of this reader the authors present some stunning graphics of the range of palaeoenvironments across Africa and Asia in the Pleistocene [see below]. These help to underscore their main contention that at different times during the Pleistocene, environmental conditions were changing such that anatomically modern bipedal apes would have had numerous opportunities to spread beyond Africa and into Asia. In that nutshell is, I think, the fundamental problem with Boivin et al. That’s because, rather that supporting their arguments, the archaeological record as it stands is telling us that the anatomically modern version of Homo sapiens, extant between about 195 and 40 kyr ago, was little better at adapting to new environments than an African bovid.

In the two maps shown below I’ve melded each of the four maps in the paper so as to produce a panorama of the pertinent geography at MIS 5 and 4.

MIS 5—Interglacial conditions between about 130 ka and about 71 ka. From Boivin et al. 2013.
MIS 4—Mainly glacial conditions from about 71 ka to about 60 ka. From Boivin et al. 2013.

During MIS 5, the authors point out, a continuous, hominid-friendly, environment spanned northeastern Africa, the southern Arabian peninsula, and southern Asia. In other words, Nature afforded H. sapiens a ‘way out’ of Africa during MIS 5. By contrast, in MIS 4, that same part of the globe was covered in red—i.e. not a nice place for hominids. So, no hominids got out. In so doing [IMHO] the authors paint a picture of a species that was so niche-specific as to be incapable of any kind of rapid adaptation to new environmental conditions. In none of the discussion do Boivin et al. appear to realize the apparent behavioural rigidity their model proposes as characterizing early anatomically modern H. sapiens. Indeed, their model stands in stark contrast [it seems to me] to the almost infinite behavioural plasticity that we’ve grown accustomed to hearing about whenever someone is listing the hallmark manifestation of we modern humans. Boivin et al. are begging the question “Were they human like us?”

By adopting this posture toward H. sapiens, the authors shoot themselves in the foot. Indeed, they appear to be arguing for a reduced set of ‘cultural adaptations’ prior to the time that people like us first set foot in southwestern Asia about 40 or 50 kyr ago. The more recent H. sapiens had a recognizably modern set of abilities, and it is those H. sapiens that, in a geological blink of an eye, spread across Asia and into Australia [the actual duration of the spread may have been on the order of 5,000 years]. What’s more, the behaviourally modern H. sapiens did so by changing gears whenever they encountered a novel ecosystem. Think of it. If Boivin et al.’s vision of H. sapiens’s capacities is anywhere near accurate they’d have a hard time explaining the persistence of the Inuit or the Tierra del Fuegans, both of which groups have managed to survive in, without doubt, the harshest conditions on Earth.

Overall, I’m incredibly happy to accept Boivin et al.’s portrait of the environments in marine isotope stages 4 and 5, the interglacial/glacial swing during which Homo sapiens arose in Africa, i.e. somewhere between about 190 ka and about 160 ka. From that time until about 40 to 50 kyr ago the authors aver that Homo sapiens didn’t just pop out once, but did so numerous times, following different pathways, and biomes.

All along the archaeological world had been aware of two excursions by H. sapiens out of Africa—one about 100 ka and the other at 40 to 50 ka. The authors propose that it may not have been as simple as the archaeological and record might have us believe, and that there may have been at least one more and possibly many more excursions out of Africa that are, at present, archaeologically invisible. Getting back to observations for the moment. At around 100 ka we see anatomically modern Homo sapiens at Qafzeh Cave in what’s now Israel. At that time H. sapiens was evincing the same behaviours as those of their contemporaries, the Neanderthals, which were distributed across Europe and into Central Asia. And here the authors’ idea runs out of gas, by not recognizing the possibility that, anatomical similarities notwithstanding, the two excursions could easily have been undertaken by two behaviourally very different flavours of H. sapiens. It has to be admitted that the Qafzeh H. sapiens at 100 ka was not acting as if they were people like us. They were, instead, behaviourally just like good Neanderthals—e.g. the same, Mousterian, behaviour with respect to working stone. Moreover, the Qafzeh hominids arrived in the Levant along with an African fauna, all of which appear to adhere to Boivin et al.’s model for expansion. But those earlier H. sapiens got no further, apparently, than that environment allowed. Because, by the time the environment had returned to glacial conditions, the Neaderthals were inhabiting the same geographic place that had been held by the Qafzeh hominids for at least 40,000 years previously. It appears, then, that the Neanderthals were associated with a western Asian faunal community. Thus, we have a picture of two species, acting in similar ways, each constrained by different environmental conditions. I’m sorry. That just doesn’t sound to me like they were much like us.

I’m not fond of nothing buttery. However, I see no other conclusion to be made but that anatomically modern bipedal apes at 100 ka were not cognitively similar to you and me, and thus couldn’t adapt to the transition from interglacial to glacial conditions. The authors state that many have called the dispersal of H. sapiens into the Levant around 100 kyr ago ‘failed.’ In fact they thrived for at least 40 kyr in the Levant in just the same way as they had done since arising in Africa—perhaps almost 200 kyr ago—and exploiting an almost identical environment to that which supported them in the Levant from about 100 kyr to about 60 ka. Indeed, the ‘failed’ dispersal that Boivin et al. refer to was no dispersal at all. It involved a creature bound to its ecosystem and its niche—albeit a different one—in the same way that it appears the Neanderthals were bound to theirs during their 200-or-so-thousand-year tenure.

Boivin et al. are quite correct in pointing out the equivocal nature of the genomic observations being talked about these past few years. Given the behaviour of the Qafzeh H. sapiens and that of the Neanderthals, a parsimonious reading of the data is that anatomically modern H. sapiens came in contact with, and may indeed have bred with, Neanderthals during the forty or so thousand years that H. sapiens was in the Levant. In all probability there was a frontier somewhere to the north of Qafzeh Cave where the two kinds came in contact for at least some portion of those 40 kyr. Such a scenario makes sense [to me at least] of the genetic evidence that we’re seeing in the present. Any interbreeding that may have gone on between the two species could have been a fait accompli by the time behaviourally/cognitively modern H. sapiens entered Europe. Thus, we dont have to imagine a time when people like us encountered and then mated with Neanderthals.

Further evidence that neither the Qafzeh hominids nor the Neanderthals were like us might be drawn from the observation that there was no extirpation of the Neanderthals coincident with the earlier anatomically modern H. sapiens expansion into the Levant between 100 and 60 kyr ago. In other words, for the 40 or so thousand years during which they were neighbours, there appears to have been no anthropogenic cataclysm comparable to that which many would argue was visited on the Neanderthals during the latest excursion from Africa of cognitively modern H. sapiens like you and me. If, indeed, H. sapiens spelled the doom of the Neanderthals between about 40 and 50 kyr ago, if the Qafzeh hominids were exactly like us, what explains the persistence of the Neanderthals? In the end, Boivin et al.’s narrative ignores the real likelihood that there were evolutionary changes within H. sapiens between the time they occupied Qafzeh Cave at around 100 kyr ago and about 40 kyr ago, when people like us colonized the world.

In the search for answers to the question of when hominids became human, I think the disciplines of archaeology and palaeoanthropology have some distance still to go before gaining a truly accurate accounting of recent evolution.

This piece took me much longer to put together than I had originally anticipated. Next time I’ll have something to say about the latest data on the latest Neanderthals in Spain.

SA announces new posts on the Subversive Archaeologist‘s facebook page (mirrored on Rob Gargett’s news feed), on Robert H. Gargett‘s Academia.edu page, Rob Gargett‘s twitter account, and his Google+ page. A few of you have already signed up to receive email when I post. Others have subscribed to the blog’s RSS feeds. You can also become a ‘member’ of the blog through Google Friend Connect. Thank you for your continued patronage. You’re the reason I do this.