While I'm At It. What's Up With Patricia Ann Kramer and Lucy's Lagging?

I miss some beauties if I'm not hyperdiligent about checking the blogs for the latest news that I don't always see on the ticker. Case in point. Another bit from Hominid Hunting, this on Nov. 5. One Patricia Ann Kramer published this in the American Journal of Physical Anthropology, 'Could Kadanuumuu (KSD-VP-1/1) and Lucy (AL 288-1) have walked together comfortably?'

A perfect fit for the Kramer article. Lucy the Lagger and her mate imagined before the discovery of a 1.5-m tall conspecific. 

Kramer's is a splendid example of tackling a research question that's the equivalent of a gnat using methods and techniques that are akin to an 8-pound mallet. Lucy, you'll remember, is the ~1-m tall Australopithecus  afarensis specimen. Kadanuumuu, on the other hand, is estimated to have stood about 1.5 m tall. After some cleverly conceived research involving a treadmill, 36 children and 16 adults. Many exhausted humans later, and much calculation, Kramer arrives at the conclusion that bipedal apes with longer legs walk faster than those with short legs [tibiae, to be exact]. I'm not given to making fun of people. So I won't. I just want to make a couple of points about this research. 

     First of all, if, and it's a big if, Lucy and Mr. Unpronounceable are the same species and contemporaries, it matters very little how fast she walked in relation to him. That's because, regardless of Lucy’s walking pace, as the female she is the one responsible for giving birth to those big males. She, therefore, is just as big as the species needs her to be. Nothing more to be said.

     Second. If the size difference between Lucy and Mr. U is typical of a single species, it represents a greater degree of sexual dimorphism than is usually considered by most workers (look again upon the evocative painting shown above). If so much sexual dimorphism existed within A. afarensis, we cannot compare them to humans. Instead, one must look at other great apes to find similar within-species size difference. And it turns out that the ape with the greatest sexual dimorphism is the orangutan. 

Adult male (at left) and female Bornean orangs. Photo by Holly Carroll (link to original on Flickr).

And, unlike chimps and gorillas, orangs don’t live in social groups, nor do they live with their mates. Yet, conventional wisdom has it that all bipedal apes behaved like chimps and gorillas do, today. If Lucy and her male counterparts were so different in size, why shouldn’t we consider the possibility that the australopithecines were solitary, just like the orang?

     Just sayin'...
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Hominid Hunting, Pinnacle Point, and Me. An epilogue.

Hominid Hunting has just covered the latest news from Pinnacle Point, the subject of yesterday's blurt. I couldn't let it go without comment. Hell, I think by now the author, Erin Wayman, probably expects it!
     It's 'awaiting moderation' as I write this. However, in case it's considered too technical or too contrary for publication, I'm gonna quote myself here, verbatim. Here's how it goes.

Hi, Erin. Pinnacle Point is quite an amazing archaeological locality. And the excavators, Brown and Marean, are doing excellent work. I know that it'll sound a bit like sour grapes, however, for years now there have been those who question not the finds, but the age estimates of these and other southern African sites. Like those at Pinnacle Point, the spectacular finds derive from caves, where organic preservation is often enhanced either by protection from the elements or the chemistry of the cave environment, or both. Unfortunately, for those parts of the site that are beyond the radiocarbon limit—around 40,000 years—the excavators have relied on less precise dating techniques. One in particular, optically stimulated luminescence (OSL), begins with the assumption that a given grain of quartz sand was exposed to sunlight for a time before final burial in the cave. Where caves are concerned this assumption is an untenable assumption, because no one is able to say ahead of time, with any certainty, that a single grain was or wasn't exposed to sunlight sufficiently powerful or for long enough. As a result, once the technique has yielded its raw results, there follows a complex mathematical dance based on all sorts of other assumptions, as a means of 'eliminating' the uncertainty of whether or not a given quartz grain had been sufficiently exposed to sunlight. Moreover, if the mathematical assumptions and the inherent complexity of the calculations are going to be in error they'll always overestimate the time since that quartz grain (and the artifacts in proximity that are of interest) was last exposed to sunlight. Logically, there's no under-estimating ages in caves using OSL. This leaves us with a question, one that I think the excavators of Pinnacle Point and elsewhere cannot logically escape. If the dates of unequivocally modern human behavior elsewhere in the world are less than about 45,000 years old, what are the odds that the anomalously early dates for similar behaviour in those southern African sites—all dated by OSL—are systematically overestimating their age? I'd say those odds were far better than the likelihood that all of the finagling involved in arriving at an OSL age estimate is yielding accurate and precise chronometric results.
[Update 0045 UTC November 10, 2012: Doh! I knew I was forgetting something! The bedrock in which the Pinnacle Point caves are developed is described as quartzitic. Wanna know how long it's been since the quartz grains in the bedrock last saw sunlight? Your guess is as good as mine. Suffice it to say that it's unlikely that they had been exposed to very much sunlight once they fell to the floor. All that matters is that the uncertainty introduced by one minimally exposed grain would introduce one hell of a wrench in any age estimate, even one that's been through the math mill.]  

I think that about sums it up. Now, why couldn't I have said that yesterday?

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Thanks for dropping by! If you like what you see, follow me on Google Friend Connect or Twitter, friend me on Facebook, check out my publications at Academia, or connect on Linkedin. You can also subscribe to receive new posts by email or RSS [scroll to the top and look on the left]. And please don't forget. Oh, and you can always put me on your blogroll! By the way, I get a small commission for anything you purchase from Amazon.com if you go there by clicking through from this site. 

Oldowan [from Melka] Kunture is Not a Star Wars Character

A couple of weeks ago I clicked through to Erin Wayman's Smithsonian blog, Hominid Hunting. The post I was curious about is part of a series called 'Becoming Human' and the article in question was 'The Origin of Stone Tools.' I was struck by the graphic accompaniment to Erin's article, reproduced here, and especially the caption from Erin's blog, which is given verbatim below it.

'Oldowan choppers are among the oldest-known type of stone tools. Image: Didier Descouens/Wikicomons'

The image depicts a chipped stone artifact from Melka Kunture, in Ethiopia. Its age and the conventions of African archaeology demand that it be referred to as an Oldowan tool, after Olduvai Gorge in Tanzania where the famous pair of Mary Leakey and Louis B. Leakey toiled for many decades. The artifacts pictured above could be as old as 1.7 Ma. However, artifacts just like these have been securely dated to 2.6 Ma elsewhere in Ethiopia, at Kada Gona.
     The caption reads 'Oldowan "choppers".' 'Chopper' is one of the names that Louis Leakey gave to these early artifacts, and so, it would seem, has everyone else since the 1950s. The trouble is...where's the evidence that this object was the desired end product such that it represents a distinct 'type'? The evidence, I'd say, existed only in the mind of L. S. B. Leakey, himself. And the trouble with that? Well, many, many archaeologists have used and continue to use Leakey's classification and, implicitly, it's underlying lines of reasoning. And, after a time, use becomes convention, convention becomes unexamined 'truth,' and pretty soon it's 2012 and the whole world thinks these objects are the typological equivalent of arrowheads--in other words the desired end product. Damage to the discipline? You betcha! Retaining such labels is counterproductive--it serves only to perpetuate and further solidify the reification that what you see in the illustration are truly the desired end products in the minds of the creatures that made them.
     So, Gargett, if they're not choppers [or picks, or discoids] what are they? It's not rocket science. I have to give the crafty bipedal apes credit for coming up with the 'idea' of banging one rock against another to remove a sharp edged fragment. Surely this was a stunning accomplishment for mammaldom. But really, aside from the energy required to remove said fragment, there's nothing unique about such an act in the wide world of animals. We all remember that a species of Galapagos finch snaps off cactus needles to use as probes to extract insects from their hiding places. How far apart are the two behaviors? In fact I'd say they were pretty much identical, and probably used about the same cognitive structures, one being the avian version and the other, the ape. Both behaviours are reductive--one species bangs a rock against another rock to remove a piece to use to cut something; the other snaps off a twig to use as a probe. Both use the portion removed to effect their purpose, not the thing that remains after the removal. We wouldn't dream of looking at the cactus, seeing that it's missing a needle, and give it a special name that implies that it was the end product 'desired' by the finch. Why then should we conceive of the rock, lighter by one shard, as being conceptually different than the cactus? The only answer to that, as far as I can see, is that there is no good reason other than the misguided mindset of numerous archaeologists over the past century or so.
     Having said that, do I still need to explain why the artifact shown above isn't what Leakey said it was? Oh, all right, in the view on the upper left, the 'chopper' has a relatively straight break margin. Thinking that this artifact was the end product, and your purpose is to ascribe a function to it, you might interpret such a shape in terms of a technology that you know modern humans have used for tens of thousands of years, and continue to use to this day. You're going to think that the object looks [very roughly] like an axe or a meat chopper.
     In a similar vein, the view on the upper right shows the artifact having a bit of a point. Using the same level of imagination that made the first view into a chopper, the one on the upper right resembles a pick more than an axe. And thus, the artifact could just as well have been classified as an Oldowan 'pick.'
     But why should we think that such artifacts were the intended end product? Isn't it much more likely that the flakes struck off were the 'desired end product,' and the remainder just the 'core?' At least if we adopt a stance like this we won't be privileging one set of behaviours over another. A number of archaeologists working today accept the essential 'core'-ness of Oldowan artifacts. However, many of them believe that we can conserve these anachronistic classifications because they allow us to quickly characterize an assemblage. My credulity is strained to the limit by such arguments. To what end? What, I ask, is the point of knowing how many lumps of rock were discarded after one, two, three, or more flake removals?
     I'll admit, it's easy to pick on the Oldowan artifact classification and see it for what it is. It's straightforward [as I see it]. Unfortunately, as I've stated before, the question of what was really the intention of the rock-knocker becomes crucial to the archaeological narrative as we get closer in time to the present. As you've seen before on the Subversive Archaeologist, it's this notion of the finished artifact fallacy that's at the heart of my critique of the so-called Levallois technique in the Mousterian [and, of course, the critiques of Iain Davidson and Bill Noble].
     I'll save another examination of the Levallois technique for another time. I hope you had a fine weekend. Back to work tomorrow!

[This article has been updated to remove text referring to the illustration as three different Oldowan artifacts. It's not. A tip o' the hat to the ever-perspicacious Marco Langbroek for breaking the news to me in one of his comments.]

Thanks for dropping by! If you like what you see, follow me on Google Friend Connect or Twitter, friend me on Facebook, check out my publications at Academia, or connect on Linkedin. You can also subscribe to receive new posts by email or RSS [scroll to the top and look on the left]. And please don't forget. Oh, and you can always put me on your blogroll! By the way, I get a small commission for anything you purchase from Amazon.com if you go there by clicking through from this site.