Origins of the Wheel

Transcript

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Speaker 1 It's often lauded as one of those pivotal moments in human history. Something that remains fundamental to many of our daily lives down to the present day.
The invention of the wheel.

Speaker 1 When was the wheel first created?

Speaker 15 By who?

Speaker 1 And for what purpose? These are questions that have fascinated various scholars for decades, if not centuries.

Speaker 1 Opinions remain divided as to where should be labelled the birthplace of the wheel, if there even is one birthplace.

Speaker 1 Recently, however, a new paper published in the academic journal Royal Society has argued that the wheel was invented in Eastern Europe by prehistoric miners who lived almost 6,000 years ago in the Carpathian Mountains and belonged to an ancient culture known as the Borlas culture.

Speaker 1 The argument is that the wheel was invented to help these metal ore miners transport large amounts of copper out of their tunnels.

Speaker 1 It's a theory that has been around for quite a few years now, pushed in particular by the esteemed archaeologist Dr. Richard Bullitt, professor emeritus at Columbia University.

Speaker 1 But what makes this latest paper groundbreaking is that the team behind it employed modern science and computing to support the archaeology.

Speaker 1 They used powerful computers to create models and simulations to add further evidence as to why this theory that the wheel was invented by copper-seeking miners in the Carpathians is likely.

Speaker 1 It's quite scientific, but the computer algorithms the team designed appear to reveal just how the wheel might have emerged in that environment and the several innovations it took for them to go from rollers to wheels.

Speaker 1 This is also a great example of how computer science and archaeology can work hand in hand today to allow scholars to make new discoveries about important inventions made thousands of years ago.

Speaker 1 Now, to unpack this theory and the science behind it, we're going to divide this episode into two parts. The first part is an interview with Dr.

Speaker 1 Richard Bullett to learn more about his work studying the world's first wheels and how he came to the conclusion that the Carpathians were where they were first invented.

Speaker 1 Following that, we have an interview with the computational engineer Dr. Kai James, who led this research alongside Richard and Dr.

Speaker 14 Lee Alacock.

Speaker 1 Kai will focus on the science behind this new paper.

Speaker 1 He will explain what computational engineering actually is and how he used his skills along with Lee's to create models that support Richard's theory that the wheel originated with prehistoric miners.

Speaker 1 It's going to be quite the episode.

Speaker 14 Richard, it is a pleasure to have you on the podcast today.

Speaker 15 Kristen, it's very nice to meet you.

Speaker 14 Now, I mean, what a topic as well.

Speaker 14 I mean, the invention of the wheel, often hailed as one of those kind of seminal moments in human history, and yet it feels like it's something that's still quite heavily debated down to today, and even if you can pinpoint it to one place.

Speaker 15 Yes, I think that the reason it is debated is because there's no obvious place of origin.

Speaker 15 Also, there is the fact that the wheel did not spread very widely in the world. Many societies decided that they did not believe the wheel was worth developing.

Speaker 15 You have the Western Hemisphere that had no wheels, but you also have Sub-Saharan Africa with no wheels.

Speaker 15 So while today everyone believes that the wheel is a marvelous invention that can be used for a zillion different purposes, historically, people did not think the wheel was a particularly riveting invention, largely because you cannot separate the wheel from the surface on which the wheel rolls.

Speaker 15 And if you are talking about simply overland country, you have trees, you have uneven surfaces, it takes a wheel of very large diameter to get over the bumps and cracks and ditches that you find in any landscape.

Speaker 15 There are histories of the wheel, but they're not histories of roads.

Speaker 14 Has there been much debate ranging as to where

Speaker 14 and how the wheel was first invented? Should we looking at one location or several different locations at the same time, almost spontaneous emergence of the wheel by particular communities?

Speaker 15 You have essentially three areas that have been put forward as likely starting places. One of them is Mesopotamia.
That's the oldest theory.

Speaker 14 That's Iraq and that area in the Middle East.

Speaker 15 Well, specifically in Iraq. For example, Egypt did not have wheels, even though it's not that far away from Iraq.
3000 BC is when you have roughly the first evidence of wheels in Mesopotamia, in Iraq.

Speaker 15 They take the form of pictures of a four-wheeled military vehicle pulled by animals that look roughly like horses, but they're not horses.

Speaker 15 And there's sort of a consensus that this animal was a wild ass native to the region. And very recently, it's been established through DNA evidence that the wild asses are actually a hybrid.

Speaker 15 between a domestic donkey and an indigenous wild ass.

Speaker 15 So now people are saying that you had a domestic animal called a kunga that was in the Middle East apparently quite some time, but entirely disappeared.

Speaker 15 In any case, in Mesopotamia, the earliest evidence for wheel is being pulled by a pair of these animals.

Speaker 14 So Mesopotamia, that was one theory, wasn't it? But you said there are two others as well. Is Turkey one of these other places?

Speaker 15 Well, let's say it's...

Speaker 15 the Black Sea, either on the northern edge, which seems more likely because that's a flat plain, whereas the southern is high mountains, so that the interior of Turkey and particularly at the eastern end around Armenia, you get the first coming of horses into the Middle East and the connection between domesticating horses and using wheels.

Speaker 15 Some people have argued that riding horses comes before using horses for pulling a vehicle. Other people have argued that pulling the vehicle comes before riding horses.

Speaker 15 But in any case, the connection with horse domestication points to either sort of southern Ukraine or into Kazakhstan or possibly into Turkey where you have more literary records.

Speaker 15 Then there's the third area is basically in Southeast Europe, in the Carpathian Mountain area, where you have no horses back 3000 to 4000 BC.

Speaker 15 So you divorce the invention of the wheel from the invention of horse harnessing.

Speaker 15 And this has not appealed to many people, but I think the evidence is quite strong that this is actually where the wheel first appeared.

Speaker 15 And then the harnessing of animals to the wheel is a second step.

Speaker 14 Well, let's explore that now then. So you mentioned, so the Carpathians, so kind of Eastern Europe area.

Speaker 14 And what is this culture that is central to our talk and to your research today, the Borilas culture? What is this culture?

Speaker 15 You have a copper age that comes before a bronze age. And the copper age made artifacts, many of them just decorative, out of copper.

Speaker 15 And the copper was mined in various places, but particularly the early copper age is in the Balkan mountains and the Carpathian Mountains of Southeast Europe.

Speaker 15 The Bronze Age comes a bit later when they start to have tin added to the copper ore and that produces bronze.

Speaker 15 But for the copper age, it started out with people finding surface deposits with a fairly high copper content. And they could simply roast those and melt out the copper in the stone.

Speaker 15 But as the surface deposits became depleted, they started to dig trenches and then tunnels to get at the ore. So the question in my mind, and this is sort of where I started,

Speaker 15 was what were wheels used for to begin with, rather than how were they built or where were they found?

Speaker 15 Because many people have thought that you would have, say, the big stones of the pyramids or something like that. You'd have to roll them into place.
So they thought there'd be rollers.

Speaker 15 But the thing is, circa 4000 BC,

Speaker 15 the loads were either divisible into loads you could handle. just carrying them on your back or even attaching them to a cow or something like that.

Speaker 15 Most things could be divided into manageable loads or else they were stones that were huge that were too big really to be rolled along. What you have with mining is that you're moving ore

Speaker 15 that has very substantial weight but has very little content of metal. So you have to move tons and tons of ore in order to smelt out a few pounds of copper.

Speaker 15 So moving this huge amount of heavy stuff, it's assumed that this was done by people who had baskets or trays, and they would slide the tray or the basket along the floor of the mine.

Speaker 14 So, as you say, it's the copper age, and already you've had many years of people extracting copper from the surface.

Speaker 14 Those have run out, so they're having to mine deeper into the mountains to extract copper.

Speaker 14 And now it's the technology that they have available to then get those large amounts of mineral, of rock, out of those. Should we say mine shafts? Would we be thinking of like narrow.

Speaker 15 Probably trenches before tunnels. Depends on how deep you have to go.
Because once you start mining, you tend to continue until you've depleted the deposit.

Speaker 15 But the Bolaraus culture had copper, but not in huge amounts. Earlier cultures in Southeast Europe had more copper.

Speaker 15 But I think as the copper became scarcer because the ores were less rich, you had a stronger and stronger need to move very substantial quantities.

Speaker 15 And one of the things no one else seems to have paid attention to in the history of all of this is that in Europe, mining continues to use small hand-pushed carts in mines from 3500 BC until 1900.

Speaker 15 And the important thing here is that if you have a trench or a mine, you are creating the floor surface that you have to move the ore along as you go.

Speaker 15 So you're actually building an underground or some surface road to go along with moving the ore.

Speaker 15 And I think that that was an important factor because for the first time you have an actual physical connection. that is very logical between

Speaker 15 the rolling wheel and the surface on which it rolls. You're in a low tunnel or in a trench, and you've a pathway that you've dug that is fairly smooth.

Speaker 15 If you have a tray or a basket pushing it up a slope to get it to the surface, you're basically simply sliding it along.

Speaker 15 Now, as soon as you put even one roller underneath it, you're making it easier to move.

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Speaker 14 Do we know what technology preceded it?

Speaker 14 How these people would have gone from you know, what they would have been using before and then potentially taking that next step to then create kind of this wheeled transport to transport this copper material out of one of these narrow spaces.

Speaker 15 We do have some very early images, but not as early as the Copper Age, of this kind of mining. People, say, carrying things on their shoulder or pushing a basket.

Speaker 15 What happened in the Bolaroz culture, this sort of late Copper Age culture in Slovakia, is that they started to drink beverages out of square cups with wheels on the the bottom.

Speaker 14 So this is archaeology discovered from the culture.

Speaker 17 Cups.

Speaker 15 So ceramics, but they have wheels on them. Yes, or they're built to have wheels on them.

Speaker 15 Usually the wheels have not survived, but the holes that the axle goes through have survived on the bottom of the cup.

Speaker 15 You know, drinking in ancient times, in a lot of cultures, is an enormously important social activity.

Speaker 15 Some cultures will drink out of the skulls of their enemies, or they'll drink out of ritons that are sort of long horn-shaped things.

Speaker 15 But even back to the earliest societies, such as Sumer in southern Iraq, you'll have people drinking out of a common bowl using straws.

Speaker 15 So the idea that drinking is a ceremonial activity that is important for the socialization of a culture, but only one place do you drink from cups that have wheels on them.

Speaker 15 This is not passing the port at Oxford High Table, where you have a trolley that carries a port bottle along.

Speaker 15 This is a cup several inches in width and breadth, and you have bosses or protrusions on the bottom with holes in them for an axle to go through.

Speaker 15 And these cups are not pulled by animals. They are presumably pushed.
You also have a number of the cups that have survived. We have about maybe 150 examples.

Speaker 14 150 examples.

Speaker 15 Wow, I've never heard of them before.

Speaker 15 No, Eastern European archaeology, before the fall of the Soviet Union, knowledge of what was being found archaeologically in the Soviet zone and the Western zone was not disseminated very well.

Speaker 15 But now these cups have been found fairly recently,

Speaker 15 and a number of them have lines on the side that make it appear that they are baskets,

Speaker 15 as if they are just putting wheels on the bottom of baskets. And again, that sort of points to

Speaker 15 the mining environment. So I think that you found a mining culture that discovered that they could move ore more efficiently using a wheel, and then they celebrated their own achievement.

Speaker 15 And so the primitive mine carts that they developed became a point of cultural pride.

Speaker 14 So these extraordinary artifacts, you know, these drinking cups which represent wheeled transport, these wheeled baskets, the theory is that it's almost the Borilaz people, they are celebrating this invention of theirs to create these wheeled baskets for their mining.

Speaker 14 And to celebrate this achievement and how important it was to them, you can see them creating miniature versions of these wheels on these very elaborate drinking cups.

Speaker 15 Yes. And then once the wheel started to spread, it was no longer that point of extraordinary achievement.
for other cultures. They were just having a borrowed technology.

Speaker 15 But the important thing about these cups that single them out from other early evidence is that they are a type of wheel that becomes obsolete in most environments.

Speaker 15 It's not been recognized sufficiently that the earliest wheels come in two different varieties

Speaker 15 and substantially different varieties. The first one, which you have in the Boloroz culture in Slovakia, is the wheels are attached to the axle in a way that they can't turn.

Speaker 14 So it's just straight, it's kind of going up and down kind of thing, not going around curves and so on.

Speaker 15 Yes. It's very clear that the wheels do not rotate at the ends of the axles.

Speaker 15 And the way you could tell that is that you have a round wheel and then you have a hole in the middle of the wheel where the axle goes through. But in the earliest wheels, that hole is square.

Speaker 15 So it can't turn.

Speaker 15 And we have square holes in the earliest wheels that are found in the Carpathians and also into the adjoining Alps. And these are the earliest full wheels we have.

Speaker 15 Whereas in Mesopotamia, we have no example of there ever being a wheel that couldn't turn.

Speaker 14 So, Richard, this is quite interesting. So, it's kind of combining all that information.
So, you have those ceramics there with the wheels on the bottom, which probably celebrating this invention.

Speaker 14 And then the discovery of an actual wheel from that area of the world.

Speaker 14 Is it using evidence like that to kind of create this hypothesis that it was these types of wheels that are invented and the purpose for it is to kind of go up and down these narrow tunnels almost, transporting copper out of the mine, bringing them back down in baskets, getting more out kind of thing.

Speaker 14 Is that how it all comes together? Because I mean, I don't know if the Borilage culture, if a physical wheel is also from that culture, or is that later?

Speaker 15 The earliest one, I think, is from the Ljubljana.

Speaker 14 Are the Ljubljana Marshes wheel, yes. Yeah.

Speaker 15 And that has a square hole in the center which means that it could not turn i think that the wheels used in the mines were smaller and they have not survived except in the drinking cups as you take this new technology out of the mine and you no longer have a groomed surface for it to roll on the wheels become larger in diameter because they have to go over a rough surface but also they use them primarily as a pair of wheels in a cart, whereas the cups show two axles and it's a four-wheeled.

Speaker 15 What you have in the mine is a small four-wheeled basket. When it comes out, you have something more like a farmer's cart.

Speaker 14 So you realize how valuable the proto-kind of mine cart that is developed by this Borolaz culture, you realize how important it would be on these baskets for transporting a lot of material out of the mine.

Speaker 15 And the mining technology continued to use this kind of wheel down down to virtually the present day. When you have an axle and the wheels are attached to the axle, there's a word in English for that.

Speaker 15 That's called a wheel set.

Speaker 15 And that is what railroads run on.

Speaker 15 So that the railroad technology comes directly from the mining technology of Bolaroz and evolved entirely within the mining community so that the first railroads are simply continuing trackways that are in European mines.

Speaker 15 And the history of the railroad is very much the modern history of the Bolaraus cups. But in the Middle East, we don't have any examples of wheel sets.

Speaker 15 In the Middle East, they have wheels that rotate independently. Now, the exception here is that in Turkey, non-rotating wheel sets were in use up until the present day.

Speaker 15 Not many of them, but they're a lot easier to build than wheels with spokes or that rotate independently.

Speaker 15 So you find a few images in Roman times and then in Turkish history, you find these non-rotating wheels outside the mining context.

Speaker 15 But otherwise, in Europe, it's the mines that preserve the Boleraz wheel design.

Speaker 15 And once the independently rotating wheels come along, almost everyone switches to that type of wheel, which is easier to turn.

Speaker 15 but harder to build.

Speaker 14 This is so, so interesting.

Speaker 14 So your theory is that the Boralas miners of Western Ukraine or of the Carpathian mountains of that region, they invented the wheel 6,000 years ago and it became such an important part of their culture, this kind of basket wheel system.

Speaker 14 How did you decide you wanted to test this theory with modern technology? What did you decide to do so that you could test this in the modern world?

Speaker 15 I'm a historian, not a technologist.

Speaker 15 And I thought that the evidence that I could produce of the continuity of wheel sets from the Bolaroz period through European mining up to the history of the railroad made a very strong argument.

Speaker 15 But there were various technological elements to the argument, having to do with when did animals start pulling vehicles, what animals were used for that purpose.

Speaker 15 After all, in the Bolaroz cultures I mentioned, they had no horses, they had no donkeys.

Speaker 15 And, you know, to get two oxen side by side in a tunnel, you'd have to build a tunnel much bigger simply to fit the animals in. So I thought there was a very strong argument based on artifacts.

Speaker 15 But how the initial breakthrough came, I did not have a clue on that. I did look at various theories of evolving from rollers, but none of them made much sense to me.

Speaker 15 And then Kai contacted me and said he had a theory about how rollers could evolve in the direction of wheels. So this is his contribution.

Speaker 15 He found the technological key to explaining how this could have occurred. But there's a lot more to do in this.

Speaker 15 And I think that technological historians have to be aware of how complicated the notion of a wheel is instead of focusing on harnessing the animals, which is very important.

Speaker 15 I've written on that subject as well. But it's not just a matter of how do you harness the animals, but it's building the wheel itself.
and thinking of what's the purpose of the wheel.

Speaker 15 After all, humans got along for tens of thousands of years without any wheels. And many cultures, matter of fact, most parts of the world got along until modern times without wheels.

Speaker 14 Okay, then, Richard, you've teed us up nicely to go to the next part of your research, which is then to interviewing your colleague Kai about what he did to kind of move this theory forwards.

Speaker 14 And Richard, it just goes for me to say thank you so much for taking the time to come on the podcast today.

Speaker 15 Tristan, it's been a great pleasure for me to be able to talk about this. Thank you very much for putting me on your show.

Speaker 1 So there was Professor Richard Bullet talking through why he believes the wheel originated with these prehistoric copper miners in the Carpathian Mountains almost 6,000 years ago.

Speaker 1 How these wheeled baskets made it easier for them to extract large amounts of copper out of their tunnels. We now move on to the science.
Dr.

Speaker 1 Kai James is a computational engineer who worked on this new research alongside Richard and software engineer Dr. Lee Alacock.

Speaker 1 Kai Kai wanted to see if his high-tech computer models would support Richard's theory that the wheel originated in the mines of Central and Eastern Europe, and how, technologically, this early wheel design was invented.

Speaker 1 How exactly can computers help with that? Well, you're about to find out.

Speaker 14 Kai, it is a pleasure. It is great to have you on the podcast today.

Speaker 17 It's great to be here. Thank you.

Speaker 14 Now, we've just heard from Richard about his work and his theory that the wheel originated with these early miners in the Carpathians.

Speaker 14 I now want to bring in yourself, Kai, and the science behind this new research. But first off, I've seen the words computational engineering.

Speaker 14 Forgive my ignorance, but what is computational engineering?

Speaker 17 So computational engineering is

Speaker 17 essentially any form of engineering that uses computers and the power of computers to solve engineering problems. Often that takes the form of solving mathematical equations.

Speaker 17 So typically the systems that we engineer are described using physics models. These models could be from dynamics, solid mechanics, aerodynamics.

Speaker 17 And so we use computers to solve the very complicated equations that describe the physics of those systems. And computers do it faster and much more efficiently than if we were to do it by hand.

Speaker 17 And then we can also involve computers when it comes to things like creating designs or models of engineering systems.

Speaker 17 And then more recently, we involve computers in the more creative aspects of engineering. So computers can assist with actual design and helping us make design decisions.

Speaker 17 using tools like artificial intelligence and other related computational methods.

Speaker 14 And so what led you to stumble upon Richard's research and I guess go from looking at maybe modern technology and new ideas and methods and theories and so on to actually look at engineering from thousands of years ago and the invention of the wheel.

Speaker 14 What brought you to Richard's research?

Speaker 17 Yeah, that's a great question. So it is a bit of a departure from my usual engineering problems that I'm investigating.

Speaker 17 So my work is in the area of engineering design, using computational methods to design engineering systems. And typically those are modern engineering systems like airplanes.

Speaker 17 But I'm also very interested in the underlying theory and philosophy of design.

Speaker 17 And so, what I wanted to do was see if we could use our computational engineering techniques to perhaps better understand how

Speaker 17 early engineers, by early in this case, I'm talking about engineers from 6,000 years ago, how they came up with their designs that were revolutionary to them at the time.

Speaker 17 Also, I wanted wanted to see if we could use computers to kind of mimic that process, to essentially simulate the way in which early technology evolved.

Speaker 17 I started out by attempting to come up with an algorithm that could

Speaker 17 on its own synthesize a wheel and axle system. So essentially the algorithm doesn't have any prior knowledge about what a wheel looks like or how it operates.

Speaker 17 It only knows that it needs to create some device that assists assists an operator in transporting some heavy cargo from point A to point B.

Speaker 17 That's essentially how it started out. So we created an algorithm that starting from a black box could synthesize a system that ultimately evolved into a wheel and axle.

Speaker 17 And then from there, it kind of morphed into, okay, well, how much does this computer process resemble the actual process that took place 6,000 years ago when the wheel was invented?

Speaker 17 And can we we use this process to gain a deeper understanding of what that human-based design process, what the human invention of the wheel actually looked like?

Speaker 14 I guess we sometimes have in our mind, don't we, that one day they have some very obsolete technology almost, or they're doing it all by basket or with a sack carrying this stuff out, and then the next day they've invented the wheel.

Speaker 14 But obviously, it's not that straightforward or click of a finger they designed this technology.

Speaker 14 Is it trying to understand that whole process of human thought as to how they might ultimately reach this end point of this early wield some 6,000 years ago?

Speaker 17 Yeah, exactly. We wanted to ask questions like, well, how long did this take? Is this something that likely happened as a kind of abrupt leap? in technological advancement?

Speaker 17 Or is this something that could have occurred through gradual iterations, through a slow evolutionary process, similar to evolutionary biology?

Speaker 17 Also, we wanted to see if we could learn about the people who were the actual inventors.

Speaker 17 And for me, that's been one of the most interesting outcomes of this research is to gain insights into, you know, why do certain societies arrive at technologies when and how they do, whereas others fail to do so.

Speaker 14 Absolutely. So, I mean, that was your objective and seeing, you know, kind of how you could answer those questions.

Speaker 14 So with your expertise and approaching this topic, I mean, what was almost the start point point to create evidence that might support this theory as to how the wheel came to be here?

Speaker 17 I really just started reading about what do we know so far? What do we know about the origin of the wheel?

Speaker 17 And so I essentially just looked up various sources, mostly academic journals, so journal articles, but also read a few books from various scholars of the origins of the wheel.

Speaker 17 And one of the books that I looked up and that I ended up reading was the book written written by the man who became my co-author, Dick Bullitt, who's a historian of technology.

Speaker 17 And I knew that working with him would greatly enhance the project. Well, for one, the credibility that I would receive, you know, as sort of an engineer entering this realm that is not really my own.

Speaker 17 But also having his insight as a historian, I thought that it would make for a really powerful collaboration. And so that's how the collaboration came about.

Speaker 17 I found his book, read it, found it really interesting, reached out to him, he responded. And so we had a Zoom call where I pitched my vision, my ideas, my hypothesis, and he was on board.

Speaker 17 And a lot of our thinking about the origin of the wheel really lined up with one another. And so that's how the collaboration was born.

Speaker 14 And if you don't mind, and I've read your paper alongside, you know, Dick and Lee as well. Lee's, Lee's the third author in that paper.

Speaker 17 Yeah, he's the first author. He's my former PhD student.
So he did basically all of the computer programming and mathematical derivations under my guidance.

Speaker 17 So yeah, he was a huge driving force in the project as well.

Speaker 14 And I've read through it and I noticed when you get to the methodology and what you guys did, there are lots of big and I must say complicated equations for me as a Joe blogs looking at this from the outside.

Speaker 14 What were some of the main algorithms that you created that helped you advance this research and ultimately come to your conclusions, which we'll get to in a bit?

Speaker 17 Good question. So I would say there are three major components.
One component was

Speaker 17 a modeling or simulation tool that we used in order to predict how the structure that comprises the wheel and axle, how it would respond to loading.

Speaker 17 So the wheel, we think of it as a mechanism, but it's also a structure. It's a rigid structure and it has to be designed to withstand significant loading.
This is key, key, right?

Speaker 17 I mean, so the wheel in essence is a, or at least at the time was a cargo carrying device. It was used to carry heavy loads that would have been very difficult to drag or to haul.

Speaker 17 So it had to be very structurally rigid. And so we created an algorithm that would simulate under these loads, how would the wheel and axle respond? How would it bend?

Speaker 17 How and when would it break in response to that loading? That was component one. And then additionally, we had

Speaker 17 another

Speaker 17 module of this broader algorithm that was designed to calculate how much effort would be required to push a cargo of a certain weight given the wheel's design, right?

Speaker 17 So if your wheel looks like this, if your atzo looks like this, and if the amount of mass you need to carry is 100 kilograms, how much effort or how much force would be required to push that weight along the ground?

Speaker 17 And so that was another calculation that the algorithm performed for us. And then the third component was

Speaker 17 what we call an optimizer. So

Speaker 17 this is

Speaker 17 a third software tool that communicates with those first two modules and says, okay, this is our current candidate design. Tell me, how does it perform in terms of efficiency, right?

Speaker 17 How much effort is required to push our mass given this design?

Speaker 17 And how does it perform in terms of structural integrity? How stiff is it? How likely is it to break under this load? And so the optimizer, this third component, takes that information.

Speaker 17 and modifies the design ever so slightly in a way that improves it incrementally. And so that process takes place in an iterative fashion.

Speaker 17 It goes through repeated loops of this cycle until eventually it converges on a design, a shape of the system that is optimal. And

Speaker 17 what that process ended up revealing is that the optimal design, given the particular objectives of the users of the wheel, was essentially, you know, a slender axle capped on either end by two round discs, which we now refer to as wheels.

Speaker 14 And that optimal design, just to give us a refresher of what Richard said earlier, it's not kind of deep tunnels with big corners that you think of maybe from the Wild West or much later.

Speaker 14 These are small tunnels, but straight tunnels as well. This is to wheel stuff out in a straight line.
So those are the conditions that you're thinking of from 6,000 years ago.

Speaker 17 Exactly. The nature of this design really

Speaker 17 fits well with the idea of the mine environment because it was likely straight.

Speaker 17 And we know that early wheel and axle systems, because they were what we call monolithic structures, they're a single part, right?

Speaker 17 And if you rotate it, everything rotates in unison, as opposed to a multi-body system where you have a separate axle and two wheels attached to it, but they can rotate independently.

Speaker 17 And a monolithic wheel and axle system can't navigate turns.

Speaker 17 So the mine environment is one that would have been conducive to this particular very primitive version of the wheel technology.

Speaker 17 The other thing about that type of wheel is that it also required very flat terrain, level terrain, and firm terrain.

Speaker 17 And that also is where the mine environment, we believe, played a key role in allowing this technology to evolve.

Speaker 17 Because if it had been used for farming and it was used to carry harvest through a field, that terrain wouldn't have been covered.

Speaker 17 It would have been less processed, so it would have likely been less flat, less firm, probably not level.

Speaker 17 The mine environment is very different, and so that's why we think that this society, which, as far as we know, had no written language, very little mathematical or scientific sophistication, but their particular circumstances were such that

Speaker 17 they were in the right place at the right time. Whereas by contrast, a civilization like the Egyptians, who were highly mathematically advanced, highly scientifically advanced, and had

Speaker 17 obviously every opportunity and every need, had a dire necessity for the wheel, you know, during the building of the pyramids, they apparently did not know about the wheel at the time that they built the pyramid.

Speaker 17 So it goes to show the importance of environment in this technological development process.

Speaker 15 I mean, it really does.

Speaker 14 And it's such an interesting piece of research to do because remember Richard saying how you have those clay figurines, which shows kind of that design, almost the end product from that environment, and maybe how they were celebrating that technological invention.

Speaker 14 So you're almost there, you have an end point to know, okay, that's what they reached. My other question then is.

Speaker 14 Do we know the key steps of innovation? Or did your research reveal more about what we think the key steps of innovation were for these people to ultimately reach the wheel?

Speaker 14 Because you mentioned ancient Egypt there, and sometimes you see pictures of them bringing up large blocks of stone or whatever, but with rollers.

Speaker 14 I mean, and that's a word that I do want to ask, because do we think it goes rollers to wheel?

Speaker 14 Or what else did your research suggest about that whole innovation, the steps of innovation to finally reach the wheel?

Speaker 17 Yeah, so our theory is that it started with rollers. Historically, this

Speaker 17 has been the subject of controversy. I would say, up until about 60 years ago, it was relatively uncontroversial that wheels evolved from rollers.
And you can kind of see why. It's very intuitive.

Speaker 17 A roller is very similar to a wheel in its geometry and the way in which it operates. And so the theory was that they started out using rollers, and then over time, the

Speaker 17 center region of rollers kind of hollowed out, revealing a slender axle. This actually began to be called into question on the grounds that rollers do not perform well in most environments.

Speaker 17 Because they require firm terrain, they require flat and level terrain. Rollers have not been used very widely throughout history.

Speaker 17 And so the argument was sledges or skids, essentially sliding your cargo along the ground on some type of sled.

Speaker 17 People believe that was the more likely precursor because they were much more widely used. Our theory is that, yes, rollers were very rare, but so is the invention of the wheel itself.

Speaker 17 If you look back through history, independent discovery of the wheel is something that may have occurred as little as twice throughout the entire history of humanity, which suggests that the inventors were doing something that was unusual, that wasn't very common.

Speaker 17 And the theory that they were invented in mine or or invented by people who wanted to use them in a mine fits this puzzle, right?

Speaker 17 It kind of explains why it's so rare and why this very niche technology, which is rollers, would have been the likely precursor.

Speaker 17 In a sense, we kind of resurrected the roller theory, which was the prevalent one until pretty recently, but we made some modifications.

Speaker 17 Earlier theories about how that sort of shape change took place left out a few steps that we included and we were able to show that these steps were necessary using our mathematical models.

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Speaker 14 Let's explore these various steps, Sakai, because I do see

Speaker 14 in your paper that you have a few visual images of almost the stages to creating this early wheel type. So let's explore this.

Speaker 17 So step one is you start with rollers. So these are cylinders that are placed on the ground in an array,

Speaker 17 side by side. Made out of wood.
Yeah, they could be made out of wood, they could be made out of logs. And so you place your cargo likely in a cart, some kind of container, and you just push it along.

Speaker 17 And the rollers are rolling along the ground, but the rollers are also rolling with respect to the bottom of the cart that's resting on them.

Speaker 17 And so we refer to that as bilateral rolling because it's rolling that takes place on two different sides of the roller. There's the roller ground interface and then the roller cart interface.

Speaker 17 Both of those are roller surfaces. And under ideal conditions, there's no friction involved in that process.

Speaker 17 So it should be fairly easy if you have the right conditions, if your ground is flat, firm, and level. The problem with rollers, however, is that once your cargo passes a roller, it becomes useless.

Speaker 17 So those rollers that we call them spent rollers, right? So they're rollers sort of that you've already passed. They're at the back end of your path.
Those rollers need to be replenished.

Speaker 17 So you typically would take those rollers and bring them around to the front of your cart. And so, in a mine or in a tunnel, this process becomes very onerous.

Speaker 17 Even though the tunnel, the ground, the terrain in a tunnel was conducive to rollers, the fact that it's an enclosure also means that rollers have this additional requirement that is very costly.

Speaker 17 And so, we believe what happened was the first innovation was to create a socket in the bottom of your cart or your container that the rollers would rest in.

Speaker 17 And so, as you pulled your cargo, the rollers would be pulled along with it.

Speaker 17 Because the rollers are sitting inside the socket.

Speaker 17 So, you no longer have to bring those spent rollers around to the front.

Speaker 14 It's almost kind of like a sledge, but a sledge that is, you know, rotating there, isn't it?

Speaker 17 Exactly. So, that's step one.
Now, the problem with this step is that it reintroduces friction. So rather than a bilateral rolling scenario, now you've got rolling on one surface.

Speaker 17 That's the roller ground interface. But where the roller meets the socket at the bottom of the cart, that's a sliding surface now.

Speaker 17 And so you're going to get significant friction there. And in fact, this is mechanically equivalent to just dragging your cargo on the floor.

Speaker 17 So we believe that this was overcome by placing grooves in the rollers so that you could apply lubricant.

Speaker 17 And with the right lubricant, the right surfaces, you can reduce the pushing force required by a factor of three or more.

Speaker 17 That step is something that wasn't addressed in previous theories about evolution from roller to wheel. And then the key step, once you arrive at unilateral rolling with lubricant, the next step is

Speaker 17 the shape change. We argue over time, the region in the center of the roller started to become more and more narrow.

Speaker 17 Now, initially, this could have been so that the operators of these carts, the miners, could achieve clearance.

Speaker 17 So if you had small objects on the ground that may obstruct your path, If you hollow out the roller in the center, you can just roll right up.

Speaker 14 It gives you that space from the bottom, yeah.

Speaker 17 Exactly. But what they would have found is that as a result of that hollowing out, the pushing force actually went down.
And so this is one of the key contributions of our paper.

Speaker 17 So we derived an equation that shows that as the axle gets more and more slender, the amount of pushing force decreases proportionally.

Speaker 17 So if you can reduce your axle so that its radius is one tenth the radius of the wheel itself, right? So the outer portions, the wheels, those are still in contact with the ground.

Speaker 17 If the axle radius or the axle diameter is one tenth the diameter of the wheels,

Speaker 17 then you only require roughly one tenth the force to push, right? So we derived an equation that showed that relationship. And so they didn't necessarily need to know that equation.

Speaker 17 I'm sure they didn't. But what they would have noticed is that those rollers that had very slender central regions would have been a lot easier to push.
And so this is the third innovation.

Speaker 17 And so that is essentially a wheel. And in the paper, we call this a wheel set because it's a monolithic structure.
It starts out as a roller and essentially you carve the axle out of that.

Speaker 17 that log, that cylinder. And so the axle and the wheels rotate in unison.
At that point, you're pretty much done. You have a wheel.
And that type of wheel still exists today in certain contexts.

Speaker 17 But the wheel, like all technologies, is a dynamic and evolving thing. I think you're right.

Speaker 14 We could talk a whole hour about, you know, all of these real innovations, but it's been fascinating.

Speaker 14 One of the main things I've taken away, first of all, just thinking of how the design changes for it to ultimately, I guess, yeah, just smallen the roller into an axle and then you have the rest of it there.

Speaker 14 And it was difficult for me to get my head around before talking to you, Kai, about that whole process of going from roller to wheels.

Speaker 14 But I mean, you've made it sound so much clearer now, and it's so interesting to see how that thought process may well have gone.

Speaker 14 And also, your work around this, and Lee, and Richard, about this kind of evolution of the wheel in that particular environment in the mind some 6,000 years ago.

Speaker 14 I guess it begs that last question, doesn't it?

Speaker 14 I guess this is a question that maybe you're not designed to answer with your research, but to think, you know, potentially just how long it took for these people to go from one step to the next.

Speaker 17 It's really hard to know. And this is one of the challenges with

Speaker 17 trying to understand deep history from times and places where the way things played out wasn't documented, right?

Speaker 17 So it's really hard to say.

Speaker 17 And the other thing is we believe that those less efficient versions of the wheel, for example, the grooved roller, which was kind of the first innovation, those things wouldn't have lasted very long because they were solid efficient.

Speaker 17 And as a result, these intermediate technological steps often don't make it into the archaeological record because in order for things to last thousands of years, I mean, statistically speaking, there needs to be many of them.

Speaker 17 And so

Speaker 17 because we don't

Speaker 17 have artifacts of those intermediate technologies, it's very hard to say. I suspect, though, that those intermediate technologies wouldn't have lasted very long.

Speaker 17 I would place it on the order of maybe a few decades just because they were so inefficient. And in fact, biology, right, and biology of living things evolves often in a similar way.

Speaker 17 So it's referred to as punctuated evolution. Species will undergo rapid transformations over a small number of generations until they reach some optimal or stable

Speaker 17 design.

Speaker 17 And then that design perseveres for many centuries, millennia, or maybe even millions of years in the case of some species.

Speaker 17 And so we believe that the wheel set is one of those locally optimal designs that persevered. And we still have it today for that reason.

Speaker 17 The intermediate steps, because they were suboptimal, didn't last very long. And so it's very hard to get an accurate picture of how long they would have been in place.

Speaker 14 One other thing that you mentioned there, which I found so interesting, was how you mentioned you need to have those optimal conditions for the creation of the wheel.

Speaker 14 And then I guess you can understand why certain parts of the world, you know, the wheel doesn't evolve until much later or be brought in much later because you mentioned Egypt and so on.

Speaker 14 Kai, I must ask to finish.

Speaker 14 You have just done this research alongside Lee and alongside Richard. This is you delving into archaeology and ancient history and you now can see how amazing it is.
But what's your plan next?

Speaker 14 Do you plan to do more research around early wheels or another part of ancient engineering or technological discoveries? What's next for you and your research?

Speaker 17 So I have a couple ideas in mind. This type of work is really just one part of my portfolio.

Speaker 17 So I still work on more conventional aerospace engineering problems like optimal design of electric aircraft and that type of thing.

Speaker 17 But as far as my forays into ancient history, I would like to see if we can use these tools to understand other seminal technologies, like, for example, the bow and arrow, which is another really fundamental mechanical invention that somewhat unlike the wheel, pops up in many different places and is discovered by many disparate civilizations that had no contact with each other.

Speaker 17 In that sense, to me, the bow and arrow kind of represents, like the wheel, an underlying fundamental truth about our physical environment so I think it's just really cool that these different civilizations all kind of came up with the same idea and so it'd be interesting to use physics and computational engineering to get a sense of why and then also I think my next project will be a little bit closer to home I want to look at the invention of the airplane and so that one's different because this is we're talking about 120 years ago so its evolution is somewhat well documented, but I have a theory that the true invention of the airplane and the innovations that led humans to achieve flight actually took place much earlier than the Wright brothers.

Speaker 17 And so I think that the evolution is more complicated and more nuanced than even aerospace engineers truly understand. So look out for that.

Speaker 14 It might be a bit too modern for us, I admit, Kai. However, there are other history podcasts that would be fascinated by that.
And that bow and arrow stuff is certainly in the ancients wheelhouse.

Speaker 14 So, I will keep an eye out for that research when it comes around, and we'll have to get you back on then.

Speaker 14 But it just goes for me to say, Kai, this has been fascinating to interview you and Richard before you about this extraordinary new paper that has been published around the origins of the wheel some 6,000 years ago.

Speaker 14 And it just goes for me to say thank you so much for taking the time to come to the podcast today.

Speaker 17 Thanks, Larist, and I really enjoyed it.

Speaker 1 Well, there you go. There was Dr.
Kai James and before him, Dr.

Speaker 1 Richard Bullett talking you through this exciting new research into the origins of the wheel, looking at the archaeology, the theory of it emerging with these Carpathian miners some 6,000 years ago seeking copper, and also this new science, the use of computational engineering to try and understand the evolution process of the wheel in those mines and how the environment was right for those innovations to happen step by step.

Speaker 1 Thank you for listening to this episode of the Ancients. Please follow the show on Spotify or wherever you get your podcasts.
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Speaker 11 Either way, you save big on three amazing gifts at Verizon. All on the best 5G network.
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Speaker 2 Dashing through the store. Dave's looking for a gift.
One you can't ignore. But not the socks he picks.

Speaker 4 Hey, Dave, here's a tip.

Speaker 6 Oh, scratchers? Good idea.