Climate Change and the Maya – William Fash Jr., Douglas Kennett, Timothy Beach, Vernon Scarborough

Tonight is the second program in our series exploring the Maya. These intriguing people are renowned for creating one of the world's first written languages, for measuring time with complicated mathematical and calendrical systems. And for figuring out complex astronomy, such as the precise movement and position of planets like Mars and Venus. But they were ingenious in a few other ways as well, and tonight's special guests are going to highlight some of those, particularly their engineering and agricultural skills that are actually still dazzling us today. We will hear from each scientist for about 15 minutes, no more. [LAUGH] >> [LAUGH] >> And then they will have a conversation together. And then, finally, you will have a chance to ask questions. So, without further ado, I will turn the stage over to our first imminent scholar, and please welcome the only Bostonian of the bunch, Professor Bill Fash. >> [APPLAUSE] >> So one of the things I'd like to emphasize in just introducing the Maya so that my colleagues and friends here can wow and zow you with all of their technical expertise and landscape management. And in sustainability of an agrarian urban tradition in a fairly complex environment was the resilience of the Maya.

And that resilience lives on. There are still over 6 million people who speak Mayan languages to set the stage for everything that they'll be talking about. I should point out that linguists now believe that the origin point of those 29 different Mayan languages that have survived was somewhere over here in Western Guatemala. And that they began to diverge about 1500 BCE. So these languages at this point are extremely diverse. They are languages. They are mutually unintelligible. And yet, Mayan peoples have survived and thrived despite all of the things that have happened since European arrival. I just want to emphasize also besides the resilience factor, the sustainable development achievements of the Maya. We're all familiar with some of the highlights of Maya civilization because their art and writing and architecture and urban planning are so compelling. But what we really are here to hear about tonight is the ways that they sustained this tradition since 1500 B.C., all the way to the present with some absolutely spectacular achievements in the central Maya area here in northern Guatemala and adjacent parts of Belize, Mexico.

And all the way down into Honduras, where I and my Harvard colleagues have working for many years. Our former student Bill Saturno wowed and zowed those few who came to his talk with his tales of daring do in the jungle and the discovery of these incredible murals dating to about 150 BC. Now has them going back to 500 BC with Maya writing, very impressive. But one of the best preserved sets of murals shows this scene of Maya making offerings to trees set up to represent the four world directions and with a sacred bird atop each tree. This is a trope that is repeated in many different Mesoamerican cultures. But it shows the reverence with which the Maya viewed their natural habitat, including such enormous trees as the Ceiba you see here that was the sacred tree of the Maya. Now there are three separate areas of what people refer to as classic Maya civilization from about 200 to 900 AD, the Southern Area Highlands and Pacific Coast, the central area or Southern Maya Lowlands, and then the Northern Maya Lowlands up here. I'm just gonna stop very briefly at four sites to introduce the work of my colleagues who will be speaking about all of the engineering marvels of the Maya. So here is the banner that's on the tower of the Museum of Science, the great ruin of Chichen Itza in Yucatan, Mexico, has a great deal to tell us about some of the challenges that the Maya faced in the past.

This is the famous Cenote, the sacred well. You see the platform here from which people either threw themselves, or were thrown into, the waters below, according to numerous accounts at the time of the contact in order to bring back the prophecy of the Rain God. The Maya were not hoping that people would die in honor of the Rain God. The idea was that because the Rain God lived in the bottom of the well, they would bring back the prophecy. The trouble is it's about 100 feet down, and an awful lot of them didn't live to tell the story, let alone the prophecy. There was one very famous fellow who came from a rival ethnic group. And he was getting a little fed up with nobody bringing back the prophecies, name was Hu Noxiel. And a number of accounts of this guy taking matters into his own hands and saying, well, nobody else can bring back the prophecies. So I'm gonna do it for you. And he jumped off of the platform here, fell into the water, managed to survive, managed to crawl out. Looked around at all of the odd populace, and said, I have the prophecy, and it is that I am king.

>> [LAUGH] >> Now, who could argue, right? >> [LAUGH] >> And then they began to declare him king, as they say. And so when you were king, you got to sit on a nice jaguar pelt and have the box seats and overlook the playing of the ball game down below. This is a reconstruction from Cop√°n where Barbara Fash, my long time colleague and partner in all things and I have been working. Here's a scene of the ball game. This is a scene, rather a vessel, that's in the exhibit. I do hope that all of you have seen it. That was one of the things that was offered to the rain god because there was thought to be a sort of reciprocity between the gods and the people. In order to receive, you also had to give. You had to pay back the debt that people owed to the gods for creating a sun and an earth and water. Water being the thing that they most needed the prophecy about.

So, when you think of Chichen and that great pyramid and that wonderful story about the Cenote, think about the fact that they were worried sick about the rain at all times because they were, for the most part in Yucatan, rainfall agriculturalists. So, we know the Maya, as we've said already, from their sophisticated art. These beautiful portraits we now know are of rulers. Of the calendrics, are absolutely astounding in their accuracy for predicting lunar cycles, solar cycles, Venus cycles, Mars. There's talk also of Mercury being recorded in some of the bark paper books, and a whole series of other media in which these inscriptions are recorded. But it turns out that an awful lot of the texts actually tell us about the lifestyles of the rich and famous. Why are we not surprised? And particularly among them, the lives, times and accomplishments of the great rulers,and some who maybe weren't so hot.

In the exhibit, you'll see a replica of Altar Q, here, from Copan that turns out to be a king's list. This is the first ruler, then next to him is the second, third, fourth, On it goes, all the way around until you get to the front again and this is the 16th and final king receiving the baton of office from the first founding king of this dynasty. And in excavating in Copan and many other places, we've discovered that the stories written in descriptions are also recorded in the architecture. And many cases, these buildings are actually very consistent in their uses through a very long sequence of time. So we get to look at the architecture and art, as well as the writing associated with all of these rulers and all of their changing times. But now my archaeology is much broader than just looking at the people in the center of the kingdoms.

Now, thanks to scholars like Gordon Willey of Harvard, my mentor and a great pioneer in the field of settlement pattern archaeology, we have a much broader sweep of Maya history. Because we have a chance to look at the lifestyles of everyone who supported the rulers in their royal palaces. And through the study of architecture and associated remains, including the physical remains of the people, we now ask a whole series of other kinds of questions. And I won't go into Copan in detail, but suffice it to say that all of this detailed mapping now supplemented by lidar technology has enabled us to learn a great deal about the rise and fall of this particular kingdom as with so many others. One of the great wonders is the site of El Mirador, the first truly urban Maya center. It's really, when you go out there and slog around in this wetland environment.

It's really kind a miracle that they were able to pull off an urban center of this size and these dimensions. This is actually much larger than the central precinct of Tekal, yet it dates to several centuries earlier. This is larger than any of the pyramids of Teotihuacan. The scale of El Mirador is absolutely astounding. So understanding the rise of this place and how they were able to sustain an urban center of this size is really a wonderful puzzle. And it's not hard to understand why people like us devote our lives to trying to figure that puzzle out. So if you're standing on the top of the tallest pyramid in Tikal, and you're looking out over to the east, this is what you see. A few roof crests, or roof combs, peeking out above the canopy. This is what's called the South Acropolis, a series of buildings that haven't been restored yet. But, you can see that they're just barely able to get above the highest levels to the canopy. And from these temples could then seen nearby places like Uaxactun or even El Mirador.

They're visible on the landscape and so a part of the motivation for Tikal's architecture is simply to be able to see the entire landscape around them. This is the central core of Tikal. It's known as the Acropolis, but people pointed out there are so many royal burials covering so many centuries of Tikal's history going back to the early Preclassic, even before places like San Bartolo Were founded. It's really a necropolis. It's a place where an awful lot of important people are buried. And it's possible to learn a great deal about how society changed through time by long term investigations. Which is what we'll be hearing about from Vern Scarborough who's devoted a great deal of time to figuring out not only what all of these public monuments in a place like the central area of Tikal, what you just saw was just this little piece of it. But in fact, how the Maya channels their roads and temples crossways, terraces and so forth to provide permanent sources of water and sustainable fields for their agricultural pursuits.

Now I'm going to close simply by pointing out that with all of this work on inscriptions, we're now also beginning to figure out what the political history of the entire Maya region was. What the tales of the fields of ancient times in the southern lowlands, or central Maya area were. This is a Stela at Copan, in Honduras, that cites the cities of Copan, and Tikal, and the Snake Kingdom, originally named Calakmul, and then the Bone Kingdom, which is Palenque. It turns out, all of these places cross reference each other, and many of the cross references are about events that are related to wars, to conflicts between them. This is the famous mural of Bonampak where you see the Mayan ruler of Bonampak dressed in his best jaguar warrior outfit with his vest and his jaguar and his hat, subduing enemies from a nearby village. And then the scene where those enemies are laid out so that they can be offered to pay the blood debt to the gods. This is a similar monument from Piedras Negras.

And this is a work of an epigrapher colleague of ours at the University of Pennsylvania. I think you can probably recognize that Simon grew up in England and so a lot of tube stations. >> [LAUGH] >> And this is though what Simon does with Maya power politics. I hope some of you can understand this better than the rest of us who didn't grow up in London. But basically he's mapping bellicose encounters in red, versus peaceful alliances in royal. Marriages in royal. Visits in royal, pilgrimages. And you see that sometimes the same place can shift from being an enemy to being a friend. So these are the kinds of things that we concern ourselves with, as it's become apparent that with time the Maya were so successful in harnessing all of the possibilities at their disposal that the population grew enormously, and you'll come to understand a bit more why that was. But that that also had consequences that played into the long term history of this fascinating civilization. So, at this point, I'll pass the baton to Vern. And I look forward to talking with all of you later, thank you.

>> [APPLAUSE] >> On the heals of what what Bill was introducing to you, I thought I would focus more maybe the ecological elements that underpin this great civilization. No doubt it's pretty powerful place, particularly during this time period. And I'm going to focus really more on this southern Maya lowland area, not really go into the highlands, which Bill didn't either. But that is also a clear component, you know, making up this complicated social order. The area is about the size of that I'm to look at, about the size of present day Britain or United Kingdom. So to give you an idea of just a context of geography. At least the expanse of it. They were an extremely long-lived group relative to many other high civilizations that we know of that are considered primary or very early, archaic states. A million and a half is no joke. And if we approach that, I'll be amazed, right? That in itself is of import, an environment that you saw was pretty unforgiving for at least a Western mentality.

And there's a lot of humidity and temperature problems that we'd have a hard time facing year in and year out. Precipitation rates too, complicate things. It rains, literally cats and dogs for about seven, eight months and then it's a drought like situation. So for upwards of four months maybe even five months as you move toward the northern extremes of the peninsula. It's really dry, it's really tough to make a living. And add to that, the backdrop is limestone, karstic limestone. So when it does rain, much of it just percolates into the jointed and porous nature of that understory and it's gone, given a stone age economy, so how do you deal with it? Well we'll come to that. Much of it does end up in large depressions. And today 40 percent of that southern Maya lowlands, that area the size of Britain, is a seasonal swamp really. And it may have been there are places where it's a little less seasonal, it can be year round. But, for the most part, it's a pretty tough place to make a living, at least from our vantage point. Okay, that's the backdrop.

Also figure that populations in that area, about 700 CE, the common era. That moment, there may have been 10 million people in this area. To give you a backdrop, that's again trying to get at those figures archaeologically is always tricky, but that is a workable figure. Okay, so that's the backdrop and now we have the water issue more specifically. What I wanna really focus on is their initial colonization during that pre-Classic period. That early part maybe 4 or 500 BCE to maybe time of Christ, maybe up to 100, 200 AD looks something like this. And this is of course a model. There are all kinds of forces that suggest otherwise. But basically the Maya were gravitating towards areas where they could make a living without a great deal of investment in technology and modifying the landscape.

They wanted an easy way to harvest this environment. So they live next to these these large depressions, these bajos as we call them down there, and tried to make a living and they did a great job doing it. They would go in and they would take the natural ponding of water in these settings during that dry period, and in the course of that, they would expand them a bit, deepen them. Accommodate the abundance that could be there and allowed the surfaces which many times were covered or closed in by clays to hold water year round. And that allowed them to do what they did. Now when they were doing this expansion you know to accommodate more water, they were building their pyramids through ball courts as well.

Basically what's going down, that fill is being used to construct their communities. So they're building in these shallow bowls in a very attractive way, very passive system in terms of water management. Water is just simply flowing off, the run off, off the helix, the ridges in proximity. With time they begin to foul their nest they really do overshoot the resource. Probably because the slash and burn agriculture in inducing more erosion. Water filled with sediment ending up in their potable water supplies. There are ground water problems that were associated with this whole model. There were also the prospects that I think Tim, the next speaker will address about drought at this early time. And all those things came together to force a different kind of settlement design. Now they could have just given up, that would be the end of the story for the Maya.

They didn't. Very clever, right? Because they did have populations on those hillocks in proximity. Well, the next series of events landscaping wise, when they've more or less damaged this environment. Or at least affected it in ways that aren't accommodating the same social level that they had in mind, they moved up to the flanking hillock. Well now, it's a different adaptation. Very clever though. They had the same mindset, the same worldview in many ways, just carrying it up to a different landscape. On the summits, now, they had to actually create a water source. And to do that, they began to excavate quarries to build their pyramids, the model they started out in the swamps. But in doing so those quarry scars were lined and carefully constructed to hold the water that ran off the paved surfaces. These were canted, your ball courts, your courtyards, your pyramids themselves are all designed in part to move water into these quarry scars that could hold water year round.

And I'll show you some examples of that in a moment. Water then, during the dry season, simply was released from these reservoirs. Simple gravity flow, moving down slope and accommodating the denser portions of the population, which are circumscribing these hillocks and ridges. As water moves down, it's being fouled, just by human use. As it ends up down here at the foot, it basically is an agricultural tank. Which can allow a third crop during the driest periods of the year. All that's possible. Now some of this was conjecture but it's a model that I've been examining for some time now. I want to now go just because of time constraints, just go to one convex example, Tikal. Okay and this is a kind of a 3D exposure of what the site may have looked like or really it does look like if you remove all of the vegetation today. And these were some of the elements that our most recent work at Tikal have revealed. One, a very large dam and it sits right here, right in the middle of the community, all right.

I'll show you some slides of it or a shot of it in a second. A second thing is how that dam was constructed was really clever. In fact, we don't find anything similar in the old world until some dams are constructed during the Islamic period in Galen okay. So that's an interesting you know cross-reference to its complexities in terms of the global effort with water movement at this early time. A cofferdam, that is a damn that's actually up here at this end of this reservoir prior to that big damn. It is holding water presumably when this tank is being cleaned. You know it's, we use it today, the Corp of Engineers is very big on cofferdams. And they are using it at least by 700 AD. Another element was ancient springs initially accommodating a portion of that population during the late pre-Classic. When many pre-Classic occupants are down here at the foot of this hillocks, some of them are living up in the zones and they're accommodated by springs. Natural springs in these elevated locations. Interestingly, spring water is very pure, right? It's potable many times, most of the time, as it issues from its locality.

That's great, but the population's increasing up here. And they are beginning to pave these areas to accommodate that runoff I mentioned early on. The downside is, you close off the recharge availability of the spring water, the potable water, because you're catching it now off these surfaces. Well, now you have polluted water, in a sense, cuz you have people up here, living, padding around on those surfaces. So how do you deal with that? Well they have, what we think, were filtration devices that were places at the ingress, that is where water is running off these surfaces before it fills your potable water supply. I'll talk more about that in a minute. Another element is our switching stations, and they're in this area down here, what we're calling bajo margin tanks, different. I mean a different kind of engineering to accommodate some tanks up here versus down at the foot of the hillock.

And we'll look at how that is accommodated in a moment. And then we have some pretty impressive canal segments that are accommodating water running off these surfaces clear down to that particular reservoir. Okay first were up high in that palace reservoir or that reservoir I mentioned was so large by virtue of a dam. Today the area basically connects one side of the site to another. If you're walking through as a visitor you think nothing of it. It's just this little corridor, this causeway. Well it's actually a dam. It's connecting one side of the site to another. And that in course you use it as a transportation, connectivity point, traffic way, and what I wanna emphasize is a reconstruction basically down here. What's happening is that you have a great deal of water, a head of water, backing up against that reservoir. That's pushing a lot of force, against it. And, the analogy of the little Dutch boy, right? If you, put a large sluice there, it could blow out that entire dam, very easily, given that pressure.

Well, it looks like what they may have done, is that there were series, of small, 30 centimeters in diameter, sluices, that were horizontally placed, but stacked, along the front side of that dam. Well, what that did of course it allowed you to pull the plug at that more elevated zone in the water line to allow a less severely pressurized release. And water would then cascade out as the water table dropped or the surface of the water drops, you do the same thing until you drain the thing and that fills up again annually with all that runoff. Ingenious I think, right? And again we do have references to other parts of the world but it does seem to be the model, the that we are employing. We've tried various scenarios to try and figure that thing out and that's the one that works right now.

Science is a moving target, as you know, so we'll see. The other kind of reservoir that's now down in swamps basically, right in the margins of them, looks something like this. We thought at the outset it'd be full of trash and debris, because they really didn't care what went in there cuz it ultimately goes to accommodate field systems in that third cropping maneuver as I suggested. This one wasn't operating that way. It's really pretty pure water that's going in there, in terms of the trash index if you will, ceramics and cultural debris that would suggest that it wasn't maintained very well, we didn't find any. It was basically a clean sediment wherever we excavated. So we think basically, what they're doing early on, that's a potable water source down there at the foot of this, hill there, unlike some of the others we excavated. And it was designed in part, carefully to prevent the random input of water into it. There's a large berm here, about seven meters, from in the bottom of this thing to top that was put in. But, what it's doing is that it's not fussing with volume.

Allowing more water in it. Rather what it's doing is diverting water so that it comes around and enters the proper location. And so we find that as well. There's a sizable or rather a deep diversion that's actually this arm, coming in and over to that location. And that's the cross section of it. Dug right into the limestone bedrock. And what's really curious about it, it looks like it was put in during the late pre-classic. A period where we're thinking there's a fair amount of drought in the zone. But what's happening during the, so it's augmenting the water supply during that dry moment, and some of these reservoirs are being constructed during that dry moment. But we know there's a degree of stability, or at least more water in later moments in history. So, they get too much water. So time is changing, this is an evolving site.

So they modify this, this system, by actually filling this thing in completely and they put in a matrix that is almost like masonry. It's so hard, it's the same kind of matrix that you'd use to put in a plaster floor. So they're basically closing up that potential erosional, can now input, and diverting it now away, okay? So at this point in the classic period, the only source of water, and it's all they really needed to fill this thing, was that ingress right there. We're finding all these nuances that suggest again a very complicated evolving system, in which you would expect in a over a period of 1,500 years. The switching station is depicted down here. I'm not gonna have time to really develop it for you. Basically the idea is that during that late pre-classic period, it allowed water in. And then during the classic period, it was closed up and water was routed out, and I'll just let it go at that. And then the sand filters I mentioned earlier.

And most of these reservoirs that we're finding are thin lenses, that's what some of these things are in this excavation unit, of sand. And there's no sand at. The nearest source of sand is about 35 kilometers away. And it's not just lateral, it's up a 45 meter climb. Well, why would you have sand in a reservoir, that was what we're trying to figure out. They're not using sand in their plaster, so what is it being used for? Well we're finding it only in the reservoirs, so we think, again it's conjecture to a degree, that they're putting these little we can call them boxes or filtration devices at the ingress as it enters these tanks. To allow water to pass through given the problem that potable water is being affected. Potentially portable water is being affected by people patting around and having trouble or having introduced pollution problems. So that's another element in this complex system we think is being played out. Again, Bill has indicated the ritualized nature of water for the clear, in the Maya area.

This is basically a bird's eye view of the site, and you can see these large water catchment areas. And it's pretty clear within this zone, which is about 62 hectares, if it rains 1,500 millimeters a year, which is pretty good conjecture. Over that seven month period, you get about a million cubic meters of water falling on that surface. Now this is up, that's the elevated portion of the site. Water is obviously moving through here and out, there's too much of it during that period. But a quarter million cubic meters of it are being held in these upward tanks, these elevated tanks. So in the dry season then, you can release them and off it goes and it's going in the directions you see. And then being used in fouled and sometimes in the case of that one location still maintaining a degree of purity. This is just shown, just quickly, by a former student of Tim and mine. Anyway, she, now, is involved with the UN, to a degree, at UNESCO, and she was asked to, kinda, look at rainwater catchment systems, globally. Now this is a qanat system from the Near East.

You don't have to go there. But all the other quadrants here, all the other depictions, are ways in which water, today, is being harvested globally. All of them are part of a Maya reality and were used then, in one way or another. They didn't have tin roofs, but it was the same idea. Water is being caught and moved not very far to accommodate water access. Remember irrigation is not our notion of irrigation. It really isn't an option in this location because of that karstic environment, and river systems are either heavily entrenched. You can't get them out, right, to a field. So, that process, that agricultural lead is not really an option. So, they do other kinds of things. So, they are harvesting this environment. And they're doing it incrementally over a long period of time. Now, on closing, all I wanna mention is that Maya are not so mysterious, right? I think we have to put them in a context, that makes them real like we are real.

And, there are many parts of the world now, we are finding that their systems, their tropical rhythms are not unlike the Maya. So, if you go to Amazonia, I've worked in Bali, I've looked at their Angkor systems. They look very similar in many ways. And I wanna just tick off some of the things real quickly. They're semitropical environments because the rainfall is seasonal, maybe 1500 millimeters more or less, a lot, right. But they're fragile, and what's really interesting about these environments is that water, biologically, allows a great deal of diversity. And yet there's a kind of a maybe a biological law, if you will. If you go into tropical settings you're gonna get a tremendous amount of diversity. We didn't know that, you read about it all the time. What is not so much mentioned is that the number of any one species, the actual number of individuals in a plot or a microenvironment or a patch, is quite limited.

So you might have one jaguar over there, one mahogany over there. It's that kind of distribution of species. Well that's meaningful when you compare it to other parts of the world like the Near East where we have vast fields of wild wheat, vast fields of wild barley, oats, rye, right? You have herd animals that won't quit. That was never an option for these folks, right? So, what ends up happening is that people begin to mimic that dispersion, right, from the outset. That's where they live their lives, and we end up with the kinds of social organizations that are very dispersed. And that's troubled folks dealing with urbanism for a long time. How can the Maya be urban if they live so far apart? Well, we're finding now that there's notions of low density urbanism at Angkor, in Bali and Amazonia. They're all very much the same model, and it has something to do with that tropical rhythm, living in that reality, mimicking those rhythms, right? There are many different pathways that people follow in those settings. The food chain, if you will, is very rapid, very immediate, but it's very flexible, so you can substitute various resources for others very quickly.

And that's a way of looking at the reality of these environments that we haven't necessarily spent much time on, but I think affected who the Maya were and even their world view. Intensification, big deal, that is the sense that in all these settings organic materials decay so rapidly, high humidity, high temperatures, go figure, right. So what is happening is that people have to contend with that reality. I'm of the opinion that the classic notion of the calendar, where we think it's a lot of stargazing and elevating rulers, very much a political device, well it's surely that. But it has an underpinning of scheduling, of allowing these environments to be tapped In a very meaningful manner. It's time sensitive. You've got to have an opportunity to harvest that resource and get it to point B and know when it's gonna be available.

And you find it in today in places like Bali, their calendar system is very complicated, as the Maya calendar was. And it's probably more complicated than we even know. There are probably calendars within calendars, which is the case in Indonesia. That is interesting in terms of scheduling the movement of food, resources, information, and road systems that we're only now beginning to understand are covering these environments. And I will include canoes, right. Amazonia is a particularly good example. You can take a canoe in the raised field systems in Amazonia and travel for 170 kilometers and not pick it up. And they're following old raised field canal systems that are there, which is I think a model in part for what we really have to start looking for in that 40% of the Maya area that's swamp.

No one wants to work in there, that's why we don't know anything about it. But that's where the secrets are. Finally, the labor tasking is a notion just that things are going on incrementally. And the people were very skilled at harvesting these environments. And it was learned and invested in, and technology was not really a part of their picture. They had a different view of things. And I think that's hard for us to internalize in the West. But figure no wheel, that's no pulley, no horse, no beast of burden, no metal to speak of. I mean, you had some religious items, copper bills and that kind of thing. But that's not cutting anything. And what am I missing? The sail, it wasn't part of their picture. Well, why isn't that? It's because they didn't need it. They had 10 million people. And they organized them in a way that was very constructive.

It was a way of organizing that I think we want to put in context globally when we talk about these resources. Thank you. >> [APPLAUSE] >> All right, thanks Vern, thank you all for coming out on this night. I came from farther away than you did, though. So I flew in from Austin, Texas this morning, and it was 79 degrees. And it's not 79 degrees here on any particular thermometric metric. >> [LAUGH] >> All right, so I am a soil science geographer, and I work on soil geomorphology. So a geoscientist, but I'm coming from the geography environment department at the University of Texas where I just moved with my wife was also a professor there. And I want to give you this kind of food farming background. This is what I've been working on. And I've also given you a whole group of new images that I've just been making in the lab in the last few weeks because I wanted to produce something new out of this. So everybody has to show a temple, so I took this shot of this temple.

I'd rather show you this soil, okay? >> [LAUGH] >> And the reason why I'd rather show you this soil is that soil holds not only all the fertility that grows all that crops that fed 10 million people, but more importantly, it holds the water that grew those crops. And without that soil, water in many places where we've lost soil and we're losing soil today, we can't grow crops at all. It's as simple as that. Soil is water, and water is soil, and soil is life. So, my talk is gonna be a little bit about food, because we've been skipping over it, a lot about farming, a little bit about forests. And then these three regions that we'll be looking at, the northern plains, the coastal margins, and elevated interior. Okay, so the food part of it is a fascinating question.

Everybody who studies the Maya knows the triad, right, the maize, beans, and squash, and of course sacred cacao. But one of the things that's coming out of a lot of interesting work at places like Ceren, this Maya Pompeii that's been covered by volcanic ash is evidence for tubers. And there's a lot more evidence for that also in pollen that's coming up. And I think in 50 years we will think of them as as much the people of tubers as they were of maize, too. As more of those lines of evidence come out. And this is coming from all sorts of fascinating macro and microbotony, as well as these excavations at Saran. People spending their lives over microscopes, as Bill Fashion and I were talking about before, all day long for years on end. And the take away from all of this kind of work is simply that there's a high diversity of plants and animals, and likely foods we no longer use or don't even recognize any more. They're probably using lots of other things that we didn't understand, which is a very interesting finding that's coming out in a lot of good microbotanical work. So in terms of farming what I like to talk about are agroecosystems, farms are really ecosystems.

And the more evolved they are and complicated they are develop over time diachronically. And I I see them in this phrase we use is Landesque Capital which means the capital that farmers put into creating landscapes that continue to provide for them far into the future. And some of the Landesque Capital that the Maya developed, just like Vern was saying, is still in place and still creating higher biodiversity than areas that didn't have Maya there. So we always think in terms of the Mayas being a degrading group of people who fouled their nest or something like that. But, they also led to a lot of biodiversity and a lot of ecosystem diversity that we often don't think about. The other thing is that a lot of these areas are anthrosols, that is their soil's created by human beings over time to be more fertile and to preserve water for a longer period of time. And so a lot of the areas that we're mapping and looking at have those characteristics of anthrosols. One of the things that I've been focusing on in my own research for years are the places that people don't wanna go work, like just Vern just said.

>> [LAUGH] >> And that is in swamps and canals. Cuz I like them actually, although I've lost so much blood from the mosquitoes over the years, I don't wanna talk about it. But at the same time, the reason why I was interested in it is because when I first got in this work in the 90s. A lot of people had given up on wetland farming as something that was actually producing any food for the ancient Maya. But I think these last 15 years we've been working on it, we've proved them wrong. We think that it's a major producing part of Maya agriculture and all of our work so far tends to make us think this. I was very skeptical to begin with in fact, but have become less so as I've excavated now dozens and dozens of these fields. And then the other thing are terraces.

Wherever you see terraces across these landscapes, means Landesque Capital. Capital people build into landscapes that preserve them from eroding that are still in place 1500 years later, which I still think is amazing. You'll see this map that my friend Doug and I, Doug will speak next, worked on. He's the originator of this, and he's looking at these various regions here, these are the wetland field regions here and over here. This interior region of Bajo and these are areas then of extensive terracing, but we've only discovered a small percentage of all of these things as far as I can see. I just made this new diagram which is supposed to be a forest diagram from across the Maya lowlands. From the savannas of the south, through the high tropical forest to the flamingos in the north to try and give you a little insight into this.

Everybody has this same picture, it's required of all Mayanists to put in all their talks as a picture of Tikal, and here it is. I hope you have one, Doug. >> [LAUGH] >> Good. So here's the first new diagram in this case, and this is a transect right through this zone. Going from areas, appear that a little bit higher in areas where farming and Landesque Capital focused on little lowland areas that we call rejolladas. There are other Mayan terms for it as well, and we think that these are probably intensive landscapes. We first saw that in the early 90s and we have been seeing more and more evidence for it. We're finding more and more evidence of these Cenote kind of environments or which have cacao, lots of evidence for cacao, even up in the Yucatan where it's too dry for these things to grow along the way. So this is this region, it looks like a region where nothing can grow, but looks are deceiving.

A lot of these areas were very productive and they produced a lot of food in the past. So one of the examples is Pakbeh. We call it the Paradox of Pakbeh, otherwise known as this landscape has 40,000 people in 600 AD. It has about 1500 people or so today and they struggle to survive, to grow enough food, but they clearly grew enough food in my view of this. We differed in our project. Some of my friends thought that they couldn't have possibly grown food so they had to get it from trade. But I think a good agricultural scientist like the ancient Maya would have figured that out and there's plenty of evidence from all that Landesque Capital in these landscapes. One thing I just gotta point out, here's the first soil. This is a Maya anthrosol, and this is the soil it was built from. It was built from this little thin, 40 centimenter soil and became an 80 centimeter giant, thick rich soil that could produce a lot of crops. These are other examples of these kinds of anthrosols.

I won't go into them in detail because I'm probably the only one interested in them. >> [LAUGH]. >> Alright so this southern coastal region is the area I've been spending the most time over the last few years. It's an area I think is dominated by wetlands and wetland farming systems. We have been studying them for years and we're doing more and more remote sensing studies of these things and also excavation of them. Here's an area over here. This is an area that's just come into our picture recently because it seems to be maybe the largest area in of wetland agriculture. We still, in the future, have to figure out what they're growing there. We've just visited so far, we haven't gone out and excavated in those sites, but we've excavated the hell out of these areas over here.

And we know what they were doing there. Here are these wetlands. All the lines you see are ancient canals, a meter deep, two meters wide or so, and all of those are fields in between. Some of them are incredibly symmetrical and regular and go on for way out under these forests. What you're seeing is savanna, but under the forest they also extend as well into these landscapes. Here's this region, and here are those canals. And and the birds of paradise that we've been studying now for some time. So we dig dirt, and here's the digging process, which means you have to have pumps if you're digging in a wetland or you drown. So we have the pumps over here pumping away. And this is the excavation, then, that shows the stratigraphy of what we're trying to look at, and here's where the excavation is in this case.

What you're seeing over here is an ancient, buried canal that provides all sorts of interesting evidence for what Maya used these landscapes for. So here's a quick model. Years of research on this allows us to build this model so back, yeah? >> I don't know if I'm very dense, are those all man-made? >> Yes. [LAUGH] >> We can come back to that in questions, but let's get back to that in questions but I'm gonna tell you that I think every one of those is man-made >> Sorry. >> No problem [LAUGH]. So 3, 4 thousand years ago, you have a wet environment, they're growing corn. These archaic Maya peoples were farmers as well. 2,300 years ago, water table rose and flooded these areas, inundated the regions. Maya being a resilient people, over time they went through some more flooding processes that occurred. There's a big flood with sands and was gypsum along the way. But in the Maya Classic Period, they came back in. And they were able to take this wetland environment and turn it into a productive agricultural system. And this is what we've found evidence for, over and over again, with a similar layer of strata, along the way. I'm not gonna go into this.

I could go into this for a long time, but I promise not to. I'm just gonna show some shots of this, just for you and for everybody else, to look at all of these anthropogenic environments. The whole Maya Lowlands is the anthropogenic environment. And this is the Maya scene I call it, rather than the anthroposcene. The Maya scene. So here's a wetland over here. This is about, a friend of mine sent me this on Google Earth. This is the beauty of Google Earth, we're discovering new things all the time. A little shout out to Google Earth, if they wanna give me some money? Anyway- >> [LAUGH] >> [LAUGH] There's about 100 square kilometers or so, we think, of these wetlands out there, nobody's ever studied before. We're hoping to get into those fields. These other fields go up the valley of the Rio Hondo over here, and more of these kind of fields, and all sorts of different shapes, and each one is a different story of course, although we can get some general pictures from them. All right, nobody's gonna get anything from this, so I'm just gonna point out what I'm showing you, this stuff that's unpublished that we're hoping to publish soon.

The outer red line is an indicator of the intensity of maize in environments. And these are reservoirs, and these are bajos, Vern mentioned these. This is the mean, these are backslopes, flood plains, terraces, wetland fields. What you get out of that is, the wetland fields were the most intensive agriculture environments of any of those areas, which I think changes our view to some degree, of Maya and the Maya agriculture, if I can get this published, anyway. >> [LAUGH] >> Elevated interior is the area Vern's been talking about over here, and you'll hear a lot more about this. It's the area where the Maya collapse occurs, in quotes, in 900 or so. And this is an environment of terraces, and bajos, and backslopes, and wetlands, and wetlands changing, becoming drier over time. Especially from the Late Preclassic, coming into the Classic period, and then from the Late Classic, which my friend Doug is gonna talk about in just a moment here. And just to give you an idea, the next part of this are the building of terraces. This is my own diagram of a soil sequence on a slope. And then what happens after it gets cut down, either by the ancient Maya or the modern Maya.

And then what happens afterward is landesque capital, on a huge scale. Now, almost all the places we've studied, not all of them, but many of them, have developed these incredible terrace systems across this landscape. Like in Bali, not too different from Amazonia, and Angkor, and other places. People had similar reactions. But of course, one of the problems now is the re-burning and the re-cutting down, and deforestation of those environments. So that comes down to two kind of options we saw, in the pre-agricultural forest gets eroded during the Preclassic, and it either just simply gets reforested, or it goes back to this reclaimed landesque capital landscape. A lot of it went this way. Some areas like Tikal, were reforested and not re-terraced in this case. But one of the things we're seeing in a lot of places, is more and more example of every square centimeter of this landscape covered by terraces, as that car call with our friend, Arlen Chase's very important and famous work there, on the right. Okay, one thing I will say, the last thing I'll say here today is that, this is over time.

What happens is is deforestation, and soil erosion, but in every case people learn, and they develop some sustainability, every place we've looked at before, and the soil erosion goes down. So we saw the soil erosion decreasing in the Late Classic period, as people were developing a handle on living in those difficult landscapes we're talking about. Exactly the same thing was recently published for the Eastern United States, in fact, right over here. This is the whole eastern area in this region, and it shows 1800 at extremely low soil erosion, extremely high soil erosion by 1900, and declining again by the current. This is just published in Geology in the last few weeks. So, the geoarchaeologist's work begins and ends in the field. We love to go to the field. So I just happened to find this soil that looks like a Nike swoosh so, Soil: Just Dig It! >> [LAUGH] >> And then lastly, every talk should have a quote from Rumi, so, be more like the soil. Thank you. >> [LAUGH] [APPLAUSE] >> Okay.

Well, let me just start off by saying that I'm thrilled to be here. I spent the first part of my life growing up in Rhode Island. So I'm actually a New Englander. At least the early stages of my life. And this is actually the first museum, large museum that I ever came to as a middle school student. And actually really piqued my interest in science, and sort of has led to a career in scientific archeology. So I consider myself to be an environmental archaeologist. So I'm really interested in how humans interact with the environment more generally, than how various structures of those societies, but also, respond to external changes, like climate change. Or some of the processes that Vern and Tim have been talking about, in terms of anthropogenic impacts occur on the environment, and how this is all interrelated. Now the second half of my life, I spent in the west coast. And particularly in southern California, and this is really where I think I become very interested in the environment.

Because in the late 80s I lived through a very long drought, and I saw how this actually impacted people in the society. I mean as a New Englander coming out to southern California, there were very strange things happening. People were painting their lawns green. >> [LAUGH] >> Yeah, but there were major problems with the availability of water. Water prices were going up, reservoirs were declining, the kind of reservoirs Vern's talking about, they were declining in the area. And there were also strange political decisions, and economic decisions that were made. There was actually in Santa Barbara, California, where I was at the time, they actually voted to invest $2 or $3 million in a desalinization plant that actually never was used, ultimately. It's actually now been mothballed.

It's never gonna be used. And that was because another decision was made at the same time, which was to connect Santa Barbara to the California Aqueduct, which has had major ramifications for population increase in that particular area, and I'd say also environmental impacts. So that's a little bit of a personal note on why I've become sort of interested in it, and why I'm interested in the Maya as sort of a historical case, where we're gonna look at the long term processes of human interaction with the environment. And the effects of these sort of external, retentional external shocks, like climate change. So, we had a very nice summary of what the Classic period Maya are, so we don't really need to get into the details of that. But I will start off with just sort of again, showing another map of the distribution of major Classic Maya kingdoms, on this map here. And this is a map produced, based on data from a hieroglyphic database that I've been working on with Martha Macra. She's the one producing the database, and I've been working with her to look at patterns within the written records themselves, sort of as a source of information about connectivity, and sort of the persistence of these kingdoms or palladies, through the Classic period.

And then ultimately their decline. Which is really what I've been tasked to talk about is really the decline of classic Maya societies. And this is an example from Copan where Bill and Barbara worked. Just showing this is a remarkable record of these individual polities, but also the connectivity of this polities, as Bill was talking about. So again, not to belabor this, but there are about 44 centers that have emblem glyphs. So these are the major kingdoms, but there are also large numbers of other centers that have dated stone monuments. And then also many, many sites on the landscape. This is just a zoomed in view of Mexico, Guatemala and Belize here to kind of give you a sense of the distribution of sites. And these are actually on the larger end of things. There are smaller sites that haven't been recorded. So again, this is a saturated environment there are lots of people as the others have been talking about.

Many many people. The other thing I wanted to highlight is that the connectivity of these major kingdoms, these major centers. And again this is work that comes out of Martha [INAUDIBLE] database that we've adopted. And looking at sort of the antagonistic relationships that Bill was talking about. But then also diplomatic and lineage based relationships, and subordinate relationships that are recorded in these stone monuments. And for me, this is interesting because you can kind of think about the classic period Maya world as a network. Of course we can identify with that today because our global community is increasingly networked. We're connected and I think the classic period Maya were also connected. These are the connections that are recorded on stone monuments. And it's sort of a proxy for that connectivity, but, as Vern mentioned, there are road systems, there are trade networks, down river systems, there are roads that have been recorded in this area. So, there's a lot of interaction that was going on in the classic Maya world. I consider this as an environmental archaeologist to be part of the environment.

This network becomes part of the environment. Okay, so let's look at what happens with the Maya collapse. So starting in sort of the late classic period when there are large numbers of centers. This is just a figure showing the number of dated monuments recorded at these various centers. And you can see under the larger dots there's lots of activity that's going on. The smaller dots are at least there's some activity going on. And then there's information about the connectivity between these centers. In the late 8th century, we can see that there's actually sort of an increase in that connectivity. It's shifted and one of the things about classic Maya society and these kingdoms is they're dynamic, as Bill was saying. So they're actually rising and falling and independent probably of the environment. There's a lot of political and social and economic jockeying that's going on through this interval of time.

So it's not surprising that any one kingdom would actually rise and fall by itself. What's interesting about the Maya collapse is that so many centers went into decline in a fairly brief window of time. And if we look in the early 9th century, we can see sort of the decline of those centers that are producing these dated stone monuments as sort of a proxy of political activity. And decreases in sort of the network connectivity within the region. Again, as an environmental archaeologist, I'm thinking the networked environment is changing and that's having an effect on other polities that are in the system. Then by the late 9th century we have a very small number of centers producing stone monuments. Not much information about connectivity between these centers.

And then there's actually some persistence at some locations, which is very interesting. And then in sort of the northern lowlands, which was a point of interest, there seems to be some persistence beyond this time period, I would argue until about AD 1000. Cuz I want to shift quickly to some of the climate work that we've been doing within this region. This is a map showing sort of the distribution of rainfall throughout the area. Just showing that it's dryer up in the north versus down in the south. This is some of the seasonal variability that Vern was talking about through the year, and it's pretty consistent from north to south. There's not much temperature variation, but you have the seasonal variability. But on this map it also shows sort of a number of climatic records that are available for the reader. So these are historical information about climate change.

And they're basically coming from two major sources, from lakes, so lake sediments provide information about climate and climate change. And then stalagmite records from caves. This is an area that is becoming very productive in the Maya region, we're getting incredibly high resolution climatic records. So this is, these are a number of records that come from different parts of the Maya region. I don't have time to get into a lot of these, but I will highlight this is the record that my research team has been involved with producing. And just to highlight sort of the quality of this record, these little Star Wars looking things up here at the top, little space ships. See the space ships, yeah? >> [LAUGH] >> See how they're very, very, narrow? Those are the dates, those are uranium thorium dates. That the error range of those dates. They range between plus or minus 1 year and plus or minus 10 to 15 years in this particular case relative to the dates on these other records which have very large error margins.

So what we can say about this record is we can actually compare it to the long calendrical dates that are in the record. So those are often down to days. And so we have a climate record and historical record that are fairly comparable in terms of their degree of precision. So you can actually start looking at relationships between the rise and fall of these polities and climate. And then here, you can see, basically, there's an isotopic record. You can see the periods of drought, at the bottom these dips, and then periods that are wetter at the top. So you can see sort of this through the last 2,000 years. Okay, so quickly this just shows the same climate record, So the dry periods and wet periods based on this isotopic information. And you can see this is for the time period that we've been talking about, the classic period. These water systems and agricultural systems, those developed during a period that is sort of unique, in terms of the amount of rainfall in, at least, the last 2,000 years.

So, there's a great deal of rainfall. I mean, there's variability, but on average, it's quite wet. And then going into the late classic period and into the terminal classic period you can see sorta this general decline and sorta more persistent drought. And then the duration of some of these droughts is quite extensive. They're up to 10 to 20 years. This very long drive is a hundred years long, starting at around A.D. 1000. This is actually well after what would be considered the classic Maya decline. This is shown relative to the stone monuments, showing through the rise. So again, the frequency of data so minus the rise and then the fall. So this is basically showing the collapse here. So, and, yeah, so I'll stop that, okay.

One feature about this that I wanted to point out is that, so you have the rise and fall, but another thing that is interesting, think about the dynamics between these qualities is that you also have an increase in warfare that goes, it's evident in their written records. Starting in the late classic and persisting into the terminal classic, that's this red bar up here. So as things are getting drier, there seems to be more tension and warfare that's going on between these qualities. Okay, so they're gonna finish off here. So why does this matter so looking at the current situation people look at the Maya. When this Maya climate paper came out there's a lot of interest in it by the media because, well there's issues with climate change today. My good colleague at Penn State, Michael Mann, who's written extensively about sort of the major shifts that are occurring in today's climate, in particular Northern Hemisphere warming.

What he calls the hockey stick so the major shift in climate that he argues is an anthropogenic phenomena, okay? Well what this means in the Northern Hemisphere is that for the tropics, is that you get more severe droughts in many tropical locations. So in the Maya region in particular, we've actually just had a paper come out yesterday showing that it is getting drier there. So we're moving it towards what some of these major droughts look like at the end of the classic period. And when you combine that with in equatorial regions where you have a great deal of hunger and human suffering, this is something that I think we need to be concerned about as a global community. And you may have said, well that's in the tropics. We don't really need to worry about that. But we need to think about networks again.

We're becoming increasingly connected, sort of the lights of the world show this connectivity. And so this is something that we need to be concerned in terms of the relationship between that connectivity and some of these major shifts in climate that are have been demonstrated to be anthropogenically altered. So, and as, again, another idea that so we live in a global community, we need to be concerned about these major shifts that are occurring. And essentially, I think we can look to the Mayas or some of the processes that occurred there to learn from about how their societies were organized and how they responded. How they were actually resilient for such a long period of time and then why, to study why they actually, ultimately succumbed to these major changes in climate. Thank you. >> [APPLAUSE] >> And now I need to invite the other members of the panel to come up and have a discussion. >> [LAUGH] >> I'd like to follow up on the last point Doug was making.

In our conversations, just in our talks, I think you might have picked up on issues of resilience but also Whether or not the Meyer infect augmented the strength of their environment as Timbo say. And whether we should really be talking about a question of whether this is a collapse of a population or is this simply a reorganization of population. Because of course, the Maya are still with us and they are still communicating their own views of their own pasts as well. But I think one of the great puzzles for me as a scholar who studies the Maya is how was it that El Mirador, one of these really incredibly huge urban centers, had to be reorganized? And so one of the questions I've always wanted to ask of Vern and my other colleagues was what lessons can we take from El Mirador.

And apply them to the later reorganization if you don't want to call it a collapse of the Maya and to the present day. Which is I think where all three of you guys are going with your research, is, how is this useful today? I'd like to hear each of you reflect on what you think happened at Mirador and what you think we can take from it. >> [CROSSTALK] >> Well, my two cents, right. In terms of Mirador of course was this huge center that Bill alluded to that is as large as anything that follows it after this late pre-classic shakeup. I talked about the business about the concave, convex, all that, it is in that concave landscape. It's right in the swamp itself, but they're able to modify the swamp and their surfaces that they're living on in a manner that allows them to create this incredible side. But it takes a hit in the late Preclassic, early Classic.

So the question for me is why they able in that moment to so cleverly reconstruct their landscapes and themselves, socially, to continue this trajectory for another, I don't know, 700 years or so, 800 years, after its demise. And I think, they're just very clever, but they weren't that clever, because at the end of the line, let's say about 800, 900, the same situation occurs again, and they don't do well. They don't redefine themselves in the manner they had earlier. Not that they don't occur. Bill and others have mentioned, of course, the collapse may be more fragmentation, you know? You have people there. >> Still a lot of people. >> Still a lot of people. But they reorganize, and they have different kinds of institutions. Their world view changes quite a bit to accommodate this new reality. So, well, those are just thoughts, and I better, let my colleagues comment.

>> [LAUGH] >> I think one thing is that, a place like Mirador, we have to remember that we have a European image of what a swamp is. It's a miasmic, nasty, place. And I don't think that that was the image of the first Maya who came into this area. These are areas with tremendous resources. They have turtles and mollusks and fish. They have water birds. This is a perfect place to live. And I think that as you build up around there off of that resource base, and up along this escarpment where Mirador is in this case, they perhaps do overshoot to some degree. I rarely every use that or think of that. But Mirador is one that makes you think that because there is a pretty strong correlation. Doug will tell you, and I know from two articles that are in review right now where this droughts that go on for a long period of time.

And these are two- >> Am I allowed to do this? [LAUGH] >> Two new sources, Doug's sources, his own, but also two new sources that are just going to come out in the literature probably in the next few months from two different kinds of proxies. >> Yeah, so that's the late pre-classic drought is this. So you can see that there's a period that's A.D., well, 150, maybe 200 to about 350, where you've got another drying cycle. And that's when, at least my understanding based on the available data that's out there on El Mirador, that that's kind of when it goes into decline. So yeah, I should've been a little bit clearer. I was kind of trying to move too fast. The way that I envision the collapse is really a political collapse first, so [CROSSTALK] I think that's basically the center is going to decline. So within these kingdoms you have a very small number of high status individuals, kings and their courts and such. But you know the vast majority of people are subsistence agriculturalists that are integrated into these polities.

So what the collapse is really is sort of the removal of the highest level and so it's really the kingdom that goes into decline. I think with that you actually get dispersal of populations and reorganization. And I think we need way more data on exactly what that looks like. That's a much more difficult problem because you're looking on small sites on the landscape, you're trying to find people that are very dispersed. So I think that's an area that I'm trying to work in a little bit more. >> Then the other big dip is about the time when Chichen goes [CROSSTALK] in a hurry. >> Yeah, that's a great point because the way that I sort of see the patterning in the Maya lowlands is sort of, it's very cyclical. One of our colleagues, Joyce Marcus, has come up with a model called the dynamic model, where you basically have kinda centralization and decentralization through time. Well, I would throw a potentially climatic element to that, that perhaps during dry intervals it favors decentralization, but during wet periods you get greater integration. And that seems to work fairly well, I think, with the pre-classic rise and fall and then the classic, and then there's some tricky business. We don't know too much about the chronology, unfortunately, of Chichen-Itza and some of these places, but that looks like it goes into decline, like Bill was saying, during this major drought here.

I would actually call this drought the true Maya drought. [CROSSTALK] That is the driest period in the last 2,000 years. >> I wonder, Doug, if there's something to do with that lag situation. We see the Maya pulling out of a late pre-classic or early classic drought condition, and then really fluorescing, right? >> Yeah. >> But at that moment when you have a 1,100 year drought, right, even though there may be a downturn politically, you would expect the Maya, given their clever and innovative ways, to have pulled out of that. But with that major drought, 1,100, maybe they were going to come out of this fragmenting or this collapse-like situation. But they couldn't continue that trajectory, as clever as they might be, because of a major drought that basically forces a degree of permanence in terms of what they can do. I mean it's changed, they can't pull out. >> Right, so there's resilience through the record, but every once in awhile, there's a knockout punch in the climate record. >> Yes, yes, uh-huh. >> Well, and one of the other things to keep in mind is, as we discuss this idea of reorganization and that wasn't that the population collapsed, it was that the population, who were peasant agriculturalists and middle class folks living out in those smaller yellow dots on your map continued to thrive.

But the urban centers were the ones that were abandoned. And this is, I think, a sobering lesson for us today because all the statistics indicate that worldwide we're becoming much more urban. And it's happening much more quickly than people are realizing, and our water sources in places like California are becoming more problematic. So these are sort of sobering things to think about in terms of a civilization with several thousand years under its belt, that urbanization ended up being a little more complicated than the people at the top of the system were able to handle. And when that major drought kicked in, there really wasn't much of a way of a recovery. When Cortes made his march from Mexico City down to Honduras where he was to quell a rebellion, he went within a few kilometers of Tikal, and nobody bothered to tell him. So Cortes could have had the first shot of Tikal that he could have shared with the King of Spain. But he missed it.

There was nobody living there. People in what is now Tayasal in Flores had no conception of a major city like Tikal. So all of these are things for us to think about in terms of our own trajectory today. >> In that context, Bill, I'm wondering, not only are we becoming more urbanized, but where we are urbanizing are on coastal margins, of course. With climate change that's gonna be very vulnerable. So I think something's gonna have to change in the next 50 years in terms of how we're occupying space. And perhaps there's some ways in which we can look at the Maya and other tropical systems where they were very dispersed, this notion of a low-density urbanism model. >> Like in Angkor also. >> Right, and maybe there's some use in examining those systems, given we have Internet. It's a game changer, right? So you can have people in the hinterlands that can communicate with a hub, that accommodate your economic system, in a different way, maybe not unlike, in a crude manner, or actually a sophisticated manner given the crudeness of Angkor or Maya.

But the idea would be that you have light rail that would go out into the rural settings with cooperatives that we read about all the time, 10,000 villages trying to help out all these folks that we see in various marketing settings. But give them a market opportunity, given our capitalistic arrangements, that would allow them to communicate, and then actually get the good in on a system that would accommodate maybe old trunk lines, old ways, current road systems. But allow it to rapidly move their goods which are being exploited anyway out there in other ways, mining operations, and all the ways in which we're harvesting and over-exploiting the hinterlands, but integrate them in a way that allows communities in those areas to do okay, right? Because, of course, the rural situation is pretty bleak.

It would cut down on the population densities in cities if we allowed people to move into those arenas. Many people, of course, now are trying to work at home from afar using the Internet. And it's a possibility, but it's gonna take a lot of thought. And one of the problems with we archaeologists, we haven't figured out how to communicate to the policymakers that we have a world we can Address, and that they can take us somewhat seriously. We're still considered ivory tower curiosities. Everybody's interested in archaeology, so they give us the time of day, but that's about it. I do think we can learn from the past. >> Absolutely. >> It's just trying to be imaginative and allowing that other part of the spectrum that those that make the decisions to maybe give us a moment. >> Yeah, I think there's actually been some pretty interesting work, broadly, on looking at networks and network connectivity. And I think this is actually something that we can learn from the Maya, and that is that the way that networks are composed, actually matters for how they respond to external stress.

Okay there's been actually a couple of papers recently, that look at this, even in ecological systems, in internet, just the way that networks are organized. And how they either resist change or promote change and how change occurs. And these things called tipping points. So you can have a structure of a network where, for instance, if you take the classic period Maya, I would argue that these kingdoms were organized fairly similarly. They had divine kings. They had a similar structure. They were fairly conservative with respect to change, I mean they had a certain, sort of system and they were connected with one another. So they were basically, fairly homogeneous with respect to the types of nodes that existed throughout the area. And you know this literature actually tell, our network actually tells us that that is the kind of system that That is fairly resistant to change up until a point, and then you can get a very fast tipping point in the system. And that's perhaps what we're dealing with in the classic period.

>> At the end of the classic. >> And what Vern was saying, that we have to think in the modern context about how. And the Maya, of course, they were just responding and developing in a certain way. We have actually the benefit of lots of information and knowledge about how our systems are actually organized. And I guess the message would be if the the classic Maya were perhaps organized a little bit more heterogeneously. That there was varying structures within the region in terms of political structure. That there may have been less of a radical shift in the 9th century in response to this drastic drying. Or at least certain areas would do better than others. And that's perhaps what we're dealing with in the northern Yucatan. >> Parts of Belize also seem to have weathered the storm a little better.

>> And maybe these are settlements that are not as integrated into this classic period network and therefore they're were actually organized in a slightly different way. And they actually persist in the face of this drought, in some of the driest parts of the Maya realm. Which is a little bit of something that's been of interest. A paradox. A paradox, yes. Paradox. >> So I think at this point we'd like to throw the floor open and we have mics that people can make use of to ask questions. >> The first question is coming from back here. >> Thanks I was just curious what the second to the last map in the last presentation was depicting? >> The second to last map. >> Yeah or the second to last line. It's a world map but it's got all kinds of lines over it. >> This? >> Yeah that guy, yeah. >> Please.

>> So this is just to [INAUDIBLE] the notion of the idea that we live in a connected world. So these are actually Facebook connections that have been mapped by. This is a map that I pulled off of CNN.com. So this shows the degree of connectivity between individuals >> Within you can see the large population centers where there's a great deal of connectivity. The point is that. >> Poor Cuba has nothing. >> What's that? >> I said poor Cuba doesn't have a lot going on there. >> Yeah, right. >> [LAUGH]. >> That could be good. That could be good. >> [LAUGH]. >> [INAUDIBLE]. >> You can tell it's kind of black, too. >> Yeah, yeah, right, right, right. >> We have a question over there. >> Yeah.

>> Doctor you talked about the groupings in Belize that may have survived better one of the next to the last drought period. They were organized a little bit differently from the classic Mayas. >> Just in the terms of the contrary? Yeah. >> Yeah, and so I'm wondering, what can you tell us about how they were organized differently? What might they have done differently that allowed them to survive other than the idea of dispersal, which has already been covered? >> I think it's the idea that the polities up in the northern Yucatan were not as connected to these larger networks and they seem to be sort of organized in a slightly different way. And actually as they persist after the decline of any of these polities to the south, they look very different. They don't really have, divine kingship is not evident.

And perhaps different governmental organization structures. So the traditions that persisted during that, for very long time during the classic period, are not as evident at those centers. There's still, obviously, they are centralized polities and they have leaders. So they didn't, just have some of the trappings, many of the same trapping as classic Maya society, like the pyramid complexes and plazas and such that the archaeological sites look similar. But they don't have some of the same artistic traditions. You could probably speak better to that than I can. >> The whole cult of personality that was in vogue for about 600 years. Where really it was all about the ruler's ability to bring the rains and to bring prosperity. And then toward the end, the rulers weren't able to deliver any more. This has happened in a lot of places around the world.

When times got tough, people decided that maybe this wasn't working for them so well. And in the case of what we think as lowland Maya civilization, all the trappings of all of these elaborate calendars. Instead of software engineers, they had calendar priests, and nobody could replace them. I mean, the whole system of prophecy depended on their ability to be able to predict things based on all these years of built up knowledge in the hieroglyphic books. But at the end of the classic period it was very clear that the rulers were no longer able to command these otherworldly forces that they had claimed for centuries were the reason why their city was thriving. Even though some other city in the dynamic model might have hit the skids and had a bad spell there. And so I think that in the north people were reacting to the fact that that whole ideology of my divine king is gonna take care of everything, including bringing the rain. When the rain stopped coming this was a serious problem.

This was the original name of the pharaohs, before they were pharaohs, they were called rainmaker kings. And, the record indicates that. If you didn't succeed, you didn't last long in the position. >> [LAUGH] >> And so some of that may have been going on in the Maya area too. One of the most popular titles is the Lord of Lightning. This is a royal title, with a lot of the late classic Maya kings. You couldn't bring the lightning, you were in big trouble. >> Next question here. Interested in whether there were, quote, wars, end quote, between the kingdoms and did they become worse with the drought? >> So, you've written about this, actually. >> Yeah, this figure here. So again, looking at the events that are actually recorded on stone monuments, the dated events, what we dated as part of this paper, looking at sort of response to climate change. And we were interested in warfare. And as Bill mentioned there's a lot in these written texts during the Classic Period about war.

And I think traditionally my archaeologists and epigraphers have focused in on the specifics of the history of those wars. I mean,tik there's wars between Tikal and Calakmul, and Tikal and Kerakola, and there's recording of it, recorded events on these stone monuments. What we do with it is part of this paper was to treat it more like a climatic proxy. We wanted to see just how frequent wars were. It didn't matter who they were between, so we wanted to plot up sort of like a climatic proxy. But this would be a warfare index, and bending the number of wars in the 20-year intervals, that's what this is, those red bars are. And then this is adjusted for the overall number of events recorded. So the number of written records goes up in the Late Classic period, so there's obviously more wars that are recorded. This index is actually corrected for the total number of events recorded on monuments, so it's a relative measure.

So it shows that in the early Classic, there are wars that are occurring, and there's actually wars, we're now going back into the the pre-Classic period, too. Some fortified sites like Pecan and some other sites in the Mirador Basin that seem to be fortified. We don't have written records about them, but clearly warfare was something that was going on between these polities. But we felt that this was perhaps a response to climate drying. We're not really thinking about the specific peaks in warfare relative to any specific peak in dry or wet conditions. We did look at that and there is no direct correspondence, but it's that general drying trend. Everything that we think is important that's kind of stressing the system that's already stressed because of the number of people that are living on the landscape.

That's what I try to highlight to the media when this paper came out was, cuz we knew that there were droughts in the late Classic. What we didn't is that before that, it was very a uniquely wet interval of time. And people were making decisions. The Maya were making decisions under these kinds of conditions. Populations grew under these kinds of conditions. People became more centralized under these kinds of conditions. And that's what failed, ultimately, in many places, as the climate started to dry. So it matters, it's not just drought, it's what comes before drought and how people respond to it. So again, I think that's another message for our modern community, our modern global community. >> Think in the US Southwest, the Colorado River and all those dams that were put in, they were put in for all kinds of good reasons. We had a military effort to beat back the Axis and all that, that produced energy, and on and on.

But they were designed for a period of time that was wet. And now, it's no longer wet. And if again, they consulted dendrodates that go back through some of the ancient Puebloan ruins, they'd find that it's very cyclic and it's very severe. And if the Corps of Engineers consulted a different data set, we might have a different kind of Colorado River right now. Just to, you know, put it in context. >> And some of the people who are studying those kind of records look at the modern world as a no, or what they call a non-analog world, that is, that our previous historical records are entirely changed by global warming world, where we have carbon dioxide levels that haven't been reached since the tertiary.

So we can't even look back at our historical records according to some of our best hydrologists in the Southwest. >> Can you tell us what the form of government was in that area at the time of European contact? Did the Aztecs extend that first south or was there some other form of government going on there at the time? >> In the Maya world, there wasn't a very large centralized city as there had been before at Maya pond that collapsed before the Spaniards got there, or was no longer a large centralized unit. Before that Chichen Itza, before that, Tical, and so forth, so there were a series of rival kingdoms in Yucatan that identified themselves as such, and to whom an enormous number of people over a large area owed allegiance. But there weren't urban centers in the way there have been before. And the Aztecs had feelers out all over Mesoamerica. They were particularly interested in what we think of as the southern Mayan area. They were very interested the cacao groves in that area, and they were interested in tapping into greenstone and other kinds of precious materials. But they weren't trading with large centers the way as had been the case in the Classic period where the functional equivalent of the Aztec empire at Teotihuacan whether it was an empire or not, it's been debated, but the most recent published work by the Chases and Mike Smith indicates that Teotihuacan was an empire.

They were dealing with other major urban centers, and we're just beginning to get inklings now in some of the Maya cities of what kinds of relationships they may have had with Teotihuacan. So Teotihuacan had the advantage of dealing with not quite pure polities, but other societies that were very hierarchical and were very urbanized and did have some degree of craft specialization, providing goods that they could not otherwise obtain in Teotihuacan. In the Aztec case, they weren't getting craft goods from the Maya world, they were mostly getting raw materials. So some very, very different setup in part because the Maya had by that point pretty much given up on urban living. >> So was it somewhat similar to the Dark Ages in Europe after the fall of the Roman empire where you had more of a decentralized? >> What do you think? [LAUGH] >> You're talking about at historic contact? >> In the Maya area.

>> Talking about the way the civilization's organized. So after the fall of Roman empire in western Europe, you had the Dark Ages period where you had these monstic setups and small villages around that [INAUDIBLE] >> Was it more similar to that situation in the Dark Ages after the fall of the Roman empire, where you have these castles and villages built up around them and You know, systems where people had some trade among the various castle villages. >> I don't want to hog this. Do you guys want to take a stab at that? >> You might be better to address it, Bill. >> Well, you know that actually was a thought for not only the time of European contact when it's very much the case that >> There were scattered populations throughout the peninsula of Yucatan and virtually nobody home in the northern. Again, Cortez walking right by and never even seeing it or knowing about it.

To the point that some archeologists in the 70s even >> I tried to recommend a futile model for the classic period, but that got shot down. Nobody bought into the idea of a futile model for the classic period because the more settlement pattern research people did, the more they realized that this was very much a saturated environment, as I think Tim said. That there were people pretty much wall to wall all over the Maya lowlands in the classic period. So, it really is a dramatically different landscape physically, politically, economically at the time of European contact. And this is part of the reason why in some of the early debates, many anthropologists refused to believe that the Maya could have ever been urban. And it wasn't until some of these new technologies came along with all the sophisticated mapping and all of the lidar showing Caracol terraces everywhere. That we've come to realize that in fact they did have urban states. And that this idea of the vacant ceremonial center was absolutely wrong.

So, they were urban and they were highly centralized. And there was really nothing feudal about it during the heyday of the Classic Period. Yes, Bob? >> Next question here. >> It was mentioned early on that there was, I don't if it was hundreds or thousands of, languages today that are not comprehensible to one another. Do you think at that time, that they did understand each other? >> [INAUDIBLE], wonderful question. >> And could they read the language that they developed across the- >> Yeah so the Aztec of course had a which was. And in the case of the Maya during the classic period the language and the hieroglyphic writing system is predominantly of what now is referred to as proto there was a language known as know Extinct, that survived into the twentieth century. And its close cousin Chor'ti', is a language that's still spoken, one of the 29 surviving languages.

So all of the Maya kingdoms that used the hieroglyphic writing system knew how to write and presumably to speak. It's a bit like the obsession with French language, French cuisine, French wine. French everything, right? That everybody had a common court language and a common court culture. Even though their surrounding population might not have been speakers. In the area where Barb and I and our students have been working for so many years, it looks as if the native resident population was not even a Mayan language. It was probably Lanka, Proto-Lanka language but that when this way of organizing society with all the trappings of the royal court was established in 435 A.D. or so, that this was adapted then by all of the nobility who all grew up bilingual and learned the court language. And so there was a common culture, common language during the late classic period.

But then it changed. There are some elements in the writing system and some of the sites in Yucatan. That's some, not all scholars believe are Yucatekan elements. The more they learn about the script many scholars, not all scholars, believe that some elements of the Mayan writing system actually came from the earlier Mejasoncayan or Olmec culture. That's a great debate. Because a lot of the long words appear to come from the [INAUDIBLE]. And they are elements that have to do what the lead culture. So there were a number of languages that were interacting at that time. But the one that was written in the hieroglyphic script for the most part is [FOREIGN]. And now, the greatest number of speakers are Yucatecan speakers. And, that is actually what Maya means, Maya refers to Yucatec only. So, other people who speak the other 28 surviving languages don't like the word Maya and they say, I don't know what this word Maya means.

I'm not a Maya. But others say well, we've gotta have solidarity. And so that's the common label and we need to find common cause, so deal with it. >> [LAUGH] >> Where does >> Is in the highlands and one of the other really large groups of surviving languages, the largest group of Mayan speakers in Guatemala. And it's not at all related to Yucatec or Tzotzil. It stayed pretty close to that origin place in the western highlands of Guatemala, as opposed to the Yucatec speakers who are among the earliest to break off. And go up in the Yucatan and their language is so different from Kiche, it would be like someone who speaks Romanian speaking with someone who speaks Portuguese, only even more distant than that. Even more distant than that. >> Yes this is a question about population. Earlier there was a mention that in this classic period that maybe there was ten million people in the area around the peninsula. What is the order of magnitude of change in the population estimate with the dispersion and the failure of these.

>> Population specialist. >> Yeah, I don't know if I can address that. I mean, the figure, population estimates are a trick issue, as you might well expect when you don't have written records. At least aren't telling us anything about how many, no census are being taken. So, it' hard to say the 10 million figure is debatable by some. >> Strongly debatable. >> Yeah, yeah. Again, it's where I liked, given having kicked around and that [INAUDIBLE] in my area. But again it depends on how you measure these things. How many people in each mound, we're actually there. How many mounds you've actually been able to find. We know that they were building at ground level many times, so I wouldn't see anything at all, right? >> In the post Classic, yeah. >> Yeah, so it's hard to estimate. I suspect there was a shake up, but I think in terms for that classic, post-classic period I think you're trying to address, there's clearly a shake up. It may have been as much as my colleagues are suggesting, a removal of that elite pinnacle, all right? In that that what was being shaken, this new world view, this new way of organizing because they no longer had all the cards. The nobility, it's you know the French revolution, I mean it's a different world right.

So I don't know, I can't address how many people were living during that post classic period. I don't know, maybe your colleagues could address that, it's pretty tough. And again we're still getting data yearly from surveys. >> But the massive drought >> [INAUDIBLE] >> Yeah, I see your point. >> I'm pretty sure have an impact on the carrying capacity of the region population. >> Certainly massive, but to what degree? >> I would argue that it does. Okay? And, particularly, the drought at A.D. 1000 to 1100. >> What we proposed in the paper was that the classic period collapse, again, was much more of a political collapse, where you lose these kingdoms. Again, it's, really, that political structure, so, really, it's affecting their ability to maintain control of their polities.

And then with that you get dispersal and perhaps some decline. And I think that we don't have enough data right now to know exactly what the regional patterns are, as I mentioned earlier. The available data suggests that at some locations, like in the Copan Valley, it appears, based on my colleague David Wessler's. Work. And he's argued that there's persistence of a population there living in agricultural communities. But people debate that because it's based on a certain type of data. In other areas, we've worked in a small called in southern Belize. And we've done a similar type of study where we've focused in on the core where there's a lot of archeological work has been done on sort of the central precincts of these big centers, but not so much on the small settlements that are associated with them.

We did both, and we determined the age of as many settlements as we could in the surrounding landscape. And we couldn't find a settlement that persisted into the post classic period at that location. So, but the cutoff seems not to be AD 850 or 900. The cutoff really seems to be AD 1000. So again, we suggest in the paper that the demographic affects, in the broader area, are probably more linked to that larger drought between 80, 1,000, and 1,100. One of the remarkable things about the Maya populations, is that they didn't come back. There's this pattern of sort of, of centralization and decentralization and then you'd think that with that trajectory, as conditions improved in the post classic, and there were very wet intervals in the post classic period. It gets wet after that big drought.

It gets wet period, but you don't really see large numbers of polities forming across the Maya lowlands. There is one though, Mayapan and that actually develops after thant and during this wet period and actually by the way goes into decline during that dry period. So again that's kind of part of perhaps this sort of centralization and decentralization and then. Perhaps some demographic effects associated with this major drought here. So I would say there probably are declining populations in the area. >> You see it, interestingly enough, I think a very divided field. As kind of an outsider geoscientist who's been working in these areas and talking with so many archeologists, I see some who strongly think the population was a lot lower than ten million people, like David Webster. And then you see others who still maintain that. >> He says one million, by the way. >> Yeah, one million. >> [LAUGH] I don't agree with him, but he says one million.

>> It's been 30 years since the Mayans came together in a conference to try to work that out. Roll up their sleeves and say, what do your data say? And I think that that's overdue at this point. >> Yeah >> And one other point from this that is a part of this all, it is really clear that the population has really declined in that elevated interior region that I showed before. And the reason why is there are no rivers one, and you're hundreds of meters from the water table. The places that persisted and that had populations were either on water bodies like [INAUDIBLE], which has a nice perineal stream, or like the Belize river which has nice perineal stream. Or is close to ground water like some other Northern Yucatan sites that are a meter or two away from the ground water table, and it's fresh ground water. >> Next question here.

>> I'm really curious, Dr. Beach you talked about the resilience and you talked about the enormous amount of variation in terms of foods and so forth. Dr. Scarborough you talked about these and you also talked about the susceptibility of the urban sites and what happens here. And you sort of knocked off the urban sites and the fact that a lot of our urban sites around the world are on the ocean. What we're seeing here is potentially, by the end of the century, as much as four degrees centigrade change. A massive change. We're seeing lots of stuff. >> What is your perspective seeing this enormously resilient group of people that get hit by a hammer bullet at one point in time make it through a lot.? We are in an environment right now of much less resilience. You have cultures which do not have the resilience of your food sources, what are your thoughts about this? >> Go to it, Tim.

>> Well I would say that the most recent publication by an international scientist on dealing with global warming is becoming a very pragmatic approach to it. And that is this approach that people have to consider geoengineering. I'm making a big jump there, but it's been an interesting evolution as I've watched it and played a small part in it over these years. >> Wherein first we were simply gonna try to get rid of the carbon out of the atmosphere. But now people have jumped to this next conclusion, driven by these kind of questions that knockout blows occasionally do occur, and that we do now have technology that will allow us to sequester carbon or to use other approaches. I'm not saying I support it one way or another. I think anyway we can sequester carbon's a good idea. So I've jumped ahead in your question to try to get at that bigger point. And that is that something will have to be done about that greatest amount of carbon in the atmosphere, some middle tertiary. And going up, as you say, four degrees Celsius is possible, which is incredibly devastating. Two degree is devastating.

Four degrees would be a, a gigantic change in moreover it's almost complete death of the oceans with the ocean acidification if you get to those levels of carbon dioxide. And that's basically the food source for a huge amount of the world's population. Not to mention the other approaches, the other problems with that, sea levels rise and so forth. But there will be at some level, winners and losers in this scenario as we evolve. And so areas that now are, well, some areas will get wetter that are already wet, and some areas will get much dryer. But there will be all that median areas that we get. First off, it's very hard to predict what's gonna happen in those zones. But it may be those zones that are gonna be most attractive, and where they are in the climate modeling and where they occur.

It, I think, is what we wanna know. I think we'll be able to predict at some level with these models, and it's maybe next to impossible, but. >> The areas where we know it's gonna get drier. >> Fairly robust. Those are Mediterranean areas and areas that are already dry. Places like Austin, Texas with Lake Travis that is 35% of the water level, and it's been in that case. Four years >> California >> In California, Las Vegas, the Mediterranean. If you look at the mapping and the best modeling, they all seem to dovetail towards those areas. And the former science advisor to the president a few years ago questioned whether Los Angeles is a viable place in 2100, with four degrees Celsius temperature increase, and a decrease, or extraction by climate, of so much of the water that's coming from the north to Southern California.

>> Yeah, that's a really good question. And then of course, the opening of the Northwest Passage. What's gonna happen up there, in terms of commerce and exchange? And that's in all over the world. >> And the issue though, is maybe one issue, it's not that you have 500 years or 1000 years to deal with. You've got 100 years. >> Yeah. >> And so you talk about political change or finding places that are better. You're gonna have wars. And this is what you're talking about. So I think that these are the kind of issues I think that you guys can, perhaps- >> Well, one thing that is really interesting, from looking at water systems, globally, and people don't really focus on this much. And you're right, water would be a turbulent issue, to say the least.

I mean, it's going to be contentious all over the world. But in the past, if you look at the record, humans have not gone to serious, major war over water. And I find it really interesting. I mean, there's been some bloodshed, a few shots fired here and there, right? But there's something about that liquid, and about it's necessity for life that it tugs on some kind of string in the human psyche that prevents us from a full-scale war over water. And, believe me, there's been, through time, the first treaty that was ever signed that we have carved in stone was between LaGauche and Uma, yeah, in the Near East, about 2,500 BC, and it was over settling a water dispute. That dialogue, I think seeing your neighbor die in four days or something, or whatever it is that sustains you without a drink of water, is a different reality. And I've often thought that if we could figure out what it is about water that prevents, or at least curtails unrest, and solidarity, and community across the globe, we would really be in a different world. >> That is a pretty robust finding.

The finding that there have been very few wars or battles fought over water, because it's so surprising, from what we saw here. We think that battles increase towards that, but, Aaron Wolf at Oregon State, and Mark Giordano at Georgetown, whom I hired because of that research, came up with the same conclusion over looking at thousands of documents of wars and water for thousands of years. >> That's right. >> But the water also is linked to agriculture. [INAUDIBLE] >> I mean, over land and productivity, and I think that's what we are dealing with in this case. They're not going to war over water, specifically. The drying conditions and these droughts are having an effect on the primary productivity and the agricultural systems in this particular area. And we actually have, in fact, this climate record goes all the way up to modern. There are a couple different interesting things about that. But one is that we've looked at the historical records. So when the Spanish came in, then we actually have historical records of droughts, and what happens during a drought in the Maya region, which is very interesting. And so one observation that we've made, and this is a paper that we're hoping will get to be published in Current Anthropology.

It looks like it will occur. This climate record that we've produced is from southern Belize. But the droughts that we see there are basically recorded historically in the Northern Yucatan. So these droughts are occurring throughout the region. Then, with these historic accounts, we know that it did in fact undermine the agricultural systems. So basically, it reduced the productivity of the corn and other agricultural produce. There were famines. There was health related issues, death. Things we don't want to think about, but during these very long, sort of multi-year droughts. If it goes longer than five years those populations are starting to run into problems. The other thing that's very interesting, because of course with the Spanish they have towns and are basically being forced to be centralized. What happens is the Maya populations disperse. In fact after a drought, say that you have a drought five or six years, there's population dispersal because people go into the forest, that's what it says in the records. And the Spanish after those intervals have to go and round them up in the forest and bring them back into these communities.

So I think that's another data point that suggests that droughts in this area really promote decentralization. And wetter intervals promote more centralization. In fact, in a historic context, Maya people wanted to live in towns. I mean, they seemed to, yeah, we want to live in towns, but not during droughts. Forget about it. >> [LAUGH].