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PRI's Environmental News Magazine

Satellite Archeology

Air Date: Week of March 30, 2012

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The ancient settlement of Tell Brak. (Photo: Jason Ur)

Mesopotamia is believed to be the birthplace of civilization, but the extent of human settlement in this area is relatively unknown. Archeologists spend a lot of time scouring the ground for clues, but now some enterprising scientists are looking to the skies for help. Professor Jason Ur of Harvard tells host Bruce Gellerman about turning satellite photos into maps showing ancient cities, and why he digs this new technology.

Transcript

GELLERMAN: Half the world’s population lives in cities, and by 2050 it’s predicted that 70 percent of us will be urban dwellers. But cities aren’t new; in fact, they’re ancient.

[MUSIC: Michael Levy “Hurrian Hymn (Ancient Mesopotamian Musical Fragment c1400) from Ancient Landscapes (Michael Levy Music 2011).]

GELLERMAN: Music from Mesopotamia. It’s here, in the cradle of civilization, that urban societies first emerged, 6000 years ago. Mesopotamia, the land between two rivers, the Euphrates and the Tigris, stretches from what is modern day Southern Turkey, through Northern Syria and Iraq.

Archeologists aren’t sure why cities first formed, or how many there were, but thanks to a new technique developed by Harvard professor Jason Ur and his college Bjoern Menze from MIT, scientists now have much faster way to identify the tell tale signs of ancient urban societies. Jason Ur says now, in addition to archeologists putting muddy boots on the ground, they can scan satellite images from space.


Brak Classifier, maps showing where people lived, and where artifacts were collected. (Photo: Jason Ur)

UR: I spent two months walking around 125 square kilometers of an area around a Bronze Age city, in northeastern Syria, and I found 60 sites.

GELLERMAN: And using your new technique, your satellite technique, how many did you find?

UR: Well, we found 14,000 places of potential interest, which we could narrow down to around 9,500 relatively reliable places and this was done on computers overnight.

GELLERMAN: Now, satellite imagery has been around for a long time, so what do you bring that’s new to this endeavor?

UR: Well, the traditional way is to get out and start walking. We look for surface manifestations of places where people might have lived, and usually this is in the form of broken pottery, they survive very well and they end up on the surface so we can find places of concentrations of broken artifacts.

GELLERMAN: Slow methods.

UR: Very slow. Today we have systemized this. We are training computers to do this for us, they are much more objective than we are. And then this computer program that I have developed with my colleague Bjoern Menze at MIT, his algorithm then does this in an automated fashion, letting computers do our job for us.

GELLERMAN: Well, let’s look, you’ve brought some images on your computer here. What is this image here? It looks like an abstract piece of art - black and white and red!

UR: What you’re seeing here as red, represents the near-infrared band of the visible spectrum; not something that our eyes can normally see. That’s one of the real powerful aspects of what we’ve attempted to do here is that we can see well beyond what the human eye can see into the near infrared and infrared wavelengths of light which are much too large for our own eyes.

GELLERMAN: So this one looks like, almost like an amoeba, an orange amoeba!

UR: Well, you’re looking at a major early city called Tell Brak. I’ve argued that this is one of the world’s first cities, if not the world’s first city, today in northeastern Syria. The area that you’re seeing that looks like an amoeba is of a high probability of ancient settlement. What we’re really seeing here is soils that have been changed by human occupation. I find this particular image of this particular place to be especially compelling because a second image that I can show you here represents the density of surface artifacts, which I collected over four seasons of walking back and forth across this place and they match precisely.

GELLERMAN: So the idea here is you take empirical studies from on the ground, what you found, and then you say: Okay satellite and algorithm, look at this image, remember this image and compare that to this other new images and see if there’s evidence of an urban settlement.

UR: That’s exactly the process. So if I give it a good set of places that I am 100 percent certain are ancient places, this algorithm can then develop a very precise understanding of what are the wavelengths that represent an ancient place, in this case the soils that human activity produce, that’s really what it’s seeing, and then it can then go find those in other places.

GELLERMAN: Tell me about Tell Brak - what kind of place was it besides just a pile of mud and brick at this point?


Settlement Mounds. (Photo: Jason Ur)

UR: In the past, it was a thriving, very early city. But what our method has shown is there were outlying neighborhoods around them that were spatially separate. They were not up against each other such as what we think of when we think of urban neighborhoods. But what we find is that with time they grow together. And this is very interesting, why initially were there distance between these different parts of the settlement and what overcame this potential reluctance for these groups to come together through time.

GELLERMAN: What do you think?

UR: Well, this is the great question! What we suspect is that there was that initial pull to bring people into a place like Tell Brak, that we don't quite understand. But I would probably say that it wasn’t top down. It was probably something that brought people in under their own volition rather than a central king or ruler compelling people to come in. If I had to guess, I would guess that through time, various institutions developed that could allow people to be more closer together. Maybe these were religious institutions, maybe these were political institutions, that’s something that requires more than satellites.

GELLERMAN: These people - tell me a little bit about the people that might have lived in these ancient cities.

UR: The majority of people living in early cities were farmers and herders. They were concerned with very basic elements of sustaining themselves. When we think of cities today, these cities are homes of the elite, the political elite, great corporations, cities are homes of consumers and producers live out on farms elsewhere. The earliest cities were almost certainly homes of the producers as well.

GELLERMAN: Tell. What does tell mean?

UR: This is a word in Arabic and Hebrew that refers to a ruin. And we don't think of archeological sites as being 'up', we think of them as 'down', you have to dig to get into them. But in fact, in the Middle East, archeological sites stand out. And this is because people build their houses using a mud-brick, and mud-brick houses don’t last very long. After about 50 years you can no longer patch it up, you need to knock it down and start over. So you level your old house, you build your new house on top of it, and through time, your settlement goes up and up.


Dr. Ur in the Living on Earth studio. (Photo: Jessica Ilyse Kurn)

GELLERMAN: So over time these cities literally built on top of themselves, or their predecessors or their ancestors.

UR: This is particularly interesting because people in the past chose to continuously reoccupy exactly the same place. And this doesn’t necessarily make sense. Because, as you go higher and higher, you’re getting yourself further and further from things like your fields and, most critically, from water. And this is what’s interesting, why did some of these places become so important that people would continue to live there even as they were putting themselves at a disadvantage in doing so?

GELLERMAN: You’ve got a hypothesis?

UR: Well, we know that cities were the homes of gods. We think that probably it was, it could have been a cosmological reason, or it could have been political power, in this case we really have to do excavation rather than looking at satellites to answer questions like this.

GELLERMAN: Did you find any cuneiform evidence? Written evidence, since these people were basically the first to use written language, I suppose.

UR: Yes. In this region, we have the origins of writing. And it’s very closely associated with the states and early kingship. However, it post-dates, writing post-dates, the earliest cities, so clearly urbanism as phenomenon was something that didn’t require this sort of administration or book keeping, and probably this is a result of urbanization but not the cause of it.

GELLERMAN: So, urbanization is a very natural process, a very human process, you know, people left upon their own devices will come together?

UR: That seems to be what I take from this particular Mesopotamian case study. I think in a lot of cases, we have a tendency to see governments as behind a lot of these processes. Especially in the past, we see things like the famous mythical king Gilgamesh, who claims to have built the great early city of Uruk. He brought this about through his own kind of charisma and political will.

Probably this is a later understanding of how these places came about, and in fact, it was probably more of what we could call an emergent phenomenon, people acting under their own motivations, but the aggregate of these actions results in something that might look very planned. And here I see a lot of parallels with the intelligent design movement where large complex things can only be the result of some central planner, that certainly isn’t the case with ancient cities.

GELLERMAN: What’s interesting to me is that these urban centers existed for thousands of years and then, they’re gone, most of them. What happened?

UR: Well, there is no single answer. There has been a big attempt in recent years to attribute this to climatic change, this is something obviously that we’re all very concerned about today and we think about this in the past. It may be that in some cases some of these cities simply over extended themselves. Places got simply too large for the existing agricultural technologies. And sometimes when these are excavated, we find that they have been burned. Archeologists love burned cities, because cities that were destroyed, there’s a lot to find there.

GELLERMAN: So probably war?

UR: In some cases. The past was a violent place. Certainly the 20th century AD does not have a monopoly on violence, that’s certainly the case.

GELLERMAN: What now for you? What do you do with all this data from your algorithm?

UR: Well, obviously it’s of academic interest. But there are other aspects of this. We can take this incredible map of settlement, and we can take this to antiquities officials, in this case in Syria, and we can say: Here’s what you have that you might want to protect. This is the past of the Syrian people, but it’s also the world’s past, and this needs to be protected.

GELLERMAN: In the current fighting that’s going on, the war that’s in Syria, are you afraid that some of these areas will be destroyed?

UR: Well, this is always a concern, how the past falls victim to modern political activities. A larger concern in the case of Syria right now, are the museums. We all saw what happened in Baghdad in 2003, will this happen again? I hope that lessons will have been learned. But this is something to bear in all places that have become politically destabilized.

GELLERMAN: Before we go Professor, I’ve gotta ask you about your name, Ur. UR, the ancient city of Ur, that was part of the area that we are talking about, it was Mesopotamia right?

UR: Certainly, yes.

GELLERMAN: So…

UR: Well, I’ve been accused of having a stage name, uh, but in fact, this is a perfectly good Hungarian name. How I ended up as a Mesopotamian archeologist with this name could be subconscious, I would guess, but I was very close to becoming a Mayanist, which would have meant that this name would have been meaningless.

GELLERMAN: (Laughs.) Well, Professor Ur, thank you for coming in.

UR: Oh Bruce it was my pleasure!

GELLERMAN: Jason Ur teaches urban archeology at Harvard University.

[MUSIC: Michael Levy “Hurrian Hymn (Ancient Mesopotamian Musical Fragment c1400) from Ancient Landscapes (Michael Levy Music 2011).]

GELLERMAN: On the next Living on Earth, too much of a very good thing on the farm has doctors very worried:

MORRIS: Antibiotics are wonderful things. It is frustrating, it is a little bit scary, to watch the gradual increase in problems with resistance.

GELLERMAN: Reining in the use of antibiotics in agriculture, next time on Living on Earth.

 

Links

Jason Ur’s website

 

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