Researchers have found a treasure trove of structures from an ancient civilization — by using a modern technology.
Luke Auld-Thomas, an instructor in the Anthropology Department at Northern Arizona University and a PhD candidate at Tulane University, along with some colleagues at schools in both the U.S. and Mexico, he analyzed a survey of land in Mexico done by lidar, or light detection and ranging. They found evidence of more than 6,500 structures from the Maya civilization.
Auld-Thomas joined The Show to talk about the find and what it could mean for the future, starting with how common it is to be able to use lidar to do this kind of work in the worlds of archaeology and anthropology.
Full conversation
LUKE AULD-THOMAS: It’s actually becoming quite common. Archaeology depends on being able to see what's on the ground, or ideally, being able to see what’s under the ground, which is often what we’re most interested in. But that starts out with being able to see what’s on top of the ground.
And the shape of the ground, if you imagine, you know, a group of houses that have been abandoned for 1,000 years, all of the perishable bits rot, all of the non-perishable bits fall apart, and you end up with basically a lump of rocks and other non-perishable material that gradually gets covered by soil.
And so archeologists that are interested in mapping ancient settlements where people lived, how they were organized, how they managed their landscapes — whether through agriculture, infrastructure or something else — we’re very interested in mapping these minor changes in topography or terrain across large areas. Lidar allows us to do that.
MARK BRODIE: So you’re looking at this image, and you’re able to take away digitally foliage and other stuff you don’t want. Is it just a matter of you notice some mounds or lumps on the ground and said, “We should go check those out?”
AULD-THOMAS: Yeah, pretty much. The longer you work in a particular part of the world, the quicker you become able to recognize distinctive kinds of topographic things as being made by people. If you imagine looking at a map just of elevation in a town in the United States — say, Phoenix — if you see a really long, narrow depression with raised bits of ground on either side, well, you're probably looking at a canal.
And so we're basically doing that but with ancient Maya houses, ancient Maya temples, palaces, ballcourts, reservoirs, all of those kinds of things. If you look at enough of them on the ground and on maps of sites that were made by archeologists working in the 19th and 20th centuries, you very quickly become able to pick out what these things look like as topographic signatures.
And then it’s just a process of going through manually. And we still do this manually. There is work focused on developing AI models that can take over some of the heavy lifting for us. But for the time being, it’s an entirely manual process of just going through and drawing all of these features and interpreting them.
BRODIE: So when it occurred to you that there might be something there, did you know at that time how many structures there might be? You found more than 6,000 previously unseen structures. Did you know it was going to be that big of a deal?
AULD-THOMAS: No, it was really fortuitous. What happened was that I went looking for lidar data sets that might already exist, because since it measures everything that the laser interacts with, lidar data is very useful for people who study forests. And so I figured that somebody out there had probably mapped parts of the Maya region for environmental or engineering purposes, and that that data was probably just sitting around.
And after looking long enough, I turned up one such data set that was collected by a group of ecologists in 2013 focused on mapping trees in Mexico. So they collected all of this data on areas that were essentially archeologically unmapped stretches of tropical forest. And they looked at the trees, and they didn’t really spend that much time or energy thinking about what was under the trees.
And I, as an archeologist, came through and did exactly the opposite, where I immediately removed all of the trees and focused my effort on making sense of what was underneath them. And it was a matter of seconds between when I opened up the data on my computer, and when I realized just what a gold mine of archeological information it was going to turn out to be.
BRODIE: So what does this discovery tell us about the Mayan civilization? Like, what, what do we know now that we didn’t know before? And maybe do we have to change the way we think about the Mayans?
AULD-THOMAS: Yeah, I think that there are two answers to that question. The first is an academic one, and the second is maybe more of a popular understanding of how people outside of the scientific community think about Maya civilization.
For archeologists, having been able to identify such a high level of regional scale, settlement density, and having through the equivalent of a thrown dart hitting the map, found a really large city in such an almost hilariously obvious location — right next to the highway, right next to a modern town — I think that that really underscores that there is not a lot of empty space in the unmapped parts of the Maya lowland.
So we have lots of blank spots on the map. And what that does not mean, categorically does not mean, is that there’s nothing there. What this kind of research shows for archeologists is that those blank areas are just going to be full of more of the same kind of stuff that we've been mapping for the last 100 years. It’s a thoroughly urbanized landscape.
Now for kind of broader understanding of Maya civilization in popular culture and popular understanding, what I hope that this research can contribute to is an appreciation that Maya cities are not little clutches of temples and palaces surrounded by jungle, but rather that the entire region was utterly urbanized. A sort of a popular version of the the realization that archeologists have been coming to, but what that means for the way that we as a as a society think about ancient civilizations, is that a lot of parts of the world that are currently regarded as wilderness have not always been wilderness, and that these areas were stuck with people.
BRODIE: So what’s next then? I would imagine it’s a combination of potentially more lidar mapping, and also, as you reference, getting in the field and really trying to see what these structures might have been like. What for you is next?
AULD-THOMAS: There are two things that I hope happen next. And you know, both of these things are, you know, are already underway from our project and others, but I hope it inspires this more broadly in the archeological community. First, I hope that this work shows the value of archeologists and environmental scientists collaborating more closely in questions of remote sensing.
The other thing that’s going to happen is that sensor technology has been developing and improving really quickly, and so the areas that we can map are getting bigger. And the quality of the data that we can collect across those areas is getting greater, and so I don’t think it’s a matter of very much time at all before we’re talking about national scale, wall-to-wall mapping where we don’t even have to worry about found data sets or samples anymore, because we’ll have just been able to map the entire thing.
And I think that’s really exciting and also a little poignant, because it means that that thrill of discovery and the lure of the unknown, at least for some of these parts of the world, will, at that point, be largely used up, because we’ll know what’s there.
