Archaeology – An Overview

For my final four-field overview post, I want to talk a little bit about archaeology.  You can find some more specific information about bioarchaeology in my previous posts, but there’s far more to archaeology than just the bones!

First and foremost, let’s clarify, archaeology is not the study of dinosaur fossils.  That would be paleontology, which is a subfield of geology.  Archaeology is, broadly speaking, the study of ancient communities through what they left behind–i.e. their artifacts, architecture, their bones etc. It may seem like an obvious distinction, but it’s a mistake made hilariously often.  My supervisor at the American Museum of Natural History volunteered to talk to a kid on a radio show, and this boy was only interested in dinosaur bones. So please learn the difference and save the soul of an archaeologist today.

Much like biological anthropology, archaeology has some pretty iffy roots in colonialism and eurocentricity.  The first ‘archaeologists’ emerged from something called Antiquarianism.  Interest in artifacts, or even bodies, was superficial in the sense that antiquarians were only concerned with aesthetic.  Provenience (the artifact’s location of origin) and context (what the artifact was associated with in situ, including geological features) were incidental to these early ‘archaeologists,’ and whatever deductions were made about these ancient cultures were correspondingly superficial. A PRIME example of the antiquarian archaeologist is Indiana Jones.  Another good way to break an archaeologist’s heart is to compare them to this particular character.  From an archaeological perspective, the boobytraps that Indy nonchalantly destroys are far more informative in regard to the community that created them than the shiny statue!  These early attitudes lead to the pillaging of colonized countries for their national treasures under the guise of ‘rescuing history.’  The Ishtar Gate, which now resides in Berlin, was originally ‘saved’ from Iraq, and the museum even uses this kind of language to justify their continued possession of this beautiful Babylonian treasure.  Even here in merrie olde England, the debate rages on about many of the collections in British museums across the United Kingdom.  The most famous, or infamous really, is the case of the Elgin Marbles. The British Museum came by these sculptures while Greece was under the control of the Ottoman Empire, bought from a man who literally lassoed them down from the Parthenon and sold them for pennies.  Most of the damage done to these statues is not because of age, rather their acquirement by the British.

This is a cringeworthy history, on a social level by stealing the ancient heritage of disenfranchised peoples, and on an academic level because we could no longer examine these artifacts and monuments in context. Thankfully archaeology has come a long way, producing truckloads of theory. With some stops in between, Antiquarianism morphed into Processual Archaeology, meaning that archaeologists began to look at artifacts in order to learn about the culture they came from.  To the Processualists, artifacts were culture manifested outside of the body and could be used to objectively examine the ‘evolution of culture’ through the scientific method. I put the phrase ‘evolution of culture’ in quotation marks as this concept is based upon the erroneous notion that evolution is a strict line of progression, with civilization (i.e. European civilization) as the pinnacle of progress to which every other culture naturally aspires.  Processualism then became Post-Processualism, which emphasizes the subjectivity of the archaeologist when analyzing archaeological remains. To the Post-Processualists, archaeological finds could only be interpreted in relationship to material that exists in the archaeologist’s experience, and in order to gain the most insight, archaeologists must remain as reflexive as possible.  And when archaeology became a subjective practice, it opened up the discipline to all types of different paradigms of analysis. With this mindset, archaeologists could look at artifacts through a Marxist, structuralist, or feminist lens to name a few. And these conversations are still happening today. Some of my thesis is based upon something called Sensorial Archaeology, which deals with the preeminence of the visual in the practice of archaeology, and how problems with the western hierarchy of the senses manifest in excavations.

Hopefully that didn’t put you straight to sleep, although I wouldn’t blame you. The methods used in archaeological excavations and analysis are a bit more interesting, but probably not nearly as exciting as the movies make them out to be. There is a lot of tedious digging in spots where you’ll inevitably find nothing. My first proper fieldwork was the test pitting stage of an excavation run through Cambridge University. It involved wading through endless fields of rapeseed in the rain, with a grim sandwich for lunch, and looking for lithics (manipulated stone) in a field brimming with flint deposits. It was an exercise in character development.

Working on the more advanced stages of an excavation was far more satisfying.  Barring the 5am wake up call, the excavation of a Roman Necropolis in Spain was incredibly enjoyable. Each dig produced finds, as we were trained how to identify the graves before we began troweling. You can see the edges of the tomb beginning to emerge here after 4 days with a literal broom and dust pan.

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From my personal experience, putting eager young undergrads into the field is an entertaining yet probably foolhardy decision.  I was so keen to get to the bottom of the grave that it took every fiber of my being to excavate slowly.  I could see from the grave I had taken over from the previous field school group, that they had suffered from the same problem. There were two individuals in this grave, with one full individual laying supine (on his back), which was a rare find, but in their excitement they had removed the femurs before the skeleton had been fully excavated.

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Look at all the loose femurs!

In these scenarios we need to be careful. A fundamental paradox in archaeology is that we excavate to reveal the context, but in so doing we destroy the context. So each step needs to be documented through field notes and sketches at the very least.  This can be a glacial process that the untrained archaeological student can mess up in a matter of minutes. Nothing is more tempting than to pull out a pesky root as you would when gardening, but roots are sneaky and you cannot risk damaging any artifacts they may have grown through by pulling them willy nilly. And as a novice I was so excited to do things like cranial reconstructions, but the taphonomy that lead to the breakage of the skull in the first place is just as much part of the context as anything else in the grave, and so it’s actually frowned upon now to glue pieces of the skeleton back together.  Undergrad Sarah didn’t understand that the reconstructed skull on the left was actually inferior to the one on the right held together by soil.

Forensic anthropology is, of course, a bit different because if we reconstruct a cranium we can then attempt a facial reconstruction or to match dental records. And in the instances when we do find relatives to return the skeleton to, a full skull helps to humanize the skeleton–which is incidentally another aspect of my doctoral thesis!

Have any questions about archaeological theory or methods?

As always, ask away!

 

 

Who were the Neanderthals?

After several weeks of eager anticipation, yesterday was finally the day.

Yesterday I received my results for 23andMe, the DNA analysis programme that gives you the lowdown on your ancestry and any genetic health risk factors you may carry.
And while my results were pretty much as I suspected, I found out something pretty cool. According to 23andMe, 2.6% of my genes come from Neanderthals!
Now that’s actually slightly lower than average for someone with who is predominantly European. But what exactly are Neanderthals and why are they so cool?

If you managed to take a look at my post about evolution from last week, you’ll remember that anthropologists have actually found a number of our evolutionary ancestors. Most of these ancestors died out before anatomically modern humans were on the scene — but not so with the Neanderthal! We had a pretty significant overlap, which we clearly made the most of in a reproductive sense. As we (humans) could successfully mate with Neanderthals, this makes us fellow subspecies of human. Modern humans are known as Homo sapiens sapiens, and Neanderthals are known as Homo sapiens neanderthalensis. There has been a lot of back and forth between their species classification, but the DNA evidence proves we could and did mate with them, so they are absolutely positively a subspecies.  So if anyone, including an anthropologist, gives you flack for this subspecies attribution–send them to me.
Neanderthals are called this because the first fossil associated with the subspecies, or holotype, was found in the Neander Valley in Germany. Although other Neanderthal remains had been found before this, they were only later categorised as such.  Here is the geographical area that Neanderthals were thought to inhabit courtesy of Wikipedia:

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So what makes a Neanderthal different from a modern human? There are a few notable differences.
Neanderthals had prominent supraorbital tori and occipital buns, meaning that their foreheads and the base of their skulls were quite large. And because their skulls were shaped differently, their brain architecture was also different. In fact, their cranial capacity was higher than ours, but because the parts of the brain responsible for speech, like Broca’s and Wernicke’s areas, were smaller in Neanderthals they would not have had the same capabilities for language.
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Image source 

In this sense, the stereotypical grunting caveman is correct. BUT there are several studies that indicate their hyoid bone, the bone in our throat, was situated higher than ours. This would make their voices correspondingly higher! So imagine a caveman with a high pitched grunt instead.
Neanderthals also had larger nasal apertures (where your nose goes). This is an adaptation to cold weather, as the air they breathed through their noses was warmed more effectively before entering their lungs. And we can still see a similar adaptation in populations from colder climates, although not as big as the Neanderthals.

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Image source Fun fact: this is Gibraltar I, and my absolute favourite. I grew up with a cast of it in my house.

Neanderthals were barrel chested and their arms burly. This has been attributed to spear thrusting but also to the scraping of animal skins. Click here for some interesting reading on the subject.

As part of the genus Homo, Neanderthals were tool makers and are also thought to have made clothing, the only other animal to have made clothing besides us.

This brings us to the question of cultural diffusion.  We know that humans and Neanderthals were living near each other and having sex, what we don’t quite know is how much influence there really was between the two groups in terms of material culture. We can identify tool making techniques that are associated with one subspecies or the other, what is slightly strange is that there seems to be little or no crossover–even when we know they were interacting with each other.  Some anthropologists argue that this makes us different species, but that is a remnant of archaic palaeoanthropological theory (more on that later).

Some anthropologists posit that the reason why humans eventually outlived Neanderthals is that we are better at learning new techniques and thinking outside the box, and Neanderthals just couldn’t keep up. But it’s still unclear. We may have just killed them all off. What we know is that they went extinct about 40,000 years ago.

Have any Neanderthal related questions? Let me know!

Question re: Sticks and Stones

A good friend of mine, Nicole, has asked a great question about the post Sticks and Stones: Basics of Skeletal Trauma.

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She says: “Love this! Also if this is the superior view would you say that the trauma occurred along any suture lines? Also out of curiosity, which bone of the skull is pictured?”

Thanks for the question, Nicole! This gives me a great opportunity to talk a little bit about the anatomy of the skull.

As the original picture only shows a bit of the skull, I’ll bring in my lovely assistant!

Here is Stan the Standard Scientific Skeleton. And here is the top of Stan’s head.

You can see that this image of Stan’s head corresponds to the left side of the image above Nicole’s question.  I’ll just take the top of Stan’s head off to make it easier to handle.

Cool. If you look carefully, you’ll see something on Stan’s skull that you can’t see on original skull. Those squiggly lines are called sutures. These sutures connect the different bones of the skull. Yes, the skull contains multiple bones! When we’re born, in order to fit through the birth canal and then give our brains enough room to grow, our skulls are divided into many different pieces. As we get older, these bones grow and then fuse at these suture lines. This is why babies have soft spots, or what anthropologists call fontanelles. Their skulls aren’t fused yet.

Nicole wants to know if the trauma on the first skull involved these sutures, and which bones of the skull are pictured.

The bones of the superior aspect of the skull are as follows:

One frontal bone (pictured pointing downwards here), two parietal bones, and the top bit of the occipital bone.

The angle of the trauma to the first skull looks approximately this. The frontal bone is now facing upwards.

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As you can see, there are two sutures involved. The vertical suture, called the saggital suture, is cut transversely.  The horizontal suture, called the coronal suture, is impacted on the right.

But why are the sutures visible on Stan and not the first skull?  Well there are two options.

As we get older the sutures fuse, but it doesn’t just end there! Often the sutures will begin to fade and become obliterated. Sometimes anthropologists will use the level of fading to establish age at death. Buuuuut they shouldn’t. Sometimes the sutures don’t fade at all, and they certainly never fade on a predictable timeline.

The second option might be that the surface of the bone is poorly preserved.

As I don’t currently have access to the bone in question, I can’t confirm, but looking at the picture I suspect it’s a mix of both.

Thanks Nicole!

Sticks and Stones: Basics of Skeletal Trauma

What you’re looking at above is the superior aspect of a human cranium, i.e. the top of someone’s head.

If your first thought was ‘holy hell, what happened to that poor guy?’ well done. You have the makings of a human osteologist.  The answer is what forensic anthropologists and bioarchaeologists call sharp force trauma, or when a sharp object injures tissue.  This unfortunate fellow was most likely the victim of a broadsword attack.

There are several types of trauma that we can see in human bone. When the injury is caused by a blunt object we call it blunt force trauma.  When the injury is caused by a projectile, like a bullet, we call it projectile trauma.  Pretty self explanatory.

Trauma is classified as antemortem (before death), perimortem (at the time of death), or postmortem (after death).  We can tell when an injury occurred by looking for remodeling, by looking at the manner in which the bone was broken, and by the colouration of the trauma itself.

Remodeling, which is the term for bone healing, will only be present in antemortem injuries.  If we can see remodeling, the injury must have happened before death.  This is the reason why doctors must set bones.  Bones are smart and will try to heal themselves, even if they are no longer aligned. So we find individuals with bones like this:

 

We can also look at how the bone actually broke. The bones in living bodies, which are considered wet bone, react to force differently than long dead bone, or dry bone.  When we see fractures that could have only happened to wet bone, we know that the trauma was antemortem or perimortem.  Greenstick fractures are an excellent example of this.  Much in the same way that a stick is easier to break in half if it’s dead, so is bone.  The wet, fragmented bone will stick together like a twig from a living tree.

(Access the original image and some complicated reading on trees here)

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Here you can see a greenstick fracture of the fibula (original image)

Comminuted fractures are another good example. This is when a fracture contains multiple fragmented pieces of bone. Below is an example of a comminuted fracture created by blunt force trauma.

This would never happen to dry bone, as it would simply shatter the skull.

In less clear cases, we can look for differences in the colouration of the fracture and the surrounding bone.  If the fractured area is lighter, it usually means that it has not been exposed to the elements as long and has therefore occurred after death in the grave or after excavation.  When damage happens after a person has been buried it’s called the taphonomic process, when it happens after excavation we call it students.

 

For more information about skeletal trauma, as always, feel free to comment or follow up in a message!

A Bone to Pick: Basics of Palaeopathology

Palaeopathology is the study of ancient diseases, trauma, disability etc. by examining human remains. Like forensic anthropologists, palaeopathologists also work with a degree of uncertainty. When most of our data comes from the examination of human bones, there are specific limitations we must contend with.

Bone can only react in one of two ways when something is wrong; the bone tissue can either grow or it can resorb. Both bone growth and resorption are normal and happen throughout your life–this process is caused by cells called osteoblasts and osteoclasts–but disease, trauma, and malnutrition can create abnormal formations of bone called lesions. The lesions formed by excess bone growth are called proliferative, and lesions formed from resorption are called lytic.

Each disease will affect bone in slightly different ways, that is if they affect the bone at all. But because of these limited types of bone reaction, certain diseases can look very similar. For example, scurvy and cribra orbitalia are both characterised by lesions in the orbitals (eye sockets) which can be hard to distinguish without training and practice.

Scurvy is a metabolic disease caused by a lack of vitamin C. As our bodies need vitamin C to form collagen, and our blood vessels require collagen for structural stability, the capillaries in the eye sockets of those with scurvy begin to bleed. The presence of blood in the orbit stimulates new bone growth and creates proliferative lesions.

Cribra orbitalia, which is often attributed to iron difficiency anaemia (rightly or wrongly is still up for debate), is charaterised by lytic lesions in the same area.

Below are pictures of both conditions, can you tell which one is which?

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These are excellent examples of each type of lesion, so this is pretty much as easy as it gets. Most presentations of these lesions will be less pronounced, more fragmented, or both. Which makes our job a bit harder.

You can check your answers and access the original images here and here.

Too easy? Let’s try this one:

Do these skulls all feature the same pathology? Or are there two pathologies? Or even three?

What differences in these lesions, if any, can you observe?

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Hint: there are two diseases and one trauma featured above. Can you tell which ones are which?

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The first skull is an example of caries sicca, a major sign of venereal syphilis.

The second skull has a penetrating gunshot wound to the forehead.

And the third skull is an example of lesions associated with calvarial tuberculosis.

We can differentiate all of these conditions by looking at the remodeling (healing) process, or the origin of the lesion–for example, did it start inside the skull and move outwards or start on the surface and move inwards?

Another practical issue palaeopathologists face is something called the osteological paradox.  And while this term seems big and scary it’s actually pretty simple.  In order for a disease to show up in the bone, it has to be around long enough in a living body. We call this kind of disease chronic.  If a disease is too deadly and kills a person quickly, it won’t have time to affect the bone.  We call this kind of disease acute.  Therefore, when we see an individual from an archaeological site with a pathology, we know that actually this individual was probably one of the healthier ones. So ironically, when palaeopathologists study pathology, we’re usually studying the healthier individuals of a community.  This can be problematic when trying to ascertain general health trends and quality of life.

 

If you’re interested in the diagnostic criteria for any specific diseases or want more info about bone biology, keep your eye out for upcoming posts or comment below!

Forensic Anthropology – An Overview

The research I’m doing for my doctoral thesis falls under Forensic Anthropology, which means I specialise in the analysis of the human skeleton and I apply this in a legal context. The human skeleton can tell us a lot, but more often than not skeletal evidence leaves us with many unanswered questions.

Forensic anthropology is a science of last resort.  In an ideal forensic world, evidence is plentiful, victims are easily identifiable, and crimes investigated as soon as possible. Never do any of these things happen in forensic anthropology.  We are called in when the death occurred so long ago that the body has decomposed and traditional methods of identification no longer work. And because we’re a science of last resort, we operate with a certain level of uncertainty. We can measure things such as biological sex, age at death, past trauma, certain types of diseases, stature, but all of these within broad boundaries. We very rarely use skeletal remains to try and identify race anymore, as there just isn’t enough evidence that those methods actually work.

When we look at a pelvis to determine biological sex, for example, we rank on a spectrum how female or how male certain parts appear.  This spectrum is Very Male, Somewhat Male, Indeterminate, Somewhat Female, Very Female. Notice how we do not say “definitely female or definitely male.” So here is a human pelvis:

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We can look at the sub-pubic angle, shown at the base of each pelvis, for an indication of sex. When it’s narrow (left) we would label this Very Male, and when it’s wide (right) we would label it Very Female.

Looking at age can be even more vague! When we’re dealing with children we can be specific to within a couple of years, but past 25 it all goes downhill and we start giving age ranges in decades.  To further compound the work of the forensic anthropologist, most research that has been done to establish these methods of analysis has been done in population specific studies.  Now this can be great if you’re looking at a specific population that has been researched already, but in an increasingly globalised world much of this research is obsolete from a practical point of view.

Something more helpful in a forensic investigation would be using knowledge of past trauma or an illness which we can see in the skeleton. Like a broken arm or cancer. But this raises issues for anyone studying poor victims who have no medical or dental records to work from. And this is critical as it creates a socioeconomic disparity within the discipline. After the Indian Ocean Tsunami of 2004, victims with dental records were positively identified at a significantly higher rate, as dental analysis was the primary method of identification. But the majority of local victims did not have any dental records. One year later, 1252 European individuals were successfully identified with dental records compared to only 21 Thai victims. In these cases, we can ask surviving relatives for what’s called ante mortem evidence—that is evidence from before death including stories, testimonies, medical histories.

Usually at this point people ask about DNA evidence. It’s totally possible to do DNA analysis but it comes with its own set of problems. First, you need to have willing living participants to compare the DNA to and outreach to survivors can be limited, it’s expensive, and the DNA really doesn’t hold up too well over time. You need to have very specific samples from the skeleton and sometimes those just aren’t available because of the decomposition process, or because remains have been moved by perpetrators and are found incomplete. It also raises certain ethical questions. A forensic anthropologist at a conference over the summer gave a presentation about how DNA testing had revealed infidelity during investigations of mass graves in Iraq. Our first and foremost obligation is to the safety and wellbeing of our research participants, and as you can imagine this caused serious problems for them.

I work in mass grave contexts, specifically post genocide.  If that weren’t grim enough, there’s a whole other set of problems specific to mass graves.  In forensic anthropology, we usually look for something call Minimum Number of Individuals (MNI).  Notice how we don’t look for Actual or Estimated Number of Individuals. There are 206 bones in the adult human body, so we need to assume that if we find 206 bones in a grave that it’s one person not 206.  Sometimes the best we can do is put the pieces from the grave together until we get as many nearly complete skeletons as possible, and this means that we will inevitably miss individuals.   And in the case of genocide, often people are targeted for being from a specific genetic group or region, or because they look like they’re from that genetic group or region.  And those physical similarities can make identification of specific individuals that much more difficult.

For more information about the methodologies used by forensic anthropologists, keep your eye out for upcoming blog posts. But as always, feel free to ask any questions you may have in the mean time!