PhD student finds lost city in Mexico jungle by accident | The Excerpt
On a special episode (first released on January 1, 2025) of The Excerpt podcast: An ancient, lost city in Southern Mexico hidden under jungle canopy for centuries, spotted via just searching on Google. Luke Auld-Thomas’ research on Mayan settlements had him poking around on the internet which led him to a LIDAR survey - a laser-based technology used in this case for terrain mapping. When he ran the data, he realized there was an entire city, of a significant size, entirely covered in dense vegetation. What’s it like, finding a whole city, without ever setting foot on the ground? And could there be more of these ancient settlements, just a few clicks away, waiting to be found? Tulane doctoral student Luke Auld-Thomas joins The Excerpt to share how he stumbled into the discovery of a lifetime.
Hit play on the player below to hear the podcast and follow along with the transcript beneath it. This transcript was automatically generated, and then edited for clarity in its current form. There may be some differences between the audio and the text.
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Dana Taylor:
Hello and welcome to The Excerpt. I'm Dana Taylor. Today is Wednesday, January 1st, 2025, and this is a special episode of The Excerpt. A PhD student of archaeology recently discovered an ancient lost city in southern Mexico hidden under a jungle canopy for centuries just by searching on Google. Luke Auld-Thomas's research on Mayan settlements had him poking around on the internet, which led him to a LIDAR survey, a laser based technology used in this case for terrain mapping. When he ran the data, he realized there was an entire city of a significant size entirely covered in dense vegetation. What's it like finding a whole city without ever setting foot on the ground, and could there be more of these ancient settlements just a few clicks away waiting to be found? Tulane doctoral student, Luke Auld-Thomas now joins us on The Excerpt to share how he stumbled into the discovery of a lifetime. Luke, thanks for being on the Excerpt.
Luke Auld-Thomas:
Thank you for having me, Dana. I'm glad to be here.
Dana Taylor:
In a video on social media, you described this experience of discovery as both deliberate and accidental. What were you actually looking for here? I know I made it sound easy, but how did the discovery of Valeriana unfold?
Luke Auld-Thomas:
So I'm an archaeologist and I use a variety of remote sensing and earth observation technologies to find and map ancient settlement. LIDAR is one of those technologies. It's a laser mapping technique where because we know the speed of light, a laser fired from a sensor can measure distance based on the time it takes to return. So if you fire a whole bunch of those lasers, in this case from an airplane, you can collect lots and lots and lots of measurements that relate to the ground and everything on it, and then using processing techniques, you can remove everything that isn't the ground. LIDAR is very useful not just for archaeologists, but for people that study things on top of the ground too, so foresters, environmental scientists, civil engineers, and all of these people collect data for their own purposes, and then oftentimes after they use it has a tendency to just sit around.
I had read a paper in 2018 that was published by some colleagues that work in Mexico where they found a data set of airborne LIDAR data collected by NASA that was used to monitor forests across Mexico, and they said, "Hey, from an archaeological standpoint, this is really cool and interesting because they're mapping all of these areas that archaeologists would not typically get the funding to map, and so it gives us this really wide perspective on the broader region rather than being focused on individual sites." When I read that paper, I thought, well, that's cool. I wonder if there more of those, and I started poking around online trying to find if there were more of them, and I eventually hit on the right combination of keywords and pages deep in the search results, and I found one such data set. So this one was collected in 2013 by a group of environmental scientists who were mapping the carbon in Mexico's forests.
They collected this data, they published their results, and then they made the data freely available on the internet to anybody who wanted to use it, but because not that many people go around the internet looking for free sources of LIDAR data that are not connected to major cities or major infrastructure projects, it was just sitting there. It was on the equivalent of a high dusty shelf accessible but not being used. And so as soon as I downloaded it, I took a look, I opened it up and did some quick and dirty processing, and it was immediately apparent that this was a really exciting archaeological region that had been mapped and that the data had been sitting there neglected without really being looked at for archaeological purposes. So it was fun to get to see it with those eyes.
Dana Taylor:
Luke, I would imagine that you questioned whether you'd really found something no one else had spotted. What was the validation process like for you?
Luke Auld-Thomas:
So it was immediately apparent that the site was not new to people because there's a town right nearby, and so the people that live in that town are obviously perfectly well aware of the site they've been farming in and amongst the ruins for generations. The question was whether it was a new site to the scientific community and whether it had ever been officially registered. And so very early on, we got in contact with colleagues that work in Mexico, including Adriana Velasquez, who's the head of Mexico's National Institute of Anthropology and History for the Campeche, which is where the survey took place, and she became a part of the process of analyzing all of this data and was able to confirm for us that it had not been officially registered on any of the registries that are maintained for this part of the world.
What's interesting on that front though, is that we eventually realized and digging through the literature that somebody had reported a couple of outlying buildings in 2004, somebody driving along the highway had stopped in this town and noticed that there were a couple of large platforms near the road, and they took a few pictures and wrote up a brief summary of what they looked like and then sent it off to a journal that published it, and that was the end of it. What it turned out, those were essentially the family compounds of wealthy families living on the outskirts of Valeriana, so a couple of houses of the city had in fact been found, and just without realizing that there was a huge downtown connected to them.
Dana Taylor:
Let's talk about Valeriana, the now named Lost Mayan City. How big is it? How many people lived there and when did they live there?
Luke Auld-Thomas:
The win, we have a decent handle on this part of Campeche saw its peak in population late in what we call the late classic period. This is between about 750 and 850 A.D. so figure around 1,200 years ago. As to the questions about how big it is? We don't know because it was mapped with a 16-square kilometer survey block that was plopped down on top of it. The downtown is up in one corner of that 16-square kilometer block, and the entire mapped area is full of houses and agricultural terraces and farm field walls and administrative buildings, all kinds of stuff. The whole block is urban. So we know it's at least 16-square kilometers large, and it goes on beyond the margins of that, but it's impossible to say how far. What's interesting about this part of the world is that we already know from work nearby that there are a lot of cities that grew together over time.
Think about the way that cities on the US East Coast have all merged into one extended urban area. Dallas Fort Worth did the same thing, the Bay Area, something very much like that in a pre-industrial manifestation went on in this part of Campeche where you have lots of downtowns and then their fringes merge into one big conglomerated urban landscape. Valeriana may very well be part of something like that that extends for hundreds of square kilometers, so we don't exactly know how big it is. And because we don't exactly know how big it's really hard to say how many people might have lived there. I think tens of thousands is a reasonable ballpark. The largest Maya cities had somewhere between 50 and a hundred thousand people living at their peak based on our best estimates that we can make.
Dana Taylor:
Have you had the opportunity to travel to Valeriana? And if so, what was that experience like for you?
Luke Auld-Thomas:
I wish I could say that I have gone. I will have to at some point because it's right next to the highway, so how could I not? But no, I personally have not had my feet on the ground there yet. Our colleagues that work in Mexico are in the process of developing plans for fieldwork there and conservation of the ruins. All of that is happening in consultation, the contemporary local community that lives there as well, and so I think there's exciting research to come from this area in the near future, but that's research that our colleagues in Mexico will be doing.
Dana Taylor:
As you've said, there are likely other cities out there like Valeriana just waiting to be discovered by a researcher or scientist like yourself poking around on the web. Are you still looking for lost cities?
Luke Auld-Thomas:
The thing that I think is kind of cool about the identification of Valeriana in particular is that it actually emphasizes that these kind of cities are commonplace. They're not rare. The fact that it was exactly next to the road and next to a town and had still gone unremarked speaks to the fact that these things are ubiquitous. They're everywhere, and so people notice them, but they're just, by people, I mean local people that live in the area today, they're just in the background of their everyday awareness. They're part of the landscape, part of the way that they think about home in the same way that old stone walls are part of the way you think about home in New England without necessarily pausing to consider quite how many people lived in every house that those stone walls delineated. So for me, yes, I think that going on to try and map more of these kinds of settlements, there's a lot to do there in the future.
I'm less interested in finding new urban areas in particular than I am in trying to understand how they fit together into a broader regional picture, and so understanding how these cities were organized economically and politically, were these peer cities all sort of at the same rank and periodically arguing and fighting with one another, or were they organized in some sort of larger scale organizational system? Who was in charge and where did they live? Those kinds of questions are very interesting to me. A broader question that emerges from that kind of regional perspective is how were these landscapes managed from a productivity standpoint? How did people grow enough food and grow enough fuel because wood is the source of fuel in this part of the world to sustain large populations, and how long could those populations be sustained? That to me is a very interesting question.
Dana Taylor:
I know that you're close to being awarded your PhD in archaeology at Tulane. What's next for you, and has your discovery of Valeriana played any role in directing your future ambitions?
Luke Auld-Thomas:
What's hilarious is that the research that we published that the discovery of Valeriana was a part of, which is, as I mentioned, a team effort that was focused on analyzing a much larger set of LIDAR survey data had absolutely nothing to do with my dissertation research, which is all based in Guatemala, also involves LIDAR data, but this was a really fun side project to be working on. What's next for me is a lot more LIDAR survey and a lot more analysis. The survey that turned up Valeriana was essentially a couple of thrown darts at a largely empty portion of the map. As technology improves, our ability to survey larger and larger areas is increasing and improving, and so I think the thing that's on the horizon for archaeology is to stop working with little scattershot samples here and there and just map the whole area.
That's something that has finally entered the realm of feasibility. It's a question of money and logistics rather than of technical possibility at this point, and so that's the next thing is to organize and coordinate with lots of other researchers and with lots of stakeholders that are involved and that have some say in how these data are collected and how they're analyzed and how they're managed, and then just mapping the entire region. That's going to be interesting when that happens too, because it'll be a little bit poignant. The thrill of the unknown is what brings a lot of people into this discipline, whether they ultimately maintain that perspective or not. I think the idea that there are a bunch of cities out there covered in the jungle that have yet to be mapped and who had names that have not been spoken for a thousand years, and that we may learn those names by finding inscriptions.
All of this is really romantic and exciting, and the day is coming when we know where all the cities are because we can map them even if they remain covered in forest, and even if scientists can't get there on the ground for another hundred years because there are too many cities for us to all go to and map in person, that moment is coming when lost Maya City, discovered in the rainforest is no longer a headline because we've reached the point where we can map them all. That's exciting, but it's also, it's a little bit sad. It's a chapter, an emotional chapter for the discipline that closes.
Dana Taylor:
I will never forget you saying that this was a fun side project. Luke, thank you for being on The Excerpt.
Luke Auld-Thomas:
Thank you. It's my pleasure.
Dana Taylor:
Thanks to our senior producers, Shannon Rae Green and Kaylee Monahan for their production assistance. Our executive producer is Laura Beatty. Let us know what you think of this episode by sending a note to podcast at usatoday.com. Thanks for listening. I'm Dana Taylor. Taylor Wilson. We'll be back tomorrow morning with another episode of The Excerpt.