Short Wave - A Lock of Hair Could Rewrite Knowledge Of The Inca Empire

Episode Date: August 27, 2025

The Inca Empire in South America was one of the most powerful pre-Columbian societies. It was known for the architecture of Machu Picchu, an extensive road network and a system of terraces for agriculture. The society also kept records known as khipu, which involved a system of tying knots to encode sophisticated information.Literacy in this form of writing was assumed to be something that only the highest levels of Inca society could do. But NPR science correspondent Nell Greenfieldboyce shares how a new analysis of a cord made out of human hair may change that assumption. Curious about science history? Email us at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, Shortwaivers, Regina Barber here. And today on the show, we are diving into an unusual part of life in the Inca Empire. In the 15th and 16th centuries, this empire ruled over 10 million people in South America, covering modern day Peru, Ecuador, Bolivia, northwest Argentina. At the time, it was the largest empire in the world. So as you can imagine, it had things like an extensive network of road. It's impressive architecture. It had a whole bureaucratic system to keep track of everything that was going on.

That's NPR science correspondent, Nell Greenfield, boys. Hey, Nell. Hey there. So there is a way that the Inca Empire is unique. Well, maybe there's lots of ways. But we are going to talk about one thing. This intersection of numbers and knots, something I actually learned about last year on top of that, like, famous Inca fortress, Machu Picchu. I am so jealous you've been there.

I have not. I learned about these knots and numbers. when I was talking to a researcher named Kit Lee, she's affiliated with the University of St. Andrews in Scotland. When you're learning about empires in school, oftentimes the way they teach them is that every empire, a big civilization has writing. So the Inca empire is almost always called out as an exception to this.

Oh, they're such a big empire that covered half the continent, but they don't have writing. How could that be? She says what's often overlooked is that they did have this elaborate system of record keeping. you know, all kinds of records that involved making knots in cords. Yeah, knots in these chords. It's amazing to think that this huge empire kept all these records. And I remember seeing this recreation of one and they were like colors in the chords.

They were really, really beautiful. And those colors were important too. Right, yeah. I mean, the colors contained meaning the position of the knots along the cord, the type of knot, the numbers of chords. Like everything was a kind of code. And literacy in this form of writing or record keeping was assumed to be this kind of rare esoteric thing that only the highest levels of Inca society could do, you know, kind of this elite practice by men in the ruling class. But, you know, what Kit and a colleague recently told me is that they came across this one set of really unusual knotted strings that has called all of that into question.

Ooh, I love where this is going. Today on the show, why anthropologists may have been wrong about which members of the Inca Empire made these ancient records. And what that means for understanding how these knots are related to objects that some people still make today. You're listening to Shortwave, the science podcast from NPR. Okay, now let's just help people visualize what these Inca knot records look like. I'm sitting here, I'm looking at this picture you sent me from the Smithsonian. and we've got this long cord sort of horizontal in the photo and then hanging down vertically from that horizontal cord are these other chords with knots in them. Yeah.

So there's the so-called main chord, the horizontal one, and then the ones hanging down from it are called pendant cords. And the whole thing, the whole record is called a kipu. The word comes from a part of the Inka language that means knot. And everything has meaning in this thing. The placement of the knots along the strings, the order of the strings, their color, everything is thought to be kind of a record of something that somebody could look at and make and read to look at, you know, a census or crop records or whatever they wanted to be counting and keeping track of. And what we're looking at right now is like half a millennia old. Like, can people still read this today? It's hard. I mean, some keepos are thought to contain numerical information.

so they can sort of tell that the knots are arranged in a decimal system with like a place for tens, a place for hundreds. I mean, there's lots of things you would want to count like that, right? That makes a lot of sense, that decimal system, to me. But the thing is, there aren't really a lot of Kipu's still in existence from the Inca Empire. I mean, they were made of cotton, so a lot just kind of degraded in the environment. Yeah. And then the Spanish colonizers actually destroyed and burned a lot of them. Oh, geez.

So in museums and universities worldwide, there's only about a thousand Kipu's still. still in existence. And there's often no information about where they originally came from. Yeah, I can see how that would make it very hard to, like, learn more about them to be able to read these records. I was talking to Harvard University Kipu researcher, Mani Madrano, and I asked him, like, to what extent can people today read Kipus? Well, it depends which Kippos we're talking about, right? Because of an Inka Kipu that came out of a grave, for example, you know, from the 1400s, I'm not aware of any modern reading, let's call it, of an object of that age that is universally agreed upon. But then you've got kipoos that have been made by communities in the Andes in more recent times.

You know, there is this tradition of kind of symbolic nodding. So you could just ask them, right? And researchers do. I mean, Kitley told me, you know, some are related to agriculture, like keeping track of herds. But you also have, during COVID, you had a resurgence of funerary kippos, which are more of a cold. the religious signifier as well. So both of them are happening. Like people are buried with a sort of long Kipu string tied around their waist. But Lee told me it's been thought that these modern practices weren't really related to the

more ancient Kipu records from the Inca Empire. Yeah. Why do they assume that? Well, for one thing, the modern kippos just look different, like they have a different shape. And then there's the people who make them. And modern kippos tend to be made by lower status people. So asthian workers, peasant laborers, herders. And like I said before, you know, records from the colonizers said that Kipu's in the Inca Empire were made by elite men. So, you know, this high-level bureaucracy at the top levels of the ruling class of this empire.

Yeah. And you said that this may be called into doubt with like this one set of nodded strings, right? Exactly. So it's a Kipu acquired by the University of St. Andrews. And Sabina Highland works there. She told me she initially thought this thing was a modern Kipu. But then she did scientific dating. And it showed that this Kipu was about 500 years old. Which astonished me. That was the first surprise.

Then Kit, I was showing it to Kit. And this was the second surprise. Kit looked at me and said, Sabina, this primary court is human hair. I love her enthusiasm. But like human hair, how is that? the key here. Well, you know, they had thought like, okay, maybe it's animal hair, but when Kit was looking at it, she's like, no, it's too long and glossy to be, you know, animal hair, like from a llama or something. I mean, this is a long, dark brown cord made of long human hair. It's like three

feet long. So it's like years of hair growth. What it is is a person cut off a hank of their hair and then they doubled it over and twisted it. The reason this is important is that she knew of some historical information, suggesting that herders and others would sometimes tie human hair to a kipu as a kind of signature, right? Okay. So she thought maybe this hair came from the person who made this kipu. But there's no way to know for sure that it was the person who made it. No, you don't know for sure, but she knew that in the Inka Empire, hair had a lot of meaning

as a sort of personal signifier. Like the emperor's hair clippings were saved during his lifetime and worshipped just as he was. Oh, okay. And so she thought, here I have this hair that could be from the maker of this Kipu, and she realized she could do a chemical analysis of the elements like carbon and nitrogen in this hair to get clues about what kind of food this person ate. This is a kind of analysis that's been done a lot in the past on like things like mummies. This is so fascinating. I love it. What did she find? Well, she says it didn't look like a rich person's diet. Wow. This person who So Pierce who made this Kipu had the diet of a commoner.

So not a lot of meat and not beer made from Mays, which was the popular ritual drink of the ruling class. Okay. And I asked her, I was like, look, maybe this person was just a vegetarian, you know? And she was like, sure, you could theoretically avoid meat. But Mays beer is different because these very high-ranking elite Kipu officials, as part of the process of getting records, keeping, they were involved in rituals in which it was mandatory to drink a lot of May's beer. She just doesn't think that was avoidable if you were in the ruling class. So then this means that this person must have not been, right?

An exalted person. They might have been a comitor, right? I mean, that's the idea. And if that's true, then maybe the Spanish colonizers got it wrong when they wrote these accounts of what they thought was going on in the Inca Empire. Very possible. Maybe literacy in keeping. Piquu making and reading was more widespread. And Kit Lee told me that, you know, the Inca Empire and the Kipus have really been mythologized to a certain extent. There's this idea of it being a glorious past of the Andes, that it's a bygone day,

you know, because of Spanish destroyed, the colonial doesn't destroy it. And, you know, if it was destroyed, then there's this assumption that, of course, these not records that people make today are just this kind of, like, degraded form of what used to be this, like, glorious past. Sabina Highland told me Everyone knew, right? The kippos were only made by high-status elites who were wiped out by the Spanish

so Kipu-U stops and anything modern people do is just almost like a triviality. I assume she doesn't feel that way at all. Not at all, not at all. Like last year, she was invited to this community called Hakul. It's this remote village in the Andes. That has kibu's, they asked me to look at it. They'd never shun their kibu's to outsiders

before. And for one thing, these ancestral kipu's she saw had human hair tied to them, which the people told her was like a signature of the maker. Ooh, this is fascinating. Yeah. And these kippoos also had a lot of tassels on them. And she told me that ancient Inka kipus can have tassals on them too. And so she's hoping to go back next year and learn more about the tassels and like what kind of meaning they have by just, you know, talking to people there. I know, talking to people. It's a radical notion. Very old school. It's not like using AI. It's just talking with people. Nell, thank you so much for bringing us the story. Oh, it's my pleasure.

This episode was produced by Rachel Carlson and lightly edited by our showrunner Rebecca Ramirez. Tyler Jones and Nell checked the facts. Maggie Luthor was the audio engineer. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Shortwave from NPR.