A Sarmatian in Roman Britain - Archaeological Science Ep 5

Imagine you're an archaeologist and you've just been asked to carry out a dig in preparation for a road development. You need to record as many finds as possible, because once the road has been built, any history that's been left behind will be lost for good. And then surprise! You find a human skeleton! You know that these bones are very old, but how can you find out more about the person they belonged to? A similar story took place near the village of Offord Clooney in Cambridgeshire, England, where a burial containing a single skeleton was found without any grave goods. Immediately, questions arose as to this person's identity, named Offord Clooney 203645. The bones suggested an age at death of between 18 to 25 years old, but they were not preservable enough to tell us whether this was a woman or a man. Virtually nothing was known about who this person was, nor his or her life story. But, thanks to archaeological science, we're starting to get some answers. I'm Madame Archaeologist, your go-to informant on everything archaeology, and in this episode, I'll show you how ancient DNA, stable isotope analysis, and radiocarbon dating have helped reveal parts of the intriguing life story of the once obscure Offord Clooney skeleton. One thing that DNA can do is that it can tell us whether a person was female or male. This is because DNA is packed into units called chromosomes, which are inherited in pairs. We have 23 pairs of chromosomes, and the last pair is called our sex chromosomes. Females have two Xs, and males have an X and a Y. The DNA of the Offord Clooney skeleton revealed that he was male, and a tooth radiocarbon dated to between 126 and 228 AD meant that he lived during Britain's Roman period. The Romans conquered Britain in 43 AD under the Emperor Claudius, and it remained part of the empire until the early 5th century. There's more that we can learn about a person from his or her DNA than just gender. I'll give a very quick rundown on the types of DNA used to find out more about Offord Clooney's ancestry and origins. If you'd like to learn more about how DNA works, I'd recommend watching my episode on King Tut's family tree or my episode on the DNA of the ancient Egyptians. Now, three types of DNA were analyzed for the Offord Clooney skeleton. The nuclear genome, mitochondrial DNA, also known as mtDNA, and the Y chromosome. Since we inherit 50% of our nuclear DNA from our mother and 50% of our nuclear DNA from our father, and they both inherited 50% from each of their parents and so on, the nuclear genome gives a fuller picture of someone's genetic ancestry. Meanwhile, mtDNA is housed in another organelle in our cells called the mitochondrion. Everyone inherits mitochondrial DNA, but solely from their mother, so we can use it to trace the ancient origins of someone's direct maternal line. Similarly, since the Y chromosome is only inherited by males from their father, it can be used to trace someone's direct paternal line. Since women don't carry the Y chromosome, this type of analysis can only be performed on males. Looking at the nuclear genome, the researchers found that Offord Clooney 203645 differed genetically from the Romano-British skeletons that have been subjected to ancient DNA testing. These skeletons come specifically from a site in York called Driffield Terrace. As per the paper, published in the journal Current Biology, the Offord Clooney skeleton is instead present-day individuals from Anatolia and the Caucasus. Specifically, he shows affinities to late Bronze Age individuals from Armenia and individuals recovered from Alan-associated contexts in the North Caucasus. Russia underscore Sarmatian underscore Alan, dating to 450 to 1350 CE, generally considered as part of the Sarmatian Confederation, but not with individuals from Armenia who post-date the Bronze Age. Statistical tests corroborated these results, showing that he, I quote the paper again, was different from the ancestry of Romano-British individuals from Driffield Terrace and he instead shared genetic affinities with ancient populations from the Caucasus and Pontic-Caspian region. For a bit of context, the Sarmatians were a group of Iranian-speaking nomadic tribes. Here is something called a PCA plot on the upper right, taken from the paper. PCA stands for Principal Component Analysis, and it's used often in ancient DNA studies when we want to compare a sample to different genetic populations. It's a useful tool because it doesn't make any assumptions about someone's genetic ancestry and it doesn't force a sample to cluster with any one of the referenced populations. Rather, it shows how genetically similar or dissimilar a sample is, broadly, to the referenced populations used in the study. Offord Clooney 203645 is represented here by the yellow square. The other images shown alongside the PCA plot include a plan of the excavation to the top left, radiocarbon dating results in the middle left, and a map showing where the referenced ancient population samples came from at the bottom. Additionally, the researchers were able to get Y-chromosomal and mitochondrial haplogroups. Offord Clooney 203645's Y-haplogroup was R1b-Y13369, a subbranch of R1b-Z2103, also known as R1b1a1b1b. In archaeological contexts, this lineage is most prevalent in ancient skeletons from Armenia. Amongst modern-day populations, it's found most prominently in the Caucasus, Anatolia, and the Near East. His mitochondrial haplogroup was K1a, which has been found in a wider range of ancient skeletons, including the pre-pottery Neolithic period in Anatolia and the Levant, so we're talking about the period when people were starting to practice agriculture, and also in Europe since the Neolithic period. Subclades of K1a have been found in ancient British skeletons from the Neolithic to the early medieval period, but these were different sub-lineages than that of the Offord Clooney skeleton. So, the haplogroups support at least an ancient origin outside of Britain. Regardless, when looking at ancestry, it's the whole genome that matters the most. Haplogroups reveal deep ancestry, and even then it's only the direct maternal and paternal lines. You miss a whole load of genetic information by just looking at haplogroups. Given that we have data from Offord Clooney 203645's nuclear genome, I would consider his haplogroups as complementing the nuclear data. Now, his story gets even cooler when considering another line of evidence. Stable isotope analysis. What's an isotope? All elements on the periodic table are made up of atoms that contain the same number of protons in their nuclei, but the number of neutrons can differ. These variants are called isotopes. Let's take nitrogen as an example. Nitrogen always has 7 protons, but its two naturally occurring isotopes, 14n and 15n, have 7 and 8 neutrons, respectively. We get those numbers, 14 and 15, by adding up the number of protons and neutrons in each isotope. There are too many technical details to outline here, but the important thing to know is that we can measure and compare isotope concentrations from different bones and teeth to find out if a skeleton was buried away from the place that she or he grew up, and to study things like diet and migration. Isotopic signatures suggested that where Offord Clooney 203645 grew up and where he died were different places. The isotopes show that he ate C4 crops during his childhood, possibly sorghum and millet grains, which grow abundantly in the Caucasus. Around the age of about 5, his diet no longer relied heavily on C4 plant protein and he was consuming instead a mixture of C4 and C3 plants, and over time there was an increase in the consumption of C3 plants, especially after 9 years of age. At 13 years old, he was eating an almost entirely C3 crop-based diet. C3 plants grow in Western Europe. This suggests that Offord migrated from his homeland to England rather than being born in Britain to migrant parents or descendant from migrant ancestors. So, how did he end up in England? Combining the genetic evidence with the radiocarbon dates, isotopic signatures, and historical documents, it's possible that he came to Britain with the Roman cavalry. According to the Roman historian Cassius Dio, Sarmatian cavalrymen were drafted into Roman legions following Marcus Aurelius' victory against them in AD 175, and 5,500 Sarmatian soldiers were then deployed to Britain. Offord Cluny 203645 could have been the son of a soldier. Although just one possible scenario, this event falls perfectly within the range of radiocarbon dates obtained for the skeleton. That's it for the episode. Overall, this case study shows how different branches of archaeological science can come together to shed light on aspects of someone's identity and life story that would have otherwise been left unknown. We may not have a name, but now we know a lot more about the Offord Cluny skeleton than from his grave alone, and that a Sarmatian made it to the English countryside, at the edge of the Roman Empire, is quite a remarkable discovery. 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