Perspectives on isotopic and ancient DNA research on migration by Hannes Schroeder

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    Interdisciplinary Approaches to Migration Research 2017/2018: a Pufendorf IAS initiative aiming to explore new conceptual, theoretical approaches as well as methodological innovations to address processes linked to migration.

    This presentation was given as part of a seminar under the initiative The Role of Genetic Geology and Archeology in Migration Research.

    Speaker: Hannes Schroeder, Natural History Museum of Denmark
    Find more information about the Migration Initiative

    okay good afternoon I would like to welcome you on behalf of puffin of Institute's migration initiative I'm the coordinator of this interdisciplinary seminar series here on migration and today's topic is for some of us it's really beyond our disciplines but for some of you probably you're more familiar with so the theme is the role of genetic geology and archaeology in migration studies and the ways in which these methods could be used or what are the challenges in using such methodologies when it comes to studying migrations in the past and without taking too much time I would like to just introduce our speakers for today so Hans Schroeder is from the Nature History Museum of Denmark University of Copenhagen and second speaker Bettina body and she's from the Institute of European and oriental studies and at academy austrian academy of sciences and she's also an archaeologist specializing ancient egypt okay now I can leave the floor to your Hennis thank you very much thanks thank you very much for the welcome thank you for the introduction it's great to be here that a little little trip up from from Copenhagen so yeah well the brief was to tell you a little bit about how in archaeology we use isotopes in ancient DNA to to look at migrations tell you straight away there's not going to be a lot of isotopes in the talk I did isotopes in another life but I'm mainly now doing ancient DNA and that's what mainly the talk is going to be about so i termed this if ancient DNA revolution in archaeology a Swedish colleague of yours Christian Christensen has as coined that phrase another revolution in archaeology akin to the kind of radiocarbon revolution and whatever we had and the subtitle is kind of migration makes a comeback and I think Patino's going to talk about Jen you know the history of migration research in archaeology so I'm not going to say too much on that just to say straight up that there was not always a popular concept in archaeology and it has changed over the years so what I'm going to talk about a little bit therefore is is any insight into the history of migration as a concept in archaeology and I'm going to get into how we use now ancient DNA in order to to study migration and population movements in archaeology are going to give you a couple of case studies - if I have time one if I don't and I'm going to talk a little bit about the challenges that we face or the criticisms that we've faced as a as a discipline I should say I was trained as an archaeologist but have been for the past eight nine years or so been working with with with genetics so in DNA so I understand some of the criticisms that are generally coming from from colleagues in archaeology so what do we do archaeologists what they're interested in generally interested in in in culture change and generally looking at material culture and then trying to come up with some sort of explanation as to why that change happened in the past you know put very simply and four at several points in the past migration was a very popular way of explaining culture change particularly I'd say in in the early days of my culture history approaches so we're talking the archaeology of the Gordon child and and and and those kind of people where migration was used as the mechanism to explain cultural change so one people on one group of people moving into another area and somehow kicking an action a chain of events that led led to changes in material culture changes in lifestyle changes in foodstuff being used and so on and so forth now this is kind of exemplified by particularly in the early days kind of these cultural historical approaches where you know here you have a table where different cultures are expanding and retracting and they have different you know kind of material cultures things associated with them you know here geon's build starting build palaces and so on and so forth and those kind of approaches also kind of culminated in kind of hyper diffusion 'us explanation so you had you know people saying that Stonehenge was built by Egyptians or you know other even crazier kind of suggestions being made of links between different people and again migration was you know the way that this should have should have happened then it really fell these kind of approaches fell out of favor particularly in the 60s 70s the post perceptual approaches in archaeology I don't know if that's a concept that you're familiar with that's so and I kind of got did my undergrad at the tail end of these of this kind of properties post perceptual approaches and migration really disappeared from textbooks and from you know explanations that were that were inferred people emphasized much more kind of or talk to us or you know local developments or cultural developments culture change as being the cause of you know local local developments and all people ignored these types of things all together and we're you know emphasizing other things like I don't know how does it feel to walk through a landscape or whatever so one of the kind of classic examples in archaeology of this this debate and and and where migration was also also being inferred as one of the kind of possible explanation is is the spread of farming into Europe so here we have a you know relatively early from the 1965 a publication showing the different dates of farming settlements in Europe and they start in the you know with the black dots in in the Near East and Turkey and then moving a little bit later you have them appearing in the Balkans and then even later you know moving into Central Europe and then into the British Isles and so on and so forth and that's bad you know you know that that process kind of spent the best part of ten thousand years or so starting perhaps twelve thirteen thousand somewhere in in in in the Near East and then moving into into the British Isles and arriving there perhaps I don't know four thousand years before present and the big question in archaeology for a long time had always been well this process was this down to a movement of people or was it down to a cultural transmission so a movement of ideas right and either you know you could support either argument with with you know with the with the archaeological evidence now we're you know kind of isotopes to some extent and then ancient DNA comes in is this that there are new methods that allow us to study migration or the movement of people by not looking just at material culture but by looking at the remains of people themselves and so the old saying of pots on art people you know that kind of always comes up in this context as well to say that if you're just looking at material culture it tends to be very difficult to try and infer whether this was you know culture change was down to movement of people or or to a movement of ideas but if you analyze the remains of people themselves you may have a better chance of trying to trying to figure those things out isotope analysis are useful in a sense that they kind of relate to a lifetime so you can establish local or non-local status of an individual you can thereby infer whether that person migrated during their lifetime but it doesn't really tell you that much about a population or an ancestral group or you know kind of those those those different levels of influence and this is perhaps where ancient DNA analysis comes in I can't tell you where an individual necessarily was born but it relates to his or her ancestry so the ancestral composition of that of that of that individual and the population that he or she belonged to and it can be used to infer migrations in the past and if we take this I'm jumping ahead here this is kind of how it works in a cartoon kind of fashion just to show you that we start off with a you know a bone or a tooth from hopefully a securely dated archaeological context you extract DNA you sequence it on some fancy machines you get sequence data out of it this is what it looks like so basically DNA being composed of four letters a C T and G and what we're interested in is really the variation between individuals or in this case what you know what you generally do at first is to map the liver and bits of DNA that you sequence to a reference and you try to see you know how it varies from that reference so here for instance just to illustrate this to kind of get an idea of what the data is that were actually looking at so here in this case the reference that we used it's called you know a human reference genome and all the bits of DNA that we sequence from this particular bit of bone tend to have you know a T in that position whereas the reference has a seat and so that's the kind of data that we're looking at single nucleotide polymorphisms as they're called mutations you can loo use you know other types of data but that's mainly what we're what we're looking at and then we're feeding this type of data for one individual for several individuals into various programs that allow us to infer things like the ancestral composition of that particular individual we can look at we can make inferences about demography so here in this case for instance this is a plot that illustrates changes in effective population size over time for I think in this case I think it's yeah I think these are humans actually and Neanderthals and Denisovans and there are other things that that one can that one can do as well so here's just a very brief list I mean while relatively long lists and so the first very you know kind of straightforward thing to do is simply determine the biological sex of an individual you just have to look at at the sex chromosomes you can look at phenotypic traits if you're interested in those so you know eye color and skin color and those kind of things we can look at k...
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