The Raw and the Cooked: Apologies to Claude Lévi-Strauss

As you might imagine, I've been wrestling in silence with Richard Wrangham's cooking hypothesis for some time now. This is what Publishers Weekly had to say about Catching Fire, RW's popular book on the subject.

Contrary to the dogmas of raw-foods enthusiasts, cooked cuisine was central to the biological and social evolution of humanity, argues this fascinating study. Harvard biological anthropologist Wrangham (Demonic Males) dates the breakthrough in human evolution to a moment 1.8 million years ago, when, he conjectures, our forebears tamed fire and began cooking. Starting with Homo erectus—who should perhaps be renamed Homo gastronomicus—these innovations drove anatomical and physiological changes that make us adapted to eating cooked food the way cows are adapted to eating grass. By making food more digestible and easier to extract energy from, Wrangham reasons, cooking enabled hominids' jaws, teeth and guts to shrink, freeing up calories to fuel their expanding brains. It also gave rise to pair bonding and table manners, and liberated mankind from the drudgery of chewing (while chaining womankind to the stove). Wrangham's lucid, accessible treatise ranges across nutritional science, paleontology and studies of ape behavior and hunter-gatherer societies; the result is a tour de force of natural history and a profound analysis of cooking's role in daily life. More than that, Wrangham offers a provocative take on evolution—suggesting that, rather than humans creating civilized technology, civilized technology created us. Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.

Ringing praise, I'd say. I could spend weeks going after the plethora of assumptions that the author incorporates in the thesis from a post-modern anthropological point of view. Suffice it to say that I have issues with it.
     But that's not why I've called you here today. Lately, I came across another contribution to the literature on cooked food and primate brains. The only advice I could have given the authors while they were still writing is: 'Look before you leap.' Karina Fonseca-Azevedo and Suzana Herculano-Houzel, ‘Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution.’ PNAS 109:18571-18576, 2012 (published ahead of print October 22, 2012, doi:10.1073/pnas.1206390109)* wrests a far-reaching hypothesis from some interesting brain- and body-size data on a range of primates in relation to the number of hours each species spends feeding. And here it is.

... by showing that metabolism is indeed limiting at physiologically relevant combinations of body [mass] and [brain mass], our data provide evidence that metabolic cost is limiting enough to impose tradeoffs in brain evolution, and thus offer direct support for the proposition of Wrangham (Wrangham RW, Jones JH, Laden G, Pilbeam D, Conklin-Brittain NL. 'The Raw and the Stolen. Cooking and the Ecology of Human Origins.' Curr Anthropol 40:567–594, 1999; Wrangham RW. Catching Fire: How Cooking Made Us Human, Basis Books, New York, 2009) that such a metabolic limitation was overcome in the human lineage by the advent of cooking food, which greatly increases the caloric yield of the diet, as a result of the greater ease of chewing, digestion, and absorption of foods (Urquiza-Haas T, Serio-Silva JC, Hernández-Salazar LT. 'Traditional nutritional analyses of figs overestimates intake of most nutrient fractions: A study of Ficus perforata consumed by howler monkeys (Alouatta palliata mexicana).' Am J Primatol 70:432–438, 2008; Carmody RN, Wrangham RW. 'The energetic significance of cooking.' J Hum Evol 57:379–391, 2009; Carmody RN, Weintraub GS, Wrangham RW. 'Energetic consequences of thermal and nonthermal food processing.' Proc Natl Acad Sci USA 108:19199–19203, 2011). In line with this proposition, a cooked diet is preferred by extant nonhuman great apes (Wobber V, Hare B, Wrangham R. 'Great apes prefer cooked food.' J Hum Evol 55:340–348, 2008). Although the earlier addition of raw meat to the diet of earlier hominins may also have contributed to increase its caloric content (Milton K. 'A hypothesis to explain the role of meat-eating in human evolution.' Evol Anthropol 8:11–21, 1999), raw meat is difficult to chew and ingest, whereas cooked meat is easier to chew and has a higher caloric yield (Wrangham 2009; Carmody et al. 2011). Besides increasing the caloric yield and making previous metabolic limitations irrelevant, cooking would also have increased the time available for social and more cognitively demanding activities, which in turn would impose a positive pressure for increased numbers of neurons, now affordable by the new diet. We propose that the combination of a newly affordable larger number of neurons with the accompanying time now available to use these neurons in cognitively demanding tasks that improved species fitness drove the rapid increase in numbers of brain neurons encountered in human evolution from H. erectus onward (Herculano-Houzel S, Kaas JH. 'Gorilla and orangutan brains conform to the primate cellular scaling rules: Implications for human evolution.' Brain Behav Evol 77:33–44, 2011). 

This article gives me an opportunity to unpack a crucial concept in evolution that I think is lost on a great many, and to counter a few of the ideas floated in the authors' conclusion, quoted above. For example, I could remind the cooked food adherents that a circumpolar subset of the human species subsists almost entirely on raw meat, which these authors have decided is 'difficult to chew and ingest.' [I won't stoop so low as to point out to the authors and to the PNAS referees that in this characterization of raw meat the authors must in fact mean 'difficult to digest,' not 'ingest.' And since when was sushi difficult either to chew or digest?] A case in point. The people known as the Inuit in Canada, heretofore known by the derogatory label 'eaters of raw meat--or Eskimo' can ill afford to cook anything in lands that are almost bereft of combustible vegetation. [Although, I suppose, Wrangham and others would counter by saying that this would explain why the Inuit didn't invent Western, Industrialized society. They obviously lost out in that evolutionary game thanks to their diet depauperate of cooked food.]
     I could also bring up the issue of what primates actually eat, and the difference between a diet comprising largely indigestible leaves--that of gorillas, for example--and one composed largely of ripe fruit or nuts. Or, that humankind's digestive system has the architecture of a frugivore, which is what truly 'allows' shrunken guts [to quote Publishers Weekly again, but also through them, Wrangham himself]. In the same vein, gorillas do not have the gut of an obligate browser, like Bos, and thus not only do they rely on low-quality food, but also they are incapable of extracting more than a small percentage of the nutrients contained therein. If humans were to subsist on a diet of leaves, I can well imagine that we'd be chewing most of our waking lives, with nothing more material to show for it than piles of caw-caw that resemble meadow muffins or more social than a group dump site. But, enough about the Cooking 'R' Us crowd and their sometimes silly assumptions.
     The major point I want to make today has to do with the way these authors seem to be thinking about evolutionary change and natural selection. I'm talking about the idea of what's called 'selective pressure,' or more generally, 'adaptation.' In their final statement, Fonseca-Azevedo and Herculano-Houzel aver that in our fossil ancestors 'cognitively demanding tasks that improved species fitness drove the rapid increase in numbers of brain neurons' [emphasis added]. Perhaps it's just a poor lexical choice, but use of the word 'drove' in this context more than suggests that the authors believe evolutionary change amounts to natural selection for advantageous traits. Indeed, the notion that nature 'selects' anything good in a species' genome allows the authors and their compadres to make the assertions they do.

      Remember your introduction to evolution? You learned, for example, about the English moths during and after the worst depredations of the Industrial Revolution. During the time of maximum air pollution and the accumulation of what amounted to soot on tree trunks, the lighter coloured moths all disappeared and dark-coloured moths predominated. Know what was happening? No, Nature wasn't gracing the dark-coloured moths because they blended into the colours of the soot-covered tree trunks. Nature was showing its callous side by arranging it so that the light-coloured moths stood out like sore thumbs on the tree trunks where they used to blend in, and were thus being preyed on more readily, and more thoroughly than ever before, and all that was left were the darker coloured variants that had always existed, but which were always genomically swamped by the better-camouflaged lighter coloured variety. In short, evolution works by selection against, rather than for any latent or novel genetically determined trait in a population. 
     As such, I think it's clear that it's altogether misguided [nay, wrong!] to conclude that the encephalization of Homo erectus and later hominids was the result of a 'combination of a newly affordable larger number of neurons [and the] time now available to use these neurons in cognitively demanding tasks that improved species fitness [which] drove the rapid increase in numbers of brain neurons ... from H. erectus onward.' In like wise, Wrangham's major conclusion-- that 'cooking enabled hominids' jaws, teeth and guts to shrink'--is failed before it even gets off the page. Not just, mind you, for the same reason as Fonseca-Azevedo and Herculano-Houzel's thesis. Instead, there are any number of possible explanations as to why cooking might have conferred an advantage on the larger-brained hominids that were capable of using fire. One possibility that comes to mind is that spending more time making, tending, and using a fire to cook would require a sheltered and in that way protected environment, such as a cave or rock shelter, or a forest glade. That alone might have lessened the chance that bigger-brained hominids would be preyed upon. So, you see, by coat-tailing on the claims for fire use more than a million years ago [about which you know what I think], Wrangham and others have generated a host of 'just-so' evolutionary scenarios that are sufficient to explain encephalization in hominids, but which are certainly not necessary for it to have occurred.
     I'm done with cooking for now. But be relieved. I could have totally gone off on Wrangham for his ideas about Homo erectus cooking, 'table manners,' 'sexual division of labour,' 'pair bonding,' and what. ever.

* Did you ever wonder what they name the kids when two people with hyphenated last names get married? 

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Stay-At-Home Modern Humans Stranded in South Africa for 50,000 Years. What's Up With That?

Pinnacle Point Caves (PPC) in relation to Klasies River Mouth (KRM)  cave and Blombos Cave (BBC), three of the best known southern African localities with modern human accoutrements as early as 70 ka to 100+ ka. 

In the midst of the recent science-media frenzy about bows and arrows at Pinnacle Point, I thought I'd best expand on my reasons for doubting, en masse, the 70 ka to 90 ka [and beyond] dates for what appear to be unequivocally modern behaviours in a growing number of southern African archaeological sites. I've been working on this for several days, and the more I look, the more I see evidence of a real problem with optically stimulated luminescence (OSL), the technique used at all of these sites to estimate the age of the deposits. As I've mentioned previously [e.g. here], the primary assumption underpinning OSL age estimates is this: each individual quartz grain removed from the archaeological deposits MUST have been exposed to sunlight for long enough to have released any free electrons trapped in its crystal lattice. Given that all of these early dates derive from cave deposits, the primary issue for the OSL specialist is eliminating any quartz grains that have not been exposed in the manner just described. It's one thing to recognize this pesky problem; it's quite another to overcome it. And that, I think, is where OSL falls down. Whether or not a given age estimate is accurate becomes a real guessing game, as we'll see in a moment.  

Three representations of the stratification at Pinnacle Point PP5-6. Source: Brown et al. 2012

As you can see above, in the recently published profile from Pinnacle Point site PP5-6, the OSL picture is evidently not straightforward. The date of 53 ka highest up in the profile is superposed on a date of 60 ka. That is consistent with the stratigraphic relationship between the sediments that yielded the dates. However, the next lowest in the column is, again, 53 ka. Then come 56 ka, 52 ka, 50 ka, followed by 52 ka, 60 ka, 65 ka, 65 ka, 69 ka, then 66 ka, 66 ka, 64 ka, 72 ka, 71 ka,74 ka, 69 ka, 77 ka, 73 ka, 71 ka, 69 ka, 69 ka, and lastly 78 ka. Clearly this is not an 'internally consistent' temporal sequence. These age estimates are roughly sorted youngest to oldest, but given the lack of coherence, how is one to assess, much less find acceptable, either the youngest or the oldest dates?
     For example, does one conclude that the real age of this stratigraphic column ranges from 53 ka to 78 ka? How about 53 ka to 69 ka? Or 60 ka to 69 ka? Moreover, with such variance from what one should expect of the age succession in a sedimentary column that has maintained temporal integrity, how do we know that any of these estimates are accurate? All this points to, in my barely savvy opinion, serious difficulty with the technique, most likely due to the intractable problem inherent in the primary assumption of the technique. And, if the very latest results of the best of the best practitioners yields such shaky outcomes, what does it say about all of the other South African site chronologies? Here, then, lies the very real possibility that the OSL technique is single-handedly creating a false picture of modern human origins throughout the southern region.

Stratigraphic profile of La Quina, the type site of the Quina Mousterian. All of the objects illustrated are éboulis, clasts of all sizes and shapes, which have spalled off the bedrock and been incorporated along with the archaeological materials.

     In this I'm reminded of what's now a discredited relative dating technique that European archaeologists depended on for a good long time. I refer to the technique of éboulis analysis that underpinned [especially] the French Palaeolithic chronology for much of the late twentieth century. Briefly, the analyst qualitatively assessed the angularity of small pieces of bedrock breakdown and assigned an age estimate that coincided with what was then considered to be a four-stage European glacial cycle--Gunz, Mindel, Riss, Würm. The most angular pieces represented cold or dry or both, and the most rounded pieces warm and wet or both. It seems a bit naïve by today's standards. However, it was gospel for decades. One day it all came crashing down. After that, everyone picked up the pieces and moved on. Thus far archaeologists of the Middle Pleistocene haven't resorted to OSL for dating. However, they do use thermoluminescence, which depends not on individual quartz grains, but rather on pieces of flint that have been subjected to high heat. There's certainly less doubt about whether or not a piece of flint has been heated than that a tiny grain of quartz was ever exposed to sunlight. 
     In making this comparison between éboulis analysis and the OSL dates from southern Africa, I don't mean to suggest that the two techniques are equal. Rather, I make the comparison because, in the past, an error-prone technique was used to provide the chronological framework for an entire sub-continent. That's the direct comparison to be made. The southern African cave sites are universally dated using OSL or other equally shaky [to my mind] techniques.

The crux of the southern African OSL dates. In relation to the earliest evidence of modern human behaviour everywhere outside of Africa, and the speed at which Eurasia was 'colonized', the southern African dates stand out like a sore thumb. 

     Having made the comparison between éboulis and OSL, I can now introduce what I believe to be several data sets suggesting that the southern African cave age estimates are anomalous when compared to the rest of the world. For, when it comes to the early dates for modern human behaviour in southern Africa there is an absence of parsimony. Parsimony, if you'll recall, is the central point of Occam's Razor, the idea that, when deciding which competing hypothesis is the more correct, the one that makes the fewest assumptions should be selected. Occam's Razor is by no means a law of nature. It merely crystalizes what empirical scientists have know for some time--the more auxiliary hypotheses you need to support your main conclusion, the less likely it is to be the right one. In the case of the early dates for modern human behaviour in South Africa, there is much that flies in the face of Occam's Razor.
     Take, for example, the overwhelming evidence for the almost instantaneous spread of behaviorally modern humans to the furthest reaches of Asia, which happened about 45 ka. Australia was colonized at this time. So were some of the the furthest reaches of Europe--England, for example, at 44 ka. The best explanation for the absence of modern human archaeological assemblages prior to this time is that there simply were no modern humans outside of Africa prior to that time. The question thus becomes, if humans could expand the length and breadth of Asia in an eye-blink of geological time, why didn't it happen earlier, when modern human behaviour is claimed to have had its start 70 ka to 90 ka ago in southern Africa?
     To explain the apparent lag between the emergence of modern human behaviour in southern Africa and that which inhered everywhere else in the world post 45 ka, the various archaeological teams must invoke untested, and indeed untestable hypotheses as to the reason for those moderns staying put for anywhere between 164 ka and [taking the youngest date from PP5-6] 53 ka. One hypothesis has that population bottlenecks occurred due to environmental circumstances [as yet unrecorded], after which cultural achievements of the modern populations were stultified, only to reappear some 30,000 years later, at which time the archaeology records the rapid spread of modern humans throughout what's been called the Old World.
     In July of this year we saw a report from Border Cave of a modern human archaeological assemblage that dates to about 44 ka, a result in accord with the beginning of modern human behaviour in Eurasia. But, because they found no earlier deposits, the authors find it necessary to replay the tape of the 'early' teams, that the Border Cave moderns must represent the hypothesized re-fluorescence of modern humans preparatory to world domination. Once again. I think such intellectual reaching is unnecessary, at best, and obfuscatory at worst. I do not mean to suggest that the obfuscation is deliberate. The archaeologists who rely on OSL age estimates have nothing else to go on. Or, at least, they have no reason to think that their information is in error. After all, the best of the best are working at Pinnacle Point. Who could doubt their veracity? Who would, much less?

Modern human artifacts from Border Cave at 44 ka. Touted to be the earliest evidence for the same culture that existed ethnographically in the vicinity of Border Cave. [Take that with an anthropological grain of sand.] Source: D'Errico et al. 2012.

     I know. I know! We're dealing with Culture. And culture theory says that the early moderns in southern Africa might just have decided that they wanted to stay put and not colonize the known universe. If you think about it, how would they have known they were choosing not to colonize the rest of the world, unless they knew there was a 'rest of the world' to colonize. And, if they did know that there was a 'rest of the world,' why is there no evidence for those modern humans until about 45 ka everywhere but southern Africa. If, and I have no doubt, the early moderns in South Africa were anything like modern moderns, or a great many ethnographic moderns, they couldn't have resisted seeing what was beyond the next ridge. Yet it would seem that they 'chose' to stay put, enjoying the fruits of their modernity all by themselves, thus endangering their persistence by allowing themselves to be buffeted by the whims of the environment. That doesn't sound like modern me to me. [N.B.: I'm only being half facetious.]
     I supposes one could suggest that there were natural barriers to their spread out of southern Africa. But, there are no natural barriers to movement in coastal Africa, nor would there have been when the sea levels were depressed during the glacial stages of the Pleistocene. If they could process pigments and decorate ochre, make beads, and arrows, they were equally capable of making boats to cross the broad reaches of Africa's rivers where they meet the sea. After all, the colonizers of Australia crossed at least 90 km of open ocean at around 45 ka. Surely the precocious moderns in south Africa at 70 ka to 90 ka could have done the same. So, the big question is why did they stay put in southern Africa? Huh? Riddle me that, Batman. Apparently the Wall Street Journal has a suggestion.

     So, you see, reason alone tells me that there's much wrong about the early dates from southern Africa. And my instinct tells me that the OSL dates must be wrong. As I've said to you before, will some kindly physicist not come forward to examine the mathematical filmflammery that accompanies OSL age estimates, and thereby save me from this empirical purgatory??? The flimflammery in question.

Please??? I'm beggin' ya.


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Panbanisha Dies From A Common Cold: Sue Savage-Rumbaugh Has Much To Answer For

From Chimp Trainer's Daughter Nov. 7

Thanks to my extended family of facebook friends in anthropology, I was appalled to read of the death of Panbanisha, one of the two bonobos famous for learning what Sue Savage-Rumbaugh has all along called human language. The other, of course is Kanzi. Panbanisha was 27, still young for a member of her species. The 'official' word came from the deposed head of the Great Ape Trust, herself, Savage-Rumbaugh.

“Panbanisha failed to overcome the cold that all the Bonobos have been fighting. She was the most sensitive, the most creative, the most intelligent of all - she always sought the path of peace. Her Presence always filled the building. She understood all that was said and saw all that was done. Yet she could not speak as humans do - and therefore was misunderstood.

“I hope to rally the souls of the remaining bonobos so that they believe there really is a future worth living for. I hope to find a way to build a better world - a world in which those who have no voice and are unjustly persecuted - can begin to feel safe and honored, a world where the good no longer die young, a world where the Ann Franks of our time can come out of the cages and meet faces of friendliness and love.

“Panbanisha was never meant to live in a cage as she was always good and she understood responsibility and morality and had immense self control. Now she is free, free at last.” S. Savage-Rumbaugh (quoted in the WestDesMoines.Patch.com)

Without prejudice, and keeping in mind that there have as yet been no charges brought against Savage-Rumbaugh, I think it might be said that the above notice belies a human being with only a slender grasp of reality. Such at least has been the scuttlebutt for many years, even before her organization ceased doing serious research and became little more than a preserve for the animals that she had once exploited [yes, exploited] in the name of science. 
     You can only call it exploitation if the researcher in question, for example, believed that it was ethical and reasonable to separate bonobo young from their mothers and other relations so that they could be raised 'bi-culturally,' loosely analogous, I suppose, to being brought up by parents who speak two languages and derive from different cultures. But it is only loosely analogous, and more precisely could be termed playing fast and loose with ethical principles and the humane treatment of animals.
     And therein lies the crux of the whole affair. Savage-Rumbaugh and her ilk are at the heart of the segment of the learned community who have lobbied long and hard for a more enlightened [in their view] assessment of our fellow great apes. They have it that chimps, bonobos, gorillas and orangutans are sufficiently like us bipedal apes as to be considered entitled to the same rights and privileges, legal and moral, as humans. I have always considered this stance to be wrong-headed, at best, and hopelessly misguided, at worst. I do not mean to say that the other great apes aren't worthy of our attention, our care and concern, or that they don't manifest extraordinary behavior and cognitive ability. But I have never bought into the notion that they are so like us as to be the equal of humans.
     I know that this position exposes me to accusations of speciesism [if that coined expression makes any sense at all], however there is nothing in the annals of great ape behaviour study that suggests to me any other conclusion but that humans are, uniquely, human. Here's why. Savage-Rumbaugh and others have long held that their captives are able to learn the rudiments of language. But there's an argument to be made that their subjects are simply learning a variety of new signs for things and actions that already formed their perceptual universe. Humans, on the other hand, are capable of creating the concept of a 'cognitive universe' and conveying the meaning  to other humans! The other great apes will never be so talented. You could say, of course, that many humans wouldn't be capable of conceptualizing such things, for example those with cognitive challenges or who are strictly speaking mentally ill. That misses the point. As a species, humans are capable of making meaning out of stones, and sounds, and pictograms, and anything else, and regularly assign meaning to different classes of objects on the basis of their meaning in a social hierarchy. Tell that to a chimp.
     I have a simple challenge for those who'd say that the other great apes are worthy of the label human. Once you have raised them in an early twenty-first century American middle-class cultural environment, once you have managed to teach them the difference between a hunk of beef tenderloin and a hunk of ground round, see how easy it is to teach them the difference in social status inherent in the two dietary choices. That, to me is a test of what it truly means to be human, regardless of whose cultural milieu. Humans in other cultures learn a different set of significances--such is the nature of human culture. The other great apes are incapable.
     To Sue Savage-Rumbaugh I say 'You have forever perverted the natural lives of the great apes in your trust. If you're even capable of realizing the harm you've done [and continue to do in their behalf] I hope that you'll live a long, remorse-filled, life.'
     Unfortunately, after reading her message to the world upon the death of Panbanisha, I can't be certain of that outcome.  

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Lest We Forget

Credit

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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Throwing in the Towel Thanks to Pinnacle Point, South Africa. As If.

At home. Under the weather. What else to do but watch the news ticker. It is ablaze with the latest news from Pinnacle Point in South Africa. The first word I had of it was a headline about this piece, just published, in Nature. 

In the article, long-time acquaintance and Mousterians 'R' Us advocate Sally McBrearty extolls the collection of more evidence for modern human behaviour at around 70,000 years. Sally was commenting on a Letter to Nature also published electronically yesterday. 

As you know from reading the SA, there are plenty of claims out there for modern human cognitive abilities or behaviours, or both, going well beyond 100 ka--blade industry at Kathu Pan 1 and Qesem Cave; hafting with bitumen or birch tar, and so on. However, as you also know, I've been critical of a great many of them. 
     Yet, according to the age estimates for unequivocally modern human activities at places in southern Africa, such activities are occurring at an age anywhere from 30 ka to 60 ka earlier than they do in Europe and southwestern Asia. For example, finds of decorated ochre and pigment processing 'kits' at Blombos Cave ca. 75 ka. In today's piece by Brown et al. we're hearing about use of the bow and arrow ca. 70 ka [I haven't had the time to examine the actual evidence for the claim other than to note that they refer to the microlithic portion of the assemblage consisting of small backed blades.]. This of course is one of the inferences frequently made for the kind of stone tools comprising the Howieson's Poort phase of what in Africa is called the MSA (Middle Stone Age). 

PP5-6 excavation. Deeply stratified and sharply inclined, much like a cone of talus [Credit: Erich Fisher; (inset) Simen Oestmo] © Science/AAAS.

     
I've previously said quite a bit about these early dates, here and here. However, this latest publication, and an earlier one from the same [or similar] group of authors, published in Science a few years back  claims [and at this point I have no reason to doubt them] that they have evidence of heat treating lithic raw material to make it more workable, between about 70 ka and 164 ka! This would be a great discovery even if a mere 30,000 years old. Unfortunately for me, these two inferences--of bows and arrows and heat treating--leave me with a new emotion--dismay--at the precocity of the ancient southern Africans. That's because these microliths and heat-treated lithics from Pinnacle Point derive from a part of the Pinnacle Point locality known at PP5-6, which is generally described as a rock shelter.

Pinnacle Point PP5-6. Tarpaulin covers the excavations. © Science/AAAS.

      In my earlier rantings I suggest that using Optically Stimulated Luminescence (OSL) age determinations drawn from buried cave sediments may be the culprit, artificially overestimating the age of these patently modern human assemblages. That's because there's really no way of knowing, a priori, whether or not an individual quartz sand grain had ever been exposed to the sun, much less for how long. [This, you'll remember, is a crucial assumption of the technique.] It's this uncertainty that causes OSL experts to undertake what appears to me to be a complex series of calculations and extrapolations designed to overcome the potential shortcomings of the technique. However, a rock shelter is a bit stickier. Presumably a rock shelter would be exposed to sunlight year in and year out, and thus you might imagine that any quartz grain that came to rest there had been exposed to sunlight long enough to have its 'clock' set to zero [unless, of course, that grain had been stripped from older deposits, redeposited in the rock shelter and immediately covered by sufficient material to preclude its being affected by the sunlight thereafter--like, perhaps, at night]. Now, after about a day and a half of off and on Googling I've been able to sight nothing written that describes the geomorphic history of PP5-6. Nevetheless, I have a hypothesis that will allow me at least some peace of mind. Given its proximity to a series of true caves at Pinnacle Point, and given its location at the edge of the escarpment that contains those caves, it seems highly likely that, while exposed today, the sediment accumulation at the site occurred inside a cave in which the roof and shoreward wall have subsequently collapsed and migrated down slope.
   So, unless I'm mistaken, I have no more reason to accept these early dates from the Pinnacle Point locality than I do the others from caves in South Africa. I know that the Very Serious Palaeoanthropologists like Curtis Marean will simply scoff at my scepticsm. Nevertheless, one can't help but wonder. And one day, perhaps, someone will try to directly date a piece of bone from one of those amazingly old stratigraphic units and Voila!
     I live in hope. No. Scratch that. As John Cleese's supine character in Clockwise moaned, 'It's not the despair...It's the hope.'

   
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Hold On to Your Hat!

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And We Wonder Why...

I'm convinced that people make the mistake of calling palaeontologists 'archaeologists' because there are two additional syllables in the word that refers to dinosaur hunters. Of course, ignorance of discipline-specific terminology [pejoratively referred to as jargon by some] is proof of nothing more than that the error is constantly being reinforced by those not acquainted with the difference.
     A case in point.

Archeologists uncover ancient mayfly with 'hitchhiker'

It's obvious from the title alone. This is going to be an article about insects in amber. Curiously, I was unable to find either the words 'archeology' or anything more specific than 'scientist' in the text of the article.
     I think this whole matter is what's known as a lost cause.

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Dang! Missed it!

When I wasn't looking, the 75,000th person took a peek at one of the articles on the Subversive Archaeologist. I think Queen Victoria was the only monarch who ever made it to the Diamond Jubilee. And I'm way younger. [And prettier.]

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It's "He Said, She Said" between Higham and Hublin: Whom Should We Believe About the Reality of a "Châtelperronian" Techno-complex at La Grotte du Renne, Arcy-sur-Cure and Saint-Césaire, France?

Whoa! That title's long enough to be the entire blurt. In fact, it could be the whole thing. After looking into the paper by Hublin et al. on the new dates and lithic refitting at La Grotte du Renne, Arcy-sur-Cure and Saint-Césaire (France), I'm no further ahead than I was before. The whole matter might easily be summed up by the metaphor 'He said, she said.'

The photo at left shows the Abbé Breuil and André Leroi-Gourhan at Arcy. You may remember that the two, although from different generations, were lions of palaeolithic archaeology in France for much of the twentieth century. Arcy-sur-Cure is of monumental importance for French archaeology [which may explain why Hublin and others are so keen to uphold the determinations of previous generations].  

     The matter at hand is whether or not the Neanderthals (Mousterian), after coming in contact with the modern humans (Proto-Aurignacian), began to fashion bone and antler into useful tools in emulation of the recently arrived interlopers. This is a big deal in palaeoanthropology, believe me.
     So, last year, when Higham et al. published 'Chronology of the Grotte du Renne (France) and implications for the context of ornaments and human remains within the Châtelperronian,' one thought that the question had been laid to rest.
     Nuh, uh. The other day, Hublin et al. [long-time supporters of the Neanderthals and the techniques and findings of earlier French archaeologists] published a response that, from my point of view is akin to a zombie, 'Radiocarbon dates from the Grotte du Renne and Saint-Césaire support a Neandertal origin for the Châtelperronian.'

In the vicinity of Arcy-sur-Cure (Yonne, France)

Not knowing really what to make of the technical bits, I set about looking at the results and ignoring what one camp said about the other's techniques [Hublin et al.'s discussion is not all that flattering to Higham et al.]. At first I thought it was just a matter of 'He Said, She Said,' and that we'd never be able to sort through the mess. Gradually I came to see what the two sets of results were really telling me. Here follows a rather untechnical treatment of two highly technical studies that are based on two highly untechnical tactics, only one of which adheres to the strategy of determining whether or not the Châtelperronian is real, or is in fact the reified construct that I and many others believe it to be. The other is altogether fallacious.

Various items that form the so-called Châtelperronian industry. 

He Said
Higham et al. hoped once and for all to put the wooden stake through the heart of the putative Châtelperronian. They selected a sample of 59 organic artifacts from above, within, and below the Châtelperronian levels at Arcy-sur-Cure (Yonne, France), a site with rich deposits from this time period. Of the 59, 19 contained too little preserved organic material to produce a date. The 40 that were left are suggestive of nothing else but that the artifacts in the Châtelperronian levels are a mixture of the earlier Mousterian occupation and that of the later, Proto-Aurignacian level.

She Said
Hublin et al. thought they could turn the tables on Higham et al. by adopting a different sampling technique, one that explicitly avoided dating the humanly modified bone, tooth, and antler artifacts. They say that those artifacts contain too little useable organic material and that they had all been subjected to a process of consolidation in which a coating of chemicals was used to keep the artifact from falling apart. Note that these artifacts are the crux of the debate, because the stone artifacts cannot be used either to date or to distinguish between the Mousterian and Proto-Aurignacian makers. So, Hublin et al. chose nondescript animal bone. They also produced 40 dates. Theirs, they say, are better.
     Not only do they finesse the issue through their sampling tactic, they also want us to accept the following. They re-dated the Saint-Césaire skeleton at 36,200 ± 750 BP. This, they argue, means that the Neanderthals lingered in Europe long enough to have been responsible for all of the Châtelperronian artifacts older than that. Of course, it also means that they could have been responsible for some of the Proto-Aurignacian, too, if Higham et al. happened to get those dates right. It also ignores recent findings from England that we arrived there at about 44,000 BP. Wow! We missed France altogether and headed straight for Mother England!  
     Technical arguments and innuendo aside, they furthermore aver that their better dates do not contain any anomalously young or old estimates, as do Higham et al. Ipso facto, presto-change-o, the Châtelperronian is REAL!!!!

Hold on a minit! First of all, let's get a picture in our minds of what the stratification at Arcy-sur-Cure is like. In the illustration below you see Hublin et al.'s rendition of the layers at Arcy.

A thing of beauty. No? Lovely, pristine, and colorful, too. But wait. In both papers, we see that samples are drawn from places with labels like 'Arcy Xb1 61.C7 (464) and 'Arcy Xb2 62.C9 (102)'. Hublin et al. only show the whole numbers, like IX and X. What's with the 'Xb1' and 'Xb2'? Here's what. In a 2006 paper by Bailey and Hublin [one and the same], the following stratigraphic section was reproduced.

There they are! The subdivisions. Oh! And look! The stratigraphic picture is a little different in this profile. Lots of wavy lenses. XIb is sandwiched inside XIa. Let's ask Harris of Harris Matrix fame how that's possible. And those dashed lines. You've all used 'em... 'Well, that must be the contact. It has to be there.' You know how it goes. If that's not a sign of archaeological wishful thinking, I'll eat another radioactive bullet. Ok. So Hublin et al. wanted to simplify the stratigraphic picture, 'cause, really, it's unimportant. What's important is that all of the dates in the Châtelperronian levels are where they oughta be. Just look at their OXCal drawing. All nicely ordered from oldest to youngest, as if they occurred in that way in the sedimentary column from which they were drawn
     Nothing could be further from the truth. They're all over the place. [Don't let the time scale at the bottom of the actual figure fool you. It's off by 5000 years.*] I've annotated Hublin et al.'s Figure 1 with the stratigraphic association and the correct dates at the bottom of the column. The first thing you'll notice is that, according to the illustration above, the youngest date is from the oldest level. And, you'll never guess. The oldest date is from the bottom of the younger level. Sandwiched in between are a hodge-podge of dates that have no internal consistency whatsoever. Moreover, I'll bet my Pirates of the Caribbean authentic Jack Sparrow tri-corner hat that the dates vary randomly with the presumed stratigraphic levels.

Embarrassing admission: the dates I've added are off by 5,000 years. 

What this tells me, and should tell you, is that this is just wrong. How can they argue that they have an internally consistent column of dates if they evidently don't? It's a mystery to me. But maybe this isn't important. After all, Hublin et al. clearly think this kind of topsy-turvey of different dates is insignificant. They'd rather berate Higham et al. for trying to date the actual artifacts!
     I'm not done yet. In the table below [of my own making, I might add] you see a bunch of numbers. They represent the youngest and oldest age estimate for a given level for each of the two studies. [For simplicity's sake I have used the lower end of the error margin for the youngest dates and the upper end for the oldest.] These, by the way, are calibrated dates.  So, they are BP.

Youngest and oldest dates by level for Hublin et al. and Higham et al. Note that Hublin et al.'s youngest dates for the Châtelperronian fit nicely into their range for the Proto-Aurignacian and their oldest dates fit perfectly into their Mousterian range. Hmmm.

Let's suppose for a moment that the Proto-Aurigancian level is an intact, unsullied stratigraphic unit [i.e. nothing disturbed the sediments such that they might be conned into moving downward in the column]. So much would need to be the case if Hublin et al.'s arguments are to stay afloat. If that's so, and even if we discount Higham et al.'s results [which Hublin et al. would want you to do], the French estimates for the Proto-Aurignacian level [modern human, remember] range between 29722 and 35020 BP. That means that Hublin et al.'s  three youngest dates for the Châtelperronian ALL fall within the range for the presumably pristine Proto-Aurignacian level VII!! Furthermore, TWO OF THE THREE of Hublin et al.'s oldest dates fall within the range of the [again, presumably] pristine Mousterian level XI. What's going on?
    What's going on is a systematic effort on the part of Hublin et al. to discredit Higham et al.'s results and to bamboozle the rest of us into accepting their claim that their dates from what they decided, a priori, were the Châtelperronian levels are internally consistent, and that therefore the Châtelperronian is a real entity and not the result of stratigraphic mixing.
    If that's not a circular argument, I'll eat a tun of foie gras.
    I'll have more to say at a later date. There's more to be said, believe me. After all, Higham et al. managed to estimate the Proto-Aurignacian dates in accord with Hublin et al. Why did they go wrong with the older stuff? Hmmm.

* I've since been disabused of my error in reading the scale in Figure 1, and apologize for any undeserved aspersions cast. I'm. Such. An. Idiot.
    
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