June 30, 2011

Why should(n't) we dig up Shakespeare?

Yesterday morning, I talked to Bob Rivers on his eponymous radio show at KJR-FM in Seattle about Francis Thackeray's plan to exhume Shakespeare and learn more about his health, cause of death, and possible drug use.  The show's production assistant described the show to me in the 20 seconds before I went on the air as "like a combination of NPR, The Daily Show, and Seinfeld."  Tall order, guys.

You can listen to their banter on Tuesday morning about the story by downloading the mp3 file here, or by clicking play below.  It's the first 12 minutes or so.  I hadn't listened to this before I talked to them, so I hadn't heard their pun on my last name.
June 28, Part 2 of Bob Rivers Show - 

And then you can listen to my Wednesday morning interview by downloading the mp3 file here, or by clicking play below.  It's the first 9 minutes or so.
June 29, Part 2 of Bob Rivers Show - 

Shakespeare's tombstone at the Holy Trinity Church,
Stratford-on-Avon, Warwickshire, England
Not being familiar with the show, I also hadn't prepared any stunningly witty repartee, and I was actually surprised by "If you could dig up anybody, who would it be?"  In all my years studying skeletons, no one has ever asked me that variation on the ol' living-or-dead dinner party question.  And the last question was, in retrospect, I think supposed to be a joke, but I took the opportunity to talk about evolution in modern humans.

This was my first experience talking to a public wider than my 180-student intro class or the audience at a conference.  Lesson learned: it's hard to not use a placeholder while you think about your response, especially over the phone and on the air, but don't overuse "uhm."

June 27, 2011

Pothead Willie Redux

It seems like Fox News is actually quite liberal... with the facts.  They appear to have originated the rumor that digging up Shakespeare and looking at his teeth will tell us if he smoked pot, when even the Daily Mail acquitted themselves nicely.  I blogged about this insanity yesterday, of course.  But today Stephanie Pappas of LiveScience did her due journalistic diligence and talked to Prof. Thackeray (and yours truly) about his plans for analyzing Shakespeare's remains (click on over to LiveScience to check it out).

Now, I don't know if drugs stay in hair and keratin for four centuries, but if they do, this seems to be a plausible way to see if Shakespeare had recently taken drugs.  That is, if Shakespeare's hair and nails are still there after four centuries.  Which is kind of unlikely, to be honest.  I also question what this test will really tell us...

  • Does testing the Bard's hair or nails for cannabis or cocaine tell us how widespread the practice was in Elizabethan England?  Or whether it was an acceptable thing to do in that society?  No.  
  • If drug tests do show that Shakespeare indulged in mind-altering substances, what does that tell us about his craft? Nothing, really. 
  • Are you more likely to slog through Titus Andronicus if you thought Shakespeare was high while writing it?  No.
  • Will some crackpot on a school board somewhere in America try to ban Shakespeare because of our moralistic "drugs are bad, mmmkay" mentality?  Quite possibly, but crackpots will be crackpots.

Perhaps the biggest question for me, though, is: is it an appropriate use of scientific resources to dig up a famous dead person and find out bits and pieces about his or her life because we're curious?  I tend to come down on the side of "no", but this may just be because I am trained as a bioarchaeologist rather than as a forensic anthropologist or a palaeoanthropologist.

Bioarchaeologists work with individual skeletons to answer questions about populations.  My current research seeks to know more about migrants to Imperial Rome, for example.  I am interested in individual migrants' lives, but one person's life doesn't make sense unless you know something of the range of variation within the population.  Forensic anthropologists, on the other hand, take the individual as their research subject.  Their field is about identifying unknown, modern individuals, which is possible because they have a reference population: all of us.  Palaeoanthropologists are kind of in the middle.  They find individual skeletons of a certain species, and they don't tend to have more than a handful of individuals to constitute a population.  So basically any new skeleton that is found helps refine and revise their understanding of hominin evolution.

My point here is that so-called "forensic archaeology" is often difficult for me to understand.  Yes, it's undeniably Sexy Science and a lot of fun to act like detectives with a high-profile ancient case to solve.  But without a thorough understanding of the ancient population (the Average Joes) from which an individual (the VIP) was drawn, it's hard to reconstruct their lives - from Mona Lisa to Zachary Taylor, Shakespeare to early Christian martyrs.  And this kind of investigation almost always singles out the privileged few who "shaped" society while ignoring the millions of others who did the actual hard work to make that society function.  My other complaint about forensic archaeology is that too many people draw from the evidence conclusions that are based primarily on our contemporary assumptions.  We need to remember that culture changes; what we think of as abnormal, immoral, unethical, or against the law today may have been perfectly acceptable among a different society in a different time period, and vice versa.

I guess we just have to wait and see if the Church of England allows Thackeray to open Shakespeare's tomb to scan the bones and take samples of his hair, nails, and teeth.  Seems kind of unlikely, but I am amused to hear that Thackeray is working within the letter of the "curse" - "Blessed be the man that spares these stones / And cursed be he that moves my bones."

Today's main take-away lesson?  The Daily Mail has better reporters than Fox News.  But that's no surprise, really.

June 26, 2011

To toke or not to toke... Will Shakespeare's bones tell us? (Uh, no.)

This is the kind of article I'd expect from the Daily Mail.  They're sure to carry it soon if they haven't yet, but I saw this over at Fox News:  "Did Shakespeare Smoke Weed?  Let's Dig Him Up and Find Out."  And it's quickly spreading to other news media.  Oh jeez.

"Heh, this is sonnet number 420." - Shakespeare
(Credit: cannabisculture.com)
About a decade ago, forensic scientists in South Africa analyzed the residue from a couple dozen 17th century clay pipes unearthed in the garden at Shakespeare's home in England (Thackeray et al. 2001).  They claim to have found traces of tobacco, cannabis, and cocaine.  The latter assertion is the most difficult to buy, since cocaine comes from the New World plant coca and is assumed not to have been made in the Old World until well into the 19th century.  Hemp, of course, was used in Elizabethan England, mostly as a fabric.  The researchers also found traces of myristic acid (from nutmeg, possibly a hallucinogen), and quinoline (which contains quinine, long used to treat malaria).  A palaeontologist named Francis Thackeray initated the pipe study and stirred up quite a controversy by suggesting that Shakespeare did all kinds of drugs.

Well, Thackeray is back.  He's now the director for the Institute for Human Evolution at the University of Witwatersrand and claims to have asked the Church of England for permission to probe Shakespeare's grave, make scans, and analyze the results.  So, how does he think this will show that Shakespeare smoked pot?

First, they have to find his grave.  People are pretty sure where Shakespeare was buried. Reportedly, he was afraid he'd be exhumed, so his tombstone reads: "Blessed be the man that spares these stones / And cursed be he that moves my bones." But hey, it was the 17th century, so who knows who's buried in the grave? Thackeray and his team plan to do a DNA test on the body, as well as of Shakespeare's wife and sister, who were buried nearby, to confirm identification.

Second, they want to figure out cause of death as well as his health during life.  Thackeray plans (here I'm reading between the lines, since the news reports are un-technical versions for the public) to look at "growth lines in the teeth" which may mean looking for enamel hypoplasias or may mean something more technical, like looking at enamel prisms, striae of Retzius, or perikymata.  OK, that's all well and good and will give us a general overview of the Bard's health during childhood, but where does pot come in?

Tooth wear from clay pipe use, 17th
century America (Credit: Smithsonian)
As far as I can tell, Thackeray's plan is to look for any evidence of extramasticatory wear on the teeth [see update below*]: that is, if there are grooves or indentations in the enamel of Shakespeare's teeth from tightly clenching a pipe.  That's it.  He's looking for evidence that Shakespeare smoked a pipe.  Which he likely did.  There's absolutely nothing tying the pipe use with cannabis use - and the evidence for cannabis within the pipe is tenuous at best. I don't care if Shakespeare smoked weed - there seems to be some evidence in his sonnets that he did - but I do care when people dig up skeletons for no good reason.

Thackeray is quoted all over the place as crowing about his "incredible techniques" and "nondestructive analysis."  Looking at tooth wear is nondestructive, but DNA analysis is most certainly destructive.  DNA is indeed an incredible technique, but there is no magical test that will tell if Shakespeare smoked pot.  We have some circumstantial evidence at best - and that evidence is, let's face it, no more convincing than the evidence we already have.  What's next?  Does Thackeray want to examine Shakespeare's phalanges for callouses, to prove he wrote all his plays and sonnets?

As usual, some researcher, bored or in need of an ego-boost, wants to dig up someone famous for shits and giggles [see update below^].  Really, this is bad science.  Thackeray's plan will in no way answer his question.  According to Fox News anyway, the Church of England claims not to have received a request from Thackeray.  Which begs the question: is Thackery full of crap, did the news media get something wrong, or is the Church denying it?

Whatever it is, I hope this goes away and doesn't become like the Mona Lisa case.

UPDATE (6/27/11) - * Seems Thackeray was misunderstood by Fox News, and I trusted that Fox had reported the news correctly. Good to know they're actually a worse source of news on this subject than the Daily Mail.  Anyway, as Thackeray mentioned to LiveScience today, his plan is to test hair or nails (if found) for evidence that the Bard smoked weed.  The part about wear on the teeth was indeed said in reference to pipe smoking, not specifically as a way to link pipe smoking and cannabis smoking.  ^ I still think much of forensic archaeology is done for shits and giggles.  After Stephanie Pappas asked me about it for her LiveScience piece, I outlined my misgivings about the practice a bit more fully here.  Perhaps it's my population bias or my need to toe the line between anthropology and classics, but something makes me root for the little people and get annoyed by the continuous attention being paid to the elite.


Reference:
ResearchBlogging.org

J.F. Thackeray, N.J. van der Merwe, & T.A. van der Merwe (2001). Chemical analysis of residues from seventeeth-century clay pipes from Stratford-upon-Avon and environs South African Journal of Science, 97, 19-21.

June 25, 2011

Skulls in the 21st Century - UM's Ford Collection Is Digitized

The University of Michigan's Museum of Anthropology has digitized their cranial collection, which consists of (I think) around 160 skeletons.  I couldn't find much information about the Ford Collection of skulls, but I assume they are not Native American and are possibly more long the lines of the Morton Collection at Penn or the Terry Collection at the Smithsonian, based on this report:
[The] collection [was] created by Corydon La Ford, MD (tenure 1854-1894), University of Michigan, Medical School, Department of Anatomy. The collection was created by Dr. La Ford during the late 19th century and it was later added to by unknown individuals until the early 20th century. The collection was used for anatomy teaching in the Medical School and no information exists as to how the crania were acquired.
What makes the Ford Collection news is that it has been fully digitized:


Click on the picture, and you get taken to a screen where you can zoom in and out.  This is great, but the picture that I chose didn't look very good over about 816x612.  I could zoom in, sure, but the image was fuzzy and had no better resolution past that point.  Perhaps there are images within the gallery that do go up to 3264x2448?


Not only are there pictures, there are full measurements for each and every skull.  You can simply click and download an Excel file or send it to Google docs, which is what I did here:


Last but certainly not least, there are screens for trauma and pathology.  You can even search the pathologies, which are alphabetized, to find all of the examples of, say, abscesses:


As far as I can tell, the collection is just of skulls, which means no postcranial data.  It's unfortunate, but it's also the legacy of skull collecting in the U.S.  (Aside: Do read The Skull Collectors if you're interested in that kind of thing.)  Not all of the images are high-quality.  And when I clicked on "metrics" and "sex and ancestry," I got the same spreadsheet.  Perhaps only some skulls have two different spreadsheets, and the ones I was playing with didn't?  Curious.  I might email and ask.

In all, though, this resource is going to be invaluable to me as I prepare to teach Human Osteology and Health & Disease in Ancient Populations this fall.  When I took Osteo for the first time way back in 1998, there weren't digital archives.  I had to scrounge through UVa's library until I finally found a book on Egyptian crania that listed measurements at the end - and I had to type each and every number in so that I could do some statistics and look at population affinities.  Digital archives present their own challenges, but I'm excited to start thinking about how to incorporate this site into a project or two.

(Hat tip to my esteemed colleague, Laura Banducci, for passing along the press release to me.)

June 24, 2011

Pyramid of Corpses in Roccapelago, Italy

Earlier this year, archaeologists working to help restore the 16th century church of Conversione di San Paolo Apostolo in the tiny north-central Italian town of Roccapelago found something they weren't expecting in the coffers of the crypt:
The "pyramid of corpses"
Credit: SBAER
Una piramide di corpi accatastati uno sull’altro, cadaveri di adulti, infanti e bambini in parte scheletrizzati, in parte mummificati, quasi tutti supini, qualcuno adagiato sul fianco, qualcuno prono, in un coacervo di pelle, tendini, capelli, abiti, calze, cuffie, sacchi e sudari. [via Gazzetta di Modena]
(A pyramid of corpses stacked one on top of the other; bodies of adults, infants, and children, partly skeletonized, partly mummified; almost all of them supine, some on their sides, some face-down, in a patchwork of skin, tendons, hair, clothes, socks, caps, bags, and shrouds.)
In all, archaeologists have found around 300 bodies, about one-third of which seem to have been naturally mummified.  It's not clear when the mummies date to, as the church was in use as a burial ground from the mid-16th to the late 18th centuries.  These were simple people, the archaeologists think, as they were "vestivano alla montanara" - dressed for the mountains in linen, cotton, and wool with no silk or lace accents:

Detail of a tomb.  Credit: SBAER

You can also watch a short video of the mummy above.  It's terribly focused in parts and doesn't say anything in addition to the news articles, but it's neat to watch, even if you don't understand Italian.

Bioanthropological study of the mummies has already started, and the Gazzetta di Modena suggests that a basic demographic analysis has been accomplished - there were men, women, and children buried here.  Further studies are expected, including assessments of their diet and pathological conditions, as well as the creation of 3D models and restorative work on some of the more impressive mummies.  Archeologia Viva has the full proposed plan of study for the mummies, written by Giorgio Gruppioni, a physical anthropology professor at the University of Bologna:
  • osteological analysis, with the help of Xrays and CT scans where necessary, as well as histological analysis in service of understanding the demographics of the population
  • palaeopathological analysis of teeth and bones to investigate trauma, diseases, diet, and hygiene
  • analysis of musculoskeletal markers to look into biomechanical stress on the skeletons
  • trace element analysis of the teeth and stable isotope analysis of the bones to reconstruct their diets
  • biological distance analysis using epigenetic traits of the skeleton, as well as DNA analysis, to look for population affinities
  • entomological analysis to investigate the conditions of burial
  • palaeomicrobiological investigations to detect pathogens and other microorganisms
  • 3D reconstruction of the faces of some of the mummies and some of the burials themselves
In addition, ancient textile expert Iolanda Silvestri of the IBC Institute for Cultural and Artistic Heritage of Emilia-Romagna will further analyze the textiles found with the mummies.  Other amazing finds include crucifixes and religious medallions, as well as a very well-preserved letter, said to be a "settlement agreement" between God and the deceased, but far beyond my skills to translate:

Preserved letter.  Credit: SBAER.

After all this work is carried out, some of the mummies will be preserved within the church for display.  The remainder of them will be buried within the grounds of the church.

I hope that these researchers get all the funding they need to carry out this ambitious project on the lives of the mummies.  I for one would love to know what they ate, where they came from (were they pilgrims or locals?), and what they looked like.

(Thanks go to Roberto Labanti - @r_lab on Twitter - for pointing me at these news articles.  And to Bill Thayer - @LacusCurtius - for the links to Italy's other famous mummies, those of Ferentillo.)

UPDATE (6/25/11) - Roberto Labanti pointed out in the comments a wonderful page at the archaeological superintendency that details a lot about the excavation and more about what's been found than the Italian news media reported.  So do check it out here if you read Italian.

UPDATE (6/28/11) - The ever-awesome Rossella Lorenzi, who writes for Discovery.com, posted a slideshow of the best pictures from the excavation.

June 23, 2011

Ethnic Cleansing of Jews May Date to 12th Century

I'm so used to reading news and even published articles that don't properly report on "determination" of "ethnicity" from skeletal remains that I was taken aback by today's BBC article: "Jewish bodies found in Medieval well in Norwich."  In the very first paragraph, it is reported that the researchers used "a combination of DNA analysis, carbon dating and bone chemical studies," and those few words make the entire remainder of the article seem reasonable.

Freaky-deaky reconstruction of bodies
in the well.  Credit: BBC News.
Seventeen skeletons were found in a well in Norwich, England, in 2004.  Originally, researchers thought it was a mass grave, possibly as a result of plague, but the eventual carbon dating put these people's death earlier than the plague, and there were no palaeopathological signs of infections such as leprosy and tuberculosis.  Through DNA analysis of five of the individuals, they have found that those individuals were all related.  Eleven of the 17 skeletons were children, and they seem to have been thrown into the well after the 6 adults were -- the adults had perimortem fractures, whereas the children landed on the adults' bodies.

I'd really like to know what their evidence is that these people were Jewish -- I am assuming it's drawn from the DNA analysis, which can show genetic affinities with known populations from different areas of the world.  Or perhaps it's based (partly) on the "bone chemical studies," which I take to mean the now-standard complement of Sr/O/C/N?  If it's based on more than burial style and head shape, the attribution is already on steadier ground than that of the "Leper Warrior."  Still, DNA tells us about biology, not culture.  It can tell us whom we're similar to biologically but cannot tell us whom we're similar to culturally.  Were the 17 people in the well in Norwich Jewish?  It's incredibly difficult to say that with any certainty, but a combination of DNA evidence, anomalous burial style, and historical records could definitely convince me.

I couldn't find a published paper on these skeletons, which isn't terribly surprising since the BBC report is in service of a TV special that aired tonight called "History Cold Case: The Bodies in the Well".  If any of my British readers happened to catch the show (or want to watch it online), I'd really appreciate a summary of the techniques they used!

June 20, 2011

Miss USA Contestants Are Idiots

This video perfectly encapsulates the sad state of science education in the U.S. (and the false but somehow growing notion that teaching science is a partisan endeavor).  Remember, these are college-educated women:




What's worse than this video?  The fact that of the 51 Miss USA contestants, only 2 - TWO - came out in favor of evolution.  What.  The.  Fuck.  (Watch the whole 15-min video with all the contestants here, if you dare.)

Anyway, some other interesting coverage of it here:
Now, if you'll excuse me, I'm going to go bang my head against a wall and wonder why I've decided to spend my life teaching evolution and other aspects of biological anthropology to college students.

UPDATEish (6/27/11) - Hilarious video hosted over at Jezebel called "Should Math Be Taught in Schools?"

June 15, 2011

Sickle-Cell Disease, Oxygen Isotopes, and Malarial Romans

Two articles published last month in the American Journal of Physical Anthropology are starting to greatly complicate bioarchaeologists' use and interpretation of stable oxygen isotope ratios in an attempt to understand migration and mobility in the past.  Science is constantly progressing, and it can be challenging to keep up with the latest research.  The real challenge for me, though, is in interpreting the isotope analyses I have done on populations from Imperial Rome - first because only one other oxygen isotope study has been done in the entire Italian peninsula, and second because the ancient Romans were quite unlike other archaeological populations in their mobility and importation of food and water.  This post, then, works through some of the ideas I laid out in my dissertation and adds to them in light of recent articles on oxygen isotope analysis.

Oxygen Isotope Redux

Studying the relative amounts of stable oxygen isotopes in ancient organic material seems to have begun with palaeoclimate studies, as oxygen isotopes are related to various climatological factors that affect the elemental composition of water. The relative amounts of oxygen isotopes of both meteoric (rain, snow) and environmental water (rivers, springs, lakes) vary by region in relation to factors such as temperature, humidity, distance from the coast, latitude, rainfall, and elevation. This means that different water sources in different areas have different ratios of stable oxygen isotopes.
Graph showing variations in oxygen and hydrogen isotopes
(credit: fig. 6 from the SAHRA website)

The mammalian body needs oxygen to survive - not just in the form of air (inspired oxygen) but also in the form of water and food. Researchers became interested in looking at the amount of oxygen trapped in mammalian tissue decades ago and began measuring the abundance of two different isotopes of oxygen18O and 16O. The ratio between these two measurements - written as δ18O ‰ (per mil) - results from fractionation of the two isotopes, which is caused by different metabolic processes.

Starting in the 1990s, though, bioarchaeologists began studying stable oxygen isotopes in order to investigate ancient migration. If the majority of the oxygen that a person ingested or inspired while his teeth were forming came from local water sources, the measured δ18O value from his hard tissue would be characteristic of the geographical peculiarities of that water, taking into account metabolic fractionation processes. It should be possible, then, to use δ18O numbers to identify individuals who accessed either local or nonlocal water sources and, by inference, locals and immigrants. In the early 2000s, oxygen isotope analysis became widely used in answering questions about past human mobility, including identifying immigrants and pinpointing their geographical homelands.

Problems with Finding Immigrants' Homelands

Within the past decade, though, researchers have learned much more about oxygen isotope ratios, including the metabolic processes that affect fractionation. In fact, two articles published online on May 3 by the American Journal of Physical Anthropology demonstrate just how complicated it can be to interpret oxygen isotope ratios from past human populations - a topic that I've been thinking about a lot lately as I write up for publication my own oxygen data from Imperial Rome.

δ18Ow contour lines in Italy
(credit: Longinelli & Selmo 2003)
Pollard, Pellegrini, and Lee-Thorpe (2011) are the first to put into print the issues with assigning a geographical homeland to immigrants identified through oxygen isotope analysis in their paper, "Some observations on the conversion of dental enamel δ18Op values to δ18Ow to determine human mobility." In essence, those of us working with oxygen isotopes have been attempting to relate our human dental enamel oxygen measurements to measurements of oxygen from groundwater, using one or more linear regression equations. These equations helpfully give us numbers that seem to put our interpretations of homeland on solid footing. Pollard and colleagues, however, do the math and show that the magnitude of the error introduced with the regression equation(s) means our approximations of immigrants' homelands based on the oxygen isotope ratio of local groundwater are really quite poor. They suggest instead that oxygen ratios derived from human enamel should be compared directly to other human enamel samples.

Sickle-Cell Disease Affects Oxygen Isotopes

Reitsema and Crews (2011) throw another wrench into oxygen isotope analysis with their paper, "Oxygen isotopes as a biomarker for sickle-cell disease?" Oxygen isotope fractionation results from various metabolic processes, as I mentioned above. In humans, differing oxygen isotope ratios can result from smoking, exercise, and disease. For example, there is increased fractionation in smokers, due to their compromised ability to diffuse oxygen through the pulmonary membranes. Conversely, people who engage in routine exercise appear to have a decrease in fractionation because of the increased rate of respiration. It has also been established that oxygen isotope fractionation is lower in people suffering from anemia, as the binding of oxygen to hemoglobin is a fractioning process.

Because of these known fractionation effects, Reitsema and Crews hypothesized that the bone tissue of an organism with sickle-cell disease would have a different oxygen isotope ratio than a healthy organism. They studied bone apatite from 24 mice - 8 control and 16 transgenic mice with human HbS (mutant hemoglobin S) genes that cause sickle-cell disease. The bones of the sick mice had a significantly (p=.002) lower oxygen isotope ratio than those of the healthy, control mice. In fact, the sickest mice had the lowest oxygen isotope ratios.

This study has far-reaching implications for bioarchaeological analysis because it is currently quite difficult to identify individuals with sickle-cell disease (and other kinds of anemia) within an archaeological population. We tend to use frequencies of observable pathologies - like cribra orbitalia and porotic hyperostosis - to infer anemia in an individual, but these are non-specific disease processes and cannot be directly tied to sickle-cell disease or another condition.

Sickle-Cell and Malaria

Three normal and one sickled RBC
(found online here)
In my bioanth lectures on population differences and human variation, I always discuss the sickle-cell trait as an example of the heterozygote advantage. But let's back up a second. Many genes have two or more forms, called alleles. If a person has two copies of the same allele for the same gene, that person is said to be homozygous, and if a person has two different alleles, that person is heterozygous. I'm simplifying this a bit, but let's say that HbA is the allele for normal hemoglobin, which is present in red blood cells and carries oxygen through the body. The allele HbS, on the other hand, produces a different kind of hemoglobin, making the red blood cells sickle-shaped. This anomalous shape interferes with the body's ability to store and circulate oxygen. Those people who have two copies of the HbS allele develop sickle-cell disease, which results in a much shorter life expectancy than normal.

If the HbS allele is so dangerous to humans, why hasn't it been selected out of the population? Well, researchers who first studied the prevalence of the HbA and HbS alleles discovered that several populations in Africa, India, and the Mediterranean had fairly high frequencies of the HbS allele - up to 20% of the populations they studied had one copy of the HbS allele, meaning those people were heterozygous. The advantage of having one copy of the HbS allele was discovered to be a partial resistance to malaria, a disease vectored by the mosquito in warm areas like central Africa, the Mediterranean, and southern Asia. This can be illustrated in the following map of Africa:

Frequency of malaria (left) and sickle-cell trait (right) in Africa
(credit: Wikimedia Commons)

The heterozygote advantage here is that people with one copy of the HbS allele have enough normal hemoglobin to survive into adulthood yet enough sickled red blood cells to fight off malaria (as the malaria parasites don't survive in the sickled red blood cells).

Malarial Romans or Immigrants?

One of the major questions facing bioarchaeologists who work in ancient Italy is, understandably: What was the prevalence of malaria in the population? This question has been tackled primarily by Robert Sallares using historical data in his book Malaria and Rome: a History of Malaria in Ancient Italy (2002) and by David Soren using osteological data in papers like, "Can archaeologists excavate evidence of malaria?" (2003).

Incidence of malaria in 1940s Italy
(found online here)
I don't think anyone doubts that malaria was endemic in ancient Italy considering its prevalence in 20th century Italy. The problem is that, as Reitsema and Crews note, it's not clearly visible in the skeletons comprising an archaeological population. A 2008 study by Bianucci and colleagues showed evidence of P. falciparum (one of the parasite species that causes malaria) in a mummy's soft tissue; but this was one mummy, and the vast majority of our ancient bodies are not that well preserved. Another problem is that we don't know the frequency of people with a heterozygote advantage - those individuals who are heterozygous for sickle-cell disease or for thalassemia, both of which confer protection against malaria. These individuals may exhibit anemic reactions but not as often or as severely as people with sickle-cell disease or thalassemia.

So, what do the Pollard et al. and Reitsema and Crews articles mean for our understanding of the ancient Romans? Let's take a look at this graph that I've been pondering for the past couple of weeks:

Oxygen isotope ratios from Portus (Prowse et al. 2007) and Rome (Killgrove 2010)

This histogram shows the distribution of oxygen isotope ratios in two Imperial-period populations: one from the cemetery of Isola Sacra between Ostia and Portus Romae (Prowse et al. 2007) and one from two cemeteries (Casal Bertone and Castellaccio Europarco) located just outside the city walls of Rome (Killgrove 2010). There are outliers in both populations - and a quite dramatic one from Portus - but the distributions themselves are different. The population from Portus Romae has lower oxygen isotope ratios on average than the population from Rome itself.

Based on what we've learned about oxygen isotope ratios, there are a number of possible explanations for this variation:

1. Water Sources. The city of Rome had a vast network of aqueducts, whereas Portus had only one. The aqueducts from Rome, though, were fed by springs at the base of the Apennine mountain range. With increasing elevation, we actually get a concomitant decrease in oxygen isotope ratios. So I don't think that water sources alone can explain the difference, since we would expect oxygen isotopes from Rome to be lower than from Portus.

2. Diet. Part of the a oxygen in person's skeletal tissue comes from the water in food. If people from Portus and people from Rome were eating dramatically different food - types, quantities, imports - or preparing it differently, then we may expect the isotope ratios to differ. There are differences in diet between Portus and Rome, as I've blogged about before in my post on the Bioarchaeology of Roman Seafood Consumption. So this could indeed factor into the above histogram.

3. Homeland. Portus and Rome were both immigrant-receiving areas. This is not a stretch of the imagination, since slavery was widespread in the Empire and both cities would also have attracted merchants, students, and travellers. But suppose each city attracted immigrants or slaves from specific homelands. Prowse and colleagues interpreted their oxygen isotope data to suggest that people may have been coming to Portus from areas with higher altitude. I interpreted my oxygen data to suggest that, while many people seem to have been local, there were plenty of people with lower and higher oxygen isotope ratios, who came to Rome from areas with higher elevation/colder climates and lower elevation/warmer climates. This interpretation has been my favorite so far - I don't know of any historical evidence that shows that different cities in the Empire pulled slaves or other immigrants from certain areas, and I think this histogram lets me at least suggest that it's a plausible scenario.

4. Malaria. The Reitsema and Crews article - although it's about bone apatite in mice rather than human enamel - brings up another possibility, though: that the people at Portus were more affected by sickle-cell disease than the people from Rome. Both areas were fairly malarial, but Ostia and Portus were famously abandoned several times as a result of malaria. A greater prevalence of malaria could have had an influence on the ancient population of Portus/Ostia, as the people fittest to survive the marshy area would have been those with at least one copy of the HbS allele. Or perhaps Portus attracted more people from Africa - another area with high frequency of the HbS allele - than did Rome, as merchants or traders.

I don't have a concrete interpretation of this graph yet. Perhaps I'm making too much out of the variation - after all, oxygen isotope analyses have only been done by Prowse and colleagues at Portus and by me at Rome. It's difficult to say with only two large samples what the variation means, and I'm not sure when I'll be able to tease out the effects of diet, water source, immigration, and disease on the oxygen isotope ratios of the Romans.

It is clear from the two recent AJPA articles, though, that the interpretation of oxygen isotope ratios is getting more complicated all around. The work of Pollard and colleagues clearly shows that populations need to be compared to one another, not to a climatological map in an attempt to pinpoint a homeland. The research linking sickle-cell disease and oxygen isotopes is still quite preliminary, as Reitsema and Crews admit. But even if this research complicates our interpretation of oxygen isotopes as indicative of immigrants to Imperial Rome, it may hold great potential for our future understanding of malaria and population variation in ancient Italy.

UPDATE - 9/23/11.  This post has been translated into Ukranian by Sofya Kravchuk and can be found here.  I'm happy that Sofya wanted to translate this post, and I hope I gain some Ukranian readers!



References:
ResearchBlogging.org

Bianucci, R., Mattutino, G., Lallo, R., Charlier, P., Jouin-Spriet, H., Peluso, A., Higham, T., Torre, C., & Rabino Massa, E. (2008). Immunological evidence of Plasmodium falciparum infection in an Egyptian child mummy from the Early Dynastic Period Journal of Archaeological Science, 35 (7), 1880-1885 DOI: 10.1016/j.jas.2007.11.019.

Killgrove K. (2010). Migration and Mobility in Imperial Rome. PhD dissertation, University of North Carolina at Chapel Hill.

Pollard AM, Pellegrini M & Lee-Thorp JA (2011). Technical note: Some observations on the conversion of dental enamel  δ18Op values to δ18Ow to determine human mobility. American Journal of Physical Anthropology PMID: 21541927.

Prowse TL, Schwarcz HP, Garnsey P, Knyf M, Macchiarelli R, & Bondioli L (2007). Isotopic evidence for age-related immigration to Imperial Rome. American Journal of Physical Anthropology, 132 (4), 510-9 PMID: 17205550.

Reitsema LJ & Crews DE (2011). Brief communication: Oxygen isotopes as a biomarker for sickle-cell disease? Results from transgenic mice expressing human hemoglobin S genes. American Journal of Physical Anthropology PMID: 21541922.

Sallares R. (2002). Malaria and Rome: a History of Malaria in Ancient Italy. Oxford University Press.

Soren, D. (2003). Can archaeologists excavate evidence of malaria? World Archaeology, 35 (2), 193-209 DOI: 10.1080/0043824032000111371.

June 14, 2011

Friends, Romans, Countrymen... Lend Me Your Rears!



Ash cloud of 79 AD Vesuvius eruption
(credit: Wikimedia commons)
Less well known than the ash-covered ancient town of Pompeii is Herculaneum.  Located 15 km or so from its more famous cousin, Herculaneum (as well as the coastal cities Stabiae and Oplontis) was obliterated with the eruption of Mount Vesuvius in 79 AD.  While excavations of the town began in the mid-1700s initially, human skeletal remains of the inhabitants of Herculaneum weren't found until 1981.  Eventually, close to 300 skeletons were found near the coast, but the study of them seems a bit unclear.

Initially, the American physical anthropologist Sarah Bisel studied 139 of these in the 1980s.  Bisel's work was cutting-edge at the time: she detailed the people's health through palaeopathological analysis and attempted to reconstruct their diets through trace element analysis of Ca, P, Mg, Zn, and Sr (1988).  She suggested that their diets were high in vegetable matter and seafood, which helped her explain the high frequency of anemia and linear enamel hypoplasias.  But Italian physical anthropologist Luigi Capasso also studied these skeletons, although he counted 143 individuals.  Capasso is notable for showing through his work that many inhabitants of Herculaneum suffered from gastrointestinal diseases, likely the result of foods contaminated with microbes. In 2002, Capasso found Brucella melitensis bacteria in some carbonized cheese and correlated this finding with an osteological pattern of brucellosis.  He later suggested that the Romans' habit of consuming pomegranates and figs was a remedy for gastrointestinal diseases, as the dried fruits were themselves contaminated with Streptomyces, a bacterium that produces the natural antibiotic tetracycline (2007).  However, as far as I know, DNA studies haven't been done to confirm Capasso's findings.
"Ring Lady" of Herculaneum,
found in 1982 excavations
(credit: Wikimedia commons)

Andrew Wallace-Hadrill, the longtime excavator of Herculaneum, suggests that there are around 150 or so skeletons from Herculaneum that still need further study (2011, p. 130).  He notes that "modern scientific study of skeletons has advanced by leaps and bounds over recent decades" and is particularly interested in looking at the origins of the people of Herculaneum because "in a population with an abundant supply of slaves, [strontium isotope analysis] can be particularly revealing" (p. 128).  I definitely agree that more work needs to be done on these skeletons - from C/N isotope analyses (since trace elements aren't used much anymore for palaeodietary work) to Sr/O isotope analyses, palaeopathological assessments (using agreed-upon standards) to simple age/sex estimations - and I would love to get my hands on this collection.  It would form a fantastic comparative population to those I studied in Rome and tell me so much more about migration, diet, and daily life in the Roman world.

Because of my longstanding interest in Bisel's and Capasso's work and the skeletons of Herculaneum, I was especially excited by a short ANSA news article that came out today on excavations ongoing in a sewer of Herculaneum (and coverage by the Telegraph, with pictures). Excavators have found the largest deposit of "organic material" ever found in the Roman world - which is a euphemism for "750 large sacks of human excrement."  You'll pardon the pun, but holy shit!

Toilet from the Baths of
Caracalla, Rome
Not many people know about the astounding modernity of Roman sanitation and plumbing (which I've written on a bit here), and these facts tend to get ignored by scholars intent on painting a picture of the Roman world as a cesspool (e.g., Scobie 1986). There were clearly oodles of communicable diseases floating around the Roman Empire, but things would have been a whole lot worse without flush toilets and indoor plumbing.  A recent book by Barry Hobson, Latrinae et Foricae: Toilets in the Roman World (2009), is well worth a read by those interested in the seemingly anachronistic advances of Roman engineers... or in Roman poop.  Hobson doesn't actually say much about the toilets at Herculaneum, as "excavation of a large sewer ... is currently in progress" (p. 47), choosing to concentrate on the better-understood toilets of Pompeii.  But there are some choice bits in this book, like a graffito found in the House of the Gem in Herculaneum that reads (p. 144):
Appollinaris, medicus Titus Imp. hic cacavit bene. (CIL IV.10619) 
Appollinaris, doctor of the Emperor Titus, crapped well here.
Early analysis of the poop from Herculaneum, according to the ANSA report, "confirmed that the human faeces were rich in vegetable fibres, and one sample showed a high white blood cell count which, according to researchers, indicated a bacterial infection."  It seems both Bisel and Capasso were right in their respective studies, and it's unfortunate that osteological analysis of the skeletons has stagnated.  I can't tell from Wallace-Hadrill's book what is holding up the analysis, but I don't think it's lack of funding.  If it's lack of personnel, I would absolutely love to be involved in the project - I can run the strontium isotopes, help with the C/N isotope analysis, and do the osteological work.  Hell, I'd even be happy to be trained in poking through poop, although my only qualification is the one time I had to monitor my daughter's diaper after she ate a gummy window cling.  I was, however, successful in that excavation.

This discovery of 750 sacks of crap (I really cannot get over the sheer volume of poop they've found) has the potential to tell us an amazing amount of information - not only about the diets or the diseases of the deceased denizens of Herculaneum, but also about how they used their plumbing.  Excavators have found other objects in the sewer, like "pottery, a lamp and 60 coins... bone pins, necklace beads, and a gold ring with a decorative gemstone."  As any parent of a toddler knows well, toilets are fun for flushing all kinds of things!  I'll be on the lookout for more publications on this front, particularly as I write up my Roman bioarchaeological contribution to the Encyclopedia of Global Archaeology in the coming months.


References:
This post was chosen as an Editor's Selection for ResearchBlogging.org


S.C. Bisel (1988). Nutrition in first-century Herculaneum Anthropologie, 26 (1), 61-66

ResearchBlogging.orgL. Capasso (2002). Bacteria in two-millennia-old cheese, and related epizoonoses in Roman populations. The Journal of Infection, 45 (2), 122-7 PMID: 12217720.

L. Capasso (2007). Infectious diseases and eating habits at Herculaneum (1st century AD, southern Italy) International Journal of Osteoarchaeology, 17 (4), 350-357 DOI: 10.1002/oa.906.

B. Hobson (2009). Latrinae et Foricae: Toilets in the Roman World. Duckworth.

A. Scobie (1986). Slums, sanitation, and mortality in the Roman world Klio, 68, 399-343.

A. Wallace-Hadrill (2011). Herculaneum, Past and Future. Herculaneum Conservation Project.

*Note: Title pun courtesy my friend and ersatz wedding singer Gwen Kern, who may need to write all my headings from here on out.

June 13, 2011

Is Anatomy Destiny?

One of my favorite things to do at lunch these days is to watch a TED talk.  They're the perfect length for a short break from my research or writing, and I often end up showing one or more when teaching.  Today, I watched Alice Dreger (professor of clinical medical humanities and bioethics at Northwestern) give a talk called "Is Anatomy Destiny" back in December.

In light of a surprising recent uptick in traffic to my April blog post "Gay Caveman! ZOMFG!", I wanted to link to Dreger's talk, which ranges from her discussion of problems with our binary sex and gender categories to her approval of the Founding Fathers' decision to move away from leadership based on blood ties to a more radical and inclusive anatomical theory, that all men are created equal.

About five minutes in, Dreger sums up in just a few sentences how science is pushing us into what she calls our discomfort zone - the realization that sex, anatomy, race, and other categories aren't as clear-cut as we once thought they were:
We now know that sex is complicated enough that we have to admit nature doesn’t draw the line for us between male and female, or between male and intersex, or female and intersex – we actually draw that line on nature.

So what we have is a sort of situation where the farther our science goes, the more we have to admit to ourselves that these categories that we thought of as stable anatomical categories that mapped very simply to stable identity categories are a lot more fuzzy than we thought. And it’s not just in terms of sex – it’s also in terms of race, which turns out to be vastly more complicated than our terminology has allowed.

As we look we get into all sorts of sort of uncomfortable areas.  We look, for example, at the fact that we share at least 95% of our DNA with chimpanzees. What are we to make of the fact that we differ from them only really by a few nucleotides? But as we get further and further with our science, we get more and more into a discomfort zone where we have to acknowledge that the simplistic categories that we had are probably overly simplistic.
Watch the whole talk below, or click over to the TED YouTube channel.

June 10, 2011

Dismembered Cycladic Figurines

On the six-square-mile island of Keros, a part of the Cycladic island chain of the Aegean Sea, thousands of broken sculptures and pottery dating to about 2,500 BC have been discovered since archaeologist Colin Renfrew started excavating there in the 1960s.  The caches of broken figurines are especially interesting, as archaeologists have been unable to find joins - pieces that fit together:

2500-year-old Broken Cycladic Figurines from Keros
(credit: Cambridge University via The Guardian)
The latest theory, outlined quite well by The Guardian today and further detailed in the Cambridge press release, is that, "the breaking of statues and other goods was a ritual and that Keros was chosen as a sanctuary to preserve the effects."  Based on the discovery of a "guest house" made of imported marble, Renfrew thinks that people made specific pilgrimages to the otherwise uninhabited island of Keros to deposit or bury broken fragments of figurines and other goods.  (Insert your own "Island of Misfit Toys" reference here.)  This practice lasted for several centuries, until about 2000 BC.

I've always had a soft spot for Cycladic figurines - for their clean lines and serene, almost corpse-like poses.  As an undergrad, I wrote a particularly terrible paper for my Prehistoric Art class comparing Cycladic figurines and the Venus of Willendorf, but that naive attempt to engage in cross-cultural comparison helped me realize I was meant to be an anthropologist rather than a classicist.

One of the few mementos I have of my summer excavating on Crete in 2003 is a Cycladic figurine magnet that lives on my fridge.  Just this morning, before I saw the Renfrew story, my 2-year-old daughter took great interest in it, and we had the following conversation:

Chickpea: "What's that?"
Me:  "That's a Cycladic figurine magnet.  Can you say 'Cycladic figurine'?"
Chickpea: "'at's an old man."
Me:  "So true."

We headed out on a shopping trip, and Chickpea insisted on taking her new friend the Cycladic figurine with her in the car.  He made it to Target and the mall, but by the time we got home, he'd slipped between her carseat and the car door, and he met an unfortunate demise:

My poor fridge magnet

Looks like I may need to book a trip to Greece - and a lovely Aegean cruise - to bury him at Keros.


Further Reading:
ResearchBlogging.org

G. Papamichelakis, & C. Renfrew (2010). Hearsay about the "Keros Hoard" American Journal of Archaeology, 114 (1), 181-185 : http://www.atypon-link.com/AIA/doi/abs/10.3764/aja.114.1.181

A. Selkirk (2011). Keros: Sanctuary of the Cycladic Figurines Current World Archaeology, 26 : http://www.world-archaeology.com/features/keros-sanctuary-of-the-cycladic-figurines/

June 9, 2011

The Leper Warrior: Persistence of Racial Terminology in Biological Anthropology

A few months ago, the news media carried a story about "Bones of Leper Warrior found in Medieval Cemetery" in central Italy.  The publication by Mauro Rubini and Paola Zaio was in early view at the time and was just published in the July issue of the Journal of Archaeological Science (see citation below). I noticed that Katy Meyers blogged about it today over at Bones Don't Lie, but I'm afraid I can't be as charitable as she is in pointing out the flaws.

8th c Avar Warrior
(credit: Wikimedia commons)
Rubini and Zaio studied skeletons from 234 graves in an early Medieval (6th-8th century) cemetery in Molise (south-central Italy).  Based on grave goods, they suggest that the people buried in the cemetery were of different ethnic backgrounds - the Eurasian Avars, Lombards, and indigenous Italians - and were semi-nomadic.  Three of the skeletons appear to have warfare-related wounds, and one of the three also suffered from leprosy in life.  The authors therefore conclude that the three were "warriors from the East."  The finding of a "leper warrior" is actually quite interesting, and I'll return to this at the end.  But there is one very problematic feature of this article that quite frankly surprised me, considering the high profile of the journal and the research caliber of the first author.

The authors offer no evidence to back up their claim that the cemetery was the burial place of people of different geographical origins, aside from the off-hand statement that "the multicultural context of the necropolis is shown by the presence of Lombard, indigenous, and Asian grave goods" (p. 1552).  Sure, different populations may have different artifacts, but the presence of, say, "typical Avar stirrups" does not prove an individual's ethnicity or background, nor does the similarity of the graves to "Pazyryk burials in the placement of the horse, body and grave goods" (ibid.).  As every bioarchaeology student knows from reading The Archaeology of Death and Burial (Parker Pearson 1999), a grave and its associated goods is much more likely to represent the values and mores of the group burying a person than of the person himself.  It's rather curious that Rubino and Zaio include a lengthy explanation of the fact that the Avars were not a distinct ethnic population but rather were "a heterogeneous, multi-ethnic population [... and] a union of multiple cultural patterns" (p. 1551) immediately before talking about the distinct "Asian" (whatever that means) presence in the Campochiaro cemetery.

Especially problematic is Rubini and Zaio's claim that the Lombard/Avar/indigenous classification is "supported also by the preliminary anthropological study of the skeletal sample" (p. 1552).  The study is not specified here, but in the authors' later description of the three graves of interest, the questionable analysis becomes clear (pp. 1554-6):
Grave n. 20 (see Fig. 3) Individual of male sex, with age at death over 55 years. Height was estimated at about 161.5 cm. The skull shows, according to the suggestions of Corrain (2002), characteristics of Mongolic type: dolicomorphous with a superior profile of ovoid shape, flat face and large, low orbit. 
 [...] Grave n. 102 (Fig. 5) Individual of male sex, with age at death 50-55 years. Height was estimated at about 169.7 cm. According to the suggestions of Corrain (2002), the skull shows characteristics of the Dinarico-Adriatic type: brachimorphous with superior profile of ovoid shape and narrow frontal.

[...] Grave n. 108 (Fig. 7) Individual of male sex, with age at death over 50 years. Height was estimated at about 161.1 cm. The skull shows a mesomorphous shape with a long and narrow face.
Just as biological anthropology in the U.S. in the 19th century was influenced by Samuel Morton's racist ideology in the construction of biological "types" and "races" (q.v. yesterday's post), biological anthropology in 19th century Italy was influenced by Cesare Lombroso's theory of atavism and "born criminals."  Morton interpreted his data on skull shape to fit his preconceived notions of race, and Lombroso did the same to fit ideas of "criminals," who all too often included the economically disadvantaged south Italians (Killgrove 2005).

Within biological anthropology in the U.S., we have worked hard to move on from Samuel Morton, Carleton Coon, and the use of the cephalic index in general.  So it always disheartens me when clearly archaic terminology is used to discuss skeletons.  Mongolic and Dinarico-Adriatic types?  Dolico-, brachi- and mesomorphous?  These terms have no place in today's biological anthropology, which is focused on understanding the diversity of the human population, both modern and ancient.  Skulls are not pots - we can't create a typology of cranial features and expect to be able to pick someone's head out of a lineup.  When we do this, we inevitably learn by using alternate methods that inter-population variation is low and gene flow was considerable (e.g., Killgrove 2009).  Classifications such as Dinarico-Adriatic are based on Coon's The Races of Europe (1939), and we've pretty clearly posthumously castigated Coon for advancing segregation in the U.S. in spite of the lack of scientific data to support clear "racial" differences.

There's absolutely no evidence within the Rubini and Zaio article that the three individuals of interest were from another geographic area - skull morphology doesn't cut it, and "ethnic" artifacts in the grave don't convince me either.  Were these "warriors from the East" as the article title implies?  Maybe.  But I'll need to see some aDNA or isotope data to consider the claim to be plausible.

Skull of the Leper Warrior
(credit: Rubini and Zaio, fig. 8a)
What is interesting about the article - and, I assume, the reason that JAS published it - is the authors' finding that a man over the age of 50 who was afflicted with leprosy likely engaged in warfare.  It shouldn't be revelatory that lepers in the past went to war, just as it shouldn't be revelatory that women in the past were active agents in war.  But considering the dearth of evidence we have for this kind of behavior in antiquity (and our own preconceived contemporary Western notions of alpha male warriors as different from frail, sickly lepers and powerless, weak women), the discovery of a warrior with leprosy is quite cool.

While I don't want to take away from Rubini and Zaio's fascinating discovery of the leper warrior, I do want to point out their employment of problematic and archaic terminology in discussing skeletal remains.  It surprises me that in the 21st century, anthropologists are still using these racially-tinged terms, and it surprises me even more that the authors claim they've found "Eastern" people with no real evidence of it.


Reference:
ResearchBlogging.org

M. Rubini & P. Zaio (2011). Warriors from the East. Skeletal evidence of warfare from a Lombard-Avar cemetery in central Italy (Campochiaro, Molise, 6th-8th century AD) Journal of Archaeological Science, 38 (7), 1551-1559 : http://dx.doi.org/10.1016/j.jas.2011.02.020


Other References:

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