Micromammals Tell a Mega-Story

Most research in archaeology happens in a lab. Despite the images of sweaty excavators and big hats that come to mind when “archaeology” is mentioned, the bulk of archaeology happens when the digging is done. It’s a truism among project directors that you plan three days in the lab for every one day in the field, but the essential work that goes on behind the scenes is largely invisible to the public.

I’m a zooarchaeologist – an archaeologist who studies animal remains – and I do most of my work in labs. Right now, I’m working at the Muséum national d’Histoire naturelle in Paris, where I study the bones of micromammals like mice and voles. These tiny remains were excavated from Bronze and Iron Age sites on the island of Sardinia (c. 1700-300 BCE), and despite their small size, they help me answer big questions about the cultures I study. Micromammals are sensitive to the environments around them. Different species have particular preferences for habitats and living conditions, which means that identifying the micromammals at a site is a way to reconstruct the site’s environment. And reconstructing the ancient environment is fundamental to understanding everything from past economies to climate change.

I use a microscope to examine bones for evidence of digestion by predators

A typical day of zooarchaeology includes multiple projects. Today, I’m working on three. I begin the day by tackling a taphonomic analysis of the micromammal remains. Taphonomy is the study of how ancient bones are incorporated into archaeological sites, and it includes everything that happens to the bones after the animals die. You can imagine why taphonomy would be important for interpreting ancient bones. Let’s say, for example, that the ancient environment was swampy, so the local micromammals were adapted to wet terrain. But if there were grasslands nearby, an ancient owl could nest in the swamp but hunt in the grasslands, scattering bones of grassland species around its nest. A case like this will give you a confusing mixture of grassland and wetland species showing up together – so what was the ancient environment really like? A careful taphonomic analysis can sort out which species died at the site and which were brought there by predators, helping differentiate the immediate local conditions from the wider surroundings.

Special software lets me capture detailed images of the micromammal teeth

After a morning in front of the microscope recording taphonomic clues, I’m ready to move to my second project. This project uses geometric morphometrics – a kind of spatial statistics – to analyze the shape of micromammal teeth. The shape of the teeth shows genetic plasticity, meaning that it changes depending on which groups of micromammals bred with each other. Looking at the shape of ancient teeth is therefore a way of tracing population dynamics, and when the only way new micromammals get to an island is by sneaking onto ships, ancient micromammal interactions become a proxy for ancient human interactions.

Drawers full of tiny reference skeletons at the Muséum national d’Histoire naturelle

I spend several hours taking images of the micromammal teeth. When I’ve captured images of all of the teeth, I’ll use specially developed software to compare the teeth with each other and with teeth from archaeological sites around the Mediterranean. Capturing the images takes up the major part of my day, but it’s only the beginning. Outlining each tooth so I can compare their shapes will take days. It’s a slow process, and I’ll work on it a little at a time after I return to the states.



I have just about an hour left in my day, so I decide to spend it studying. My third, long-term project is to do an environmental reconstruction for my site in Sardinia – Sa Conca Sa Cresia – which I excavated with my colleague Mauro Perra in 2009-2011. Even though we completed the excavations a while ago, I’ve only recently finished sorting the heavy fraction to remove the tiny micromammal bones. To prepare to do a complete environmental study, I first consult The Atlas of European Mammals to see which species are currently known to exist on the island. Then I visit the Muséum’s reference collections to familiarize myself with the characteristics of these species’ bones – and especially their highly diagnostic teeth.

The number and shape of the cusps make teeth “diagnostic,” meaning they can usually be assigned to a species

By the end of the day, my brain is fried. I cover the microscopes, turn off the lights, and make my way to the metro line 7, then transfer to the 6. I’m in a bit of a daze, but it’s a good kind of exhaustion – similar to how muscles feel after a trip to the gym. It’s an exhaustion that lets me know I deserve to take the night off. And there’s no better place for a night off than Paris. 


Research Takes Forever

Today is the seventh day of my bone study. I’ve been getting up at 5:30 am, arriving at the lab before the sun is above the horizon. The bakery across the street is the only building where the lights are on. I’ve worked seven to ten hours every day since I started last Saturday, and I’ve identified 1028 specimens so far, an average of 146 specimens per day.

When I plan a zooarchaeological study, I estimate that I can do 200 specimens in an eight-hour workday, 25 specimens per hour. Most of the time, I hit this rate. Sometimes I even exceed it. But what I forget is that this is the ideal rate, the rate I achieve after I’m settled into a study, with my database exactly how I want it, my reference materials in familiar locations on my laptop and work table, the measurements I need to take fresh in my mind. I forget that this is not my rate during the first week of the study.

Each bag starts out a jumble

Careful research takes time, and preparing a study is one of the most time-consuming parts. It took me this whole week of working with the specimens to get my database sorted out. I started designing the database before the bones were back in the lab. I made a list of everything I needed to record and how I would record it. It took a full day to create the database in Filemaker, then a second full day to edit and improve it. When I started identifying specimens on Saturday morning, the database included 111 fields. But in the past seven days, it has grown to 125 fields: working with the material has reminded me of important types of evidence that slipped my mind during the design phase. I was still adding fields to the database yesterday, and who knows – I may realize tomorrow there’s yet another field that should be added. But I’m crossing my fingers that I’ve finally hit the point of diminishing returns.

For every specimen I look at, there are 125 types of evidence I may have to record.  I can usually eliminate many after a brief glance. For example, I don’t have to record the circumference of the shaft on a bone that doesn’t have a shaft. But some types of evidence take time to figure out. One of the hard ones is carnivore gnawing. Dogs and other carnivores often gnaw bones, and their teeth leave marks that are fairly easy to recognize on a fresh bone. But when that bone is also gnawed by rodents, then exposed to the elements causing cracking and flaking, then buried and etched by the twisting roots of plants, it becomes much harder to decide whether a particular pattern of indentations comes from the teeth of a carnivore or from some other type of modification, what bone specialists call taphonomic processes.

Then I start to organize – by species, by bone type…

Teasing out taphonomic processes isn’t the only thing that takes time. Today, I had to investigate several bags that had been mislabeled. Figuring out their correct contextual information was a small feat of detective work. Fortunately, I keep good records, but the puzzle had me rereading the project notebook I kept back in 2009-2011 to see exactly which units my team was excavating on – for example – 14 June 2010. Needless to say, I did not average 25 specimens during those hours.

But these are the frustrating things that slowed me down. There were also exciting things. One of the great joys of archaeological research is the unexpected discoveries. As I examined my specimens for signs of taphonomic processes, I also noticed that several showed characteristic burnishing on the points and edges, a sign that they had been used as tools. I bagged and labeled each one and set them aside for a colleague who specializes in analyzing worked bone. Studying bone tool production is new in Nuragic archaeology, and the work my colleague will do to understand the worked bone industry at my site, Sa Conca Sa Cresia (Middle Bronze Age, c. 1700-1450 BCE), will result in only the second publication of its kind. As my colleague says, “È tutto da scoprire” – it’s all to be discovered.

So there are many reasons why research takes forever, but take forever it does. I’m a little nervous looking at the many bags of bones. Will I manage to identify every single one? At this point, I can’t say. But, like a good scientist, I took the time to design my study carefully. I will at least have a statistically significant sample – enough evidence to draw robust conclusions about the animal economy at my early Nuragic site.

And slowly, things come together

Sa Fogaia

The corridor nuraghe Sa Fogaia is one of my favorite monuments in Sardinia for many reasons. Some of those reasons are personal. Sa Fogaia was the first monument I explored on the Siddi Plateau. It was my first experience of the archaeology of the Middle Bronze Age, a fascinating period when the Nuragic Culture was first developing and the social and cultural practices that later became widespread were just being figured out. Sa Fogaia also happens to be located on the edge of a windswept plateau overlooking broad, golden lowlands that are striped by olive groves and dotted with small towns. I can’t deny the exhilaration of emerging from the ancient staircase and gazing out over that view.

The view from Sa Fogaia

But the main reasons I love Sa Fogaia are archaeological. Sa Fogaia is an unusual monument as corridor nuraghi go, which makes it an important reminder that – as useful as broad categorizations are – they can obstruct our understanding of human social processes when we rely on them too heavily.

What do I mean by that? If you read the scholarly literature on corridor nuraghi (which is easier if you read Italian, but there are a few things published in English), you’ll find statements that describe corridor nuraghi as having

“… strong rough stone walls and smaller internal areas…. There is no typical floor plan and some are elliptical, some quadrilateral, and some circular. All of the monuments have an internal corridor which is either straight or elbow (‘a gomito’). The buildings may have two entrances. Sometimes, apart from the corridor, there are other small spaces. It is not rare to find a stone stairway in the corridor, which leads up to an upper terrace. We hypothesize that the original buildings were between eight and fifteen meters high.” (Depalmas and Melis 2010: 169)

This is an accurate summary and serves as a good introduction to the concept of corridor nuraghi, which is what the authors intended to provide (I assign this article as background reading when I bring students to the field). But if – like me – you’re fascinated by corridor nuraghi in particular, you should note an important phrase: “Sometimes, apart from the corridor, there are other small spaces. It is not rare to find a stone stairway in the corridor, which leads up to an upper terrace.” This phrase covers a lot of real architectural variation among corridor nuraghi, variation that is important for understanding social processes among early Nuragic people but that isn’t highlighted when all corridor nuraghi are put in the same category.

I won’t attempt an exhaustive comparison of Sa Fogaia with all known corridor nuraghi – that would be material for a master’s thesis – but I will point out some features that make Sa Fogaia interesting.

Stones in the lower courses of the false-tholos chamber are smaller than those in the upper courses

The first thing to note about Sa Fogaia is its complexity. Most corridor nuraghi are structurally pretty simple, but Sa Fogaia is downright impressive in the number of chambers, corridors, and staircases it includes. Especially impressive is Sa Fogaia’s beautiful “false-tholos” chamber. It is notoriously difficult to photograph inside nuraghi, but this picture shows the important detail of a false-tholos chamber: unlike in a true tholos chamber, where the stones are smaller at the top than at the bottom, the stones in a false-tholos chamber get larger as you build higher, and the great weight of the stones themselves is used to counter-balance the small part of the stone that overhangs the empty space of the chamber. It’s a technique that succeeds in creating a comparatively large open space, but the result is much too massive to allow a second chamber to be built on top of the first. False-tholos chambers are rare, making Sa Fogaia one of only a few examples of how Nuragic architects experimented with construction techniques to arrive at the true tholos style that enabled them to build the multi-story towers of the later Nuragic period.

But the architects of Sa Fogaia didn’t stop after building the false tholos. They couldn’t build more false-tholos chambers on the second story, but they did create an elevated paved terrace that could be used as work or living space (some corridor nuraghi show evidence of huts being built on these terraces), as well as a corridor leading to the remains of a small chamber and two staircases: one that leads down to the courtyard below and one that leads tantalizingly upward, evidence that there was once a third story of some kind.

The staircase leading downward is another important feature of Sa Fogaia. At one point,

The entrance to the staircase was partially blocked with smaller stones

the staircase appears to have lead all the way to the courtyard, but at a later phase the bottom part was blocked up, making it harder to get up to the top if you’re trying to enter the staircase from the courtyard. Dating different phases of stone architecture is extremely difficult, so it’s currently impossible to say whether this change was made during the Nuragic period or during a phase of later reoccupation (and Sa Fogaia hosted a fairly extensive re-occupation in the late Punic and Roman periods). However, it’s interesting to note that this change made the upper part of the nuraghe a little more “exclusive.”

Although we can’t be sure when this change to Sa Fogaia was made, it’s interesting to think about it in terms of other nuraghi in the area. The UNESCO World Heritage site Nuraghe Su Nuraxi is only about 10km away, and Su Nuraxi, though it dates to a later phase of Nuragic development, also shows evidence of changing over time to create greater exclusivity. When it was first built, Su Nuraxi had an entrance at ground level and numerous small openings to the outside, probably to allow light into the structure. But a later refacing wall was built around the entirety of Su Nuraxi, and this wall closed off all the ground-level openings and created a new entrance 7m above ground level. The new entrance could only be reached by a ladder or staircase, and anyone entering the structure then had to navigate a narrow passage through the walls before using a second ladder or staircase to descend into the courtyard.

Spatial exclusivity like this can serve many functions in a society, and it often serves more than one at a time. Exclusive spaces can emphasize the social differences between the people who are allowed in and the people who aren’t, and this in turn can be used to justify unequal power relationships. Exclusive spaces can also be protective: they make it physically difficult for people to get in, both disaffected members of the group as well as hostile outsiders. When we’re speculating about the meaning of spatial exclusivity in nuraghi in particular, it’s important to remember that nuraghi of all periods show great diversity in their construction, including highly varying degrees of spatial exclusivity. It’s impossible to answer the question “what were the nuraghi for” on anything other than a site-by-site or system-by-system basis.

What was once at the top of this steep little staircase?

A final thing I love about Sa Fogaia is how much evidence there is that the structure was once even more complex than we see now. This little bit of staircase is preserved in part of the wall of the courtyard. What it once led to is impossible to say. A small platform? An extension of the second story? Perhaps another terrace? Whatever it was, it’s a reminder that the monument we see now is only part of the original construction. Corridor nuraghi are often treated as a uniform set of structures whose main historical function is to usher in the multi-story towers of the later Nuragic period. This approach is shown in the traditional architectural typology of nuraghi, in which “corridor nuraghi” are usually a single group and only the later tholos structures are divided into “simple” structures with a single tower and “complex” structures with multiple towers. But Sa Fogaia shows that corridor nuraghi also range from the simple to the highly complex, a strong indication that the social interactions that made architectural differentiations important in the later Nuragic Culture were already developing in the beginning.


* Depalmas, A. and R. T. Melis. 2010. The Nuragic People: Their Settlements, Economic Activities and Use of the Land, Sardinia, Italy. In Landscapes and Societies, Martini and Chesworth (eds.), pp. 167-186. Springer Science+Business Media B.V., Dordrecht.

Evening sun shining down the staircase leading up from the false-tholos chamber


In Quest of a Tweet

I’ve been in Sardinia less than two weeks, and I’ve been called out twice for not doing enough to share my research in Italian. It’s a fair criticism. I gave a well-attended public lecture in Italian at the end of the excavation I co-directed with Dott. Mauro Perra in 2009-2011, but since then I’ve done very little. The reasons are complex, and I did offer to give five weeks of public lectures on local archaeology in the summer of 2014, but it was eventually decided that English lessons would be a bigger draw (and I have to say, I delivered my English lessons to a packed house, and many Siddesi still greet me on the street with an accented “how are you”).

But the criticism stands, and the fact is archaeologists face a variety of challenges that can discourage us from speaking directly to the communities where we work. Combatting this issue is one of the missions of Public Scholar Outreach, a non-profit organization that two colleagues and I founded this year. It’s also the reason why the book I’m preparing with Dott. Perra to publish the results of our excavation will have summaries of each of the chapters in Italian. But the book won’t be out for a couple of years, and that’s too long to wait to start redressing this problem.

On my way to Sa Fogaia

Which is why I found myself trekking through Siddi’s countryside at sunset in search of tweet-worthy images of local archaeology. Italy celebrates European Heritage Days this month (September 23/24), and so in honor of Sardinian heritage, Public Scholar Outreach is featuring a full month of bilingual tweets and Facebook posts celebrating the archaeology and history of this beautiful island (follow us @ScholarOutreach).

I set off just after 6pm, phone in hand, to capture the fading light at one of my favorite monuments: the corridor nuraghe Sa Fogaia. Corridor nuraghi date to the early development of the Nuragic Culture during the Sardinian Middle Bronze Age (c. 1700-1365 BCE). They don’t reach the impressive heights of the later tholos nuraghi, but many – including Sa Fogaia – are complex structures with several chambers, multiple stories, and architectural features that suggest successive building episodes. Corridor nuraghi are often treated briefly in the scholarly literature. Few have been well excavated and even fewer published, and in many corridor nuraghi, later reuse destroyed the early Nuragic deposits, so even careful excavation may result in limited new information.

Because the corridor nuraghi are less frequently excavated and their deposits often damaged, our understanding of the early development of the Nuragic Culture is limited. Raising interest in these structures is one way to encourage more research to get done. So I walk. The most direct path to Sa Fogaia climbs a few gentle hills and then rises steeply up the side of the Siddi Plateau, the site of an important Middle Bronze Age settlement system of which Sa Fogaia is only one part. I pass a shepherd and his flock, and we exchange a few words about the coolness of the evening after the painfully hot day. He’s not someone I know, and he seems pleased that a foreigner is on her way to see the nuraghe. “There are lots on the plateau,” he tells me. I nod.


The last few meters up the wooded sides of the plateau

It’s a sweaty climb to the top, but the view, as always, is worth it. Sa Fogaia glows in the slanting sunlight and I get several good photos for Facebook and Twitter. Turning these photos into informative posts and tweets that will encourage people to engage with Sardinian archaeology is a whole other challenge, of course, but tonight I’ve taken an important first step.

Made it!