Digging up the Year in Archaeology
This week we take a look back at a year's-worth of Naked Archaeology including a dig through some Pomepiian poo for clues about the Pompeiian lifestyle, the art of spear throwing with an atlatl and exposing the most recent neanderthals of the Caucasus. Plus we identify alien donkeys and learn how to make history from prehistory!
In this episode
02:28 - How do you throw spears?
How do you throw spears?
with Mike Bumstead, University of Aberdeen
Tom:: Well today, I've turned up in the middle of a field, a park rather. It's sunny, it's windy, and I'm meeting up with my friend Mike Bumstead. Mike, why are we here in this field today and why are there some long darts on the ground?
Mike - Well, we're going to learn about spear throwers today.
Tom - Ahh, spear throwers. I see. Okay, so can you just describe what you've got in your hand for us please.
Mike - Well I have two pieces of the technology that we refer to as spear throwers: one which is Native American, central Native American in design and it's an atlatl, something you would pronounce in a different way in this part of the world.
Tom - Okay, wait. So let's just take a step back. We've got a spear thrower and then you use this word 'atlatl.' So, there's different names for this thing.
Mike - Yeah, there are. Basically, what it is is a long stick with a hook on the end. Sometimes it's a grooved, sometimes it's not with a counter balance which you use to throw darts: what we call spears. Long, sharp objects at things.
Tom - So, we call it the spear-thrower, this other one you have in your left hand is the Inuit version isn't it from the North and Circle Polar regions, so some people might call that a throwing board. What's the Australian one?
Mike - The Australian one is called a woomera. Now unlike these ones that I have here which are single purpose objects which have sort of a bone hook at the end, the woomera is a longer, narrow curved board and it was a bit more multi-purpose. Some of the existing examples have stone sharp edges placed on one side and some of them in fact, as I understand were used as shields. Some of them were of this size and so they're more than just a single-use spear-thrower.
Tom - Okay, so it some spear-throwers are multipurpose. That's quite fascinating. The ones Mike are holding are quite different. The native American one he is holding which is a replica has a stone weight about a third of the way down near the handle and as there's bone point he's talking about -it's just a bit longer than my forearm- and I believe they should be about that size for individual. I mean, how do you use them, Mike? Can you just show me and I'll maybe describe to our listeners what you're doing? He'sholding this 3 ½ or 4-foot long darts. These are aluminium competition darts you can use like soft woods and there is a flight in the end. So it looks like a long arrow... I see..! Can you describe what you're doing, Mike?
Mike - All right. The darts have a knock in the back. So you place that on the hook, this bone part at the end that we've been describing, we refer to as the hook. And then you hold the dart along the length of the board with the handle in your hand and you hold the dart in the same hand as you hold the handle, sort of like a pen.
Tom - Okay. Yeah, so at the moment, Mike has got thespear-thrower in his hand. He's holding it a little bit like a tennis racket or a badminton racket and at the same time on top of this spear-thrower, he has the dart lodged into the knock and he's balancing it on his thumb and first two fingers. A bit like a pen, yeah. So you're holding that now. What are you going to with it?
Mike - I'm going to aim at the target that has been provided today which is the box for a Delonghi brand convection heater.
Tom - The rare mammalian species that has decided to grace us with its presence. Now Mike is - I'm be standing back for safety reasons - that's a long way, Mike. That's a long way. You've missed the target quite a bit.
Mike - Well, the target we've had setup which is setup for practical class that we teach at the University of Aberdeen is probably about 40 yards away from our position. And of course, these kinds of technologies, these spear-throwers are not really designed for close range hunting. So that being said, I'm also not very good with them, so I'll probably not going to hit your Delonghi anyway.
Tom - Okay, with second try, that's much closer, but that's great. So, I mean, that's a good 60 metres that's travelled and how far can these things go do you think?
Mike - Ancient technologies, I mean, we're using aluminium competition darts so these actually flow quite far and you can throw them probably anciently 250 to 300 meters. The longest throws in the modern era are probably two times as long.
Tom - Okay, that's quite a long distance. Now with atlatl, one thing we have to mention is that this technology compared to just throwing a spear with your hands allows you to throw the dart much, much further. I mean, the dart and the spear, we must make a distinction here mustn't we? They're different things aren't because this isn't - when I would thought we're doing spear-throw today, this isn't a spear, Mike. This is 3 ½, 4-foot long aluminium pole.
Mike - Yeah and these modern ones that we're using are - they're exactly as you've described them. They're really, really big arrows.
Tom - Yeah.
Mike - With this technology when we say spear-throwing, that's what we're talking about. We're not talking about javelins or a prodding stick with a stone tip on it, right?
Tom - That's the more traditional idea on a spear I think: 6-foot long staff, massive, iron point on it, but we're not talking about that at all. We're talking about launching big arrows basically.
Mike - Yeah. Even that being said, those what we think of as stereotypical spears, there was an evolution in how to throw those as well. Ancient Greeks used a leather strap that was tied around the base and then what you would do is as you released it, it would serve the same purpose as these spear-throwers that we're using, but it would also cause it to rifle. If you think about how a bullet works as it comes out of a modern firearm, the grooves are on the inside of the barrel to allow it to fly more stably and straighter - those kinds of other strappings that were used at that point would serve the same effect. It'd help to stabilise and straighten the flight of what you would say a more stereotypical spear would fly as.
Tom - Okay, so let's just have a - I might have a go in a minute actually Mike, if you wouldn't mind. I think I can give this, if you just hold that.
Mike - Okay. All right, you've got it setup. You've got it lined up.
Tom - Okay. I'm going to kill it. I'm going to kill it coupled by...
Mike - So do it.
Tom - That was pretty bad. Okay, I'll just for our listeners, it's not as easy as it looks as Mike has demonstrated. I think I might have another go...
Tom - So, despite my three attempts at throwing a spear with a spear-thrower, I think we've concluded Mike that I'm not your natural hunter. But it's not always about hunting, is it? These were offensive weapons that were used. You were mentioning to me earlier about Montezuma.
Mike - Yes. The Aztecs were very well-known for using these spear-throwers. The Aztecs in fact, when the conquistadors arrived in Spain terrified them with the potential havoc that could be upon the Spanish with these weapons. And it's really not until Cortez convinces them that he's their God and trouble occurs for that civilisation.
Diana - Other electrical appliance boxes are available. That was Naked Archaeologist Tom Birch and Mike Bumstead who's a post-graduate researcher at the University of Aberdeen.
10:38 - Bayesian Prehistory
with Alex Bayliss, English Heritage
Diana:: Next up, computer programmers and archaeologists recently used a technique known as Bayesian chronological modelling as a window through which to look at the real political and even military events which shaped Britain's pre-historic past. The new research based on computer refined radiocarbon dates strongly suggests that farming lifestyles were introduced from the continent through Kent and Essex by immigrants and not simply through the transmission of knowledge and ideas. The work also suggests that large structures known as causewayed enclosures only emerged in Britain once there was enough farming going on for allow leaders to lead ever larger groups of people. To tell us more, Alex Bayliss.
Alex - Radiocarbon dating used on its own has quite large error terms. If you've just got a single radiocarbon date, typically in the 4th millennium BC, it will cover about 250 years. But because radiocarbon dates is a probabilistic process, if you get 10 radiocarbon dates for a site, they will scatter around the true dates of that site. So some will be a bit earlier and some will be a bit later, and it will look - even if all those dates are from the same Thursday afternoon in 3000 or 600 BC- you know, the earliest radiocarbon date will 250 years earlier, the latest will be 250 years later, and it will look like that the actual site was in use for 500 years where in reality, it was used for one afternoon. So, the basic problem when we started was that normal radiocarbon dates kind of put the early Neolithic of Britain into a kind of splodge. Okay, we know it's early Neolithic but it's this kind of undifferentiated splodge somewhere in the 4th millennium BC.
Diana - Okay, so how do you go about differentiating that splodge then?
Alex - So what we do is, instead of just relying on the scientific information - the radiocarbon dating, we put together both the archaeological information with the radiocarbon dating. Now, I'm the scientist on the team but I've got colleagues at Cardiff University and together, we worked out what that additional information is. So, for example, if you have a sequence of deposits through a ditch and you have 3 radiocarbon dates, it is very likely from archaeological information that you would know that the sample at the bottom of the ditch is earlier than the sample in the middle, is earlier than the sample at the top of the ditch. And so, you can actually use that relative dating that you've got in archaeological sequence to refine the radiocarbon dates.
Diana - That sounds lovely, but what did you get out once you had this amazing sort of level of refinement?
Alex - Okay. Well the project that we actually were working on, the group of monuments we were working on and this was a joint project funded by English Heritageand the Arts and Humanities Research Council in Britain was the dating of early Neolithic causewayed enclosures. Enclosures seem to be gathering places that are used periodically there's evident for really big feasts where several cattle would be killed all at the same time. You know, they had a massive great barbecue basically. Now causewayed enclosures are the first big monuments that we have in England. They can be about 300 metres across. They have at least one, sometimes four, circuits of ditches. The ditches can be rock cut, but they have lots of different entrance ways that's why they causewayed enclosures. Some of them also have palisades and timber lacings in the earth around parts that were formed when the spore from the ditch is coming out. So these are fairly big things, you would need several people for a month to build one.
So what we did was we went back to the archives in the museum, no new excavation and we dated all the ones that had holes in from the past. So we've dated about 40 out of the, roundabout, 90 that are known. Mostly in southern Britain, although there were few in Ireland, and a few currently on excavated ones further north in England. And we found that they actually covered a very tight span. Previously, these things had been thought to be built throughout the early 4th millennium and to be typically in use for maybe 300 or 400 years. We actually found that they appear very suddenly, roundabout 3700 BC and when I say 'roundabout' I mean we did a generation of within 25 years at 95% probability. They appear first in Kent and then they spread very rapidly across southern Britain until about 3625 BC. About half of all examples, things that have been built in the first 75 years. So we have a boom. We have a real big construction boom and that is of course followed by a bust because then there's evidence that for about the next 50 years, it becomes, for whatever reason, they become very unpopular. And then in the generation around 3550 BC, again, it becomes popular again, so we have a boom and a bust, and another boom, and then they just go out of use and nobody seems to build them anymore. So there's a final bust.
Diana - Right. So if the initial building just occurs in one generation, what are the implications of that then if that kind of proliferation of building style? What does that mean?
Alex - Well at this point, you kind of have to get to the stage where you know, a date is just a number because if you've got no context, you know, we suddenly knew far more about enclosures but we can't - I can't answer that question- without telling you what happens in the rest of the early Neolithic. So we had to kind of unpick the rest of the splodge. Okay, so to do that, we just looked at - there's about 1500 existing dates. We got details of all of those, looked at all the archaeology and did a model for that. And so, we've written basically a completely new story for the early Neolithic in from Britain.
So what happens is, around about 4050 BC, probably the first pioneer settlers arrive from continent in the Thames gateway. Then the idea of farming, basically it got Kent to Cheltenham in about 200 years. Then round about 3850 BC and by 'round about' I mean, within about 25 years of 3850 BC, some kind of critical mass seems to have been reached because suddenly the Neolithic appeared everywhere, bang! Within the next 50 years, it gets from Cheltenham to Aberdeen. Then in around 3800 BC, things really start to rock. It seems like the pioneer phase of Neolithic settlers is over and what they're trying to do is build a society because we have so many innovations in the next hundred years of which enclosures are just the last. But the point is you've got national exchange networks for high quality stuff being established, and at the end of this process, this century of real dynamic innovation where really everything is changing, that's when causewayed enclosures appear.
So to now get back to your question: Why do causewayed enclosures appear? Well, what's interesting is that both long barriers and causewayed enclosures are typical Neolithic monuments that occur on continental Europe. So the question is not so much why did it appear in 3700, but why didn't it appear in 4050 BC with the initial colonisation? You know, this idea was already around on the continent but they didn't bring it with them. So maybe the idea is that the reason they didn't was because maybe they didn't have the resources to invest in that sort of stuff, they were too busy building their flocks or they were too busy setting out their fields, and actually, maybe what we're seeing in the 3700s and with enclosures is an attempt to have control of what happens at the festival when they had their enclosure meeting. Who could get their hands on all these new exotic stuff that was being traded. So maybe it's actually about the emergence of power is perhaps our idea. Now, we've emerged from the splodge, there's this story and we've actually got a dynamic narrative and because, what have I been talking about? I mean, I've been describing a political narrative of southern Britain 5000 years ago and we simply couldn't do that before without the dating.
Diana - So from this study, it looks like farming was brought in by specific group or groups of people rather than as a spread of knowledge through indigenous populations which marries really well with the genetic data, and ultimately, it's their fault we have big community buildings. You can read more about Alex's team's work in the book "Gathering Time" dating the early Neolithic enclosures of southern Britain and Ireland.
20:18 - Petrified poo gives clues to Pompeii people's lifestyle
Petrified poo gives clues to Pompeii people's lifestyle
with Andrew Fairbairn, University of Queensland
Diana - We're looking at the fundus, the base and bottom of archaeology with some archaeological poo smothered in volcanic ash in 79 AD, the site of Pompeii isn't just known for the incredible preservation of its residents and buildings. Also preserved at the site are the ephemera of daily life including waste, but what sort of information can we glean from Roman poo? Andy Fairbairn explains.
Andy - Well, we're very interested in the long term - I guess economic - development of Pompeii and especially the life around the port of Stabia, the Stabian gate basically through the several hundred years of Pompeii's existence. The project that I'm part of, it's run out of the University of Cincinnati in the US and it's a multidisciplinary project like most archaeologic projects are known these days and it's really trying to disentangle just the long term economic change at Pompeii and you know, how did the site, how did the city, how did the lives of the people their change over time as the Roman empire actually formed and then had various economic reforms.
Diana - But how can Roman fossilised poo or copulate helped?
Andy - Well the material that I've been looking at, it's really the leftovers from sewage and rubbish I suppose. It's a mixture of hard bits that go through the digestive tract I suppose, and also, the soft bits and I'm very interested in plant material actually. I'm interested in the seeds and fruits and bits of leaf matter that people eat in their lives. Basically what happens when in soft pits and in wet areas in general in archaeological sites if there are very low oxygen levels and high water content, you can get plant material and soft tissues and all manner of things preserved. Yet, even when they normally decay very rapidly, if they were left lying around on the surface or if it was a very dry kind of environment. And what's happened in Pompeii in the context I'm actually looking at is that the sort of sewage, the rubbish, and all that kind of thing has been dumped long enough to basically fossilise much like a dinosaur bones or other things do when they're left in the ground for long periods of time and the right kind of chemical conditions.
Effectively, all the soft tissue has been replaced by minerals and those minerals come out of, all the rubbish and whatever that's actually reserved in these cesspits pits. They're effective barrels, the guard robes, the holes dug in the ground and lined often with ampiron in there actually used as a lining which people have then emptied their waste into. Now what this actually allows us to do is to investigate some of the things that were actually eaten by people in the past.
In most archaeological sites in Pompeii is another great exception to this. The remains that we find there are dominated by the tough stuff and the bits that are often preserved in the case of plant material when they're burnt basically. And we often get lots of rubbish, it's all mixed up - that's what we get to look at from archaeological sites. So we can actually quite tell what people have really been eating you know, what they have actually been consuming in aparticular place, maybe a particular family or something like that.
The fantastic thing about sewage and faecal matter is that we have a pretty good idea that the things in it were actually consumed. So, this is the great value for this kind of thing at Pompeii. Andrew Jones otherwise known as 'Bone Jones' at the University of York as called has investigated the bottom end of the market. He loves this kind of stuff and my former Professor used to call this stuff 'Pearls beyond price' because of the rare glimpse it gives us. Really, if you haven't got kind of a direct effluent ,sewage, you went to look around for a very rare find like bodies and mummies and things like that to give you this kind of information. So in an occupation site like Pompeii, it's wonderful stuff really and it allows us to key right into what those particular people in those particular houses were actually consuming at times in the past.
Diana - Okay, so from whom did these brown pearls come from?
Andy - Well the particular samples we've been looking at so far certainly from the later phases of occupation in the Port of Stabia. Really, they're come in from houses, building that were associated with basically retail outlets if you like. I guess aRoman equivalent of the burger or that kind of thing. This is where the great masses ate really in the Roman urban world. Now we're not actually sampling those people who were out the front, eating the food that was being served up in these places, basically restaurant, cafes, that kind of thing, but really, fast food joints. You go along, you pick up a bite to eat and you head off on your daily routine. But we're actually looking at the people who are behind that, the people who were preparing and serving up that food and people who actually lived in the houses in that area. So, we're not talking about the top end of town here. We're talking about maybe some of the business owning classes and some of their tenants. So really, I think we're looking at the lower end of Roman social world.
Diana - Well the question I've got to ask is, does it still smell?
Andy - Oh, no. Absolutely not. It just smells of delicious moist soil actually. It's very pleasant stuff to work with actually and I would say, quite attractive to look at. I've seen a lot of archaeological material in the microscope and a lot of the seeds, fruits and all bits of plant material I look at usually look pretty narly and blackened, and they're not particularly aesthetically pleasant, but we get all manner of things preserved. It was beautiful to look at actually, these sort of basically fossilised mineral casts of things that were found in the past. I have to say that it's not just the plant material which I'm kind of obsessed about, so I love looking at it, but we get all manner of things including fly Puparia, all manner of insect bits and pieces they need too because we're not just getting the actual sewage, the effluent, we're getting all the things that actually live on it too, and they can actually be quite - I guess to my eye anyway- quite beautiful to look at in fact and they're beautifully preserved.
Diana - What's the strangest thing you found in there?
Andy - There is a certain amount of rubbish in there, yeah, definitely. But most of the rubbish seems to be actually derived from food preparation so you get things like, bits of fish heads and you get small bits of bone vertebra that have been chopped up. You can see where they've been butchered and maybe then removed from the food during preparation or maybe the leftovers of somebody having a nibble of something. I think the most unusual thing, the most interesting thing from my point of view are actually the insect remains to be honest. They haven't been analysed in any way yet. Dr Mark Robinson is going to be working on those. He's a world-renowned expert in identifying this kind of thing and I find them probably the most fascinating of the materials that we find because often, these things are quite - the insects are actually very specific to particular environments. And so, what they can tell us, yeah, they can say this is a big smelly pile of old poo if you like, but they also can give us all manner of, potentially anyway, information about the actual - the surroundings in the rooms for example that these toilets were in.
We know from sort of generalised historical records that the Romans had a very different view of hygiene to us. They often had the toilets in the kitchen so you could throw out your kitchen scraps as well as food that had already been eaten if you like. And so, we can use the insect fauna that we have potentially to tell us what those sort of conditions may have been like in the kitchen so I'll find that most interesting. But I have to say rather sadly, you don't get things like bits of gold jewellery or anything like that in there. It's all rather mundane in my end of town.
Diana - Well, when there's muck, there's pearls as they say. Andy Fairbairn, Senior Lecturer in Archaeology at the University of Queensland. And you can find more interviews like that at thenakedscientists.com/archaeology.
28:18 - How were fat and thin body images portrayed in Roman and Greek cultures?
How were fat and thin body images portrayed in Roman and Greek cultures?
with Mark Bradley, University of Nottingham
Diana - Let's now move forward to the Roman world and how they thought about being portrayed as fat or thin. Today in the western world, being slim is most often seen as a sign of health and wealth while the overweight often lambasted, but what happened back then? Was it fashionable to be a little more corpulent? Mark Bradley.
Mark - The problem I'm trying to solve is to think a bit harder about how fat and thin bodies were evaluated in Greek and Roman culture and religion and society. That is not simply to translate the categories in the pre-occupations that we have in modern society about what is obese, what is corpulent, what is thin, what is a emaciated, but to try and think about how those categories and how those body shapes were being talked about, discussed, debated, criticised. Particularly in Roman society.
Diana - And what are you looking at to try and answer that question?
Mark - I'm looking at a range of visual evidence, not just bona fide Roman art but I'm looking at Greek vase paintings that were part of the visual culture of Roman Italy, I'm looking at Hellenistic sculpture, I'm looking at wall paintings, and I'm looking at Roman portraiture, so a full range of evidence to try and get an overall view of what corpulence, excessive weight, excessive emaciation looks like in Roman art.
Diana - And so, how would you say obesity is thought of in Roman art? Is it positive? Is it a sign of wealth or is it something else?
Mark - There are two very different discourses responding both to obesity and to emaciation in roman art and one discourse sees fleshiness as a sign of affluence, of the good life, of access to lots of food and resources. And this plays out in examples of Hellenistic rulers for example or certain Roman emperors who wanted to imitate Hellenistic rulers, who wanted to show how many banquets they had, and how rich they were, and how affluent they were. But at the same time, there's a discourse which sees paunchy stomachs and cheeks part of that kind of comedic culture where these people have eaten too much and they've let themselves go. And obesity, fatness, big bellies are linked to decadence and softness, and sometimes effeminacy. So two very different discourses going on at the same time but it's important to recognise that they both exist symbiotically.
Diana - And do you think there might be an element of poking fun at those people in power, those people who were putting themselves across as being a little bit overweight. Perhaps linking them to comedy might be something to do with that.
Mark - Absolutely. Absolutely, so we get thesame emperors, we get emperors like Nero, we get emperors like Vitellius who follows Nero, who evidently are quite podgy, and they make the most of this in the portrait showed by coming across as these affluent, well-fed, rich rulers, but at the same time of course, you have critical responses from people around them, describing them in very, very negative terms. So, yeah, absolutely. I mean, both interpretations seem to exist at the same time.
Diana - Do you get fat jokes?
Mark - Do you get fat jokes? They're quite serious fat jokes. I don't think there's any sort of light humour surrounding this. I think there's always these underlying moral connotations about how these really fat people have let themselves go and are therefore incapable of looking after their state because they can't look after their own bodies. So, I mean, there's always this deep satirical way of approaching obese people in Roman culture.
Diana - Well that's interesting given our current preoccupation with how much obesity costs the NHS. But you mentioned emaciation as well. How is that portrayed?
Mark - We can assume in most pre-modern societies in Europe that food is not - you know, food is scarce and is not always going to be available consistently throughout the year. It has been assumed that with famine, hand in hand with famine, comes for the majority of people, of thin emaciated bodies that this is the norm and indeed, when you get you know, elite artists and writers representing the poor, you know, one way you recognise them is by their thin frames. Workmen, tradesmen, and particularly sort of old homeless people, lots of everything represented as being very, very thin. So that's one clear way of interpreting emaciation.
But the other side of the coin which I guess is a little bit like the affluent ruler with access to all of the food and resources, the other side of a coin is that you get figures, particularly philosophers and thinkers, intellectuals, writers, and stern, self-restrained generals and commanders who are actually quite thin and emaciated, and you always get Julius Caesar with sunken cheeks, and very bony features as part of his kind of -he is in control of himself. He doesn't need to let himself go. He doesn't need to eat too much. He's a man of thought. He's a man who's restrained and dignified, and so on and so forth. So again, two very different ways of approaching it.
Diana - And so, what's the next problem to solve then? Where are you going to take this research next?
Mark - Where am I going to take this research? This research has led me in a rather different direction from what I was originally focusing on which was looking at you know, simply unpleasant bodies in Roman culture which is about much more than just unpleasant bodies as I've described and I need to sort of turn myself back a bit and look at other features of the body in Roman culture which was perceived as transgressing boundaries or unpleasant or disgusting in certain ways.
The alternative thing that I could do with this research once I've written up as an article is to maybe think a bit more generally about the role of obesity, corpulence, and emaciation in ancient medicine, in ancient literature in a broader range of genres So maybe I'm thinking of a bigger project, depending on how this particular project is interpreted.
35:06 - Dating the Neanderthals of Mezmaiskaya Cave
Dating the Neanderthals of Mezmaiskaya Cave
with Tom Higham, University of Oxford
Diana - Let's now take a trip back several tens of thousands of years to early humans. One of the key debates for people working in Paeleontological archaeology is the overlap between modern humans and Neanderthals who did seem to live side by side for a few millennia. But the length in nature of that co-habitation is still a bit murky. The most recent Neanderthals of the Caucasus were only this year re-dated to confirm just how recently they live there and it wasn't as recent as we once thought. To tell us more, Tom Higham...
Tom - We've been interested in chronology building and precise radiocarbon dating for many years. That's one of our main research interests and traditionally, our lab focused on archaeological dating, so we really specialise in that area. And one of the most challenging parts of radiocarbon is dating old things and that's because radiocarbon is an exponentially decaying isotope and by the time you get back to five or six half lives, more than 30,000 years ago, you start to find that the amount of radiocarbon is very, very low and becomes increasingly difficult to measure.
And not only that, it becomes very difficult to distinguish what is radiocarbon dead, in other words, beyond about 55,000 and within the period of 40,000 to 50,000. The period that we're discussing here is very important for looking at the questions regarding Neanderthal extinctions and they're rather the first modern humans into Western Europe. It's been a real challenge to radiocarbon date this.
In the last 10 years, we've been using newer techniques and this has led to a number of revisions of previous dates which we found to be often very much younger than they in fact should be. So for example, when we radiocarbon date a bone from one of these sites using the ultrafiltration method that we've now begun to adopt, and we compare it with dates for the same archaeological samples, or archaeological samples from the same sites, we often find that the ultrafiltration dates were much older and we would consider them to be more reliable because the challenge is always in radiocarbon dating this material to remove modern carbon contamination. That's the real headache for dating this type of material simply because when went down at 30,000, we then got about 3% of the amount of radiocarbon that we have in the modern period.
Diana - What's the situation that you had that Mezmaiskaya then?
Tom - Mezmaiskaya cave is a very important site in the Caucasus, in the southern Caucasus, of Russia and it's important because it's produced physical remains of Neanderthals. There were two infant burials there and one of them has produced DNA that's been used in a Neanderthal genome project, this is the Leipzig based project which has been working for the last few years on developing the Neanderthal genomic sequence. So it's a very important site. Not only that, but it's produced one of the latest dated Neanderthals in Eurasia, around 29000 BP, before present. So it's one of the most recent dates and it's important because it's been taken to suggest a late survival of Neanderthals there compared with other parts of Eurasia.
So we were interested in testing whether or not this was true, using the ultrafiltration techniques that I was discussing just before. And when we went back to the site and we took the whole lot of samples from throughout the archaeological sequence, we found, as we have in detailed at many other sites, that those young dates just simply went robust and when we re-dated some of the bones, we found that they were up to 10,000 years earlier than they otherwuse would appear to have been. And this is very important of course because it changes the interpretation of the survival of Neanderthals in that area and the amount of time that they may have overlapped chronologically with modern people.
Diana - Okay, we'll get to that exciting bit in a minute. So, can you compare ultrafiltration to ordinary methods of carbon dating? What are the differences?
Tom - Yeah, well often what we find is that ultrafiltered collagen dates are much older than dates using other less refined techniques. An ultrafilter is sort of like a molecular sieve. It filters out very small molecular weight components and traps above the filter, larger, long collagen molecules that are less likely to be degraded, altered, and contaminated. And so largely, what we find is older dates using ultrafiltration methods, but not always. In cases where we have well-preserved bones for example, with lots of collagen in from permafrost areas, areas where the bones have been well-preserved and sealed, we don't see these effects. It manifests itself most often in places where the collagen levels are low, the contamination possibilities in the sites are quite high, and that's where we see the greatest differences when we use ultrafilters, compared to when we don't.
Diana - So, why don't more excavations use this technique to re-date their find.
Tom - It's only in the last few years that we published the data that shows this. The technique itself was developed in the late 1980s, but surprisingly, it wasn't widely adopted by radiocarbon labs, and we started using the technique in the early 2000s. It was only when I started collaborating with a colleague of mine from the British Museum who was interested in looking at the British Palaeolithic, the British archaeological sequence, that we began to do some serious in comparing old dates with new dates, and comparing different types of pre-treatment chemistry. And it was then that we discovered these dramatic differences that sometimes occurred. And since then we've extended the work into the European sequences where you find many, many sites that include this period. As I've said, we found that often, the ultrafiltration does have a major effect and it seems to produce results that are not only reproducible but also, produce patterns in the data and seem to be much more reliable. We have independent evidence also that backs up the reliability of these techniques.
Diana - And what does this 10,000 years change in date mean for the human populations at that time?
Tom - Well at the moment, there have been huge debates that have been raging in the paleontological world about what happened when the first modern people entered Europe in terms of Neanderthal populations that were living there. And there are a number of huge questions that arise regarding the mechanism of this dispersal and later extinction. Much of this debate hinges upon the amount of time over which populations were contemporary or not. For example, there are huge questions about the amount of interbreeding, if any, that might have taken place when the first moderns reached Europe and found Neanderthals there. Similarly, how much cultural exchange was there between the two, and this have been really strenuously debated for many, many years - did Neanderthals copy modern humans and did they copy aspects of the technology? Was it the reverse? Did Neanderthals come up with their own version of the upper Palaeolithic revolution? Did they develop new techniques of making stone artefacts and bone tools which were then copied by incoming modern humans? And as I said, it all comes back to the chronologies.
If we have radiocarbon dates such as the one we had from Mezmaiskaya which is 10,000 years younger than we now know that they are then this changes completely the interpretation of the contemporaneity of these two groups of humans. So, when we go back and we re-date these sites and we find that the dates actually don't stand up to scrutiny, you can imagine that what's called for then is a much wider project in which we date many, many sites, once again, to find out the real chronology. But I think that rather than seeing a long contemporaneity, the most likely scenario is that there isn't probably a great deal of overlap between the two populations and for whatever reason, we think that Neanderthal extinction parallelled rather closely the arrival of the first people. That's our hunch looking at it now, but we've got a lot of work still remaining to do and a lot of modelling that needs to take place before we're 100% confident in publishing our data yet. But I think that's probably what we'd expect to see.
43:35 - Dead horse in Pompeii was actually a donkey.
Dead horse in Pompeii was actually a donkey.
with Susan Gurney, Cambridge University
Diana - Now, to mysteriously extinct horses in Pompeii. In 1987, five equine skeletons were excavated from the famous site, but one was a little unusual. The first set of researchers to analyse the DNA of the misfit, determine that its DNA was indeed quite different from that of the other four skeletons. So different that it seemed quite unrelated to surviving modern horses, but Susan Gurney together with Peter Forster and colleagues reanalysed the data and found that actually, this alien horse was a donkey...
Susan - So the remains were taken from an excavation in Pompeii from a house which is called the Castiamanti house which is the house of the chaste lovers and it's so called because of the friscos depicting romantic scenes which were found at the house. And this house was owned by a baker, a wealthy baker and so, it's thought that the stables could have horses and donkeys in them because donkeys and mules were used within bakeries to pull the mill. So, it would make sense that possibly, one of these equine skeletons belong to a donkey. And so, the town of Pompeii is quite important archaeologically because it was covered by ash from the eruption of Mt Vesuvius in AD 79. So by excavating the town, archaeologists are looking at what life was like back then and it means that in terms of genetics, we can also see what animals, what species of animals, were present at that time and how they differ to the species that exist today.
Excavation was performed initially in 1987 but the DNA analysis of the skeletons, the equine skeletons, didn't take place until 2004. So they extracted DNA from the remains of five skeletons which were found in the stables, and they were wanting to find out how closely related were they to modern horses. And so, with one of the remains that was quite interesting because part of the DNA sequence didn't match any of the DNA sequences that we have for existing modern horses, so the Italian group who did the work concluded that it was possible that these horse remains were actually from an extinct horse breed which we don't see today.
Diana - And how likely could this have been? I mean, how similar or dissimilar was the DNA from a potential extinct horse?
Susan - Well, because there were five equines found in the stable, you would assume that the DNA should be quite similar between all five of them but one of them had a very high number of additional mutations. So, it should immediately have looked slightly odd that if you're looking at ancient horses, you've got a sample of five from a period of time from AD 79 that they should be fairly similar, but one of them definitely stood out as being different from what they concluded were horses. Four horses.
Diana - And how did this problem land on your doorstep? How did you get involved?
Susan - Well I'm doing a research project with Dr. Forster who's also part of Cambridge University and we're looking at horse profiles. So we were looking at all of the published data on horses and we've also generated some of our own so we were actually looking at the ancient DNA sequences which have been published when we came across this very interesting sequence, and it was when we looked at it further that we've realised that actually it wasn't an extinct breed as had been published but was actually a mix of a donkey sequence and horse sequence.
Diana - Oops! Okay, so how could this have happened?
Susan - Well there's three possibilities: it could be a contamination that took place during the excavation, the bones could've been mislabelled, it could've been a contamination that took place in the laboratory when they were actually extracting the DNA and doing the laboratory processes, or it could have taken place while they were actually writing the paper or during the computer simulation of the work - so trying to assemble the DNA sequences, they accidentally assembled a donkey to a horse. So there's three possibilities.
Diana - So how did you actually go about disentangling the problem and what kind of methods did you apply to it?
Susan - Well we had the initial DNA sequence that the researchers have published and what we did was we used an alignment program- you choose a reference sequence which we chose as a horse or a donkey and then you align the DNA sequence that you have so it then identifies where the mutations lie. So initially, we did it with the horse sequence and found that all the mutations were at the beginning of the sequence which they'd examined. Whereas at the end of the sequence, it actually matched the horse quite well and then we thought, well it doesn't look like a horse. What are the other possibilities? So we changed the reference sequence to be a donkey and we found that the mutations which appeared at the beginning of the sequence actually disappeared because they matched that of a donkey, but then we found that mutations at the end of the sequence appeared because that was in fact actually a horse.
Diana - Okay, so this shows the kind of problems that can happen with ancient DNA. But are there any interesting things that have turned up about this donkey, now that you've got it?
Susan - Yes. So although it's not an extinct horse, it's still of interest because if we can confirm that the remains are from an ancient donkey, it would actually be some of the first evidence of the donkey lineage actually being in Italy. There are two donkey lineages - the Somali donkey and the Nubian donkey, and within across Europe, we see both of these occurring in many of the European countries. But in Italy, it's predominantly the Somali donkey lineage which this is an example of, so it could be actually the earliest date of a donkey actually being in Pompeii in Italy from this lineage.
50:06 - New technique to tell whether rocks are man-made or naturally occuring.
New technique to tell whether rocks are man-made or naturally occuring.
with Stefano Curtarolo, associate professor of mechanical engineering and materials sciences and physics at Duke University; & Kristin Poduska, associate professor of physics at Memorial University in Newfoundland
Diana - Next up is a new development in the field of man-made or naturally occurring material identification. An international team have put their heads together to find out what the differences are in the crystal structure of materials such as calcite. Now calcite can appear naturally in rocks or as part of wall plaster and even ash. So this team have come up with a simple infrared light method that can be done in the field to spot the difference. I spoke to Christine Poduska and Stefano Curtarolo.
Christine - Well I've always had an interest in materials and usually spent time trying to understand how to synthesise them to control properties, but what I did for a sabbatical leave was I worked with a group in Israel that was led by Steve Whiner and they are interested in applying these kinds of material characterisation techniques to archaeological materials. And so, what brought Steffano and I to this project basically was trying to understand how the crystallinity of a material, how well ordered the atomic level structures in a material, affects how we interpret how that material was used, and there was a very need example related to calcite. Calcite forms as a rock but it's also exactly the same chemical composition that you'd find in plaster that you'd use to make a wall or a floor. And so, we were basically trying to use material characterisation techniques that physicists and engineers might use both experimentally and theoretically to apply this to archaeological contexts.
Diana - Right, so it becomes useful in trying to work out what's man-made and what's not?
Christine - Exactly.
Diana - Okay then. So Steffano, how did you go about actually researching this to find out what the differences would be?
Steffano - Okay, we use our quantum calculation so we start from quantum mechanics and through quantum calculations, we can calculate and predict the effect of disorder in the vibrational spectrum. Aatoms at the nanoscale move. Okay, so everything moves depending on temperature and light, and so on. when Christine, with her infrared laser, shoots light on these particles, all the atoms start moving, always a mode. Everything starts oscillating. The way they oscillate is correlated to the disorder that is left over inside these structures. Since one of my expertise is to calculate vibrations with respect to disorder then we decided to try it. So we created some artificial disorder.
Based on the artificial disorder, we calculate how these vibrational modes are changed and then we discovered that the way they change is some sort of fingerprint of every material. So every material, every crystal, has a set of variation of these vibrations with respect to the characteristic disorders that we can create. In the case of archaeology, materials that have been made by man or materials that have been made by nature, , nature always have infinite time, there's a lot of time of nature to find the proper crystal structure. So all these materials, depending how fast they grow, how long they relax, and how long they stay under high pressure, they become more or less ordered and the left over disorder is responsible of the way this spectra changes with respect to size. So what Christine is measuring which is the spectrum for different size of particles because she keeps grinding and then see how the spectrum moves is a fingerprint of each material. And the way they move is explained through our model.
Diana - Okay and Chris, how did you go about actually proving that this was working? I mean Steffano has just mentioned a little bit about you know, creating your own artificial crystals, but could you go into a little bit more depth about the tests that you ran?
Christine - Sure. Yeah, just to describe how the experiment works, it's neat because it's very simple and it's a kind of experiment that people might do in a chemistry lab, in a university kind of setting, but it turns out it's very easy to take this out and use this in the field which is why it's so good for archaeology. So what we do is take a very small amount of our sample. Small means that if you drew a period or something on a piece of paper, that amount of material we use would basically fit in that, so it's a very small amount of material. And we grind that up, just by hand with a mortar and pestle, and then we add another bit of material and it has sort of disperse our sample within that. Then what we do is we press that into a small little pellet and shine infrared light through it, and that's the same light that you would be using for example in your TV remote to change the channel. That information we get, basically there are some frequencies that are absorbed and that tells us about how the molecules in that material are vibrating. And from that, we can use that as a finger print to identify what type of material that might be chemically, so we can tell for example whether its calcite or whether it's quartz or some other kind of material like that.
And so, what we found and what's a little bit different about our work is we were able to use some more specifics about those spectra that we get to differentiate how well ordered at the atomic level the calcite was. And so, what this allowed us to do is it turns out that if you make a plaster, wall or floor for example, the atoms aren't very well ordered and on the other hand, if you have a rock that's been around for awhile, it turns out that's very well ordered at the atomic level. And so, we were able to use this simple method to help us differentiate whether this was material that had been made by nature or had been made by humans.
Diana - And have you been able to use this on any archaeological material yet?
Christine - Yes and in fact, the group that Steffano and I were both affiliated with, Steve Whiner's group at the Kemmel Centre for Archaeological Science at the Weissman Institute has been using this technique for a few years now and they were the first to notice that you could differentiate a little bit about this spectra. Basically, how wide the peaks were gave some information about whether it was plaster or it was rock. And so, what Steffano and I did was demonstrate that this was indeed related to how well ordered at the atomic level these materials were. So, we've been able to take this out on a site so we can take this instrument which is reasonably portable. It does require an electric generator to be out there, but then we can run these measurements actually onsite and check right away to see what these materials are. And we can look at things other than calcite as well and that's a little more standard. So for example I mentioned differentiating between calcite or quarts or sediments, and this sort of thing so we can also use that as a finger print for other different kinds of materials as well, and that's something that Steve's group at the Weissman Institute does quite well.
Diana - Right and Steffano, where do you want to take this research next, now that you've got this new tool?
Steffano - Well now, we can make fingerprints for a lot of other materials that have not been investigated in the same way. So, our method which so far describes what is known, now becomes predictive because finally we have an explanation and there is no reason why other systems that grow and are formed is in a way than calcite should not have the same properties. In the next months and in the next few years, we'll put a lot of effort in determining these shifts and these fingerprints for all those materials that we believe that might be of interest to be analysed on field.