 Over the past 10 years, ancient DNA and the science around it has revolutionised our understanding of different aspects of the past throughout the world. And lying at the very westernmost point of Europe, Ireland, has and is yielding many fascinating insights about the movement of humans and animals. And at the very forefront of this research have been Dan Bradley and Lara Cassidy, both from the Smirfit Institute of Genetics in Trinity College Dublin. And I would like to now welcome Dan and Lara to the stage for their lecture entitled Tales from a Small Ireland Ancient Genomics on the Ancient Edge. Good evening, everyone. Yes, that is a hard act to follow. This is a difficult slot between the performance and the drink, but I'll try and keep your attention anyway. So, first of all, thank you, Eileen, and the organisers. It's a real honour to be asked to co-give this lecture. And it's fantastic to be here. It's genetics and archaeology are such different disciplines, and it's difficult to get the interplay between the two. So it's great to be here and get the chance to listen over the week to so much archaeology. So what we're going to talk about in the spirit of weaving and art are three tales. This comes from work that we've done in the Department of Genetics in Trinity College over the last decade or a little bit more in an app that's co-led by myself and Lara. And what I'll do is I'll tell you something of an introduction and something about migration. And Lara will then move into the cousin's tale, which is about kinship, biological kinship, and survivor's tale because genetics, of course, is very important for health and has a central to evolution. So the first thing is to say whenever we talk about migration. Migration, it really was a culture shock for me some 10 years ago to find that migration was actually quite a value laden term in some parts of archaeology. It's not genetics, it's just something you measure. But anyway, how do we detect it? How do we measure it? And what is it about the genetics of ancient Europeans and what methods do we use that allow us to do that? So there are three aspects really that give us the power with ancient DNA to measure an unfair migration. The first is the scaling up of data acquisition, which is something that has happened in recent years. It took the first human genome, something like $300 million in a decade to be sequenced now or human genome because of medical technology can be sequenced in an afternoon and costs less than $1,000. I'm not even sure how much it costs now because it costs keep on decreasing all the time. That's a modern human genome and costs more to sequence ancient human genomes. Secondly, new haptotype methods, that's ways of computing and inferring relationships from ancient data and modern data. And thirdly, the material we're working with, the divergence that is there in prehistoric populations. So what is genetic data? And it has quite a pedigree, quite an ancient pedigree in terms of academia that on the left here is a slide from one of my predecessors in the Department of Genetics in Trinity. And it's a slide of Reza's negative frequency. That's one genetic locus. And as you can see, there's a gradient measured in 1958 and drawn on this old glass slide across Ireland. And that's because of history, you know, genes of a past and the patterns we see today are because of that past. And on the right is the gradient of another gene, the old blood group, you know, a single segregating variant. And it has a geography across these two islands. And it's a recent geography because I've just put in a circle there. And that's a sample that we sequence some years back of individuals of Britons from York from the Roman era. So it's a geography, a genetic geography that's changed. And these are interesting. You know, they tell us something, but they're a bit limited in that they're based on one locus. And one locus is not a lot of data. So what do we work with now? Well, in ancient and modern genomes, we work with hundreds of thousands of genetic loci. So we have gone up a factor of 10 to the 5 in sort of data we work with. So it's been a huge change. And what can you do with this sort of data? Well, what you can do is you can plot individuals in genetic space. So this is a map of European individuals all coded by the two letter codes, ES for Espana, PT for Portugal. And as you can see, people with Spanish and Portuguese ancestry clustered together down here in this two dimensional genetic space in a sort of genetic Iberia. In a peninsula, you can see another peninsula here. This is IT Italians. And here are some unusual Italians. Turns out they're Island Italians. They're Sardinians up at the top. We've got GB breaking away from Europe, as you can see, not quite managing it. And IE not quite breaking away from Britain either, as you can see. And why would it? But as you can see, there's an east, west, north, south genetic geography, which we can plot and unfair. And it has implications for different things, including forensics. But the second thing I was going to mention is haplotype matching. So what this is, this is for illustration, it's a detection of plagiarism from a student. And how do you detect plagiarism? You don't do it by single words, you do it by strings of words and sentences and sentences have genealogies. And if you submit a paper and the genealogy of your sentence is from somewhere else, it's detectable because you can detect in strings and genes are the same. They occur in chromosomes and you can infer genealogical relationships very securely using this method, which is identity by descent. Based on strings of matches. So genealogical relationships, strings of variants in DNA is a very secure way of detecting relationship. And then thirdly, whenever we now know from ancient DNA and some of this is done by us, but of course, much done by other excellent research groups in the field. Whenever humans emerge from the ice in Europe, they emerge in very divergent populations. And why is that? It's because these populations overwintered in different places. They follow different trajectories through time. They were separated and they're different. And they mixed together in modern Europeans. I've just, I mean, Emily Breslin, one of our group is giving a talk on some of the apopleolithic work on Saturday. This one's an interesting one. These are early European farmers. With the advent of the Neolithic, they spread through Europe and have a profound effect in European populations. And later these other two to the right, they, they mix in in the third millennium BC. Again, altering European genetics. So the question I'm going to ask and try and answer in my little bit of the talk is if one looks at Ireland, we're just going to look at Ireland. Was the population of Ireland. Was its history through time a smooth one or rugged one? We had change everywhere has changed. But where the change is gradual. Or in a temporal sense, episodic where their cliff edges. That's the question where their cliff edges in the population history, population prehistory of the island of Ireland. So I'm going to use three samples for illustration. The first is a Mesolithic genome sample. The second is from Ballinahati, quite close to here, a Neolithic sample. And the third is from Rathen Island, an early Bronze Age sample. And what we're going to do is plot them on our map of Europe. So where did the Mesolithic hunter gather samples? Not just the Irish sample, but Western hunter gathers. Where do they fall? They fall above. They fall northwards in the plot of Europe. Up here at the top in a sort of genetic Valhalla. It's a genetic place that doesn't exist anymore. Because their descendants do exist, but their descendants don't exist in the farm they were. They've mixed through into the population. Who that is Europe today? Secondly, what happens whenever you look at a Neolithic sample. And this is just to point out that the first genomes from the British Isles were sampled and sequenced by ourselves in a collaboration, which was a Trinity Queens University Belfast collaboration. So we're very proud of that, actually. And what's the story they told? This is Ballinahati. She's from a Neolithic tomb a few miles away from here, very few miles away. And she's famous. And she falls down here close to Sardinia. And in fact, this is typical of Neolithic samples from from Western Europe. This is where they fall. And this distance between the earlier Mesolithic genome and the later genome, it's too far for this to have been just from indigenous drift. This indicates a severe change in composition, which comes from migration. And was that migration? Was it? Was that typical? That's only one genome. Well, in fact, whenever we look at a whole range of genomes, 42 Neolithic genomes from from our own sample from different tombs, you find that yes, it is typical. And with one exception, or one individual from Carton-Jones's excavations in part Nubinia and County Clair. And this is an interesting individual because using the genealogical detection technique, the plagiarism detection technique, we were able to infer that one individual out of the 42 had a Mesolithic great great grandparent. And that great Mesolithic great great grandparent was an Irish Mesolithic because it was more similar to the Irish sample than to other Mesolithic samples. Now that's interesting because first of all, it shows that there wasn't a full population replacement at the Neolithic. So there was some some inheritance genetically came through from the Mesolithic. But the other side of it shows it shows we have the power to detect great great grandparent ancestors and only one out of 42 showed that. So therefore there are 672 ancestral genomes that were surveyed and only one of those was an Irish Mesolithic. So it was a fairly overwhelming genetic process, this transition to farming. Secondly, now all our earliest genomes were from Northern Ireland. It's not because I'm from Northern Ireland, it's because we have this collaboration from Queens. But we were fortunate enough to get the chance to sample some early Bronze Age samples from Rathland Island. This is the Kisperial they're from. And where do they fall? Well, this is an example. It falls up here not so far actually from where populations from the Western parts of the British Isles falls today. So, and again, this is a radical change. It's a radical change. That's only one genome plotted here. Is that a radical change that occurred? Instantaneously or sharply, not instantaneously, but sharply, or is it is a part of continuum? You know, it's only one data point. So what we need are more data points from the Bronze Age and beyond to answer this question. Was the transition into metallurgy roughly 2400, 2500 BC on the island? Was it one that was linked to genome change or not? Was it a cliff edge? So if you plot the percentage of Anatolian ancestry roughly for individuals through time. So this is just a plot of a percentage of the Anatolian ancestry through time, which starts out low zero because these are just two mesolithic genomes. Then it rises sharply just after 4000 BC. And then you have a plateau of Neolithic ancestry, early farmer ancestry, Anatolian ancestry, whereas the majority component. And then there is, yes, there is a cliff in ancestry, which occurs around about 2500, 2400 BC. It's pretty sharp. Now, there is complexity because if you color those samples, these are colored according to age apart from the ones from 2400 on where some of these burials are from reuse of megaliths in the Copper Age struck Bronze Age. And then some are not. And you find there's a difference. There's less of a change in those from the megalithic context than there is in the others. So it is with complexity, but it's still profound, massive. And I would argue in in archaeological time, pretty sharp as a cliff edge. Lastly, just a shout out for Victoria, who's giving a talk again on Saturday, and she's looking at the same period with cattle. And cattle, cattle don't show a cliff edge. There's a spoiler, but there's more to our talk than that. Hello. Okay. So I am going to be moving us on to the second of the three tales. And this is going to be the cousin's tale. And in this, I just want to consider a little about what ancient DNA can tell us about kinship. And obviously there's a lot of things that cannot tell us. But one thing DNA does provide is direct information on on shared descent, which Dan touched on earlier. It allows us to construct true genealogies and map genetic relatedness between members of a community. And those patterns, they are going to be inevitably shaped by the kinship systems and the marriage customs of those communities. And I want to say I am not saying here that genetic relatedness alone determines kinship. It's almost actually the reverse. We're more leveraging the fact that culture and a kinship system can determine genetics in the archaeological record. And that's how we can learn about kinship. So how do we detect shared descent in the genetic record? Dan touched on this, but people who share a recent ancestor are going to share long chunks of identical DNA sequence inherited from that ancestor. So to say we've got two cousins here, you can see they share this orange chunk inherited from their shared grandparent. And just for example, some of you might have done a 23 and me test. And if you did, you might have gotten a result that looked something like this telling you that they've discovered your second cousin, who are you are now a morally obliged to invite to your wedding because that's how kinship works. And this is all down to you sharing these IBD segments that we can detect on the chromosomes. You can see them here. But what's really exciting is that we're getting to the stage in ancient dynamics where we can actually match this level of resolution. If we generate good enough quality data, we can apply the exact same type of analysis to ancients as we do with moderns. And as a matter of fact, I've kind of cheated the result I'm showing you here. It's not from 23 and me. It's actually from our lab. And this is not too modern individuals. This is a result for two adult males from Neolithic Ireland. And we found that these men, they're approximately fifth degree relatives. So they too could be second cousins, but their median radio carbon dates are about 200 years apart. So that's something 23 and me doesn't really have to worry about at least yet. So we could be sampling something closer here to direct ancestor descendant relationship. But there's something actually quite unusual about these two relatives, and that is that they weren't found in the same location, not even close. They were actually interred over 100 kilometers apart in two of the most spectacular monumental landscapes in Ireland, some would say in Europe. And this came from the mega passage to new Grange, which I think some of you have already visited today or yesterday. And the other site, and some of you might not know as well, but I think deserves just as much love. This is Carol keel in County Slago. And this is another really incredible passage complex where the monuments are purchased on top of various hilltops. So then our question here is how to relatives come to their final resting places. There are persons such as vicious locations, but also so far away from one another. And the most parsimonious explanation we have here is that we are sampling members of an elite along distance kinship network between monumental tombs is something we'd expect for quite a complex society with elite mobility. And we have two additional pieces of evidence for that elite. The first is that we found that other pairs of passage to samples from other sites. They also show some excesses of genome sharing, causing them to cluster genetically, which you can see in pink here. The second is that the individual from new Grange, he was not only exceptional in his sampling location. So his remains were a sample from the right hand recess, which is a focal point in Irish passage tombs. And then obviously new Grange itself is a focal point within the wider ritual landscape of Bruno Buena. But this man's genome, it was also exceptional in that he was the son of first degree relatives, which is an incredibly rare observation in both modern and ancient genomic data sets. And that makes sense because we know that the first degree incest to boo, that's one of the few cultural universals, probably for underlying biological reasons. And we only have a handful of confirmed historical cases where this behavior was sanctioned by society. And all of those are sibling marriages among dynastical elites. We also see that the practice strongly associates monumentality and a degree of political deification. So this is interesting that potentially observing such a rare marriage custom could tell us something about politics or even the religion of a past society. If a neographic analogy can be considered a useful tool in archaeology, which I think it can. And I actually think it's one of the most exciting things about genetic data at the moment that it's opening up a whole new avenue for cross cultural comparisons for understanding how human societies vary through spaces. And timing and even maybe why they vary. Hey, so we're now going to jump forward in time to the bronze age. And here I want to talk about a related application of IBD analysis. And this is the potential to produce detailed maps of connectivity between archaeological sites. So this isn't about the flow of trade necessarily. This is about substantial movement of people and marriage partners. So we're talking about people for once not pot. We know this is influenced primarily by geography, right? It's way easier to marry somebody down the road from it. But culture is obviously going to play a very important role as well. Political boundaries, ethnic differences, economy and technology can all influence and shape choice of marriage partner. And as an example of this, I want to look at the Bronze Age population from Rathland Island that Dan mentioned earlier. Since 2016, we sampled a lot more genomes from Bronze Age Ireland and other ancient DNA labs have been very, very productive as well. So we now have something like 132 genomes from across Britain and Ireland that are amenable to IBD analysis. And now what we can do is put the Rathland population into much better context. The question being which sites showed the most shared ancestry with the Rathland population. And we can visualize this with a nice interpolated map here where more red is more IBD shared with the Rathland population. And what we're seeing is that Rathland's IBD neighborhood, it's quite a maritime one, right? Its top pits are along the north coast of Ireland and also the west coast of Scotland. So this is a really interesting pattern because it suggests that these populations may have had a relatively strong seafaring culture. Perhaps not unlike the one we see millennia later in the medieval period when we know that there were close political ties between these two seaborts. So in some societies, depending on culture, depending on technology, the sea might not act as a barrier, a geographic barrier to move in, but could even potentially be a unifier in some cases. And just to contrast, here is another Bronze Age population we sampled this time from outside of Dublin, a keynote. And here what you're seeing is that the highest hits are further south, actually in and around the modern day province of Lester. While our Rathland population, in contrast, is showing very little sharing with these sites on the eastern seaboard. So what we're basically catching here is different spheres of mobility and potentially even different spheres of influence. And at that resolution, that's only going to sharpen the more we sample. And so this is one of the really, I think, exciting kind of horizons in ancient DNA. Right. So this is the third and the final part of the Cousin's Tale, we like doing things in threes. And this is going to bring us to the early medieval period. So moving forward in time. And what I want to do now is look at kinship within a single site. And this site, it's an enclosed rural settlement and a secular cemetery at Ranala in County Roscommon. And this is part of a bigger multi-disciplinary project with TII and again with Queens. And this type of site, this is a very common and a very well studied site type in early medieval Ireland. It's been argued that most probably represent familial burial grounds, although it's possible that some serve larger communities. And this is something that we can now start directly testing with ancient DNA. And Ranala is also interesting in this regard because it grew into something of a regional hub through time. And that could have potentially changed how the cemetery was being used. So the first thing we can ask then is, OK, are we finding then a lot of genetic relatives at Ranala? And how does that relate to the different phases of the site's usage? So here you are seeing the number of relatives identified for each individual plotted against their median date. And what you see is that during the main phases of occupation here, nearly everyone is related. You can see geological links as lines and they connect nearly all individuals over the course of about three centuries. So that's really nice. That's confirming what has long been hypothesized about these types of sites. And suggesting that even in Ranala's heyday, it seems to be acting primarily as the burial ground for one family. Another thing we also see is that a single Y chromosome lineage dominates at the site, which you can see in pink here. And that fits very well with what we know from the historical record about Gaelic land ownership and how that was organized around patrilineal descent groups called Dervenia. So that's something we're actually quite lucky with in Ireland that we have this very old and very rich vernacular history, including Gaelic inheritance laws. And we're going to be able to compare them to the genetic record going forward and see how they relate, but also see if they always agree with each other and differences between sites. And then finally, the last point I want to want to make here is that we do have also individuals with no relatives yet detected at the site. So you could ask the question then if this is a familial cemetery, who are they? And importantly, they still could be family members. They could be spouses who married in with no descendants. They could be fostered children. One thing we also really need to remember is that we have a limit of resolution here at about the degree of third cousins. So we're not going to be able to detect individuals from more distant branches of the clan. So yeah, what I'm saying again is DNA can't alone give us a full picture of kinship at any site. And we're always going to have to consider other forms of data. And one of the most important is of course going to be the burial context. I'm just touching on this, but one example we could look at is spatial distribution. So here at Ranala, I've highlighted burials in light blue who don't have any detectable genealogical ties to the main family. And you can see that they tend to fall at the edges of the main area of burial activity. This is the pattern so far. So that could imply a different status either within the family or maybe these are not family members. They could be dependents of the family. And kind of going maybe in that vein, we can then ask another question is okay. Well, are these individuals still then from the local area around Ranala? And we can do that using isotopes or DNA or if you're very lucky, both. Both is usually best. And just one example of Ranala, we have actually found two of these unrelated individuals are also outliers with respect to their geographic origins. So this is a woman and an infant who were buried together, but they are also not related to each other. And their genetic profiles you see here, they are not typical for medieval populations from the west of Ireland, which you see down here. Instead, we're seeing a substantial amount of British type ancestry. So I could go into a lot more detail here. I'm not going to. But if you do want to hear more about sort of these fine scale approaches to identifying non-locals, please do check out one of our groups talk Maeve on Saturday, where she looks into this more. Final then of the three tales. This is going to be the survivor's tale. So genomes are genomes. They don't just hold a record of our ancestry. They also tell stories of life and death. We know malnourishment, infectious disease and high rates of child mortality. We're all the norm for populations like the one living at Ranala and many in the past. But every one of you here today is the descendant of survivors, people who lived long enough to have children of their own. And we would expect any traits that increased those odds of survival. These would increase in frequency over time in the population that is natural selection. And it's incredibly powerful evolutionary force. And I just want to touch on one of the most textbook classics, classic examples, natural selection in humans, such as lactase persistence, this ability to drink milk into adulthood. And Ireland actually has the highest frequency of this trait in the world. But we wanted to ask the question, well, when did this trade actually undergo selection? When did it rise in frequency in the population? And this is actually a question we've only been able to definitively answer relatively recently with ancient genomes. So we now know that the associated mutation was rare in the early Bronze Age, but it has risen rapidly and relatively steadily through time, maybe plateauing a little in recent centuries. So that's really nice. That answers the question of when. But the more difficult and more interesting question is also why? Why was milk such a matter of life and death in Ireland in the past? And I should mention recently Nick Patterson and colleagues looking at a similar data said in Britain, they suggested this might be to do with differences in dairy economies between the islands of Britain and Ireland and those on the continent during the Iron Age. And that that could indeed be one factor. But for the pressure to remain constant for so many millennia in Ireland, that suggests some more fixed underlying environmental pressure. And like so many issues in Ireland, the problem could possibly be the weather. So other genes we found with signatures of selection in Ireland, these paint a picture of a sun starved population. And we need UV light from the sun to synthesize vitamin D. And vitamin D is essential for efficient calcium absorption, healthy bones and a healthy immune system. And we saw this even during the COVID-19 pandemic where vitamin D deficiency and calcium deficiency were strongly correlated with the disease severity and poor prognosis. And actually the same is true for tuberculosis. So lactose increases calcium absorption in the gut, which could have given ancient immune systems at the boost they basically needed when they were constantly being battered by infections. And it should also be noted that ancient DNA allows us to actually study the evolution of those infectious agents themselves. And don't worry, I'm not going to talk about that. But if you're interested in that topic, do again, I'm going to do another plug. Check out Eastwood Jackson's talk on Saturday on dental pathovions and the oral microbiome. Okay, and then to finish, I've been talking a lot about how long term hardships that were endured by our ancestors that these can shape genomes over many millennia. But ancient DNA also provides snapshots of population and individual health at particular points in time. And there's an old cut a cliche adage that mended bones are the earliest manifestations of human compassion in the archaeological record. But DNA also lets us move beyond the bone and understand the experience of individuals with genetic diseases and disorders that may be quite invisible in the archaeological record. And as an example of this, I'm just going to bring us full circle back to the Irish Neolithic to pull Nebron portal to where we sequence the genome of a male infant with three copies of chromosome 21, which results in Down syndrome. And we also found that this infant, he had an isotopic signature consistent with being breastfed. So that could suggest that this infant then was cared for in his short life. And his internment, I pull Nebron also suggests that his death was of some significance to his community. So as you've seen during this talk, an ancient genome can tell stories that span centuries and millennia even. But at the most base level, a genome belonged to an individual and it can also help humanize that person and tell us something of their own life story. And I'm going to leave you there. I just quickly like to acknowledge all the members of our research teams at Trinity are amazing, wonderful collaborators, too many to mention. All funders, the organizers of EAA for giving us the honor to talk to you all today and you all for listening. I hope everyone has a fantastic year. Thank you, Laura. And thank you, Dan. And it's like the Decameron of genomics with all those tales and I'm pleased that Laura's connected it with with sessions over the next few days as well. So but you know who they are. So you can you can go pester them over a pint of milk outside now. And but we're very fortunate to have the quality of academic excellence shown by Laura and Dan and by Eileen sitting next to them and others in this audience here in Ireland. You are changing the narrative we weave of Ireland's past in such a transformative way. It's quite remarkable and it's very, very exciting. So thank you, Laura and Dan. We're almost before the milk at the end of the opening ceremony. And as I mentioned earlier, we're in for a bit of a treat now. We're going to be led out of the ceremony and into the reception by our archaeological colleague and friend James McKee. He'll be playing a fourth century a replica, I have to say to museum colleagues, a replica of a fourth century horned instrument discovered at Loch Nishade in County Armagh. James will then be accompanied by his fellow performers from the world renowned Armagh Rhymers who will keep that entertainment going in the reception area. The Rhymers wear masks. They're crafted from flax, willow and straw. And their activities are based on the traditional practice of mummy. And this masked tradition of rhyming with its unique blend of music, drama, song and dance dates back over two and a half thousand years. And it's a very important part of Irish folk traditions. And with that, it's a wrap. The narrative we have, I feel chosen to weave this evening is is one of partnership. It's one of friendship. It's one of solidarity. It's one of recognizing cultural diversity here in Northern Ireland and elsewhere is one of recognizing academic excellence of recognizing the talent and and hope of youth and and of the hope and ambition of this place and indeed for archaeology. Put your hands together for this place, for Belfast, for conference center, for all the prize winners and all those involved this evening and all the organizers and the everybody to far too few to mention all those wonderful artists who've entertained us this evening. And thank you for attending. And on behalf of all involved may have a super, super time here in Belfast.