Palaeopathology and beyond

WARNING: contains a photo of archaeological human remains.

Hello everyone,

I’m Laura Castells and I am the new osteoarchaeologist for the COMMIOS project. As Charlie explained, us osteoarchaeologists are concerned with the analysis of human remains which usually involves the assessment of sex, the estimation of age and stature and the analysis of trauma and pathologies observable on the remains.

But this is just the beginning.

There are two ways to analyse that data: we can deep-dive into the analysis of one individual in what we call ‘osteobiographies’ or we can bring together all the available data for all the individuals and try to tease out population and chronological trends (i.e. who was suffering from what and what this might tell us about social structures and dynamics). But are these two ‘perspectives’ truly independent? Are we individual monoliths who develop diseases, or are we part of a much bigger network and thus our health is influenced by what happened before us and what happens around us?  

This is where pathology stops being recorded for curiosity’s sake and starts being a tool to understand life and societal dynamics. But for it to become a valuable tool, we must first understand how these diseases develop and, this my friends, is the first huge boulder in our path.

Two boulders, really: the first is that bone responds in very limited ways to injury or disease, so it’s very possible that different pathologies may result in similar-looking lesions. This means that we have to depend on the lesion distribution throughout the skeleton, the biological characteristics of the individual and their societal and archaeological context to be able to offer a diagnosis (which, in many cases, even when bone preservation is excellent, will be tentative). An example of this is periosteal new bone formation or periosteal lesions: a layer of new bone with an open and sponge-like appearance which appears when the periosteum (the connective tissue that envelops every bone) is irritated. Periostosis can appear as a marker of unspecific infection or inflammation (Dewitte and Bekvalac, 2011) or it can be associated with a specific pathology like leprosy (Ortner, 2003). Whilst the lesions themselves can be very similar (Figures 1 and 2A), it is their distribution and the combination of periostosis with additional bone changes in leprosy that allows the distinction to be made between them.

Right femur, thigh bone, of a juvenile individual from the Roman cemetery of Santa Caterina (Barcelona, Spain). In the middle of the shaft it has a darker patch of porous bone diagnosed as an unspecific periosteal lesion

Figure 1: Unspecific periosteal lesion (arrow) on a right femur of a juvenile individual (UF 726) from the Roman period cemetery of Santa Caterina (Barcelona) curated at the Barcelona History Museum (MUHBA). (Photo by LCN).

A. Distal halves of tibia and fibula, shin bones, of a young individual from the Roman cemetery of Santa Caterina (Barcelona). The bones are covered in a layer of bone with open holes characteristic of periosteal lesions. 
B. First, second and third metatarsals,   long bones of the foot, of the same individual. The bones have been remodeled, tapering towards the end, and are half the size they are expected to be. 
The combination of the periosteal new bone and the deformation of the metatarsals suggest a likely diagnosis of leprosy.

Figure 2: A. Periosteal lesions (black arrows) at right tibia and fibula of a young adult individual (UF710) from the Roman period cemetery of Santa Caterina curated at the Barcelona History Museum (MUHBA). B. These periosteal lesions were accompanied by remodeling and resorption of the metatarsals (and facial lesions not shown here), thus the diagnosis of leprosy is the most likely. For reference to the right, a drawing of the normal shape of bones (modified from Standard Anatomy, CC BY-NC 4.0). The numbers in the image and the drawing indicate 1st, 2nd and 3rd metatarsals. (Photo by LCN).

So far, so good – we can, mostly, do this.

The second boulder is that (sadly) for most of the lesions that we see on bone, we have only a simple understanding of their cause and how they develop. So, it’s not uncommon for the interpretation of a lesion to change or be associated with a myriad of conditions. Good examples of these are cribra orbitalia and porotic hyperostosis, which are clusters of pores at the orbital roof and the cranial surface, respectively (Figure 3). These have traditionally been associated with iron deficiency anaemia, but more recently been linked to a plethora of metabolic deficiencies associated with malnutrition and poor living conditions (Walker et al., 2009), possible childhood anaemia (Brickley, 2018), malaria (Schats, 2021), and respiratory infections (O’Donnell et al., 2020), among others.

Inferior view of the frontal bone of a young adult male individual from the post-medieval cemetery of Sant Cugat del Rec (Barcelona). At the roof of the eye orbits, it shows a cluster of porous of less than a millimeter in diameter diagnosed as cribra orbitalia.

Figure 3: Bilateral cribra orbitalia (black arrows) in a young adult male individual (M3) from the post-medieval cemetery of Sant Cugat del Rec (Barcelona) curated at the Barcelona History Museum (MUHBA). (Photo by LCN).

How do we disentangle this? I hear you ask.

Well.

With patience (first) and then considering where the knowledge of the pathology stands in terms of clinical, physiological and metabolic research, and (again) bringing together as much information about the individual as possible. For example: are there other lesions in other parts of the skeleton? How old was the individual? What do we know about their living conditions? And sometimes, we’ll need to stop here and recognise the limitations of our understanding and that maybe the best we can say (for now) is that these porotic lesions may be non-specific lesions associated with nutrient deficiency which can easily increase susceptibility to infection and, indeed, each feed of the other.  

Add another boulder, I hear you request?

Sure, let me present to you the Osteological Paradox. Until Wood and colleague’s (1992) paper, the interpretation of pathology had been considered fairly straight forward: more pathology – worse health. However, they argued that the relationship between health, risk of death and mortality was slightly more conceptually complex when they noted that: ‘the presence of a healed lesion indicates survival of a disease process earlier in life and thus may signify an individual whose frailty is low compared with those who died at earlier ages’ (Wood et al. 1992, 352). Or in other words: were those who died without any visible pathology actually healthy? Did they die of a disease that left no mark on the bone? Or did they die of a condition that could have left marks on the bone but the person died before the bone became affected?

Oh, the joys of being an osteoarchaeologist.

How does this not deter us from doing research in palaeopathology?

Now that I read what I have written, I find this to be a good question. But one that I can only answer for myself.

I believe that, despite the conceptual and technical complexities, palaeopathology and analysis of archaeological human remains is still the most direct way we have of exploring communities and individuals: who they were and how they lived. Basically, because we are asking them. So, for my part, I recognise, embrace and work with these boulders, because this is the only way to really explore what I am most interested in: how identity and life history, socio-economic context and environment of an individual may impact their health.  

This may seem a bit of a jump, so to help us we use theoretical approaches (often borrowed from medical and social sciences as well as public health, ta) to frame our analysis and interpretation. Here I will only explore two, intersectionality and syndemics, but there are others, such as Developmental Origins of Health and Disease (Gowland, 2015) and One Health + One Health Approach (e.g.Urban et al., 2021), which are well worth keeping in mind.

First, intersectionality recognises that identity is the combination of multiple axes of identity that exist within a single individual such as age, sex and sexuality, gender, socio-economic status, ability, ethnic group. These overlap and interplay creating and preserving social inequality and discrimination (Crenshaw, 1989), thus contributing to the individual life experience and, equally important in our discipline, impacting the individual’s health (Mant et al., 2021). Meanwhile, syndemics recognises the compounding effects of biological, environmental and social factors such as poverty, poor nutrition and stress on community and individual health (Larsen and Crespo, 2022, Perry and Gowland, 2022). The combination of intersectional and syndemic approaches, therefore, considers that our own health, as well as that of those who lived many centuries before us, is not an isolated factor but is the result of the interaction between biological, social and environmental factors and variables.   

Fair enough, but what does this really mean for COMMIOS?

When studying archaeological human remains such as the communities from Iron Age Britain, it is a reality that some of these axes and factors will be invisible to us. But we can still try to grasp as many aspects of identity as possible by combining the information obtained from macroscopic analysis of the remains (i.e. age at death, biological sex and pathology) and combine it with the mobility, diet and kinship information obtained from isotope and ancient DNA data. Equally, we can explore social and environmental contexts by gathering information on burial and archaeological context, as well as environmental data. In juggling all this data, we can start exploring questions such as:

  • Given the diversity in burial practice, can we get a better picture of who was buried where, and if, for example, type of burial is related to social status?
  • Can we see differences in social structures? And if so, do these different structures have any impact on the health of their members?
  • In the British Iron Age there are communities living all over the islands: is it the same to live in Iron Age Cornwall as Yorkshire? Which are the health trade-offs for those communities living in harsh environments (such as wetlands or areas with arid soils)?

So, to go back to the beginning: humans are certainly not monoliths but the result of complex interactions between ourselves and our environment (understood in its broadest terms). Therefore, palaeopathology is not about identifying interesting diseases, but it is the exploration of what these pathologies (in combination with every other bit of data) can tell us about those who lived before us.       

References

BRICKLEY, M. B. 2018. Cribra orbitalia and porotic hyperostosis: A biological approach to diagnosis. American Journal of Physical Anthropology, 167, 896-902.

CRENSHAW, K. 1989. Demarginalizing the Intersection of Race and Sex: A Black Feminist Critique of Antidiscrimination Doctrine, Feminist Theory and Antiracist Politics. The University of Chicago Legal Forum, 140.

DEWITTE, S. N. & BEKVALAC, J. 2011. The association between periodontal disease and periosteal lesions in the St. Mary Graces cemetery, London, England A.D. 1350-1538. American Journal of Physical Anthropology,, 146, 609-18.

GOWLAND, R. L. 2015. Entangled lives: Implications of the developmental origins of health and disease hypothesis for bioarchaeology and the life course. American Journal of Physical Anthropology, 158, 530-540.

LARSEN, C. S. & CRESPO, F. 2022. Paleosyndemics: A Bioarchaeological and Biosocial Approach to Study Infectious Diseases in the Past. Centaurus, 64.

MANT, M., COVA, C. & BRICKLEY, M. B. 2021. Intersectionality and trauma analysis in bioarchaeology. American Journal of Physical Anthropology.

O’DONNELL, L., HILL, E. C., ANDERSON, A. S. A. & EDGAR, H. J. H. 2020. Cribra orbitalia and porotic hyperostosis are associated with respiratory infections in a contemporary mortality sample from New Mexico. American Journal of Physical Anthropology, 173, 721-733.

ORTNER, D. J. 2003. Identification of pathological conditions in human skeletal remains, Academic Press.

PERRY, M. A. & GOWLAND, R. L. 2022. Compounding vulnerabilities: Syndemics and the social determinants of disease in the past. International Journal of Paleopathology, 39, 35-49.

SCHATS, R. 2021. Cribriotic lesions in archaeological human skeletal remains. Prevalence, co-occurrence, and association in medieval and early modern Netherlands. International Journal of Paleopathology, 35, 81-89.

URBAN, C., BLOM, A. A., PFRENGLE, S., WALKER-MEIKLE, K., STONE, A. C., INSKIP, S. A. & SCHUENEMANN, V. J. 2021. One Health Approaches to Trace Mycobacterium leprae’s Zoonotic Potential Through Time. Frontiers in Microbiology, 12.

WALKER, P. L., BATHURST, R. R., RICHMAN, R., GJERDRUM, T. & ANDRUSHKO, V. A. 2009. The causes of porotic hyperostosis and cribra orbitalia: A reappraisal of the iron-deficiency-anemia hypothesis. American Journal of Physical Anthropology, 139, 109-125.

WOOD, J. W., MILNER, G. R., HARPENDING, H. C., WEISS, K. M., COHEN, M. N., EISENBERG, L. E., HUTCHINSON, D. L., JANKAUSKAS, R., CESNYS, G., ČESNYS, G., KATZENBERG, M. A., LUKACS, J. R., MCGRATH, J. W., ROTH, E. A., UBELAKER, D. H. & WILKINSON, R. G. 1992. The Osteological Paradox: Problems of Inferring Prehistoric Health from Skeletal Samples [and Comments and Reply]. Current Anthropology, 33, 343-370.

Behind the paper: mobility and migration in Bronze and Iron Age Britain

WARNING: contains a photo of archaeological human remains.
This article relates to Maddy Bleasdale and Claire-Elise Fischer’s joint first-author poster.

Recently the COMMIOS team, along with many other institutions and authors, published the largest aDNA study to date! We generated genome-wide data for a staggering 793 archaeological individuals (Patterson et al., 2022). But what did we find? And why is it important?

Early European Farmer (EEF) Ancestry

Genetic data has shown that present-day people from England and Wales have more Early European Farmer (EEF) ancestry than people from the Bronze Age – but when did this happen? By analysing hundreds of individuals from across a large time transect we tried to find out! The  skeletons were analysed at the Reich Lab at Harvard Medical School, USA.

The genetic results revealed that the increase in EEF ancestry occurred between the Middle c.1600 – 1200 BC) and Late Bronze Age (c.1200-700 BC), but did not affect all regions to the same extent, as the increase in EEF ancestry was not detected in Scotland. Once this was established, we quantified this component in all samples and were able to determine an average for each period – this is shown in Fig. 1 (graph) on our poster. With these values, we were able to identify individuals who are ‘outliers’, i.e. their genetic signature differs from what would be expected for a given region/period. 

Interestingly, we noticed that many of the so-called genetic ‘outliers’ were found in Kent. Previously published mobility isotope results also showed non-local individuals at several of the sites sampled in the aDNA study (Millard, 2014; Millard & Nowell, 2015). Due to its geographical position and the archaeological data, this area has already been identified as an important contact zone between Britain and the continent. But now we want to look even closer at this region and try to answer: what was the nature of these migrations? And can we see any differences related to age, sex (and possibly gender)?

The gateway to the continent: ‘the eastern route’

Archaeological evidence for Kent as a contact zone dates back to at least the Neolithic period, called ‘the eastern route’ by T. Allen (Allen, 2012). A significant archaeological find that encapsulates this cross-channel trade and exchange, is the Dover boat, which is a magnificent Bronze Age shipwreck which is around 3500 years old. Kent occupied a major position in the bronze trade, linking tin from Cornwall with copper from across the UK and areas of France (e.g.  the Haut-Rhin), and later lead from Wales. Thus, it is argued that an extensive and complex system of intercontinental trade and logistics existed at the end of the Bronze Age, with coastal Kent sitting at the heart of the North European intersection of major trade routes (Allen, 2012)

At a broad-level, archaeological and genetic data has revealed that Kent was an important contact point.

The Dover Boat, https://100objectskent.co.uk/object/bronze-age-boat/

How can genetics contribute to identifying the origin of individuals?

This is what we call phylogeography. In Europe, current populations are made up of 3 principal components: the hunter-gatherer component, the Anatolian component brought by the first farmers during the Neolithic period, and the Steppe component, also called Yamnaya, brought by pastoralists from the Pontic and Caspian Steppes at the end of the Neolithic/beginning of the Bronze Age (Allentoft et al. 2015; Haak et al. 2015; Olalde et al. 2018). What changes, however, is the proportion of each component within the populations. What is true for modern populations is also true for older populations. At least after the Neolithic-Bronze Age transition.

If we look at a PCA (Principal Component Analysis) with modern-day populations and the Bronze Age and/or Iron Age populations, we notice that the ancient individuals fit into the variability of the modern populations. For example, Iron Age samples from France fall into the diversity of modern French populations, and there is a genetic structure linked to geography with, for instance, French samples occupying an intermediate position between Great Britain and Spain (Fischer et al., 2022). On a basic level, this data can allow us to identify ‘outliers’: the Margetts Pit individuals from Kent (Fig. 2 in poster), for example, plot closer to the Bronze Age populations from Germany or France…so that’s the first clue! 

We can then carry out more detailed analyses, such as f3-statistics, which allows us to measure the affinity between two given populations. We can assess whether the Margetts Pit samples have more similarities with populations in England, France, Germany, etc. We can also use qpWave which can tell us if, in relation to a model with X components (e.g. hunter-gatherers, Anatolian farmers and Yamnaya from the Steppes), two populations form a clade*, i.e. if they can be explained by the same model. We can also apply qpAdm, which works on the same principle but, in addition, tells us the percentage of each component! We can also test, for instance, whether the Bronze Age populations of a given region can be used to explain the Iron Age populations of the same region. It was through this kind of analysis that we were able to determine that there was an influx of new populations into England during the Middle to Late Bronze Age. 

We carried out these analyses for individuals from Kent, particularly from Margetts Pit. It turns out that these individuals do not form a clade with the other Bronze Age individuals found in Kent. However, they do form a clade with the Bronze Age individuals from the south of France. And that’s also reflected in the PCA. Therefore, we are beginning to generate several lines of evidence to discuss the geographical origin of these individuals. 

What’s pretty cool is that for some of the outlier individuals, the isotopic data obtained in previous studies have also shown evidence of mobility…

What can the isotope results tell us about mobility?

Previous isotope work using strontium and oxygen has identified a number of ‘non-local’ individuals at archaeological sites in Kent. Most notably, the site of Cliffs End Farm shows a high degree of variation in human oxygen values with many individuals having values that are not consistent with having grown up in Britain. 

Published data from Cliffs End Farm (Millard 2014, Figure 4.11). Strontium isotope values against drinking water oxygen values. Note that individual 3673 on the left hand side of the plot is not in the ‘local’ range for oxygen.

Our poster highlights one individual in particular – ‘bundle burial’ 3673 from Cliffs End Farm. 

This individual was an adult male (~30 years old) who was transported to the site already in a partly decomposed state (i.e. in a ‘bundle’). They were buried on top of a cow’s foot along with an as-yet-unique object consisting of a copper ring and worked piece of bone, which may have been some sort of pendant. 

LEFT: Plan of Cliffs End Farm Late Bronze Age communal grave 3666 containing individual 3673. Image taken from poster by Wessex Archaeology.  RIGHT: photo of individual 3673 ‘bundle burial taken from article by Wessex Archaeology. 

Tooth enamel analysed from this individual gave a strontium value that fits within the range for the UK but their oxygen value is consistent with somewhere north or east of Britain (Alpine areas of Europe, or Scandinavia) (Fig.3 in poster). 

Isotope methods used to look at mobility such as strontium and oxygen are best viewed as exclusion methods (they can tell us where a person isn’t from) rather than an “x marks the spot” approach. This is why it is common to use different isotopes to try and help form an interpretation of an individual’s likely origin. We can also combine isotope results with genetics too! Now we know this individual has a high EEF ancestry value we have proposed it is more likely they came from Europe (potentially an Alpine area).

So, what next?

The COMMIOS team plan to continue to bring together all the available results (archaeological, funerary, genetic, isotopic, osteological, etc.) for Kent to figure out who these individuals were and where they came from. 

We also plan to do some new work too! In addition to applying these methods to sites not yet analysed for ancient DNA or isotopes, we also want to conduct more isotope work at the site of East Kent Access Road (previously only 4 individuals were analysed – see Millard 2014). And plan to conduct a pilot study using lead (Pb) analysis on some isotopic outliers from Cliffs End Farm.  

We are all very excited to see what new results our work will yield!

References

Allen, T. (2012). Bronze, Boats and the Kentish seaboard in prehistory: the role of coastal Kent in a major trans-continental trade route. Archaeologia Cantiana, 1, 1–21.

Allentoft, M. E., Sikora, M., Sjögren, K.-G., Rasmussen, S., Rasmussen, M., Stenderup, J., Damgaard, P. B., Schroeder, H., Ahlström, T., Vinner, L., Malaspinas, A.-S., Margaryan, A., Higham, T., Chivall, D., Lynnerup, N., Harvig, L., Baron, J., Casa, P. D., Dąbrowski, P., … Willerslev, E. (2015). Population genomics of Bronze Age Eurasia. Nature, 522(7555), 167–172.

Fischer, C.-E., Pemonge, M.-H., Ducoussau, I., Arzelier, A., Rivollat, M., Santos, F., Barrand Emam, H., Bertaud, A., Beylier, A., Ciesielski, E., Dedet, B., Desenne, S., Duday, H., Chenal, F., Gailledrat, E., Goepfert, S., Gorgé, O., Gorgues, A., Kuhnle, G., … Pruvost, M. (2022). Origin and mobility of Iron Age Gaulish groups in present-day France revealed through archaeogenomics. iScience, 25(4), 104094.

Haak, W., Lazaridis, I., Patterson, N., Rohland, N., Mallick, S., Llamas, B., Brandt, G., Nordenfelt, S., Harney, E., Stewardson, K., Fu, Q., Mittnik, A., Bánffy, E., Economou, C., Francken, M., Friederich, S., Pena, R. G., Hallgren, F., Khartanovich, V., … Reich, D. (2015). Massive migration from the steppe was a source for Indo-European languages in Europe. Nature, 522(7555), 207–211.

Millard, A. (2014). Isotopic Investigations of Residential Mobility and Diet. In McKinley, J., Leivers, M., Schuster, J., Marshall, P., Barclay, A.J., Stoodley, N (Ed.), Cliffs End Farm Isle of Thanet, Kent. A mortuary and ritual site of the Bronze Age, Iron Age and Anglo-Saxon Period (pp. 133–144). Wessex Archaeology Ltd.

Millard, A., & Nowell, G. (2015). Chapter 13 -Appendix. Isotopic Investigation of Residential Mobility of Individuals from the Zone 12 Middle Iron Age Cemetery. In P. Andrews, Booth P Fitzpatrick, & K. Welsh (Eds.), Digging at the Gateway: Archaeological landscapes of south Thanet. The Archaeology of the East Kent Access (Phase II) Volume 2: The Finds, Environmental and Dating Reports (Vol. 8, pp. 429–432). Oxford Wessex Archaeology.

Patterson, N., Isakov, M., Booth, T., Büster, L., Fischer, C.-E., Olalde, I., Ringbauer, H., Akbari, A., Cheronet, O., Bleasdale, M., Adamski, N., Altena, E., Bernardos, R., Brace, S., Broomandkhoshbacht, N., Callan, K., Candilio, F., Culleton, B., Curtis, E., … Reich, D. (2022). Large-scale migration into Britain during the Middle to Late Bronze Age. Nature, 601(7894), 588–594.