Ancient DNA and the Future of the Past

Introduction to Story

0:00In death, their mother's face was finally peaceful. The deeply etched lines softened, the taut mouth relaxed, the perpetual scowl disappeared. Her life had been one of endless stress and worry. Raiders from the next tribe, drought during the rainy season, pests in her field of wheat, sickness among her cattle, her wayward eldest boy's propensity for getting in fights until one finally did get him killed,

0:34her daughter's fondness for the chief's foolish layabout son, an endless array of problems, large and small, defined her life. She was 42 years old. Her younger son and daughter buried their mother with a pot that she'd made from long coils of clay and then decorated with incised lines. The five children, who hadn't survived, were buried all around her, ranging in ages from newborn to 17. Their graves marked with wooden posts taken from the hazel trees surrounding their farmstead. Her husband was a bit more distant from the rest, near the tree line.

1:06She hadn't much cared for that man, she said, after his death. A hard woman, their mother, the son and daughter agreed, but they shed tears for her nonetheless. Even before his death, their father had never run the farm. This was her land. It had belonged to her father, and her siblings were buried in this same field, hemmed in by the hazels. Their father had been an outsider here, taken in a raid as a boy and adopted into the clan to replace a dead member. Their mother had chosen him deliberately, since she could be sure he had no grasping relatives to try to claim the land.

1:37He was a strong back and, she said, had once been a handsome face. That was their mother, the son and daughter reflected, always plotting and planning and grinding, literally and figuratively. The two of them had agreed that the son would keep the farm so long as he provided a suitable dowry for her marriage to the chief's son. Their mother was right, the young man was a fool, but he was the chief's son, and the daughter liked him. A century later, there were dozens of graves in the cemetery. The farmhouse was one of a half a dozen buildings on the site.

2:07The brother and sister had dozens of living descendants spread across a dozen farms across the countryside. A century after that, they had descendants spread across hundreds of farms. A millennium later, they had tens of thousands of descendants living throughout a continent.

Ancient DNA Explained

2:20These are the kinds of stories we can tell through ancient DNA, the most powerful new technique that has entered the field of archaeology in decades, perhaps ever. Access to the genetic records of the distant past allows us access to aspects of the human experience we could never before see. So today, let's explore the world of ancient DNA.

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Host Introduction

3:56Hi, everybody. From Wondery, welcome to another episode of Tides of History. I'm Patrick Wyman. Thanks so much for joining me today. One of the wonderful things about getting to make tides for as long as I have is that we've seen fields of study change in real time. The fall of the Roman Empire doesn't look the same as it did when I started Fall of Rome 10 years ago. But the further back in time we go, the more things change.

4:29Because we have so many fewer sources of evidence, any new discovery or the application of a new method can dramatically change what we think we know. At the very beginning of our season on the deep human past, Season 4, Episode 1, I told you all that I fully expected our interpretation of the topics I covered to shift in real time as we were covering them. New studies on everything from the variety of archaic human species that once roamed the Earth to the spread of language families to patterns of migration have appeared in those almost six years. So have responses to those studies and responses to the responses to the extent that what I said at the time looks ludicrously simplistic or even flat-out wrong today.

5:07In no field is this shift more obvious than ancient DNA. Ten years ago, paleogenomics, the study of genetic material recovered from archaeological contexts and remains, was just coming into its own with huge, overarching studies. Five years ago, the need to make those huge studies more nuanced was just being recognized, with tons of archaeologists making strong arguments against the approaches they were seeing from geneticists. Now, in 2026, we're finally starting to get the synthesis between the hyper-specific needs and wants of the archaeology community and the geneticists' desire to apply their incredibly powerful tool in the most groundbreaking ways.

Ancient DNA Studies

5:43In today's episode, we're going to explore the broad landscape of ancient DNA studies. Where it's been, where it is, why it matters to our understanding of the human past, and where it's going. This is going to be a rather more personal account than I usually write here on Tides, because I've been around personally for all of this. I know many of the players, I've interviewed them and spoken with them informally, and I've watched these debates and developments unfold in real time. Ancient DNA is the poster child for what's often called the Archaeoscientific Revolution, or more precisely, the Third Science Revolution in Archaeology.

6:18The first of those revolutions in the 19th and early 20th centuries marked the beginning of archaeology as an organized discipline. With established ways of excavating, organizing, and analyzing material. The works of scholars like V. Gordon Child up through the 1940s, you can hear Indiana Jones talk about V. Gordon Child in the classroom scene of Raiders of the Lost Ark, put a capstone on this age of study. It focused on big-picture questions and relative chronology, putting the vast amounts of material archaeologists were pulling out of the ground at individual sites into some kind of coherent order and arguing for major driving forces in prehistory.

6:52The concept of an archaeological culture, the idea of a group of people bound together in some way by their use of a common material package, has its roots in this first major reorganization of archaeology as a field. So too do concepts like the Neolithic Revolution, which was one of Child's contributions. A great many of the famous archaeological sites you probably know about were excavated during this period, and to this day, the way they're understood is rooted in the concepts of this age. The Second Science Revolution started with a bang, the 1949 discovery of radiocarbon dating, a technique that measures the amount of carbon in a sample and gives it an absolute date before the present based on carbon's known rate of decay.

7:33That phrase, absolute date, is important. Never before had archaeologists been able to assign even imprecise dates to sites without extraordinary luck, such as a reference to a known Egyptian pharaoh and a source relating to Minoan Crete. All chronologies had previously been relative, depending on sites that had a sequence of deposits. What was older was below the newer stuff, and while this kind of stratigraphic or layer-based chronology was useful, its shortcomings were equally obvious. Radiocarbon dating changed everything, and plenty of old interpretations were found to be wrong once we had absolute dates in hand.

8:09However, radiocarbon dating had serious limitations. While it provides absolute dates, those dates are themselves pretty imprecise. A radiocarbon date is actually a range based on probabilities, not an actual year, and all sorts of factors aside from the sample's age can impact that range of probabilities. A piece of charcoal found in an archaeological layer might have worked its way downward from a later layer. Old water effects might make a sample's date much earlier than it actually was. And, most fundamentally, radiocarbon dating requires organic remains, which aren't present at every site.

8:43Nothing was ever the same after radiocarbon dating was invented and came into use, but it was not a magic bullet.

Third Science Revolution

8:50This brings us to the third science revolution in archaeology, the one we're currently experiencing today. Now, I wasn't alive for the first two, but in my professional opinion, what's happening now is orders of magnitude more transformative than both. The reason lies in the nature of this third revolution. Rather than ordering archaeological material or placing it at some absolute point in time, the third science revolution fundamentally changes the nature of what we can consider as archaeological evidence.

9:20This is a pretty big series of statements, so let me explain them. Initially, archaeology focused on digging up really impressive finds, like the treasures Heinrich Schliemann found at Troy and Mycenae, or sites with visible surface remains, as in Egypt and Mesopotamia. Sure, there was plenty of other material, and archaeologists did excavate other kinds of sites, but that was the focus. In the course of that second revolution, other kinds of sites entered the record more frequently, not just big, visible ones. Archaeologists also increasingly recognized the value of all the material a site could produce,

9:52not just the finds that looked good in museum catalogs. Useware patterns on stone tools, the importance of animal bones in rubbish pits, a careful accounting of human remains, and a thousand other small shifts meant that archaeologists were making more of the scant material they were able to get out of the ground. Everything mattered now, down to the microscopic level. But this new revolution goes much further, because its tools unlock whole new ways of understanding the human past. At a basic level, most of the achievements of this archaeological age can be described as molecular archaeology.

10:26Useware patterns on broken stone tools are great. Being able to chemically source the stone from which the tool was made to a specific quarry is effectively magic. Knowing that the copper in a 3,500-year-old bronze tool found in Greece came from Sardinia rather than Cyprus, because its isotopic signature matches known mines, provides us with a whole new way of understanding trade and movement. A piece of pottery is stylistically informative, but chemical analysis of the residue still clinging to the pottery reveals what the vessel once held.

10:57Analyzing human bones for patterns of age, sex, and physical condition is the starting point, but looking at the strontium, oxygen, nitrogen, and carbon isotopes in those bones tells us what those people ate and where they lived at different points in their lives. When combined with powerful tools for statistical analysis, the horizons of what we can hope to learn about our ancestors open up dramatically. We didn't even know that we could access that kind of evidence 50 years ago, and now it's at the heart of practically every cutting-edge study in the field of archaeology.

11:27But the most powerful of these tools is ancient DNA. When I referred to ancient DNA as the standard-bearer for this new revelation in archaeological science, that's because new studies tend to receive huge amounts of attention. Science journalists cover these developments in the pages of the New York Times and a variety of popular outlets. Perhaps that's thanks to Michael Crichton making the concept famous in Jurassic Park, or because experts in paleogenomics tend to operate as part of large, well-funded labs with publicists to pitch the stories out to journalists. That stuff really does matter in terms of shaping public perception and public awareness.

12:01Nobody ever said scholarship was a level playing field. But, generally, I think ancient DNA's prominence is a fair reflection of just how transformative this new field really is. Isotopic analysis of human bone can tell us a bunch of different stuff that we'd dearly like to know, but think of it as like finding a couple of really informative scraps of paper in a garbage dump. Ancient DNA, by contrast, is like not getting a few scraps of paper, but a whole new book with thousands upon thousands upon thousands of pages. DNA is fundamentally a record of ancestry.

12:36We inherit roughly half of our DNA from each parent, who each inherited half of their DNA from their parents, and so on back through time. Because the number of ancestors doubles each generation, they pile up pretty quickly. You have 128 five times great-grandparents and 4,096 ten times great-grandparents. That means that a single individual's DNA gives us insights into all of their ancestors going back thousands and thousands of years. If we took a sample of your genetic material right now,

13:07we would be able to see what ancient and modern populations you were most closely related to. We could see how much ancestry you have from Neanderthals and other archaic humans, where in the world your ancestors came from, how isolated or connected to other ancestral populations your ancestors were, and a thousand other things. In crude terms, ancient DNA looks directly at the results of human mating networks, the patterns of reproduction that directly shaped every single living person on the planet. The number of different ways to apply those insights is almost infinite,

13:38and we're just now scratching the surface. Whether you're exploring your current fascinations or discovering new ones, Audible has all the stories that'll introduce you to your most fascinating self. Tap into a whole new world of heated conversations with a saucy romantic-y series. Become your friend group's sci-fi expert on the latest blockbuster book-to-screen adaptation. Or find unexpected reveals through the exclusive episodes of a viral true crime podcast.

14:14However you choose to listen, Audible keeps you fascinated, so you can be just as fascinating. All in one easy app with plans now starting at £5.99. You'll get access to over 900,000 audiobooks and podcasts, including trending bestsellers, the hottest new releases, and exclusive podcasts you won't find anywhere else. Sign up now to become a member and get any audiobook every month, plus exclusive podcasts. Plans now start at £5.99. Audible. Be fascinated. Be fascinating.

14:49I'm Raza Jaffrey, and in the new season of The Spy Who, we tell the story of Dr. A.Q. Khan, the spy who sold nuclear secrets to Iran. He was the scientist spy who stole nuclear technology from the Netherlands and used them to give Pakistan a bomb. But he didn't stop there. He became a black-market atomic salesman, a fix-it man for rogue states seeking nuclear weapons, including Iran, Libya, and North Korea.

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15:32Follow The Spy Who now, wherever you listen to podcasts. You can also listen to the full season of The Spy Who Sold Nuclear Secrets to Iran early, that free, on Audible.

History of Ancient DNA

15:51The concept of ancient DNA has been around since the 1980s. 1984, specifically, when researchers extracted the genetic material of the extinct quagga, like a zebra, from remains in a museum. The possibilities of unlocking the genetic code of creatures that lived millions of years ago was obviously pretty exciting, and a raft of studies almost immediately appeared purporting to show the DNA of dinosaurs and other extraordinarily ancient animals. This is where the core idea for Jurassic Park came from, a time when the potential of this brand new technology seemed essentially unlimited.

16:23As it turned out, however, those studies hadn't actually found extremely old DNA in dinosaur fossils or bugs trapped in amber. Instead, the researchers had picked up and analyzed the DNA of far more recent stragglers who hitched a riot on their samples in the past several thousand years.

16:40There's a cautionary tale here, one that's played out time and again since the very beginning of ancient DNA studies. The tendency of researchers and those covering their work to amplify, and in the process of amplifying, to distort what they've actually found and the implications of their work. Few missteps have been as enormous as this first one, but the basic pattern plays out time and again. A new study comes out, maybe it's truly groundbreaking, maybe it's not, but the abstract of the paper makes a big claim that's generally more nuanced in the actual text of the study.

17:11Either the researchers themselves or publicists for the institution with which their lab is associated pitch out the new research to journalists with the strongest form of the argument the paper makes. Journalists pick up that strongest, least nuanced version of the paper's argument and put it in the headlines of their publication. It's basically a game of telephone where everybody's incentives run in favor of making the biggest splash. This is entirely understandable and perhaps unavoidable, it's more of a problem with our media culture than anything to do with science, but it has the net effect of inflating claims

17:44about both the technology and individual pieces of research. When new studies come out that refute or modify the findings of that previous work as they always do, those studies are fighting an uphill battle in public and even specialist perceptions of the topic.

18:01Working with ancient DNA is actually really, really difficult. In fairness to those early researchers who made that first round of big claims, they didn't yet know that, but decades of work in the field has since made it clear. Making sure that the DNA you're analyzing is actually ancient and not modern contamination is much harder than you might think. A historian doing some early collaborative work with geneticists back in the 2000s told me a story about how he and a group went to a lab. The geneticists passed around a human tooth that was a couple thousand years old and all of the visitors touched it.

18:33The geneticists then took the tooth, ran it through pretty extreme cleaning and preparation protocols, and set about sampling it for DNA. Despite the cleaning protocols, the geneticists still found the DNA of each and every person who had touched it on the sample. Now that was a while ago, and protocols are much better than they were 15 or 20 years ago, but the point remains. If you're not careful, you'll end up sampling, amplifying, and analyzing a lab worker's genetic material, not that of an ancient person. That's the first issue.

19:04The second issue is that ancient DNA is pretty hit or miss in terms of preservation. Generally speaking, the warmer and wetter the conditions, the less likely it is that DNA will preserve at all. Cold, dry conditions are the best. The oldest genetic material that researchers have sequenced as of 2026 is a million years old. That DNA came from two molars that once belonged to a woolly mammoth in Siberia, precisely the environment that most favors preservation. We also have DNA from Greenland that's 2 million years old, but that material wasn't recovered from bone,

19:36but the environment itself. The point is that for our current technology, the theoretical upper bound of ancient DNA preservation is between 1 and 2 million years old. As much as we might want to find dinosaur DNA, that currently seems to be impossible. Under perfect conditions, a dry Siberian cave or deep permafrost, genetic material might last tens or hundreds of thousands of years, but there's no guarantee. I've read plenty of studies of more recent periods, like Greco-Roman antiquity, where researchers couldn't get enough or any material from some of their samples

20:06to generate a full genome, even when the preservation superficially appeared to be excellent.

20:13Now, this leads us to the third problem. Even when we're lucky enough to recover DNA from an ancient sample, that doesn't mean we're getting a pure, complete genetic record of that individual, with the ability to peer into each one of the millions and millions of base pairs. Even the best-preserved DNA still degrades over time, fragmenting and becoming unreadable as whole chunks of the genome are simply lost. There are technical terms for this. When geneticists talk about genome coverage, they're discussing the completeness of the data they've been able to extract. Even when you're looking at the exact same portion of the genome,

20:45you want more than one look at it or read, because there are likely to be variations. At best, you're looking at 100x coverage, meaning you've looked at the same sequence more than 100 times to catch all the possible gene variants. Most studies of the whole genome, the entirety of a person's genetic record, are what we call draft sequences, meaning that they're shooting for 90% of the total. Very rarely do we see more than that in archaeological contexts.

21:12But even whole genome sequencing is a relatively recent innovation in genomics. Up until about 2010, the vast majority of ancient DNA studies weren't looking at the whole genome. They were focused on Y-chromosome and mitochondrial DNA haplogroups, which are much easier to get out of the raw data from a limited and degraded sample. Y-chromosome and mitochondrial DNA haplogroups tell us about direct ancestry in the male and female lines, respectively. Men inherit their Y-chromosome haplogroup from their father, and both men and women inherit their mother's mitochondrial DNA haplogroup.

21:43People who have the same haplogroup trace their lineage back to a common ancestor, the progenitor of that line, the first person to have the characteristic mutation that defines the haplogroup. Now, these studies can be incredibly revealing. If all the men buried in the elite part of a cemetery with fancy grave goods belonged to one haplogroup, and all the men buried without grave goods belonged to different haplogroups, we can say that belonging to the elite in that time and place depended on common descent from an ancestor in the male line. Similarly, if we find people with the same mitochondrial DNA haplogroup

22:15at all the sites from a specific archaeological culture, we can guess that the people making those objects were largely descended from the same population. Conversely, if all the haplogroups varied, then those objects weren't tied to a group whose identity had a basis in common ancestry. Used with nuance, these kinds of studies tell us a great deal. But think about your family tree, those thousands upon thousands of ancestors everyone has stretching back into the mists of the past. A vanishingly tiny portion of them actually fall into the direct male and female lines.

22:47Your paternal grandmother? She's gone in every single case if all you're looking at are the haplogroups. If you're a man, your maternal grandfather won't show up. When we go back further, the percentage of your ancestors you're seeing in those haplogroups gets smaller and smaller. Remember your 128 five-times great-grandparents and 4,096 ten-times great-grandparents, and then realize that focusing on the haplogroups eliminates all but a couple of those individuals. Now, there's nothing wrong with these studies, and particularly in the early days of ancient DNA,

23:17defining haplogroups was kind of the best-case scenario. The problem was how these studies were used, the kinds of claims that were made on the basis of what even at the time seemed to be extremely flimsy evidence. One infamous paper argued for an apartheid-like social structure in Anglo-Saxon England on the basis of not even ancient, but present-day Y-chromosome haplogroups in the United Kingdom. Because haplogroups associated with the North Sea were so much more common in modern England than in Wales or Scotland, the scholars worked backwards to argue

23:48that indigenous British men must have been excluded from reproductive opportunities during the early Middle Ages. Even assuming present-day genetic data can tell us directly about things that happened 1,500 years ago, pretty questionable assumption, the conclusion was too overarching and lacked real support. When archaeologists complained about genetic studies, as they did a great deal, and with real validity in the early 2010s, this was the kind of work they were criticizing. It really poisoned the well for a lot of people, and I even used to teach that specific paper to undergraduates

24:18as an example of how not to use ancient DNA, or DNA in general. Now, fortunately, those days are mostly gone, and we're now in a new and much more productive era. We can actually pinpoint the starting date for that new era. It began in 2010, when the legendary geneticist Svante Pebo and his team at the Max Planck Institute in Leipzig published the full genome, not just mitochondrial DNA, from an extinct species, Neanderthals. This was where the revolution truly began, and in the blink of an eye, it transformed our understanding of the human past forevermore.

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25:53or binge the whole series ad-free right now on Audible. Start your Audible subscription in the Audible app. Whether you're exploring your current fascinations or discovering new ones, Audible has all the stories that'll introduce you to your most fascinating self. Tap into a whole new world of heated conversations with a saucy romantic-y series. Become your friend group's sci-fi expert on the latest blockbuster book-to-screen adaptation. Or find unexpected reveals through the exclusive episodes of a viral true crime podcast.

26:24However you choose to listen, Audible keeps you fascinated so you can be just as fascinating. All in one easy app. With plans now starting at $8.99, you'll get access to over 1 million audiobooks and podcasts, including trending bestsellers, the hottest new releases, and exclusive podcasts you won't find anywhere else. Sign up now to become a member and get any audiobook every month, plus exclusive podcasts. Plans now start at $8.99. Audible. Be fascinated. Be fascinating.

26:54The mapping of the Neanderthal genome

Neanderthal Genome Mapping

27:04was a turning point for a few different reasons. First, and I can't stress this enough, it was a genuinely transformative achievement. The first full look at an archaic human species' genetic code extracted from bone tens of thousands of years old, revealing that modern humans and Neanderthals had interbred and that almost everyone alive today carries a bit of Neanderthal. That's something we never could have hoped to learn purely from archaeological evidence, despite decades of argument over the relationship between our two species. Second, the fact that the researchers published

27:34the full genome, and not just the haplogroups, set a new standard for what geneticists working with this material could hope to do. Moving forward, full genome coverage would be the standard rather than a rare exception, opening up vast new horizons for investigation. Finally, and this might seem crass to academics, the sheer amount of attention the discovery generated made ancient DNA the hot field on the tip of everybody's tongue. I know that because I was one of the people who read those headlines and thought, wow, what an amazing new thing. What else can I learn about this?

28:06That's what good journalism is supposed to do, expose broad audiences to exciting new things. So while we need to be aware of the ways in which coverage can distort what the scholarship is actually saying, it really does matter.

28:20The sequencing of the Neanderthal genome sparked a raft of fascinating discoveries. We learned that Neanderthals were only one of several archaic human species with whom we shared the planet until rather recently. We still don't have a full set of Denisovan remains, but we know a shocking amount about the species' population history and its interactions with different groups of modern humans. That's all thanks to ancient DNA and our increasing ability to read it like a text, inferring everything from the time-depth of lineage splits to narrowing down where exactly these archaic groups must have lived.

28:51It is now fundamentally impossible to do paleoanthropology, the study of archaic humans, without being familiar with genomics. It's not the only interesting work being done in that field, but it's certainly the richest and most promising right now, and I do not see that changing. But let's turn to more recent periods, namely after the last glacial maximum, the time when pretty much everything we associate with a world we recognize came into being. There's plenty of great archaeology on the last 15,000 years that doesn't have anything to do with ancient DNA. Archaeologists dig new and exciting sites,

29:23categorize artifacts, use radiocarbon dating, and employ all the other tools that have been around for decades to help us understand the past. The myriad of other approaches from what we've called molecular archaeology, like stable isotope analysis of human bone and paleoenvironmental studies, are becoming more and more common as the pipeline of researchers trained in those methods leaves graduate school. Based on my conversations with archaeologists, they're building that kind of data collection into their plans for the sites they excavate and finding people with that expertise for their research teams. It's basically mainstream at this point.

29:55Over the years, I've interviewed all sorts of experts who work with this kind of material. I spoke with Dr. Christina Chung about using stable isotopes to study the victims of human sacrifice in the Shang Dynasty back in 2022 for Season 4, Episode 88. I spoke with Professor Cameron Petrie in 2024 for Season 5, Episode 69 about how isotopes in animal bone change our understanding of the Indus Valley civilization. We have a much more textured, nuanced, and deep understanding of these ancient societies because of the tools of molecular archaeology.

30:27But ancient DNA, especially those first big studies in the years after the Neanderthal genome was published, focused more on really big-picture questions. With this new data in hand, researchers attempted to solve the kinds of problems that had vexed archaeologists for years. Was the expansion of farming driven by demographic expansion, people having children who carried on their lifestyle, or by outside groups adopting a new technology and way of life? Where did the Indo-European languages and other major language families around the world today originate? To the extent that these questions

30:58can ever be definitively answered, the ancient DNA did answer them. Farming spread so far and so fast because farmers had tons of babies over many generations, and the Indo-European languages came from the Eurasian steppe, precisely the place many archaeologists had been arguing for over decades. For some archaeologists, not all, but some, even asking these questions was missing the point of their work, falling back on discredited, age-old assumptions about migration and cultural change. There was some real truth to their concerns

31:28because the idea of coherent peoples as bowling balls rolling around the landscape from place to place fell out of favor in archaeology for good reasons. Namely, the Nazis and their use of archaeology to justify their desire for Lebensraum in Eastern Europe, among other, less genocidal concerns. The fact that these early genomics papers generally presented the archaeological record in terms reminiscent of a long-past age of research rankled archaeologists with good reason. How could these genomics papers be useful if they weren't actually engaging with what people who knew the material

31:59had to say? I remember being in the comment sections of the blogs that were covering these papers and arguing with geneticists, some of whom had worked on the papers, who just didn't get why it was even a problem. The problem was that outside the realm of those very largest questions, the limitations of marrying ancient DNA to long-outdated models of how societies worked, changed, and spread over time were pretty obvious. Migrations are real and they matter in human history, more so than archaeologists tended to believe when these studies first came out.

32:30But understanding migration as bowling ball groups of siloed people rolling along is wrong on every level. We know how migration works because we've seen it work in more recent periods, and it turns out that migration in the past worked pretty similarly. These genetic studies were right about the big picture, farmers really did have lots of babies and Indo-European languages really did have an identifiable origin, and sorely lacking when it came to explaining how and why these things happened. What processes took these migrants from place to place?

33:00How did their material lives and identities shift over generations? The question of why exactly that information mattered was never clear either. Were these instances in which genetic data answered the big questions outliers, or were they representative for all or most big cultural changes in the archaeological record? That's leaving aside ethical concerns about sourcing human remains for extracting ancient DNA, something that's still kind of an issue in the field?

33:27Now, I have a lot of sympathy for archaeologists who raised these kinds of questions and got a vibe of high-handed superiority from a few members of the genomics community. Conversely, however, I do not have a lot of sympathy for archaeologists who dug in their heels on the basic question of migration, or who failed to grapple with how ancient DNA might enrich their own work and understanding of the past. Nobody ever said it was easy to learn how to engage with new forms of evidence, and that new evidence might well lead to the slaughter of some sacred cows on which folks had built their careers and reputations.

33:58And that's not an excuse. It's like being an old-school baseball guy who refused to embrace advanced analytics in the moneyball era, but with tenure and no consequences for being completely wrong. I read a half-dozen critiques of ancient DNA and genomics-based approaches, some of them widely cited and shared, that made me want to tear my hair out. It's taken a while, but I think we're past all that, or at least most of it, for one major reason. Archaeologists and geneticists are increasingly working together, not just on papers resulting from fieldwork, but from the very beginning

34:29of the big projects they're planning. The legendary archaeologist Mike Parker Pearson, whom I interviewed back in 2021, Season 4, Episode 74, about his work on Stonehenge, was one of the lead designers of a massive interdisciplinary project on the Beaker people of the early Bronze Age. This project utilized traditional archaeology, new molecular archaeology methods, and ancient DNA. Its insights are simply stunning, painting portraits of ancient people and the groups to which they belong with a level of detail we could never have imagined even 20 years ago.

35:00Diet, ancestry, settlement patterns, social relationships, all of them illuminated through the combined application of many different methods. Ian Armit, who works on the Iron Age and whom I also interviewed, is another archaeologist who led an interdisciplinary working group focused on Britain and its interactions with the continent during that period. Ancient DNA was a cornerstone piece of that project, but the results of the ancient DNA studies were insightful because of the ways that experienced archaeologists applied the data to their specific questions.

35:32The key word here is interdisciplinary. Archaeology has always been a group project far more than history. It's one of the things I've always enjoyed about it, especially at the bar. But as archaeology has changed thanks to these molecular tools, the tent has to get bigger to keep up with the need for a wide array of expertise. Genomics is another tool in the toolbox, an extraordinarily powerful one, but it has no value if it's not being applied in rigorous and nuanced ways. Ancient DNA labs need archaeologists.

36:03Teams of archaeologists need geneticists who can extract and analyze ancient DNA. Archaeologists who excavate human or animal remains that might contain preserved DNA and choose not to investigate that data, assuming they have the funding for it, are leaving major insights on the table. Conversely, geneticists who spend years assembling the data for a big ancient DNA project but don't know how to ask meaningful, well-crafted questions of that data are wasting their time and their institution's money. The possibilities ancient DNA offers

36:33are nearly endless. Who has children with whom isn't a neutral thing, and ancestry, what DNA gives us, is extraordinarily revealing of deep economic, social, cultural, and political patterns within and between societies. I'll give you a few brief examples here. The archaeologist David Anthony, one of the pioneers of combining ancient DNA and archaeology, told me in an interview from Season 4, Episode 50, back in June of 2021, that he and his team had found two closely related men in the Bronze Age who probably shared a grandfather.

37:04One was in present-day Hungary, the other was in southern Siberia, and both were high-status individuals buried in prominent mounds. This tells us quite directly that in this Bronze Age society, status and power were passed down through the male line, and that has really profound implications for how we understand it. Turning a bit further west, the individual buried in the central chamber at the Neolithic monument of Newgrange in Ireland was a product of incest, probably between siblings. That's something we couldn't hope to know without ancient DNA, which also tells us

37:35that the individual was closely related to other high-status burials throughout Ireland. In other words, ancient DNA told us that there was a hereditary, closely related elite in a Neolithic society that we never saw before. And here's one final example. A mass grave from the Battle of Humira in 480 BC between the Carthaginians and Syracusans in Sicily is interesting on its own. The combination of stable isotope and ancient DNA analysis tells us where the people in that grave came from. Many of them

38:05had come to Sicily from distant parts of the Mediterranean and beyond, something their bones alone could never tell us.

38:13I love these individual stories. I love trying to figure out what brought someone from Illyria or Greece or Iberia to Sicily and thence to a mass grave. Ancient DNA is a tool that allows us to get at those stories, even more so than the other incredibly exciting tools in molecular archaeology and the third science revolution. We might use large-scale studies of ancient DNA or any other archaeological evidence to ask huge questions about societies and civilizations. Those are important questions to ask and I'd like to know the answers to them

38:43as much as anyone. But societies and civilizations are aggregates of people and in a thousand different ways DNA allows us access to that person's life, world, past, and even their future or at least that of their descendants and relations. We are still only scratching the surface here. Every new genome sequenced isn't just an individual. It's their thousands of ancestors, their adaptations to their environment, their inherited disorders, and the web of relationships that bound them to others in time and space.

39:14As ancient DNA becomes more integrated with archaeological practice, we'll see the evidence deployed to answer questions we haven't even thought to formulate yet. I, for one, couldn't be more excited about those possibilities. I hope you're excited too.

39:28Next time on Tides, we'll turn to one of the fields of study that ancient DNA has helped to unlock. Migration. It's one of the most important concepts in the human past, but how do we understand it now? That's what we'll discuss next time.

39:49Tides of History is written and narrated by me, Patrick Weinman. Sound design by Molly Bach for Airship. The sound engineer is Sergio Enriquez. Tides of History is produced by Morgan Jaffe. From Wondery, the executive producers are Jenny Lower Beckman and Marshall Louie. Thanks again for listening. Until next time, from Wondery, this has been Tides of History. Follow Tides of History on the Audible app or wherever you get your podcasts. You can listen to all episodes of

40:19Tides of History ad-free by joining Audible. Follow Tides of History. Hey, we'll scroll down. What'sive coming in, how do we keep your organization and you have seen and you and you have let go to U