IRA FLATOW: This is Science Friday. I’m Ira Flatow. When you think big urban cities, what places come to mind? Maybe it’s New York, right? With its skyscraper-dotted skyline and Times Square all lit up, or maybe it’s the Central Plaza of Mexico City and all those surrounding galleries and museums.

But have you ever considered Cahokia or Angkor? These were huge, sprawling, ancient cities that existed thousands of years ago. They had complicated infrastructure and political systems that governed the tens of thousands of residents that live there. And these cities were also eventually abandoned. One of them was a major part of what we now call St. Louis.

We may have missed these cities in their heyday, but my next guest is here to take us on a tour of a couple of ancient civilizations and to talk about who built these places, how the residents lived, and how the ecosystem of a city works, and eventually, what became of them. Annalee Newitz is a science journalist and author. Their latest book is called Four Lost Cities, A Secret History of the Urban Age. Welcome back.

ANNALEE NEWITZ: Hey, thanks for having me back to talk about this.

IRA FLATOW: What got you interested in this?

ANNALEE NEWITZ: Well, I love cities. I’ve lived in San Francisco, which is a city, for a long time. And I think like a lot of writers, I always want to ruin things that I love by studying them really, really intensely and finding out everything that goes into making them.

IRA FLATOW: Although this, as you point out, this idea of a city being lost is a bit of a myth, isn’t it?

ANNALEE NEWITZ: It’s really a myth. And in this book, the four cities that I talk about, which are all sort of famously lost, none of them were ever actually missing. The people who lived near them knew about them. In the case of Angkor, which is in today’s Cambodia, when Europeans arrived there, there were monks living there.

In the case of Cahokia, which is near St. Louis, when white settlers arrived there, there was a tribe living there, called the Cahokia. And so the people who found it said, oh, it must be Cahokia. But of course, the Cahokia tribe had not actually built the city. They were living in the ruins of the city.

IRA FLATOW: Are the Cahokia tribe still around?

ANNALEE NEWITZ: No, they’re not. We think that the people who lived in Cahokia, the city, the original city, which was kind of a going concern about a thousand years ago, probably joined Siouan tribes. And the Cahokia have also moved on because, of course, white settlers moved into the area.

IRA FLATOW: Well, I want to talk about Cahokia because I mean, I’ve lived in this country my whole life. I’ve never heard of it, but it’s right in our backyard near St. Louis. Do they know in St. Louis? Do people in St. Louis know what the history of that city is?

ANNALEE NEWITZ: A lot of them do, and a lot of them don’t at the same time. When I’ve written about Cahokia in the past, I get a lot of emails from people saying, wow, they forced me to go there when I was in elementary school, but I never realized it was a huge city. I just thought it was a boring, old place.

And in fact, of course, it was a thriving metropolis. It was at the heart of a massive civilization called the Mississippian civilization that was thriving about 1,000 years ago all along the Mississippi River. And Cahokia was kind of a spiritual center, where people came and had big pageants and parties. And about 30,000 people were there, which rivals the size of European cities like Paris at the time. So it was really quite large and impressive.

IRA FLATOW: Something that’s different than other civilizations, you point out in your book, is even though they had this huge plaza, this huge square, in other civilizations, this would be a common marketplace, where people bought and traded goods and services. But that wasn’t what they used it for in Cahokia, was it?

ANNALEE NEWITZ: That’s right. At the base of Monks Mound, this huge mound at the center of Cahokia, there was this massive grand plaza that would have been quite a feat of civil engineering. People building it would have had to grade the land to get it very, very flat, and then would have covered it in a nice layer of sand. And its footprint is about the size of the pyramid at Giza, just to give you a sense of how big it is.

And it has two terraces and a flat top where archaeologists have found remains of large structures. So we know that there was some kind of temple complex up there or maybe even housing for very important people. They had a game called chunkey, which is still played today. The Cherokee play it. And there’s no evidence of a marketplace here at all. It seems like the area was used for chunkey games, which makes sense. It’s a big sports arena.

But it was also probably used for public gatherings. When people spoke from the top of Monks Mound, their voices could be easily heard, kind of booming across this plaza. So it could have been a place for political rallies or spiritual gatherings. And we know that there was feasting there. We know that people partied. There’s huge trash pits just full of barbecue, half eaten meat and things like that, all around that area. So it was clearly a party zone.

But we don’t see evidence of commerce. And when I was visiting there, I kept asking archaeologists, well, obviously, people came here to trade. Why did people come to Cahokia? And they all kind of shook their heads and looked sort of sad and said, no, no, everyone thinks that, but it wasn’t that kind of city. It was a city for spirituality and pageantry. And people had their own farms. And so it seems as if family groups were feeding themselves through farming and didn’t need to do large scale trade and large scale economic engagements with other groups.

IRA FLATOW: And you write that eventually, Cahokia was abandoned. But it seems like the households planned for this. And that runs counter to what we, you point out, think in Western cultures, that cities, normally, they start out, they rise in a peak, and then they collapse. But that’s not true here.

ANNALEE NEWITZ: It’s not true here. And I mean, really, it’s not true anywhere. I mean, we don’t really see this neat, little pattern of collapse in any area. But in Cahokia, it’s especially notable because we know that there was a cultural ritual that archaeologists call closing up house. And any time that someone left their home for whatever reason– maybe someone died and they weren’t using their home anymore– the next group that was going to come in and build a house on that spot– all the houses were made of wood– they would burn a lot of items on the floor of that house. So you have to imagine a sort of clay floor.

And these items would be things like precious plates or mica, which was a really treasured sort of sparkly mineral and other kinds of offerings, baskets, or maybe some grain. They would burn it, and then they would smooth a new layer of clay over top of the burning, as if they were kind of saying, all right, this house is sealed up. The old house is gone. Here comes a new house.

And they seemed to take that same approach to the entire city, that there’s this notion that any house, any structure that’s built, has a life span. And it does go against our Western idea of cities where, when we think of cities, we think of building something that will last forever. And we think of a city being successful if it never is abandoned, that if a city is abandoned, that it must have failed in some way.

But it seems like the framers of Cahokia and the people who lived there didn’t have that same attachment to the idea of a city lasting forever or a house lasting forever, that, somehow, abandonment or leaving behind was built into the city from the beginning. And when we see people starting to leave the city sort of in the 1400s, they’re leaving in dribs and drabs. They’re not kind of all leaving at once.

But it seems like kind of a natural progression. There’s no kind of big, horrible thing that happens. There’s no pandemic. There’s no fire. People just start saying, I think I’m going to go somewhere else now.

IRA FLATOW: They just migrate someplace else.

ANNALEE NEWITZ: That’s right, and that’s exactly what they did. A lot of them just got on the Mississippi and found new places to live, smaller communities, different kinds of tribes. It doesn’t seem to have been a struggle. We know that this city went through a lot of changes. Cahokia had definite social movements that changed the way the city was laid out and changed people’s relationships to some of the monuments in the city. But it doesn’t seem like any of those big changes were part of what made people leave. It seems like leaving was just something that they did.

IRA FLATOW: Fascinating, fascinating. Another city that you looked at is Angkor, known for all of its wats. How was this city planned and laid out? And you seem to point out that it was planned with sort of a fatal flaw built in.

ANNALEE NEWITZ: That’s right. So Angkor was at the heart of the Khmer empire, which stretched across many nations in Southeast Asia. And Angkor is now located in Cambodia, but you have to remember that that would have been a city that had tentacles out into Thailand and Laos and other places in the area.

And it was built near rivers, and it’s also a city that is at the nexus of two monsoon systems, so this is a city that’s just battered by water. And so every iteration of this city, which, at its height about 1,000 years ago, had almost a million people living there. So it’s huge.

And the centralized planning came from the royal family and all of their retinue of engineers and spiritual advisors. And they really wanted a way to have lots of water stored up from those monsoon seasons for all the dry seasons. Because this is a city that’s vacillating between basically drought and floods.

So when you go to Angkor, as I know that you did, one of the things that you’ll immediately see is that there are these huge reservoirs downtown, enormous, like eight kilometers long, these big, rectangular– they’re called barays, where people held water. And those are just the biggest ones.

The city is full of smaller reservoirs. It’s got an incredibly elaborate canal system. And the canal system would have been for bringing water in, but also for transit, for boats for bringing in supplies from all of the different satellite cities, places where they hewed the rock that helped build Angkor Wat, for example.

And the problem is all of that water infrastructure requires a lot of human labor to maintain. And so, the city catastrophically flooded a number of times. One of the big problems that they had was things like silt getting into the canals and just not having enough labor power to shovel all of that silt out of the canals.

And so, you’d get an inability to bring water down from the mountains because these canals were getting silty. So they’d build more canals, and then when they had a wet season, suddenly, that silt would get washed out, and you’d have water coming in from a huge number of canals, which, again, would overwhelm the city’s water system.

And so, it really looks like this was a big part of what led to people abandoning the city, was that it was just being mismanaged. Things were falling apart. The water system wasn’t working the way it used to. And it was just hard to live there. It would be like, if you were living in a city now and your water didn’t work part of the time. Or the city was flooded half the time, and nobody was doing anything about it. And the government would say, well, too bad. We’re over here in Angkor Wat, and we don’t care. [LAUGHS]

IRA FLATOW: Well, if I remember correctly reading your book, is that the emperor did not listen to the engineers, who told them, you’re asking us to build these canals in the wrong direction for flooding purposes.

ANNALEE NEWITZ: Yeah, that’s right. So, at the time that the West Baray was being built, which is this eight-kilometer long reservoir right next to Angkor Wat, the famous temple, the king really wanted everything to be built on an east-west grid because that’s basically what his spiritual advisors were saying would be the most promising way to build it, the luckiest way to build it, the most in harmony with the cosmos.

And so, the king was like, great. The way that you build is you build in harmony with your spiritual beliefs. And the engineers said, well, if we do that, this reservoir is on a slope. So it’s going to be– it’s never really going to fill because it’s on a slanted hillside. And the king didn’t care and just said, nope, go with the ideology. Don’t go with the engineering.

IRA FLATOW: This is Science Friday. I’m Ira Flatow. In case you’re just joining us, we’re talking with Annalee Newitz about their latest book called Four Lost Cities, A Secret History of the Urban Age. I want to bring up a topic that I have asked many people about since I was at Angkor Wat. And when I was there, I saw a very interesting relief. It was an engraved image– to me, what looked like a stegosaurus dinosaur engraved right into the wall. Did you see that?

ANNALEE NEWITZ: I did see that. It’s so famous that now it’s in all the guidebooks.

IRA FLATOW: Is that right?

ANNALEE NEWITZ: Yeah, that’s right. So when you visit the temple complex at Angkor Wat, which is huge and there’s a number of different temples in it, and it’s surrounded by this beautiful moat, you’ll be directed to the stegosaurus because I guess, Westerners have become so excited by the idea that there were dinosaurs 1,000 years ago in Angkor, that they want tourists to know–

IRA FLATOW: Well, could they not have dug up the bones of a stegosaurus?

ANNALEE NEWITZ: I mean, anything’s possible. It’s really hard to say. This is the thing that I love about archaeology, is that there’s always these wonderful ambiguities where, yeah, could have been that they dug something up and imagined it or could have been that it was just a representation of one of the many serpents or monsters in the mythology of the area.

But I will add that one of the things that’s really wonderful about visiting Angkor Wat is that there actually are a lot of Easter eggs in the carvings. There’s tons of carvings everywhere, all these Bas-reliefs on the walls. And tons of artisans would have been employed by the royal court to do these.

And there’s a famous part of one of the temples that’s called the Hall of Dancers. And as advertised, it’s a hall full of Bas-relief of dancers. But off in one corner, behind a kind of a niche in the wall, one of the artisans carved a dancer with no pants. So just a little Easter egg for anyone who is in the hall who kind of snuck off into the corner to kind of be alone, and there, you’ll see–

IRA FLATOW: Wow.

ANNALEE NEWITZ: –the one dancer.

[LAUGHTER]

IRA FLATOW: Now you have two things to go look for when you go visit.

ANNALEE NEWITZ: Exactly, look for the dancer with no pants.

IRA FLATOW: Annalee Newitz, science journalist and author. Their latest book is called Four Lost Cities, A Secret History of the Urban Age. It’s a terrific read because you’ll learn stuff you never knew about civilizations there. Thank you, Annalee, buzz saws and all in the background, for taking time to be with us today.

ANNALEE NEWITZ: Yeah, thank you. They’re working on the tree in my backyard.

Copyright © 2021 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/