Sunday, 25 November 2012

Can We Talk? 'My ancestors, myself' by Jonathan Marks

Before I get started, please rid yourself of the expectation that I'm going after Jonathan Marks about his recent piece on Aeon, 'My ancestors, myself: Fossil genomics is opening new windows to the past. But the view through them isn't as clear as we like to think.' On the contrary. I fully agree with him...right up, that is, to the part where he characterizes the Neanderthals according to the same orthodox archaeological interpretations with which yours truly has a long-standing dispute. Jon can't be blamed for this. As a consumer of archaeological knowledge, he's more or less at the mercy of conventional wisdom. So, read on, s'il vous plait.

Illustration by Richard Wilkinson
Can we talk?
     A couple of days ago Jonathan Marks gave us much to ponder about our present understanding of Neanderthals, especially the recent genetic comparisons with modern humans. If I might be allowed to compress it into a sound-bite, Jon's* is an eloquent essay on the post-modern anthropological insight that, either when one is studying present-day humans, or our recent and fossil relatives, we need always to keep in mind the cultural 'baggage' that we bring to our investigations. In particular, he hopes to persuade us that biology, alone, is no measure of a fossil species. I couldn't agree more. I like to use the following example as a means of illustrating what's meant by this notion of one's 'stance,' 'background,' 'cultural baggage,' or however you want to put it. Ask yourself this question: 
What do you think lurks in the cultural and social background of neuroscientists who seek to find structures in the brains of males and females to 'explain' perceived differences in the behaviour of the sexes? Is it reasonable to suppose that these invesigators must have 'bought into' the idea that, e.g., 'girls' can't do math [but that boys can], or that 'boys' are inherently rambunctious [and girls are sugar and spice], or 'boys' are promiscuous [but 'girls' are chary]? 
I'll admit that unexamined presuppositions like these might not always be the reason for such scientific enquiries, but it would be an odd coincidence if they weren't. Jon Marks constructs his argument along these lines, to remind us that our background and experience will enter, more often than not unnoticed, into our deliberations on the ancestry of Homo sapiens, if we don't at least make an effort to examine our motives and beliefs from the outset.
     Jon makes a great number of very apt observations about the way the Neanderthals are treated in the popular imagination, and in the minds of anthropologists and geneticists. Drawing on recent revelations from genomics--that we share some of the same novel genes with the Neanderthals--he muses on what this might have meant about our relationship with them. Specifically, he asks whether or not the new, modern form of bipedal apes that appeared in Europe around 45 ka would have seen the congeneric Neanderthals as people like them. 
     And it is here that Jon and I diverge. Even though Jon's applying a set of thoroughly anthropological principles to a perennial question, I'm dismayed because his essay presents as 'fact' a picture of the Neanderthals that is, in aggregate, a mélange of what was, what might have been, what never was, and what could never have been. In other words, his 'take' on the Neanderthals may be informed by an unknown number of what one day could well turn out to have been archaeological myths. In that, Jon confidently represents the Neanderthals in a way that undermines his own argument.
     He thus applies a culturally constructed 'skin' on the anatomical and biological Neanderthal that draws on the orthodoxy of interpretation, without acknowledging that the 'skin' comprises what are at best provisional findings as to how they behaved and what they were capable of in comparison to modern humans. [I realize that my own 'take' on the Neanderthal archaeological record isn't mainstream, and most of my peers would dismiss my quarrel with the mainstream as unreasonable. Nevertheless, I have a legitimate dispute with archaeological orthodoxy, and thus my alternative interpretation of record leads me to be cautious, at a minimum, regarding the stories told about the inhabitants of Europe before the time of modern humans.] Jon introduces his Neanderthals in this way
Their bones show lots of evidence of healed fractures; their teeth are worn as if they were being used as tools; and their muscular development was strikingly asymmetrical. Whatever they did, it was rigorous, it was cultural and it was humane (at least, they took care of friends with broken arms better than chimpanzees do). They often buried their dead, but never sent any grave goods along with the deceased for the journey. They didn’t build anything, or at least anything lasting or recognisable. If they decorated themselves, or had any aesthetic sensibility at all, it was rudimentary at best. 
Jon is unequivocal in his conviction that the Neanderthals were 'cultural' and 'humane.' But how does he make such claims with such certainty?
Shanidar 1 Neanderthal humeri. Individual suffered a crushing
blow to the left temporal, probably leading to blindness and
abnormal development of the right side (shown at left). 
The distal fracture is healed. Researchers conclude that the individual
must have been nursed to have survived such injuries. (Souce: Smithsonian)

Sandhill crane humerus. Individual rescued after months of
flightlessness. X-ray shows a healed, overlapping fracture.
(Source: Wildlife Rehabilitation Center of Minnesota)
In support of this he first mentions healed fractures. These tell him the stricken Neanderthal's friends and relatives must have taken care of him for a time after the injury. Jon's referring to the Shanidar 1 remains. This disappoints me, because, quite unreflexively, he is accepting, carte blanche, a thoroughly ethnocentric interpretation of the skeletal evidence--i.e. that to survive such injuries, this individual must have been nursed by relatives and companions. Dettwyler, in the early 90s, pointed out to us that, ethnographically there is a great deal of variability in the way the injured are treated, such that the conventional wisdom about Shanidar 1 is, at best, a sufficient, but not necessary explanation.   
     Besides, there are plenty of examples from the non-human world demonstrating that, even in the absence of palliative care, animals are capable of recovering from injuries that most of us would assume to have been mortal [just as those of Shanidar 1], either immediately, or over time because of reduced mobility and ability to acquire nourishment. You might have thought that a bird with a broken wing would surely perish. Not so. The X-ray at left illustrates a healing fracture of a bird's humerus. It belongs to a Sandhill crane. They inhabit wetlands, and are stealthy hunters. But their natural history includes plenty of flying about. The X-rayed crane apparently survived for months before the Wildlife Rehabilitation Center of Minnesota rescued it. Presumably it could have survived for many more. So, you see [I might be wagging my finger a bit just now], consumers of archaeological findings must be very careful--those inferences might simply be in error.   
     As for teeth worn from using them as tools, there is broad morphological similarity between the dental attrition visible in Neanderthals and many ethnographic human groups. However, no one, as far as I know, is able, unequivocally, to argue that the two are the result of identical processes.
     I think you can probably guess the eventual outcome of these comments on Jon's essay. But don't stop here! Immediately, Jon brings up another very tenuous claim about Neanderthals--that they buried their dead. [But, don't kid yourself. None of this can be treated as fact,  which you'd know if you've been paying attention. However, if you're coming fresh to this material, I could recommend a one or two articles that might make you think twice about the 'fact' of Neanderthal burial. Hell! It made Harold Dibble think twice, and he and his colleagues eventually found good evidence that in the case of an infant Neanderthal long believed to have been purposefully buried, the evidence is, at best, equivocal. And, some would have it, that in those cases, the argument for purposive, mindful behaviour, is *cough* gravely weakened.] I find it odd that he states they built nothing that lasted. Although I have to agree, the absence of such evidence is, you'll forgive me, not evidence of absence. They could have been building log cabins, for heaven's sake, which leave no post holes, and which surely would have decomposed over the millenia. Moreover, a number of archaeologists have treated their findings as evidence of structures--the mammoth bones at Moldova, for example, or the imprint of wood in travertine in the Abric Romani rock shelter. I find Jon's assertion here to be curious, to say the least. So be it.
     Next, he turns to a discussion of how present-day humans [that would be you and me] might have viewed the earliest moderns in Europe, as a way of illustrating his thesis that our cultural baggage gets in the way of a more inclusive 'take' on the Neanderthals. He suggests that those modern humans 
also led rigorous lives almost unimaginably different from your own. For most of their existence, they lived without writing or the wheel, without crops or tame animals, without metal, matches, or even fish-hooks. If you were transported into their world, you wouldn’t last five minutes without them to help and teach you. We have to realise that they were in fact not much like us at all. 
True enough. They may not have been very much like us. But neither are New Guinea highlanders. His point here is that regardless of the specifics of the difference, whether one is talking about Neanderthals or the first moderns in Europe, present-day humans like you and I would have experienced them both as exotic. However, this comparison cannot hold up against the archaeological record, nor that of the ethnographic. In contrast to the traces Neanderthals have left behind [for upwards of 250 kyr], throughout Europe and Asia from about 45 ka modern humans left behind an archaeological record that is readily recognizable to us. That record includes behaviours that in some cases persisted into the twentieth century in many parts of the world [and in remote places continues to this day]. Not so the Neanderthals.
     That same archaeological record shows us that the modern skeletal form of Homo, which emerged briefly from Africa nearly 100 ka, conducted itself in an identical manner to that of their Neanderthal contemporaries--i.e. unlike anything that modern humans have been capable of producing since about 45 ka. Compared to them, we would undoubtedly have recognized as human the first people like us in Europe, and in much the same way we have viewed ethnographic peoples--who're often very different from westerners. I don't think the same can be said for the Neanderthals without straining credulity. And so, when Jon writes 
there is no reason to think that people 100,000 years ago would have seen you and thought, ‘Hey, there goes another one of us forehead-and-chin guys’. More likely, they would have regarded you as at least as alien as a Neanderthal, based on the criteria we generally use for such assessments: what you’re wearing, how you’re groomed, whether you can communicate sensibly and can behave properly [emphasis mine]. 
Quite simply, there's no unequivocal evidence that either the modern form at 100 kyr ago, or the Neanderthals throughout almost 250 kyr ever 'thought' at all. Thinking, you see, may be unique to the modern humans that spread throughout the old world in the blink of an eye around 45 ka. Our experience of the world, beyond the instinctual, is little else but thought. On present understanding, we simply can't assume that those relations at 100 ka were capable of communicating 'sensibly' or behaving 'properly.' 
     Jon worries that our view of the Neanderthals is based purely on the physical differences between us. But, as I hope I've convinced you, physical differences are not the only yardstick that we use to classify or characterize the similarities and differences between the two. He is correct when he says
we tend to use cultural criteria to sort who belongs where. Do you really associate only with people whose head shapes resemble yours? Of course not; you associate with people who tend to speak like you, dress like you, and share your general interests. 
And, if I might add, people that look like you. Once again, we're being asked to accept the inference that Neanderthals spoke, dressed, and had anything like 'general interests.' They may well have not.
     Here is where Jon paints himself into a corner. He's trying to tell us that the way we see the Neanderthals is coloured by our preceptions, much in the way a bigot is disposed to treat another group as inferior or worse. Yet, he's asking us to accept that the Neanderthals are human, and for that reason we should be more reflexive and cut them some slack. As he puts it
we make sense of the Neanderthals by seeing them in distinctively cultural ways. We imagine that, because we scientists juxtapose ourselves against them anatomically, people in the Late Pleistocene must have done the same, although that goes against what we know of modern human behavior. 
As I've tried to point out in this blurt, in his acceptance of mainstream inferences about the Neanderthals, Jon is also 'seeing them in distinctly cultural ways,' equally unexamined, but different from those he's arguing against. His view of Neanderthals is every bit as culturally constructed as that of those he seeks to enlighten in this essay. 
     As I said at the outset, I have no quarrel with Jon. I hope it's clear that I've used his essay as a stepping-off point. Sure, I've found what I believe to be flaws in 'My ancestors, myself.' But those flaws simply convince me that Jon is an unwitting victim of what is a collection of archaeological myths of unknown proportions. 
     Well, I hope you've enjoyed this side-trip to the biological anthropological view of the Neanderthals. And I very much thank you for visiting us.
*I sincerely hope that using his given name's diminutive I'm not being presumptuous. He and I have a facebook acquaintance, but we have corresponded within that. So, here's hoping. I just don't feel right referring to him as 'the author,' or 'Marks.'

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]. Oh, and you can always put me on your web page's blogroll! By the way, I get a small commission for anything you purchase from if you go there by clicking through from this site. 

Saturday, 24 November 2012

I'm Workin' On it!

Jonathan Marks published a brilliant essay the other day, called 'My ancestors, myself' alongside which was this  cartoon worthy of Whistler, himself. I'm hard at work putting a subversive archaeologist's spin on it. Bet you can't guess what that means...  
Illustration by Richard Wilkinson

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]. Oh, and you can always put me on your web page's blogroll! By the way, I get a small commission for anything you purchase from if you go there by clicking through from this site. 

Friday, 23 November 2012

Penny Spikins, Handaxes, and the 'Trustworthy' H. ergaster: The Annual Subversive Archaeologist Thanksgiving Day Turkey Shoot

A number of colleagues have commented that it gave the appearance of an argument for inherent violence among the great apes, especially humans. That canard was presumed dead and buried—in absentia—in the 1970s.

Those wishing to see the Subversive Archaeologist's plucky gaggle of remarks with respect to Penny Spikins's theory of the meaning of handaxe shape are welcome to click over to the original content at

Thank you for visiting, and for your cooperation.

So long!

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]. Oh, and you can always put me on your web page's blogroll! By the way, I get a small commission for anything you purchase from if you go there by clicking through from this site. 

Alice's Restaurant Massacre a Must-Hear Experience on the American Thanksgiving.

This is an unforgettable experience, even if you've heard it thirty times. If this is your first, remember that this was 1967.

Anti-Vietnam War 'sit-in' at the Pentagon 1967.

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]. Oh, and you can always put me on your web page's blogroll! By the way, I get a small commission for anything you purchase from if you go there by clicking through from this site. 

Wednesday, 21 November 2012

Part One of [Probably] Many: What Does It Mean To Be A Subversive Archaeologist?

I'm betting most people are surprised to hear the word 'subversive' spoken in the same breath as 'archaeologist.' After all, subversives work against evil governments or brutal oppressors, not university subjects. So, what's up? 'Subversive archaeologist' seems almost oxymoronic. You're getting close. Oxymoron is from the Greek words for 'sharp' and 'foolish.' In archaeology, as in life, one is either 'sharp' or 'foolish,' and from my perspective, there's no in-between. 
     This blurt is about the distance between getting it right and makin' stuff up, between a good theory and a bad myth, a well-warranted inference and a mistaken one. Whoa! Wait a minit! Inference? Don't people infer stuff from partial information? Exactly. But, that doesn't sound like science to me. Well, that's science, and in this case, archaeology, all over.
     It's not up to me to comment on the way knowledge is made in the other sciences. But in archaeology, artifacts don't come out of the ground with labels on 'em. Believe me. I've spent years on my hands and knees, scraping back time, in search of a long-forgotten past. And you don't 'discover' the past, you make it up. Sort of.
     Archaeologists dig to find traces of the past. And those traces don't speak for themselves. In a very real way, archaeologists give those things meaning. We try to get it 'right.' We don't try to pull the wool over your eyes. But much of the time the bits we find are ambiguous, and sometimes we don't find that out until years later. That's how archaeological myths are born. The job of a subversive archaeologist is to reveal the ambiguity, and in that way to help in dismantling both the myth and the web of mistaken beliefs that it spawned down through the years.
     The work of a subversive isn't popular with the 'government' of archaeology--the hierarchy of Professors and Directors and such. And they let you know it, in various ways, overt and insidious. So, being a subversive archaeologist, like a lot of subversives, is almost like being in an armed conflict. There are skirmishes, strategies, tactics, logistics, even outright war in archaeology. And it's all because of the tension between 'getting it right' and getting it embarrassingly wrong. Come with me and I'll show you worlds you never imagined [there's a lot of that in archaeology], and ideas you hoped you'd never have to grapple with.
     No worries. I'll talk you down. We'll have fun. Honest.
     Maybe an example will help. You've probably heard of the Piltdown Man, once considered a fossil ancestor. You may even have heard that it was a hoax. It was. But thanks to the guile of the hoaxster and the gullibility of most archaeologists of the time, it's reality was unquestioned for decades. That's because the people who study our fossil relatives decided that it was a proper piece of the jigsaw puzzle of human evolution. That expectation and the acceptance of Piltdown Man held back real scientific progress, real knowledge, for nearly forty years.
     Piltdown is still a small country crossroads in southeastern England. Too far from London to be built up. It had or has a gravel pit. In nineteenth and early twentieth-century England that meant one thing--there be fossils here.
The Piltdown Pub, Piltdown, East Sussex, England. (From Wikipedia. This image was taken from the Geograph project collection. See this photograph's page on the Geograph website for the photographer's contact details. The copyright on this image is owned by Nigel Freeman and is licensed for reuse under the Creative Commons Attribution-ShareAlike 2.0 license.)
Group portrait by John Cooke, 1915.
Back row (from left): F O Barlow, G Elliot Smith,
Charles Dawson, Arthur Smith Woodward.
Front row: A S Underwood, Arthur Keith,
W P Pycraft, and Sir Ray Lankester.
To make a long story short, in 1912 Charles Dawson came across a skull and jawbone that looked to him as if it was the 'missing link' between the apes and humans. [For the time being we'll ignore the specious distinction between 'ape' and 'human,' since we're all apes. Humans just happen to be the only apes that habitually walk upright on their hind legs--A.K.A. obligate bipeds.] The Piltdown specimen was readily accepted because it had a modern sized skull and teeth and jaws like the other apes [the lower jaw was actually that of an orangutan, with its long canines literally filed down]. This all fit perfectly with conventional wisdom of the time--that the essential difference between apes and humans was our big brains, and that the 'missing link' would have a big brain and [most likely] a body like an ape. Therefore, the Piltdown specimen 'fit' with what scholars expected to find, and what the hoaxster knew they'd be ready to accept. Unfortunately the strength of scientific orthodoxy meant that for nearly forty years no one seriously questioned the find. Well, almost nobody.
The 'Taung Child' (Australopithecus africanus).
South African anatomist and anthropologist Raymond Dart knew differently. But for most of those forty years he faced a sceptical discipline that pooh-poohed his work. You see, in 1924 Dart had discovered a tiny skull of a very ancient, infant ape. It had a little ape brain, and big ape canine teeth, just as you'd expect in an ape. But it had one huge difference. The place where the spinal cord emerges from the skull wasn't near the back of the skull--the normal place for apes--it was instead almost directly underneath it. That's where yours is, and mine, too [though some have called me a little monkey now and then for my *clears throat* efforts, I'm still human when it comes to the big hole in my head. That's funny. Having a big hole in my head is actually something people have accused me of. But they must have been thinking of my anatomy, and not my intellect. Maybe not. Actually, that hole in our heads has a scientific name--foramen magnum--which is Latin for *almost under his breath* 'big hole.' Look. I can't help it if eighteenth-century European scientists thought it'd be cool to use Latin for scientific discourse, most likely to get past the problem of having about a million languages in the Europe of the time. Besides, doesn't foramen magnum sound more learnéd than 'big hole'?]
Raymond Dart
     So, Dart had this infant ape that would most likely have walked upright as an adult. [He knew its age because it still had its baby teeth. Yes, chimps and gorillas and people all have baby teeth. But as far as I know only humans have the tooth fairy...] ] That it walked like us was a perfectly plausible inference. Having the foramen magnum underneath the skull, Dart's new species must have evolved to have a bipedal gait like ours. This was a bold argument, since he had no fossil bones from the rest of the body to compare with ours. But it was a brilliant induction, just the same. [Yes, yes, I meant to say induction. Sherlock Holmes was actually mistaken in his use of the word 'deduction' to describe his characteristic brand of reasoning. Math problems involve deduction. 'This is a three. This is a two. What must you subtract from three to get two.' There's only one possible answer. That's what's known as a deduction. Rather like what happens to your pay when the tax is taken out! Doh! Focus, Rob. Most things that we know about the real world are inductions from insufficient observations. Think about it. We don't actually know that, after we step off the curb, a car isn't going to appear out of nowhere and wipe us off the face of the planet. In the love of truth--the original meaning of 'philosophy'--we really can't know such things. There'll always be a possibility, however remote, that something we don't expect is gonna happen, regardless of the evidence from long experience. But, even though we can't be certain that we're gonna be wiped out when we cross an empty roadway, we can be comforted by the fact that, so far, it's never happened. Moreover, we have no reason to think that it might--unless, of course, you believe that the movie Back to the Future was a documentary. But, don't take my word for it! Read anything on informal logic. You'll see. I'm right!]
     So, there was Dart. A [literally] small man, with a small, unique fossil skull, living in a small backwater of the British Empire, trying to subvert [in the eyes of the scientific establishment] the conventional wisdom of the English scientific aristocracy. Fat chance. So, Dart labored mostly in obscurity for decades, accumulating more fossils. Over time, he and Robert Broom found more evidence that the English scientists were mistaken, and that the Piltdown fossil MUST be a fake. I don't need to bore you with the details of how that fake was exposed. It's all there in books by people much more steeped in the minutiae of Piltdown hoaxery. Read them.]
     Wow! As examples go, that was a long one, eh? Unfortunately, that's one of the downsides of being a subversive. Almost always the effort it takes to unravel a bad inference is way more than it took to make it in the first place. The reasons for that will, I hope, become clear to you as you work your way through future blurts on this and other matters. [Whaddaya mean you don't wanna hafta work while you read? You always have to work when you read...unless, that is, you believe everything you read, or hear--like the people who watch Fox News. I suspect you don't, otherwise you wouldn't have clicked on a link to The Subversive Archaeologist. You're ready. I know you are. And I know you can 'do the work.']
     If you're up for more, I sure am. Let's go, shall we?

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 if you go there by clicking through from this site. 

Tuesday, 20 November 2012

Disappointed? You Must Have Missed the Subversive Archaeologist's Weekend Double-Header on the Latest From Kathu Pan 1.

This message is dead simple.
Part One
Part Two
Thank you for your kind attention.
*bows* Exits stage right.

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 if you go there by clicking through from this site. 

Sunday, 18 November 2012

Part Two of There Ya Go Again! The Putative 500,000-Year-Old Hafted Spear Points From Kathu Pan 1 VS Reality: What's the DIF?

In the previous blurt I did what I could to point out the problems with the putative spear point OSL dates from Kathu Pan 1. As promised, I'm now going to address the primary claim of Wilkins et al. 2012, that some of Kathu Pan 1's pointy stone artifacts bear evidence of having been used as the business end of a composite armature, a projectile in fact, specifically, a spear. Let's have a closer look at their argument. Shall we?
From 'Evidence for Early Hafted Hunting Technology,' Jayne Wilkins, Benjamin J. Schoville, Kyle S. Brown, and Michael Chazan. Science 338, 942-946, 2012; DOI: 10.1126/science.1227608
Wilkins et al. begin with a qualified statement of conventional wisdom regarding bipedal apes and sharp, pointy rocks.
Because Middle Stone Age (MSA) hominins and Neandertals probably both had stone-tipped hunting equipment, it is possible that H. heidelbergensis also possessed this form of technology. [Frankly, I'm surprised to see the word 'probably' in this passage. Perhaps the Subversive Archaeologist doth not protest too much, after all, and some of the cautionary tales I've spun are taking root. Then again, maybe not.]
So, the authors start from the presumption that hafted spears were commonplace in the Middle Palaeolithic. Why not, then, suppose that the last common ancestor of us and them was also capable of putting two and two together, and making a spear? No reason not to, I guess, unless you're suggesting that there's a gene that codes for spear-making! Never mind. The authors feel that they must say something of the kind, since they're getting ready to tell us about stone artifacts that they believe are contemporary with H. heidelbergensis in Europe.
     As you may have read in my previous post, the early dates on the alleged spear points are irrelevant. To summarize. The artifacts in question derived from a spring vent that blew threw Stratum 4 at Kathu Pan 1 some time before the upper reaches of Stratum 4 were stripped away by an erosional process [most likely wind] and before Stratum 3 was laid down. You'll remember that the very early dates of ~500 ka were estimates based on quartz grains drawn from the spring vent. And, of course you'll have retained the knowledge that there is no way on God's green earth to know whether or not the dated sand and the artifacts are in association. So, feel free to throw out the dates. It's astonishing that the authors didn't even flinch at the context of this collection of Kathu Pan 1 booty. And, as you'll see, the rest of the paper is as confusing a a House of Mirrors at an amusement park.
   So, from what amounts to a lag deposit of stone artifacts and faunal remains found in a spring vent of unknown age, the authors recovered 210 pointy stone artifacts like the ones shown above. Of those, a mere 29 have at least one 'Diagnostic Impact Fracture' (DIF). These are of two kinds: step termination fractures (see below, item 1), occurring when a bending force is applied to the flake margin, whether that be where the two lateral margins converge (i.e. the 'tip') or on the margins proper. The other DIF is a burin removal [per se], which is a flake the axis of which follows a lateral margin for some distance, and terminates  in a step or a hinge fracture or simply feathers out. The first kind of DIF, the step termination, can occur anywhere on a flake margin where the thickness and brittleness are such that a small flake can be removed by a force applied from either the dorsal or the ventral direction. By definition, where pointy artifacts are concerned, the burin fracture DIF can only occur at the tip. Such forces can and do occur at the tip and along the edges of true projectile points. However, other, post-depositional processes are capable of producing such modification, including trampling by all sorts of large mammals, from bipedal apes right on up to elephants.

What's the DIF? Step terminating fractures and burination. From Villa et al. 2010
The authors are quick to admit that processes other than projectile impact can and do create such scars. Nevertheless, they are equally quick to rule those out, first by argument from authority. They state that 'Similar-appearing fractures can result from post-depositional processes, although their frequency within assemblages is low.' In dismissing post-depositional processes in this fashion and for this reason, they cite one paper, by Justin Pargeter, who undertook trampling experiments to see if pressing down on some home-made flakes in an artificial substrate was capable of creating DIFs. His results are tabulated below. Those that have been crossed out are not considered DIFs, per se.
Table 1. Detailed macrofracture results from the trampling and knapping assemblages. (CT: cattle trampling; HT: human trampling. D: dolerite; Mq: milky quartz; Qtz: quartzite; BF: bifacial; UF: unifacial. Note that one tool may have more than one fracture on it). From Pargeter 2011.
     Pargeter attempted to control for the density of the substrate, and to account for differences in the strain resistance from one raw material to the next. However his efforts are a weak hook on which to hang Wilkins et al.'s sweeping dismissal of post-depositional processes. Looking at Pargeters table of results, above, you see that very few DIFs were produced during both the cattle and the human trampling parts of the experiment. He found that step terminating fractures were less common, although any comparison between single-digit results ends up inflating the differences. All up, out of 450 pieces over four trials using cattle and barefoot people, only four [count 'em, 4] flakes were found with step terminating fractures. Burination occurred on a slightly larger number, five.
     Importantly, DIFs occurred on amorphous flakes as well as pointy ones. It is for that reason, I suspect, that Pargeter concludes with the following statement.
[Diagnostic impact] fractures should only be considered diagnostic when found on pieces that are morphologically potential hunting weapon components or together with other use-wear traces.
In other words, they're not DIFs unless they occur on pointy stones. You can forget about DIFs that occur on amorphous flakes, because, clearly, they wouldn't have been useful for piercing hide and flesh. So. To paraphrase, it's random and inconsequential if the flake's amorphous. It's okay to think that pointy rocks with DIFs are spear points. Does this sound a bit suspicious to you, too?
     Albeit Pargeter's experiments were carried out in good faith, their shortcomings aren't trivial. For example, we know that substrate density will have a bearing on damage from trampling--for example, between sand and bedrock. Every kind of substrate in between sand and rock will yield a different result, as, moreover, would the size of the animal doing the trampling. Presumably giraffes, rhinos, and elephants would be capable of inflicting more damage to all sizes and shapes of flakes than cows or people. In the case of Kathu Pan, one can imagine that the water-seeking animals that congregated when there was standing water wouldn't have been restricted to people and cows [or gnus, for that matter]. Nevertheless, Wilkins et al. think it's quite all right to play down the role of trampling on the basis of Pargeter's single experimental effort. This, as much as anything, gives lie to the remainder of Wilkins et al.'s paper.
     Following their near-effortless dismissal of post-depositional processes, Wilkins et al. report on their own experiment, to demonstrate the kinds of modifications that can occur when a pointy bit of rock is thrust with force into a small dead animal (see previous discussion for a graphical representation of these experiments). In that experiment, 106 trials were successful in penetrating a dead springbok. And how many DIFs resulted from 106 penetrations? A total of 9 points incurred DIFs (i.e. in about 8.5% of the total of 106 trials). So, you gotta hand it to the authors, the experiment was successful in producing DIFs by spearing a dead wild animal, despite the small percentage that displayed damage characteristic of spearing something. Those same 106 trials produced 5 points that suffered 'crushing' (i.e. 5% of the trials), which one must presume occurred at the distal tip. Fully 16 times out of 106 the experimental points suffered no damage (i.e. 15%). There were 2 snap fractures (i.e. about 2% of the trials). The residual trials, those which resulted in no notable outcome, make up the remaining 70%. It's also satisfying to note that their hafts failed 12 times (i.e. in about 11% of the trials). [Bites tongue, blood drips from corner of mouth. If you've ever looked at the butt/proximal end of a great many Mousterian points, you'll know that they're practically unhaftable--at least compared with the bificially thinned sort that modern humans produce whenever they want to haft something.]
     Now, as most of us are aware, replicative experiments demonstrate that a phenomenon can occur as a result of a particular set of actions. Nevertheless, they do nothing other than to suggest the means by which that phenomenon might occur. It's a hypothesis. A starting place. Sufficient to explain the phenomenon of interest, but by no means necessary. Thus, while great fun, the authors' experimental results are patently inconclusive, and oddly have very little bearing on their thesis. In addition, no amount of statistical tap-dancing can replace the kind of contextual evidence that would readily indicate the use they propose for such artifacts--a point embedded in an animal bone, for example, or, at a minimum, one associated with the remains of a carcass in an unequivocal manner.
     True, Wilkins et al. did find the KP1 points in association with animal bones. But, as I pointed out in my last outing, those items almost certainly came together as the result of post-depositional processes, and there can be no no way of knowing if the bones and stones were in association when the animals died or the stone points were discarded or lost. In this, I have to say, the authors' naïvete is breathtaking.
     Perhaps knowing that their arguments were thin, they conduct one further analysis. They decide to look at plain old damage, rather than DIFs, as a means of diagnosing spear points from cutting tools. Apparently, in addition to the damage categories discussed above, the authors found a considerable amount of simple 'edge damage' on their experimental pointed flakes. Here, they think, is a means of getting at the function of the KP1 points without even bothering with DIFs (which, you'll remember, were meant to be the diagnostic damage that sorts mere flakes from projectile points. Their analysis gets weirder by the minute.
... we recorded the macroscopic edge damage that was evident on all complete points... . Edge damage was more frequent at point tips than along point edges, and distributions were similar between left and right sides (Fig. 4A [reproduced further down]).
     Taphonomic processes can be ruled out as the sole source of damage on the KP1 points. Post-patination scars, which are easily identified ... [see below], reflect damage not related to use of the points and occur as frequently on point edges as point tips (Fig. 4B). In aggregate, the damage along the dorsal surface of the KP1 points was similar to the distributions of post-patination scars … whereas the damage along the ventral surface was different... Therefore, we focused on the ventral edge damage to test hypotheses about the function of KP1 points.
From Wilkins et al. 2012
From the look of the chip indicated in D, above, the 'post-patination' scars could easily have been made yesterday, the result of trowel trauma or the banging around that the artifacts must have experienced as the spring was bubbling through Stratum 4 at some unknown time in the past. And, is it just me? Or, do the authors plain fail to adequately explain why they focussed on ventral damage? It sounds to me as if they're saying, 'There's no differences on the dorsal surface that'll allow us to distinguish between natural and artificial edge damage. However, we see differences on the other surface that do, sort of, therefore we'll only include the ventral damage in our analysis.' Huh? I know. We should just write them off right here. But, whadda ya say we give 'em the benefit of the doubt for now.

The illustration above depicts ventral edge damage to 106 of the loverly, pointy flakes--the complete KP1 points. Columns A and B are meant to show us that there is a 'real' difference between the locations of pre-patination edge damage (A) and those that occurred post patination (B). The authors recorded an extraordinary amount of damage on the KP1 points--an average of 38 scars per flake! The total of 1,973 in A are considered the result of use, and the 2,145 in B are said to be 'post-patination' [or, irrelevant to their analysis]. Notice that in A, a greater degree of use damage occurs distally than either the post-patination damage (B) or that of the presumed cutting tools from Pinnacle Point 13B.
     The authors favourably compare the degree of distal damage between KP1 points and that occurring on their 32 experimental stone points. They see this as proxy evidence that the KP1 points were used for thrusting into live hide and flesh. But, in fact, the experimental flakes sustained an average of only 21 edge-damage scars each. This is no doubt significantly different, statistically speaking, from what the KP1 points experienced in non-post-patination damage. If we are to accept that the spearing experiment is a proxy for what the KP1 points went through during their use-lives, the difference between the two samples in numbers of edge damage events suggests the real possibility that the 17 additional scars suffered by each KP1 points may indeed have been post-depositional, but pre-patination, something that the authors never consider. Instead, the authors seem very keen to focus on the predominance of damage to the distal tip as a means of diagnosing a spear point.
     In all of this focus on edge damage to the exclusion of DIFs, the authors make no mention of the type of scarring--i.e. the morphologies--of the edge damage. You'd have thought that, if one class of damage were qualitatively different from the other there might be more reason to suppose that the differences were due to the different functions for which the points were intended. Especially curious is that the authors make no mention of the most likely reason, in a physical, mechanical sense, for both a qualitative and quantitative difference between edge damage on the dorsal surfaces of the KP1 points and that visited on the ventral surface. I'll explain.
     Think of the cross section of the vast majority of MSA (Middle Palaeolithic) unifacial lithic flakes, which is how the authors describe their KP1 points. Those shown below are some 'blades' from Qesem Cave. Notice the ventral surfaces--the smoothly curved lower sides in the cross sections of examples 2 through 10. The ventral surfaces of these flakes would naturally be much more susceptible to edge damage in comparison to the dorsal side. That's because of the additional mass on the dorsal side, which provides a natural buttress against bending force. Ask any knapper. A much greater force would be required to remove a flake from the dorsal surfaces of any one of the examples.
Notice how the dorsal surface is buttressed by the dorsal mass relative to the ventral. From Shimelmitz, Barkai, and Gopher 2011.
With this in mind, one is tempted to ask, 'Other than the authors' preference to view their data in whatever way they choose, why should we accept as a given that the thousands of scars inflicted 'post-patination' were the result of a completely different set of processes than those scars that they say are the result of use?'
     By now you should be as suspicious as I am about the veracity of Wilkins et al.'s claim to have found evidence of hafting and use of pointy rocks as projectile points. After all, a litany of shortcomings attends this paper. First, they have failed to accurately date the finds. Second, they have failed to imagine a wide enough range of possible sources of damage. Third, they have failed to take into account the greater natural susceptibility of ventral surfaces to incidental chipping compared to that of the dorsal. Fourth, they have failed to give a good reason as to why they didn't include dorsal damage in their calculations, other than to aver that dorsal damage wasn't diagnostic or otherwise helpful. But, on what grounds, one wonders? There are no data provided. I believe strongly that we should be allowed to judge for ourselves on this point, yet we're given no help whatsoever by the authors.
     Once again I'm forced to say, as I did relative to Wilkins's earlier article on the putative 'blade industry' at Kathu Pan 1, that the data presented are inadequate to support this latest, even more spectacular claim to have found evidence for composite tools deep in the Middle Pleistocene of southern Africa. This is going to be my last word on the subject. Promise.
     Sorry. Can't resist. One more word. I find it sobering that the Science referees failed to notice even one of this paper's methodological and analytical shortcomings. But then, I guess we should be getting used to that, by now.

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Friday, 16 November 2012

There Ya Go Again! Part One--The Putative 500,000-Year-Old Hafted Spear Points From Kathu Pan 1 VS Reality: What's the DIF?

It's now officially an international media feeding frenzy. -  Stone-tipped spears used by human hunters much earlier in time
National Geographic -  Stone Spear Tips Surprisingly Old—"Like Finding iPods in Ancient Rome"
Science News - Oldest examples of hunting weapon uncovered in South Africa
New Scientist - First stone-tipped spear thrown earlier than thought
Daily Mail - The birth of weapons: Researchers discover man began hunting with stone ...
Voice of America - Archeologists Identify Oldest Spear Tips
Scientific American - Human Ancestors Made Deadly Stone-Tipped Spears 500000 Years Ago
Christain Science Monitor - Gone spear hunting: Ancestors used stone spear tips 500000 years ago
Times of India - Man began spear-hunting 200000 years earlier than believed
U.P.I. - Stone-tipped weapons older than thought
Vancouver Sun - Scientists spear animals to make point [my home-town newspaper. *sniff*]
China Post - Early human beings used stone spear points at least 500000 years ago: experts
Windsor Star - Spear study gets to the point
The Independent - Prehistoric arms race started earlier than previously thought
The Daily Telegraph - Man hunted with spears half a million years ago
News 24 - SA spear tip made by earlier ancestor
The Seattle Times - Prehistoric man became deadlier earlier than previously thought - Stone Spear Tips Suggest Weapons Were Developed Much Earlier Than Previously Thought
Science News - Archaeologists Identify Oldest Spear Points: Used in Hunting Half-Million Years Ago
Business Week (!) - Prehistoric Man Was Deadlier Earlier Than Once Thought - Study: Stone spear tip made by earlier ancestor
From Wilkins et al. 2012
This is beginning to feel like one of those squirmily popular horror series like Hallowe'en. You know? Freddie of the long fingernail knives. A tip o' the hat to Physorg for pointing us in the the direction of the November 16 print edition of Science, where one finds this:
'Evidence for Early Hafted Hunting Technology,' Jayne Wilkins, Benjamin J. Schoville, Kyle S. Brown, and Michael Chazan. Science 338, 942-946, 2012; DOI: 10.1126/science.1227608
Yes, sports fans, the same Jayne Wilkins who gave the Subversive Archaeologist fits a while back [here, herehere, and here] with her claim of a 'blade industry' at Kathu Pan 1 in South Africa. It's also the same Kyle Brown who was the lead author on the Pinnacle Point microliths and ancient heat-treating of lithic raw material. [South African archaeology is obviously a closely knit community.] These latest claims from Kathu Pan 1 are made for stone tools recovered from the same site as the earlier 'blade industry,' an infilled sinkhole, or doline. This time around, some pointy artifacts with step fractures on the distal (pointy) end and huge proximal (butt) ends are claimed to be evidence for, as the title would suggest, composite tools. And, once again, the claim is made for a VERY early date, and I quote '~500 ka, coeval with H. heidelbergensis [or H. antercessor, if you prefer].'
     I hope you'll forgive what will undoubtedly end up being a very long blurt this time around. It's dead necessary. If your Subversive Archaeologist is going to spot shortcomings that undermine the arguments made in a paper like this, he's going to have to spend way more time, and marshall ten times the breadth of expertise than did the referees. And, remember, these are Science referees. There're no flies on them [at least in the opinion of the Science editor(s)]! So, this is not a task that lends itself to brevity.

Vicinity of Kathu Pan 1 (from Wilkins et al. 2012). 
The authors are well aware that such claims cannot be made simply by bold assertion. In today's case, the extraordinary conclusions are accompanied by some truly impressive morphological and metrical analysis, and actualistic experiment with a purpose-built crossbow, some hafted spear stand-ins, and a deceased wild springbok [small ruminant artiodactyl]. Unfortunately for the clever archaeologists, the basis of their claim rests not in their analysis, but rather in their arguments. It's the same old story that the Subversive Archaeologist has told before. Funny thing is...few, it would seem, are listening. Maugre their ultra-scientistic approach.

Notice the veritable totem pole used to 'analogize' a throwing weapon. The 'business end' is a flake hafted to a 1-1/8" (2.8575 cm) clothes-closet dowel, inserted into a piece of 1" galvanized pipe joined to a piece of 1-1/4" pipe. Not that it makes any difference to their conclusions, but this is less analogous to a javelin than it is a small tree-trunk! (From Wilkins et al. 2012)
I'll save my mirthful response to the use of a springbok for such an experiment for a quiet moment alone in my mother's basement. But, seriously, unless the thing were lying dead on the pan, can you imagine H. heidelbergensis [or you or me, for that matter] sneaking up on a nimble beast like this one and driving home such a weapon? They might as well have chosen a dead elephant [but that might not have impressed the authorities].
     This article has two major shortcomings, as I see it. The first is in convincing a sceptical archaeologist that the dates are from contexts in which the association with artifacts is well-warranted. Their second mistake comes in the background knowledge that they draw on in making their claim that the only way their bits of stone could have been modified in the way they were because they were hafted to a stick and poked into an animal. I'll deal with the dates in this part; the stones themselves will have to wait.
     Wilkins et al.'s troubles have their origin in the Kathu Pan 1 doline's depositional history, and in their evidently weak expertise in interpreting the depositional agents of various sized clasts. There is no indication that the authors are even aware of the potential for mixing in a sediment trap like the one in which they're excavating, much less the action of the occasional spring that came into being during the site's depositional history. The authors appear to treat each excavated artifact and sand grain chosen for OSL [yup, again] as if they had been, for all time, temporally associated. How else could you explain their naïve acceptance of the OSL age estimates?

Filled circles are OSL age estimates; filled triangle is U-series/ESR age estimate. From Wilkins et al. 2012.
To get the critical ball rolling, check out the schematic excavation profile above. The authors describe the sediments thusly:
From top to bottom, stratum 1 [not shown] is characterized by 1.5 -2 m of interdigitating calcified sand and organic peats. Stratum 2 [not shown] is characterized by well-sorted aeolian sand that becomes increasingly calcified toward the top. Artifacts in strata 1 and 2 are very sparse, but Beaumont tentatively suggests a ceramic LSA or Iron Age designation for stratum 1 and potential Robberg affiliation for stratum 2.
In other words, too young to be of interest to the authors.
Stratum 3 is ... gravel with sub- angular to sub-rounded pebbles in a greyish sand matrix. 
Stratum 3 is dated at 291 ka.
Stratum 4 consists of two substrata, 4a and 4b, which are distinguished from each other based mainly on the lithic and faunal assemblages, though Beaumont ... also reported a thin pebble lens that divided the substrata. The artifacts were recovered from a yellowish sand matrix.
Stratum 4 sounds like well sorted sand. Most probably wind-borne. In fact, I'd bet my lower central left incisor that these are fine to medium-sized sand grains, typical of aeolian transport and deposit. [I should tell you that I can make good on this bet. The orthodontist that the tooth be extracted before they put braces on my pearly whites, and I still have it under my pillow, waiting for the tooth fairy.] Moreover, I'd bet that the period during which the sands were deposited was an extraordinarily dry and windy one. That's because there is evidence of what could only have been scouring out by wind in the non-conformity between 4 and 3. Stratum 3's coarser, unsorted sediments bespeak a later, wetter period when surface water flow was transporting a range of small-sized sedimentary grains into the doline.
     But, here's the kicker. The really old dates are from an intrusive geomorphic feature, one that would undoubtedly have brought older fine sediments up to the level of the excavations, and described by the authors as follows.
In the process of cleaning the section, two well-defined vertically-oriented spring vents in stratum 4a were revealed and described as the ‘Upper Vent’ and ‘Lower Vent’. The Upper Vent, which is in the uppermost levels of stratum 4a and truncated at the top by Stratum 3, is densely packed with lithic artifacts and fauna, and the area outside the vent contains few, if any, artifacts. [The 464 ka sample] was recovered from sediments in direct association with the concentrated lithic artifacts and faunal remains within the vent. 
What does this tell us? And how does this relate to the veracity of Wilkins et al.'s claims? Plenty.

A brief accounting of karst features.
To begin with, think of how a big hole in the ground [the doline] came to be, and then filled up. There's a clue in the name of the site, Kathu Pan. A 'pan' is what would be called a playa in North America. It's a broad, nearly horizontal valley bottom that seasonally collects water from precipitation, hosts a shallow lake for a time, then dries up and awaits the next wet season.
     For a doline to form, the pan must be underlain by lithified fine sediments, such as limestone, siltstone or mudstone. These are the kinds of geological strata that are susceptible to karst processes--cave formation, among others. The illustration above is a succinct depiction of the kinds of geomorphic features that can occur in areas of karst. Those below are real-life dolines.

Guatemala City, Guatemala, 2007. A 'swallow hole.' It will need to be bridged. Filling it in is out of the question.
Florida. This is more of a 'sink' than a sinkhole. But just as devastating. 
A doline [or sinkhole] is the surficial expression of a subsurface void, or cave, the 'roof' of which became too thin near the surface and collapsed. Sinkholes are common in the middle of the US, and anywhere that the bedrock can be dissolved by surface water percolating downward. [The Santa Cruz campus of the University of California, where I've worked for the past 8 or so years, is built on mudstone that hosts a cave system, and in many places there are sinkholes at the surface.]
     So, once formed, the Kathu Pan 1 doline and its associated solution features began to fill in with any sediments that were transported by wind or water to its gaping maw. According to the authors, the pan in question is still somewhat depressed relative to the surrounding surface, and is thus still filling in. [It's likely that, as the underlying bedrock evolves, voids get larger, leading to settling of the fill material. Thus, a feature like the Kathu Pan 1 doline will always be a dynamic sedimentary environment, and might never be, truly, filled in.]
     The basal geology of Kathu Pan 1 would be of no intrinsic value to this discussion of the OSL age estimates were it not that Wilkins et al. observed 'spring vents' in their site. Your subversive imagination should, upon hearing such a statement, see a red flag. A spring vent is an opening in the surrounding sediments that concentrates ground-water discharge to the Earth’s surface. In other words, it's like a do-it-yourself geological pressure release valve. In the case of Kathu Pan 1 these spring vents could only have occurred at a time when the underlying karst system was chock full of water under pressure from the local water table. Some of that pressure was relieved through a 'vent' that formed in the unconsolidated sediments of the doline's fill. Think of it. Everything in the vent would be turned into a slurry as the water passed through it toward the surface. As in any transport process involving moving water [even water moving vertically through sediment] the smaller and lighter clasts would be more mobile, and the heavier pieces would tend to form a lag deposit. [Exactly fitting the authors' description: 'concentrated lithic artifacts and faunal remains.'] In a vertical column that contains fines like sand and larger pieces like stone artifacts, the heavier artifacts would literally sink as the smaller grains were randomly removed from beneath them--just the way your feet sink when you're standing on a beach and a wave washes ashore and then recedes.

     It simply can't be argued away or ignored. The authors' concentration of artifacts and faunal remains is almost certainly the result of the these processes I've described. I'm not makin' this stuff up! Karl Butzer, one of the lions of geoarchaeology in the early days, thought that a spring vent was an important enough disturber of archaeological traces that he put a wonderful illustration in Archaeology as Human Ecology, shown below.
     So, quite apart from the claims of hafted stone artifacts, the authors have a big problem with their dates. If it isn't already patently obvious [and there's no reason it should be] the dates from Stratum 3 and the spring vent are suspect. We have no way of knowing the stratigraphic origin of the coarser sands and pebbles in Stratum 3. All we know is that they came from somewhere else further up the fluvial train. They could have been eroded from the older sediments in which the doline formed, or any deposit created since then. How to know? [More OSL mathematical flim-flammery, I suspect.]
     In a different way, but with the same result, the fines selected for OSL dating from the spring vent were undoubtedly a porridge of old and young clasts. Since the water was pushing upward through older sediments, we can have NO WAY OF KNOWING where they came from or indeed how and if they are related temporally to the artifacts that almost certainly derived from a younger level or levels. The spring vent could be as recent at Holocene in age, given the other uncertainties raised by the depositional circumstances in Stratum 3. Bottom line: we could never know the true age of any artifact in the spring vent that passed through Stratum 4 (a and b).

There is no question that a spring vent, such as that occurring at Kathu Pan 1, would wreak havoc with the sediments in its path, and those nearby.
I've raised a lot of questions in this piece. So, to summarize, the OSL dates from Kathu Pan 1 cannot be relied upon. Because of the depositional environments--a sinkhole and a spring vent--there are too many unknowns when it comes to the association between the artifacts that interest the authors and the sediments selected for dating. Too. Many.

     I'm truly sorry if this comes across as a harangue. I get so frustrated by the way people working in my business are so concerned to get a spectacular result that they ignore very basic principles of stratigraphy and geomorphology, to say nothing of informal logic. The present authors are no exception [as we've seen before].
     Watch this space for a discourse upon the stones, coming soon.

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Thursday, 15 November 2012

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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