Enseignement 2023-2024 : Nouvelles approches de l’histoire du climat
Séminaire du 8 février 2024 : Towards an Archaeology of Sustainability and Resilience in Southwest Asia
Intervenant : Dan Lawrence, Professor, Durham University
Over the past 8,000 years, Southwest Asia and the Eastern Mediterranean have seen the rise of cities, states and empires. Climate fluctuations are generally considered to be a significant factor in these changes because in pre-industrial societies they directly relate to food production and security. In the short term, “collapse” events brought about by extreme weather changes such as droughts have been blamed for declines in population, social complexity and political systems. More broadly, the relationships between environment, settlement and surplus production drive most models for the development of urbanism and hierarchical political systems. The archaeology of this region provides us with a rich archive of information on adaptation to climate change, successes and failures which should be highly informative for current debates on sustainability and resilience. However, practitioners in the historical sciences have not been successful in translating their insights into sustainability science and policy circles. This lecture will critically review some of the ways in which climate change has been linked to social change by archaeologists working in Southwest Asia, and suggests some new ways to generate genuinely useful insights from the past for the present using archaeological data.
Retrouvez les enregistrements audios et vidéos du cycle et son texte de présentation :
https://www.college-de-france.fr/fr/agenda/seminaire/nouvelles-approches-de-histoire-du-climat
Chaire Avenir Commun Durable
Professeur : Kyle Harper
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https://www.college-de-france.fr/fr/chaire/kyle-harper-avenir-commun-durable-chaire-annuelle
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Okay good morning again you will notice that I’ve slipped into that other language um I thank you in advance for indulging us um having a a seminar in English uh we have eight seminars planned for this course um I think they’re all wonderful I’m very excited I invited people from whom I
Want to learn uh and we have a variety of people some of them will be in French some of them will be in English uh and one thing thing I attempted to do was to bring a mix of approaches um so we have uh historians we have climate
Scientists and I really wanted at least one archaeologist historians and archaeologists work hand inand to understand the past there’s some very important work happening in archaeology to understand the history of climate change and human response to climate change um so I’m thrilled that we have to start the first seminar Dan Lawrence
With us he’s an archaeologist he’s associate professor in the department of archaeology at Durham university in England he is by training a landscape archaeologist who works in Mesopotamia and Southwest Asia um who does very long-term history of the environment and human settlement patterns his thesis which he finished in 2012 was called
Urbanism in the Fertile Crescent uh or was on the subject of urbanism in the Fertile Crescent uh he’s worked on remote sensing applications in archaeology cultural heritage uh and above all interest to me um climate where I think he’s done some of the most stimulating um work among archaeologists
Uh that that I know so um he directs the climate landscape settlement and Society project which looks at the relationship between complex human societies and climate change over the last 8,000 years he’s a prolific author um I recommend his his faculty page which has uh an
Easy way to find all of his Publications but for now um please join me in providing a warm welcome to Dan Lawrence thank [Applause] you uh thanks Kyle and thanks very much for having me everyone uh I’m very sorry I’m a typical English person where I
Don’t speak very good french so I’m the reason why we’ve gone into the this other language uh yes so I’m I’m talking you today about uh archaeology and about sustainability and uh and resilience uh oops yes uh so an outline of the talk what I want to do is give you an
Introduction to Southwest Asia and to archaeology a little bit and to some ideas about sustainability and resilience and then I’ll talk about three different kind of approaches that archology can take to climate change so we’ll start off looking at shortterm events at climate and collap which is a big word that’s often bandied
Around in in archaeology and in other historical approaches to human societies which Kyle’s been talking about a little bit but also some of the things that Archaeology is really good at which is much longer term Trends over centuries and even Millennial scales and that’s where we can do things in archaeology
That perhaps other scientists and other historians struggle with so we’ll talk about that a little bit and then one of the things that I’m getting really interested in now is this relationship between how we can learn from the past and what human societies need in the present and that’s something again that
I’m sure over this lecture series uh Kyle will talk about and others will talk about and there’s sort of optimistic and pessimistic approaches to the degree to which the past can be informative so what I’ll try and do is give an outline of how I think archaeology can be informative um
Through a couple of different analyses and finally I’ll conclude and I just wanted to start with this graph um for two reasons firstly to remind me that there are some graphs in this um in this presentation I’ll try to explain them all but if you all look confused or
Start shaking your heads or something I’ll try to explain them in a bit more detail um but this graph I think is really useful again for a couple of reasons so what you’re looking at here is on this side the annual energy consumption per head per capita in
England and Wales and you go from 1500 to 1850 and you can see two things one there’s a huge expansion in energy capture and uh going up this way so that you get to 100,000 megga per head now modern Americans who have the highest energy capture in the world in terms of
Their energy use every year are about 400,000 they’re somewhere up here in the ceiling and that’s one thing the other thing is that all of the societies I’m talking about today are much further in the past than chudah England and they don’t really have fossil fuels at all
Some tiny bit in China and various places but really not very much and that makes a massive difference to how they relate to climate because if you can see you can’t probably can’t but what we’re talking about here this is cold the kind of orangey one but everything else wind
Firewood draft animals human labor they’re all reliant on climate change or I’m sorry on particular aspects of climate they’re all reliant on agricultural productivity which is massively then affected by climate so in all of the societies I’m talking about today climate change is much more of an immediate threat and an immediate
Response is required so just a brief outline of why ancient Southwest Asia um is interesting for this um so South by Southwest Asia I mean what’s called the fertile crant which is this kind of fertile as you can see uh this is rainfall and you can see
There’s the step with low rainfall out here there’s the mountains up here in turkey and then there’s this kind of cresant which gives it the name of uh of very rich agricultural land and very high rainfall in places um and then it’s split we split it as archaeologists and often as historians
As well into the Levant which is the Mediterranean Coast Northern Mesopotamia Mesopotamia meaning the um the land between the rivers so the Euphrates and the tigis river there’s northern Mesopotamia where you can get a lot of rainfall and there’s southern Mesopotamia where you’re reliant on agriculture irrigation for agriculture
Sorry and this is one of the areas in the world where you have the earliest evidence for agriculture of any kind we also have about 6 and a half thousand years of of urbanism uh so of cities it’s an area where cities were first developed 6,000 years
Arguably of States as well so complex um human societies of different forms and 4,000 years of of Empires right of really huge multiethnic states of various kinds too and all of those are some of the longest um periods that we have those sorts of things in the
World so it’s an area of what we call Pristine development of a lot of these different things so by pristine what I mean is that something merges in this area it’s not influenced like the rest of Europe it’s not influenced by what happens somewhere else it is in fact an
Autoist development an internal development of this area and that’s really important too because it allows us to think about the the formation of these sorts of approaches right how did these complex societies emerge they didn’t for example in in Britain for example we don’t really have cities in
Any meaningful sense until the Romans arrive and then the Romans deliver US cities as a fully formed idea and a fully formed thing that we can then we then use as you know British people or whatever here we’re talking about the emergence of cities it’s quite a
Different um Vibe and it can tell us something quite different about how human societies operated in the past so this is just an example of a map um by gr Boral which they update regularly which shows when agriculture emerged and how it spread and again you can see that
That that Cresent there is the earliest part of agriculture in the world it’s also a diverse and semi arid environment so you’ve got the kind of mountains around here you’ve got the step out here and you’ve got this kind of Zone The pedol Zone of lowland very rich agriculture in that
Zone um and it’s semi- arid in most areas and that’s really important too because it means quite small fluctuations in climate change and especially in rainfall can have really quite dramatic effects across this region right so uh small shift which in somewhere like a tropical rainforest you
Know 100 mm less of rain rainfall a year would not make so much difference if you’ve got 2,000 mm of rainfall but here 100 mm of rainfall difference would suddenly mean that large areas of this region become essentially uninhabitable for dry farming so you get big spatial shifts in the possibilities afforded by
This kind of landscape and just an example to show you this is Northern Mesopotamia um and that that’s what sites look like in this region this is Tel bra which is a huge uh mound of mud brick it’s about 40 m high this is an ancient city where what
People do in this region is they build houses out of mud brick mud brick falls down quite easily it’s much easier to just flatten it and then build on top of it again rather than try to repair it like you would a kind of a more standard
Brick or stone building and so over time you get this layering over time which in this case this is about 6,000 years of layering on top of each other of people just continuously living and living and living which produces a thing which looks in this landscape like a hill even
A mountain um but is in fact entirely human and constructed and you can see what you’re in here is quite a nice kind of green area this is in the summer uh sorry in the winter when you’ve got uh lots and lots of Rain full and you can do dry
Farming you can grow crops here without needing irrigation whereas in southern Mesopotamia that’s your much more traditional irrigated landscape that’s very different you’ve got date palms and you’ve got um lots and lots of man-made canals and and irrigation channels which you absolutely need to make this landscape
Work there are also a range of different climate trends that occur across the holam so the last kind of 12,000 years and the the two kind of main ones are that you’ve got a very long-term drying Trend that starts about the mid hollene about 8,000 years ago and gradually we
Get Dyer and drier and dryer and that’ll become important later in the talk and we also have what’s called um RCC events or rapid climate change events where a big fluctuation happens um and those are related to things like Bond cycles and and um aspects of the climate um the
Kind of global climate models um and I’ll talk about some of them I’ll I’ll try and talk about both of these a little bit today so what you’ve got through this really long history and prehistory of complex societies this diverse environment um and these different kinds
Of climate change is a is a really useful kind of Laboratory for thinking about past climate change and past human responses to that climate change because you’ve got a lot of iterations of things like cities and and states and and settlements and even households things
Like that um so you can I like this um this quote from Jacks Nel you’ve got a series of completed experiments which allow us to think about the drivers behind sustainability and resilience um and collapse over time what you’ve also got in this part of the world is a a really long history
Of of archeological research so um people have been doing excavations in this region for um a couple of hundred years of different kinds you’ve got huge excavations like those of people like Leonard woly or um lots of amazing French archaeologists as well um par Mar all these guys um doing fantastic stuff
Um in very very large uh settlements mostly in southern Mesopotamia then you’ve got a long history of what we call Landscape survey which is part of what I do which is basically moving around in the landscape and trying to find new sites and dating those sites and then looking at questions around
Settlement patterns and the movement of people across a landscape so you don’t excavate in quite the same way you don’t dig big holes in sites but you visit lots and lots of sites and grab the pottery date it and then start to look at what those patterns can tell
You and also now modern modern technology of various kinds drones that sort of thing is having an impact we also have the longest written tradition in the world uh so writing emerges um probably about 5,000 years ago a bit earlier depends how you define writing um but we get these G form
Tablets um from very early on that continue all the way through um until the kind of near Babylonian from the Persian period that tell us lots of things and importantly the very early tablets are very concerned with something that’s quite related to climate which is agricultural production
So again that’s really useful for us um it’s not like in other parts of the world so places like China where the earliest writing is much more about kind of cultural production or um or uh you know predictions of the of the future and this kind of stuff what these guys
Are interested in is real bread and butter like how much grain have you got how many sheep have you got what’s going on here and again that’s really useful for us to understand the ancient economy and to relate that to climate so alt together we’ve got this huge abundance of data of various
Different kinds um from which to think about the from an archaological point of view from a historical point of view the relationship between complex societies and climate change over the really long term so I’ll start off by um in my three my trip tick of different things I’m
Going to talk first about climate and collapse um so collapse in in Mesopotamia particularly um is related to these rapid climate change events and for the last perhaps uh 30 years or so there’s been a quite sort of heavily deterministic idea about the relationship between these rapid climate change events and social change
Different points so this is from um from that paper by stuster and Harvey Weiss and and what they show is basically that every time there’s a um a rapid climate change event at 8.2 th000 BP there’s an idity cooling event 5.2 BP so that’s before present so 5,200 years ago and
Then 4.2 BP again and they cause the collapses of the late oric Society collapses of the Acadian empire collapse of Huna Villages and then there’s this idea of habitat tracking as well which is quite important which is the idea that when you get climate change what
People try to do is move to areas where their original climate still exists and what that implies is that there’s a really significant amount of Mobility that happens when climate change occurs right people start moving all over the place to try to kind of recapture the levels of rainfall in the
Particular kinds of environments that they were previously used to so that’s the the model I’m going to focus on this one the collapse of the Acadian Empire um which is the 4.2k event perhaps the most famous certainly most written about in academic circles so what’s supposed to happen at
4.2k um so what we’ve got here is this is um southern Mesopotamia in the red and then the green is Northern Mesopotamia and around about 2350 so that’s 4350 in the um in the way that that climate scientists would talk about this so climate scientists tend to
Use BP before present and we tend to use uh BC before uh Christ so apologies if that’s gets confusing but just added two on to their right so 4 350 or so about 150 years before the 4.2k event the Acadian Empire gains control of northern Mesopotamia so accad down here um is the
Important city here and it conquers first of all all of these other cities then gradually um moves further north to unify this whole area and it’s the first Empire that really manages to do that to unify both northern and southern Mesopotamia and the idea is that grain
Is then shipped from the North in vast quantities down to the south in a form of um what have you I is called Agro imperialism right so it’s all about capturing agricultural land um and a dynasty emerges from the first king sgon who does that um and there’s lots of
Really interesting innovation which I won’t go into but innovation in the way that kings are portrayed so naram sin who’s the grandson of sagon um in this Victory stey which you can go and see in the Lou just down the road which is what I would hope to do later today um he’s
The first person uh to uh to depict himself as a God right he he has he’s larger than everybody else he’s got a kind of horned helmet which previously was all reserved for gods in in the way that we in the way that they uh produced their images so you get really interesting
Innovations about this time in the way that power is being organized and and pushed forward and it’s to do with almost kind of the scale of the Empire right that they these are the first guys to really unify the whole of Mesopotamia and then the 4.2k event
Rapid climate change hits um and the idea here is that there’s a prolonged drought um what Harvey has called a mega drought um which precipitates the collapse of the Acadian Empire because the Empire is so reliant on these very large agricultural um caces from the north that get dragged down to the South
To fund the the Empire you get a big abandonment of urban sites especially in this Northern Region and a massive population decline as a result and more recently there’s been ideas that you get similar kind of event driven rapid climate change event driven collapses across the old world so
Potentially Egypt um also in the Indus parts of Europe and even China as well have been the 4.2k event has been argued to have a significant effect there so I think where we’re at with this there’s a growing consensus on the climate side from the climate um proxy
Uh work and also from climate modelers um that there is a real sentennial scale so Century long at least uh uh aridity event at this point there’s more of an argument about how much of a drought it was right was it kind of absolutely catastrophic no rainfall for for 50
Years or was it actually a more subtle decrease in rainfall um so the magnitude of the drought is not quite settled but the idea that there was a drought at this about the right time is is quite settled but the archaeological evidence that has been examined so far has either
Been very local it’s been people working on individual sites and saying well my site collapses at this point so it must be the case that the 4.2k event caused it um or it’s been really sort of large and synthetic where people talk about the indis valley or Mesopotamia in general
But they don’t do it with very good empirical data so the some of the work we’ve been doing is um is to try and kind of nuance this model a bit using various different kinds of data so a couple of things we use we use um radiocarbon
Dates and we take as many radiocarbon dates as we can possibly find uh where people have dated seeds and charcoal and things from archaeological sites that have been excavated and we add them all up and we assume that the more dates you get at any given moment the more
Population you have so it’s a proxy for population and then what we also use is is total settlement and total sites that we’ve found from archaological survey across all of these different surveys across this region so each of these black boxes sorry black polygons uh is an archaological survey where people
Have done some work and each of these black dots is an urban s that’s been excavated where we have a sequence which crosses that 4.2k event uh point and so we can see what happens to that Urban site so we’re working on in one sense a larger scale than what people have
Tended to work on before so um the uh Harvey wi’s workers mainly on the their land survey which is up here so he found results from that survey but he didn’t look so much at what was going on elsewhere so can we see the collapse when we look at this larger scale but
Still use empirical data to try and understand it and here’s where I have to apologize for the slightly horrible graphs um but what you’re looking at here is this one’s about settlement and this one’s about those radiocarbon dates and the fun thing that I’ve done here is so this is this is
More and less obviously and this is the time along the bottom and what we’ve done here this kind of gray area is what we call a logistic model of population so it’s an assumption about how population should change over time based on essentially um models of of birth and death rates and
What we’re assume is going on so we would assume that most of the time the uh the population that we find in this black line which is the radio carbon dates should be within this envelope because that’s the expectation of what’s what comes out of the model so
When it goes out of the envelope something weird is happening and what we can see here is that there’s a good correlation between both the the radiocarbon dates and the urban settlements which is nice so the urban settlements is this kind of blue Bluey weird one
Here and on First Look it looks quite good right so if we say this is the 4.2k event period That’s the period up there when the event happens we get declines be quite steep declines in both the numbers of urban sites and the radiocarbon dates and the small rural
Sites which is what this gray one is so everything seems to be going right right we we’re kind of proving the hypothesis is correct that there is a collapse at 4.2k but the really interesting thing for me is this this part beforehand which is that what happens here in both
Urban sites and in the radiocarbon dates is a kind of Boom before the bust a boom before the collapse and we can see it here that we we disappear out of this gray confidence interval so we’re going into a place where we don’t think that logistic logistic um uh population
Models can explain what’s going on with this population so exceeds our expectations so what it looks like is that before that collapse happened there was already a massive expansion of settlement and population which then was hit by the 4.2k event so it changes our ideas a little bit about what was going on
Here and we can see some quite interesting spatial patterns too and so in this one uh the green on these graphs is the sites in areas where you can do dry farming very easily so where it’s very wet and easy to do agriculture and the red is the kind of Step Zone where
It’s much more difficult to do Agriculture and this is just the urban site so you can see you get a kind of rise in both of them um and then a change over time at the 4.2k event you can see that collapse is happening but actually when we look at
The spatial patterns of that so so what you’ve got here is this is the nice area this side of the black line and then this is that step Zone Beyond which it’s difficult to do dry farming agriculture it’s much more risky to to work in these kinds of
Environments when you get to that boom that I was talking about you can see that there’s a much greater density of occupation but also a big push out into the step zone so that’s this red line here and then when you get to after the 4.2k event what you’ve got is continuity
In the green line so that the cities that are in the dryer sorry the the wetter area are okay but the big collapse happens in the red line in the step so it’s almost like the tide going in and out right the tide goes out into the step and then comes
Back in again as a result of the um of the likely 4.2k climate change and the model that we’ve developed for thinking about why that might be the case um is pretty simple but relies very much on sheep because what happens at this time is that you get the domestication of wool bearing
Sheep and Wool is really important as a um as a product right as a textiles are a m massive part of the economies of these sorts of early cities so if we’re thinking about collapse what’s going on well it seems like there’s declines in population that
Are visible at about the right time we do appear to have a collapse as it were of population a really high magnitude change in the number of people living in these regions but the importance of the Boom in creating the bust is is um is really
What I want to emphasiz here right that um we it looks like our logistic model suggests that we’re moving out of kind of sustainable population levels in that region to create a society that’s kind of really overclocked in terms of the way it’s using its environment and its
Landscape so um the reason why that happens is we’ve got this early Bronze Age urbanism that’s the period we’re talking about is really connected to the exploitation of this much more arid Zone what um I really like this this term the zone of uncertainty where agriculture is not so certain right because you’re
You’ve got slightly lower rainfall and there it’s a really productive landscape under certain economic and political conditions especially when you’ve got sheep and goats that you can then use for wool which then you can process in your cities with your big army of of urban laborers who can then uh
Manufacture textiles for you start swapping that all around so w bearing sheep are a really significant part of this that produce this kind of large scale textile production economic boom we’ve got texts from um from cities like EA which suggest that they might have had between
Half a million and 2 million sheep under the control of the City itself which is just extraordinary numbers I mean more sheep than there are in Syria today so we always there in a climate induced collapse perhaps It sped up a process but broader kind of systemic collapse seems to have been likely
Anyway right the this kind of use of the landscape couldn’t have gone on forever the boom was um was too great check the time okay so thinking about longer term Trends in climate change um uh I coin this idea of kind of climate decoupling over the holos which is
Really interesting so I’ve already talked to you a little bit about this but what we’re doing here is taking uh a slightly larger area and we’re looking at those radiocarbon dates again and we’re looking at archaeological settlement data so um excavations and surveys we’ve got about 22,000 um bit
Over 22,000 sites from Anatolia from Mesopotamia and from the Levant and population estimates from radiocarbon dates and what we’ve done is taken the um the climate proxy data that we’ve got from this region as well so again this it’s a bit frustrating because as you can see there’s not very many climate
Proxies in this region and lots of them come from um around the edge over the area that we’re really interested in which is this kind of Mesopotamian area so all the green ones are archaeological proxies which are not so useful the the kind of light blue and dark blue dots
Are um spms which is a cave so SPM from a almite in a cave you can get the Isotopes out of that in in various ways reconstruct climate and also from Lake cores as well so um the similar kind of argument that um things like pollen form nifer and
Isotopes as well collect in the bottom of lakes and we can call those lakes and try to understand what’s happening and so don’t don’t bother to look at that too closely but what we’ve got here on this side is all of those different climate proxies from different
Lakes from different spms and then we’ve got all of the different population proxies that we’ve got from the different regions and what we did is basically just a very simple correlation between the the population and the climate over the last 12,000 years and what you can see here is
Essentially from all of those different regions this is a a graph of how correlated those two things were and we go from the early hallene the middle hallene and then the late holos where we are now and what you can see this this is the side to look at
Population versus climate that we start off with high values because population and climate are quite well correlated right so when population goes down climate goes down climate goes up then population increases too then we get in the middle hallene this big drop so suddenly population and climate are not so correlated together
In this middle hollene part and then in the late hallene we have a bit of a problem because our uh proxies for population are not very good but actually what we know is the population increases a lot and climate gets worse so it looks like um uh that should be much
Lower so in the second half of the mid Holocene we get this kind of decoupling this snapping of the link between population and climate which is contemporary with the earliest urbanism which might mean that cities are some kind of adaptive strategy right cities allow people to to transcend climate in some way
So I’ll quickly um move on to the last part of the talk which is thinking about the relationship between historical narratives and sustainability science but building on some of those long-term trends that I was just talking about so thinking about sustainability is um uh is complicated it’s a word that
Is often kind of bandied around but actually relatively rarely defined so what I’m taking here is the um the UN definition which gave rise to the United Nations sustainability development goals which come from this bruntland uh commissioned um former prime minister of Norway um bruntland did this report in
1987 and her definition is that meeting the needs of the present without com compromising the ability of future generations to meet their own needs and that has two kind of implications for me I think one is continuity the idea that systems will continue through time and the other is equality across those
Generations and those are the things that we can think about as archaeologists um in various different ways and actually some recent work has helped us to do that so I’m going to talk a bit about persistence the idea of the duration of of occupation of sites and societies and I’m going to talk
About uh Genie coefficients and house size as a way of thinking about equality and inequality and then I’ll try and Link those together so another way of thinking about sustainability is really um very basic one which is to say that a sustainable system is one which survives
Or persists if you can keep going through time then you’re sustainable oops and if that’s the case then archaeologists are really in a good place to start dealing with this kind of stuff because one of the things that we deal with a lot is long time durations
And also the the starts and ends of things we’re really interested in dating um how how the how sites work how States work when do they begin when do they finish what happens in the middle what attributes are associated with those sorts of things so we use things like
Pottery we look at the density of pottery we can tell tell you how cities change in size through time uh all of that kinds of stuff and what we can you do is use persistence as a way of um kind of articulating in relation to sustainability and from that we can then
Leverage all the things that Archaeology is really good at doing like telling you what kind of City it was was it a big Palace was it a small Palace what kind of settlement um and think about which ones of those help to to drive sustainability so I’m going to talk
About some other variables that we can deal with um as archeologists so time uh land use and City size just as some quick examples of how we can think about sustainability using this persistence concept and to do that I’m again using this kind of Mesopotamia in the Levant
Data set of sites so you can see this is southern Mesopotamia this is the North and the Levant over here um and what I basically did is I just took all the sites that we know about that are over 10 hectares in size from 10,000 BC to 0
Ad and looked at how long they lasted and and that gives us about 500 sites if you can see there about 700 occupation phases and we compared it to a model of land use which is a way of thinking about the productivity of the landscape um in a particular region so this was
Constructed for a very different project but what you can see here is basically the The Greener it is the nicer it is to live in and then when you get to this kind of pink and orange that’s the step Zone you can see the fertile Cresent really nicely there and this is the
Irrigated landscapes in southern me poia so what that gives you is a kind of a forance map an idea or in in um uh in ecological terms the fundamental Niche not the realized Niche so this is what you could do in this landscape what the
Best thing to do is but humans go there and they do that right they do some different kinds of things in that landscape so it’s not necessarily what was happening but it’s the the kind of optimum way of exploiting this landscape so what do we find out well if
We look at the urban sites by land use what we’ve got on this side is the count of sites literally just how many sites there are and on this side the density of SES per kilm squared and we’re going from kind of the nicest areas over here to the nicest
Areas here so we’re going from marshes and irrigated Landscapes and an optimal agriculture to essentially the step and the desert and you can see it kind of does what you’d expect right people like to live in areas which are nice for agriculture that are productive and so
We find lots and lots of cities in those regions and the kind of nastier you get the fewer cities you get over time so just to show that those are the kind of different the different regions but if we look at persistence by land use we get something quite
Different which is to say again we’re doing the same thing so we’re going from uh nice to nasty over here and each of these uh is the group of sites that are in that landscape and that’s how long they last with they’re kind of mean and
The and the um the sand and Dev the cortile range and that sort of thing and this is the duration of occupation so what the first thing to notice is that particularly compared to that one there’s a lot more homogeneity here right cities tend to last the same
Amount of time um which in itself is quite interesting it suggests maybe some ideas about the kind of Lifetime or lifespan of cities but what we also have is some interesting um differences so for example it looks like some of the least uh long lived cities are actually in the highest nicest agricultural
Zones which again is is something that I wasn’t expecting quite interesting and then in the kind of Agriculture optimal aboriculture zones you get some Long Live cities and then it kind of continues but also in this very um in this very last category where you’re really in the
Proper kind of step and the desert we still have some really and very long lived cities now I think to explain that I I think out here you’re in a world where there’s very few places where you can actually have a Long Live or have a city at all right you’re talking about
Places with oases with particular kinds of um castic sinks or Water Resources so what that means is that if you found a city then you tend to stay there in the same place because it’s it’s there for a reason it’s on a trade route or something like that but you can’t move
Around in the landscape very easily and so that’s why these ones are quite long lived I think these ones it’s to do with irrigation and infrastructure and the requirements of living in these kinds of Landscapes right so here you need lots and lots of people configured in particular kinds of
Ways in order to manage your Canal systems in order to um build on all of this kind of stuff whereas in these more kind of agricultural optimal dry farming landscapes in northern Mesopotamia then you can move around much more easily persistance Through Time time again is an interesting one so the first
Thing to see here so this is by this is Millennium and this is when the city was founded and this is the duration of occupation and what you can see over time well we start off with um kind of chipstone very small sites with chipstone then we get pottery and then
We get better ways of dating things up to coins and pottery and that kind of stuff those are the earliest real cities but the the main thing to notice here is that you’ve got a really clear Trend in longev right that that cities as they go through time they last less
Long by the time you get to those kind of territorial Empires I was talking about before individual cities grow and die much more quickly than in prehistoric periods and then finally just looking quite very quickly with sight size so this is the duration of occupation and
This is the size in in bins and you can see that there’s an increase in duration as you go through different sizes of site so large capitals centers of religion and power seem to last for longer and we get some really nice examples of this
This is the temple at eridu in um in Iraq where you go from a tiny tiny Temple um up to a huge kind of Temple complex but they’re all built on top of each other and the whole site is occupied for several thousand years so
You can see how that would give you a kind of really significant Persistence of place in that particular site there’s also kind of clearly a glomeration effects and the kind of um path dependence and sunk cost effects right if you’ve invested lots of uh energy and lots of materials and lots of
Resources in making a great big Center then you’re probably going to try and stick it out and live there for as long as you possibly can so that’s clearly having an impact too so what does all this tell us well the data suggests that if we want to
Survive um we should move to small smaller cities in either very nice or very nasty but locally nice environments ideally about 11,000 years ago that’s when we’ get the maximum level of persistence but there is a sobering thought here which is that the more complexity and Landscape intervention leads to less
Sustainability so more complex societies and those Societies in south southern Mesopotamia where they’ve changed their landscape a lot with irrigation and that kind of thing um those seem to be less sustainable and we live in the most complex uh and interventionist Society in our Landscapes that’s ever existed by
A long shot right so there’s something something interesting to think through there but we also do get examples of persistence over Millennia that are um cities that are able to persist despite all of these things through time so to turn to the other side of um sustainability which I think is often
Quite neglected certainly by archaeologists um and some to some degree historians thinking about this kind of stuff um is the other side of it is equality right um so what we’re talking about here is ways of thinking about um uh accessing equality in the past because essentially if we want to
Emulate some past Society if we want to learn from what past societies were doing we’ve got to think about the equality side too it’s no good kind of trying to emulate a society which was 60% reliant on sa slave populations or something like that I’m not sure we’d be
Up for that as Society in the present so thinking about this side of sustainability is is really vital and we’ve been doing some work using uh house sizes and the difference between house sizes as a proxy for um for inequality so what you do here is again
It’s making use of exactly the kind of data that archaeologists generate a lot which is this kind of plans of sites where we can identify all the different houses in a site and we look at the different sizes of those houses and we assume that basically bigger houses are
Associated with richer people uh and poorer houses are associated with poorer people um which means that you know hous size is a function of the capacity to procure space within a settlement and to mobilize materials and labor in its construction and what we’ve been doing is using the Gen coefficient again I
Won’t go into this too much but essentially uh this is a a way that modern economists often use to uh to look at these kinds of disparities in things like income and wealth in modern societies uh kard Genie invented it um uh in the 20th century and the thing to
Remember about this is that essentially it’s a scale between n and one where n is perfect equality where everyone has the same share of of wealth one is perfect inequality where one person has all of the wealth and everybody else has none and then in reality you get various different
Measures so uh the United States today is between 0.6 and 0.7 on this scale in terms of inequality um for some reason when they when they use this they always use as an example but Slovenia is 0.41 or something like that uh Britain is about 0.5 something like this um and
That’s on income data so what we’ve done is taken again the same you’ve seen this map a lot now the the kind of fertile cresant area and we taken data from all of these different papers and uh smooshed it together to give us 77 sites uh 100 or
So phases about 2,000 houses and again we’re looking over the really long term here so what you’re looking here is the mean sight date so this is going from uh 8,000 BC to 1,000 BC and then each of these red dots is a site and that’s the
Genie coefficient of the houses at that site over time so what you can see is that over this kind of neic calic period you’ve got a very long but relatively stable period of gradual increase in inequality through time so farming happens very gradually people start to get richer but
They inequality doesn’t change too much and then you get this period of the earliest cities and the blue dots of cities and the red dots of the um are the rural sites and the interesting thing here is that those cities sit within those rural sites so it’s not the case that those
Early cities engender massive inequality that only happens later where you get a plateau in the um uh in the curve but really what’s happening is that cities are becoming incredibly unequal and those rural sites are becoming equal but quite poor so this is what the cities look like at
That point you’ve got palaces and also mixed neighborhoods of rich people and poor people this is from uh in southern Mesopotamia whereas these rural sites start to look um like pretty kind of depressing places to live to be honest um they kind of oops um they kind of
Remind me of like row houses in in Northern Britain like a the miners cottages and that kind of thing so that’s in itself a really interesting um sort of phenomenon that I’ll come back to also if you look at this in other kinds of ways so we look at long-term trends
In relation to different kinds of polity um so from family level to empires in terms of the scale of the polity using uh this book which lays out a couple of ways to kind of categorize societies like that that’s a kind of old school anthropology way of dealing with
Societies to kind of classify them in those sorts of ways and um it’s not super useful but it is quite interesting just as a quick way of getting into the data and what you can essentially see is that over time as uh as we move into different levels of complexity of
Societies the um uh the genie values of individual sites at those societies increase so it’s doing what we think right as you get to more complex societies inequality increases and then just something that I’ve been doing very recently um uh is looking at this on a more global scale
Uh through a project called Genie but confusing the old capitals um led by Tim carer Andy Bard in Oxford um and what we’re doing here is collecting data on all kinds of houses from all sorts of places around the world from North America from Europe and and China bits
And pieces in Africa and oania as well all sorts of different types of houses these are from oania that’s from uh the um inco I think and that’s from the Indus Valley and what we can do with that is then compare the genie coefficient with persistence with how long sites
Last and this one’s really interesting so at a global scale more unequal sites persist for longer so that means that there’s this this strange link between sustainability right the two sides of sustainability seem to be actually a little bit more intension than we imagined so um so it
Might be the case that inequality and persistence are functionally linked together right one gives you the other so what does that mean for sustainability where um persistence and and inequality sorry and equality are supposed to go together it’s it’s um interesting to think this through so there’s this you know famous
Uh book by a couple of um British uh medics in fact where the spirit level why more equal societies almost all always do better that might be the case in in modern periods but it looks like actually if we’re taking uh Persistence of sustainability um then more unequal
Societies actually always do better in the uh in the past so I thought I’d finish by trying to kind of tie all this up together with one more graph um which is a bit of a kind of Mickey Mouse version of what I was I’ve been saying so this is just
More or less of whatever I’m about to show you and this is time so what happens over the holos scene as I showed you is that climate broadly speaking gets worse for humans to live in this region in Southwest Asia um particularly rainfall which is the the one that we normally
Use while at the same time population increases explodes in fact so right there you’ve got a paradox right it’s getting harder for people to live in a place but they’re getting better at reproducing and in fact living in it and as I was showing before settlement Persistence of individual
Settlements and of cities is going down too right so um the settlements are getting less good at persisting as we go along and again there’s a tension there between population and settlement persistence right so we’ve got high level of population but low levels of actual sites being occupied so
Everyone’s just moving around more you’re getting more and more kind of churn in this um in these complex systems and then you’ve got more and more inequality and hierarchy through time so again you’ve got these these sort of different things going on and it’s difficult to make sense of what
Could be kind of um allowing that to happen and I think the thing that we’ve got to focus on as archaeologists and perhaps historians now is the role of kind of complex social systems in allowing that to happen so what I showed you with the urban uh rural site divide
Is really important here is that you’re moving from Individual sites being their own things that kind of just operate uh in their own Landscapes to a much more complex system where cities are reliant on Rural sites and they’re integrated together and possibly what’s happening is that those cities are able to draw on
The resources of rural sites of much wider areas to manage resources in various different ways to produce um uh greater persistence at a population level even though individual sites underneath all of that are moving and moving and moving so to conclude a kind of archeological perspect archaeologists
Perspective on uh on this kind of relationship between climate and and social change um we can link those two things together in the past climate change can be causally linked to social change in the past in the short term we have these rapid climate change events which are implicated in collapse
Narratives people have said that in quite a deterministic way um you get one of these events and it’s essentially impossible to survive it that’s just the end of that kind of civilization but uh for me those are a little bit overstated actually um what we need to think about is what collapsed
How ubiquitous the collapse was and for whom and also to think about um and also to think about the importance of those booms right in creating the bust maybe the reason why you have a collapse is because you’ve got this kind of overclocking of the landscape this environmental extensification um which is perhaps
Implicated and then over the long term um we have Urban urbanism and and greater social complexity which we can link to this kind of decoupling of population and climate Trends so climate stops being so important over time and that links into ideas around kind of the long anthropos which I won’t go into
Today but but um but it’s quite an important thing to think about in terms of what then we think about in terms of sustainability and thinking about sustainability um so archaeology uh can provide a kind of unique repository of information on really long-term trends in human social and ecological systems
And I’ve tried to show that today we can really talk about Millennia um and and patterns that exist over that sort of time frame what we need to do that is good questions and especially really good proxies and I think um what I’ve tried to show is that persistence this idea of
Just simple duration of particular kinds of system um is a really useful way of thinking about this stuff because it allow us allows us to say what kind of ecological social economic strategies have enabled that longevity and conversely what kinds of situations are sites which are really shortterm and
Full to bits quickly what kinds of situations are they in but the really interesting question for me as well is at what cost so um we need to bring in equality and ways of thinking about equality wealth inequality income um into our ideas of sustainability in order to make them
Really useful for thinking about a just future thank you very [Applause] much