Stone Age Technology with Dietrich Stout

of fun. A stone age technology is so much more fascinating than you would think, Yeah, because in looking at it, we're looking really at the roots of a human invention and innovation, Like where does the entire tree of human technology spring from? Yeah, and how did ancient technology shape us? So this is going to be a conversation with Dr Dietrich Stout. Dietrich Stout is an Associate Professor of anthropology at Emory University, where his Paleolithic Technology labor tory investigates

the role of technology and human evolution. Dr Stout is also Associate director of Emory's Cross Disciplinary Center for Mind, Brain and Culture, which promotes diverse and integrative research into

human nature and experience. His research focus on Paleolithic stone toolmaking and brain evolution integrates field research at Early Stone Age archaeological sites in Ethiopia with laboratory and museum research including artifact analysis and experimental replication, functional and structural neuroimaging,

behavioral analysis, and psychometric testing. Now, if you want to check out those centers I mentioned the Paleolithic Technology Laboratory, you can find that at Scholar Blogs dot Emery dot e d u, slash Stout Lab, and then the Center for Mind, Brain and Culture. You can just go to c MBC dot Emery dot e d U. Yeah, this is a super fun interview. I should stress this was

an in studio interview. Yeah, one of a couple of interviews we recorded about a month ago where we said, hey, let's let's reach out to some local experts on some various topics. We don't necessarily we enjoyed jumping on the phone with with folks, but why not have some some local talent coming to the studio. And that's what we did here. It was a lot of fun, uh, and I think you will really enjoy it. So I'd say, without any further ado, let's go straight to our conversation

with Dietrich Stout. Hey, Dietrich, thank you so much for joining us on the podcast today. Can you start by telling our listeners a little bit about who you are and what you do. Yeah. Well, I'm an associate professor of anthropology at Emory University. I'm also the associate director of the Center for Mind, Brain and Culture at Emory as well, which is a center that promotes interdisciplinary research

on mind, brain, and culture. And those are basically my interests come at it from the direction of archaeology and the hope that we can learn something from the past about made us the way we are today. So how did you first get interested in Stone Age technology? Well, um, it's not something that you typically encounter in most high schools around the country. Uh. So, you know, when I went to uh to college, I really had no idea of the possibilities that where they are for anthropology, for

the archaeology of human origins. I did know that I was interested in the way the human mind works, in the nature of human experience. Uh And at the time, I thought that meant that I wanted to be a philosopher. When I got to school, I realized what I said before, that a lot of the way we can understand how we are today and the nature of human experiences to understand the evolutionary processes that brought us to where we are. UH. And I had a really great UH professor as a

freshman and a freshman seminar. He told me to take some archaeology classes. I did, and I still I just remember one lecture that my professor gave. I know, she was talking about these ancient stone tools in a particular kind called a little vow wa technique UM, and he was pointing out that you could see every individual action and and blow against the core that this person had done something like fifty or a hundred thousand years ago, and you could reconstruct what they were thinking, the plans

that they made. And that just struck me as as an incredible window on the past and how our minds became the way that they are today. And that's what got me started on it. Like seeing into a dead person's imagination. Yeah, to be able to recapture that, I mean. And now I've worked at sites that are half a million years old where you can literally trace individual decision making processes. It's it's it's pretty incredible. Actually held a

core at one of these sites. I was looking at it and I was wondering why they didn't do something that that I would have done with that core, that piece of rock, and I twisted it around to look at where I was thinking about, and so that they actually had tried well I was thinking, but it didn't work. So both of us made the same mistake, separated by half a million years. That's almost a little spooky. Um. So, obviously we know that the Stone Age means stone tools.

But what as an expert in the area, what does the Stone Age mean to you? What do you think about when when this age is conjured? Uh? Yeah, Well, I think really of the time period uh, for which we have evidence of human behavior in the forms of archaeology, but extending way back into the past so that we have information, but it's also an evolutionary time depth. You know, we're talking millions of years, more than three million years at this point of time. Uh. So that's what gets

me excited about the Stone Age. Uh. And of course you know it's called the Stone Age for a reason. Most of what we have are the best evidences of stone tools for behavior. Um. So that's what I've focused on. And when you think about the very beginning of the Paleolithic obviously we're talking about hominid ancestors then, but not not Homo sapiens, right, And so when these organisms were alive, when when they were trying to survive and and stone tools began to play a role in their lives? What

was that role? What was the earliest role you think stone tools played in in these organisms survival? Yeah, well, I should say at the outset, there's a lot of things we don't really know with any great certainty about

the earliest Paleolithic. Uh. I think that there is strong evidence that some of the earlier tools were used for for butchery of animals, because you can recover actual cut marks on bones when somebody accidentally nicked a bone as they were butchering an animal, and so that's a direct evidence. Now what else they were used for is much harder to say because the plant materials, all those things are gone.

So there's very limited evidence of that. And it's only in the past couple of years that that it's been reported a much earlier site. We used to think the earliest stone tools were two and a half million years old. I've worked at some of those sites, but now they go back to three point three million years and we as yet have very little evidence of what they might

have done with those tools. Hopefully in the next few years there'll be the kinds of evidence that I was talking about, but it's just not there yet, so a lot of unknowns. If I had to say, these things are cutting tools, and the most important thing probably for early humans to be able to cut was animal flesh to access that, but they could have used them for a lot of other things, including making other tools. Uh. One of the great things about having a cutting edge

is your ability to shape other tools. For instance, in would if you have a knife in the form of a stone flake, you can make a spear. You can make a digging stick. Again, though the wood's not there anymore. So if they did that, we have a hard time knowing for sure. And when you mentioned those dates a minute ago that's referring to, Uh, is that that modified

stone tools we're not talking about like found stone tools. No, And in fact, it would be nearly impossible to identify and differentiate a found stone tool from a rock at this point. Um, So that's all right. We know chimpanzees use rocks as tools, and so it's you know, likely that are very early ancestors did. Um. But yeah, by by three point three we have evidence of them actually fracturing rock on purpose in a controlled way to produce

cutting edges. And that's something that we can definitively separate from a natural process, so we know it it occurred at that point, Um, correctly if I'm wrong. But are there are there broad stroke um classifications for the different levels of tool creation, Like I want to say, it's something like nature, fact, artifact, etcetera. Uh, could you walk

our listeners through that? Yeah? Well, um, you know, of course you could have on modified rocks used as tools, for instance, to crack open and nut as uh as chimpanzees and some monkeys maccaque monkeys do that as well. Um, that's a tool, you know, it's a stone tool. Um. But what we see by three point three million years is the actual modification of the rock on purpose in order to make a different kind of tool. Uh. And that's generally a process simply of fracturing the rock to

produce sharp shards or flakes of stone that then become knives. Um. And so that's loosely called like mode one. Uh. The most well known industry that does that is the Old One named after Old of I Gorge where Mary and Louis Leaky worked. Uh. And that's a very simple form of stone toolmaking. Uh. It does require quite a bit of coordination. It's not easy to break rocks. Um. They're hard. You have to hit them just right and with a lot of force. UM. But it's pretty conceptually simple. You're

not gonna make flakes. Um. And then after that you've got what variously is called like mode to or loosely called Julian after a site where it was first described in Europe, is the manufacture of these things that archaeologists call hand axes. And that's where you're not just shattering the rock into flakes, but you're actually shaping the rock

to make a tool. UM. The classic tool from this sort of stage or time period is uh the hand axe, which would be a flat rock UM with cutting edge most of the way around the perimeter and a tip at one end can be good again we think for a large animal butchery. Uh. And so that's where you've moved then to actually having the intention, having a goal in mind, and the techniques that you have. The control

over the stone that's required is more um Uh. Following that you have what we call prepared core technologies, in which you shape the rock in a careful way so that you can remove one final piece that's already pre shaped the way you want it to be, and then you can do that over and over again, so it

becomes a very efficient way of making tools. And then there's all sorts of variations on that um and that's the point in which we think there's a big change that they start actually putting these things on sticks, for instance hafting. Right, So you have composite tools, and you have all sorts of other techniques and materials that then enter the process and things become much more complex. So you mentioned the hand as, I'm interested to know a

little bit more about that. I may be mistaken, but there there have been identified, I think, different schools of hand as construction. Is that right? Well, yeah, I mean there are different ways of making something that we call a hand ax. Um. Now we also, I would be very careful about that. We should always remember that when we call slaying a hand act, that's a name that we came up with to describe a bunch of things

that we think are all similar to each other. That doesn't necessarily map onto what anybody was thinking in the past, or whether they knew each other or or whatever. So it's a tool, but we have to be careful about it. And you put a name on something, you think you understand it. Uh. But yeah, So, as I mentioned, the hand acts has a particular form. There's a lot of different ways you could achieve that, and a lot of

different starting points. For instance, I might start with just a big rock and then shape that rock into appointed in hand ax, uh you know. Or I could start with an even larger rock and then I knock off a giant flake, you know, more than more than ten centimeters long is generally they cut off, and that's almost already what I need. You know, it's got a big cutting edge all the way around the edge. And then

I shape that flight just a little bit right. And that's a very different way of making a tool that in the end probably as a similar function and looks quite similar. And then there's all sorts of different sub variants of ways of doing that. Uh. So that's what I think when you're talking about different schools, is these

different methods of making the hand access. Now there's as a raging debate over what the variation actually means, you know, the sort of naive ascension early on was every time you find a different way of doing something, that's a different quote culture, even though we don't really know what we mean by that term at that point. Now now there's you know, people saying that these are just recurring rediscoveries of simple solutions to the same kind of problems.

They don't necessarily imply any sort of cultural continuity or contact between people. There's even been suggestions that there was some kind of large genetic component to the way that people made these these hand axes. So now it's up for debate. But the variation is what we we study to try to understand what was going on in the past. That's where we have a sort of an insight into

what was what was happening. Well, I was definitely going to ask you the naive question about whether that's a result of culture, But is there so if we don't make that assumption that the different forms or shapes or approaches to hand axes are necessarily the result of cultural traditions or cultural contact, is there anything that you think looking at tools like this Stone age tools could possibly

tell us about the culture of the creatures that made them. Yeah, well, and so this is where we have to get into the sort of stuff that you can learn through experimental archaeology. UM. For instance, how difficult is it to discover and use particular techniques, you know, so you know, if they're if there's two people that do something the same way, if it's an obvious answer, then there's no reason to think

they learned it from each other. But if it's this really sort of obscure and and and hard to learn technique that they share, and then it's much more likely that they learned it from each other. So I mean, so there's this thing in in the issue in a uh sort of a geographic patterning um to where you have far fewer hand axes in East Asia than you

do in Africa and Western Asia and Europe. And also none of them really to appear to be as refined as some of the nicest examples from from further west UM. And so people have debaded for a long time with this geographical patterning means, and I tend to interpret it, you know, in terms of there are some techniques that are pretty hard to discover on your own and some that are easy, you know, and so you have a lot of reinvention of sort of easy hand acts making

here there in the other place. You know, but these particular advanced techniques may only have been invited it once or twice or a couple of times, and so their geographic spread is more restricted. So that's sort of the way that you make a relationship between understanding the way that you actually make the tools and then how they

might spread through ancient populations. So you mentioned experimental archaeology. Um. I know a lot of people probably when they think about the data collection part of archaeology, they probably think primarily about digging. Um. But but tell us a little bit about what experimental archaeology means and what what what kind of things that has helped us understand that we

couldn't understand just from looking at actual artifacts. Yeah. Well, you know, what you can understand from just looking at the artifact is actually a bit limited. You know, these things they don't they don't come out of the ground with with labels on them. Uh uh. You know. I like to do this when I give a presentation that you show a picture full of a table full of a bunch of old one stone tools and say like Okay,

now what does this tell us? And in most people, you know, you can't even tell that there are anything other than just rocks if you're not used to looking at them. So what you have to do to understand what these tools that we dig up can actually tell us is, uh, basically experimental archaeology. We use analogies, We try to learn how to make them ourselves, and then you can manipulate. Well, if I make it this way, then it looks like that. If I make it this way,

it looks like that. If I use it this way, this happens to it. Um. So then we make these analogies, these sort of inferential arguments that processes we can observe and manipulate experimentally now are the same ones that produce the same effects in the past. Uh. I mean, if you think about it, we do this you know any time, even in more recent time periods, when you look at an artifact, I mean, you're making an analogy with something

you're familiar with. Usually even it's just implicit. You know, obviously, um, this is a sword. You know, I've seen things like that before, and now you don't really know that you're right, but it's similar enough to things with which you're familiar. That that that's you know, that's reasonable. When you dig off something from two and a half million years ago, you've got nothing to go on, right, So we have to actually do some of this work to establish robust

or strong analogies that we can use. Now you've mentioned your own experiences creating stone tools. How long does it take you to create a hand axe? Oh? Yeah, I mean it takes me maybe half an hour. I'm a little bit slow with that. Uh, and uh, you know, it depending on how nice you want to make it. And that's already assuming that I'm I'm sitting in my outdoor lab with a pile of rocks right next to me,

and I just start making the thing. You know, if, of course, in prehistory you would have had to go get the rocks and all these other things to take a lot more time. But yeah, uh something that's that's quite good. It at it nine twelve to fifteen minutes, you can yeah. Yeah, So you mentioned that we think a lot of these early stone tools were used in butchering meat. Have you ever had food prepared with stone

tools you've made? Uh, well, let's see myself. Uh yeah, only actually recently, one of my colleagues had a pig roast where we used some of the stuff that I had made. Yeah, but back in uh in in graduate school, and it's quite common in these labs and places where people do this sort of work to have the occasional animal roast where you uh and you you learn things like you know that obsidian um is really sharp and great, but it also crumbles and leaves little bits of like

glassy kind of gridgy stuff. Yeah, not so great. I like flint, right, So do we find uh, do we find little grains of obsidian and ancient teeth? I'm not aware. Um, you know, there's always I'm not well versed in later prehistory and so as possibly there's something out about that I'm not aware of them actually getting any dental wear

from the stone tools. Of course, you get very similar looking dental where when you you eat like a TUBERSI dug out of sandy ground, so you do get cut marks on teeth, which is very interesting because uh way commonly to eat things if you don't use silverware or chop sticks or anything like that, is you hold it up to your mouth, you clench it in your teeth, and you cut away from from there, so you're cutting right next to your mouth, and occasionally they did hit

their teeth um, and so you get these little little cut marks on the front teeth and fascinatingly sorry, yeah, a lot of things can take the gross but one of the one of the cool things you can actually infer which hand was used, because there's a you know, a sort of an ergonomics. You're slicing down and in one direction, so you can tell. And so people have used that to identify really examples of predominantly right handed populations. Even the gross stuff, there's always something you can you

can get out of it. You know, we encourage you to mention all the gross stuff. We're not we shy away from that here. So how is the study of modern stone tool users such a such as a stone tool users in New Guinea? How has this informed our understanding of ancient stone tool use. Basically, the whole goal of experimental archaeology is to generate analogies that we can

observe in the modern day, uh to understand the past. Um. One of the things we have to be careful about, though, is that when you design experiments and you control things, you build in a lot of your own assumptions, even if you're not aware of them, about how things are done or why things are done and so forth. You're also dealing with a very artificial environment in the lab and without any social context or anything like that. UM. So another source of analogy UM that you can use

to understand the past is UH ethnographic observation UM. And by that, I would stress it you you can include also people, for instance, in the United States that do this as a hobby. There's a community, there's things we can learn from them. I was lucky enough to UH to visit some modern tool acres in New Guinea that are part of a different tradition UH back in I

was there UM. And one of the things that that that just broadens the number of different examples of ways to do things UM that we can use to understand

the past UM. And one of the one of the really cool things about it was I was expecting this to be a very uh you know, very foreign experience, experience to be in the highlands of New Guinea, and but once we got to the stone tools, they talked about a lot of the same things that I, as an archaeologist, was already used where they had names for the for the same kinds of features of the stone tools and they Uh so there's a real common ground there because we were all based on things that happened

when you try to break stone in a controlled way. And then that's very validating for an archaeologist because it means we can expect that, even moving them to the total unknown of the past, there's gonna be these constants that shaped human behavior, and if we can understand them today, it looks like they affect different people from very different

cultural backgrounds in similar ways, and so so that's very validating. Um. The other thing that was really exciting there is is just how they incorporated stone toolmaking into their own particular cultural and social context um, which obviously, if you study hobbyists in the industrialized West is one context, but this

was horticultural context. And the way they had a sort of a system of apprenticeship for learning this, and the just the amount of time that it takes to become an expert in the they had a particularly you know, advanced kind of toolmaking, um. But the the the sheer effort and the social values they attached to sticking with it and practicing the support they provided for learning that way, I thought. I found that to be all very inspirational

UM for my own research. So in in in dealing with the stone toolmakers in New Guinea, UM, I'm assuming there was a there was a language barrier, there is a translator. What was How did did that reveal anything or back up anything that you any pre existing thoughts about the effects of tool use and toolmaking on language and uh and then the origins of language. Yeah, well I think it was there's there's been an idea for

for some time, UM, which were increasingly are articulating that. Uh. One of the things that may have led to the evolution of language in terms of UH an evolutionary pressure or favoring language evolution is is they need to be able to teach each other. UH, and particularly the ability to teach people that you're related to, because then you get sort of the genetic benefit and all that kind of thing. UH. And in in New Guinea, it was really uh striking the amount of social support UM in

various ways that was provided for people learning. UM. I found that very informative. So of course language, you know, talking, I have to do this, don't do that, or we call this this, you know. And and um also use of language to tell stories, um, which establishes you know, sort of these cultural norms. They tell a story about someone who is a great toolmaker because he spent all of his time practicing and he neglected his yields and didn't talk to his wife, you know, and all that

sort of stuff. UM. And that the socializing that they do. They sit together and it makes it fun. Um. All of these things are really important to learning something that's very frustrating and difficult. Um. You know, maybe you can think of analogies see in your own experience. Uh. And so that that was really really cool. And then just the uh also all of the gesturing of the pointing, and just the context of having particular places where you

do things. You know, this is where we go to get the rocks, this is where we all sit down and make tools together. There was a structure, so there was so much about what they were doing socially that resulted in the the sustaining of this technology. And I thought, you know, obviously you can't just project that into a particular past context, but we need to expand our thinking broadly to think about these other dimensions that may be

implied by some of the ancient stone tools that we find. Okay, time to take a quick break, but we will be right back with more of our conversation. Thank thank Alright, we're back. Let's jump back in now. Obviously this is a different question from how the crafting of stone tools might have changed our neuro anatomy over time. But I wonder does making stone tools just change the way you in your life think about your relationship with the earth, Like do you do you find yourself out walking and

looking down and saying, oh, there's a good one. No, that's not a good one. Yeah, yeah, I mean, I mean now, I mean, particularly if you've been doing a lot recently, you can't see a rock without picturing breaking, you know. It's a uh And of course just doing being an archaeologist does that too. Um. You know, I'm always looking at little pebbles and my wife will catch me looking at the landscaping, you know, and like that would be a good hammerstone or something like that, you know.

Uh So so yeah, it does influence uh some of the resources that you're aware of that are really not particularly relevant for most people in their daily lives. But we're once incredibly central. Well, I think about ways that that that type of thinking um can take on more

complex kind of mental dimensions. Like I think about the way when I go shopping, Uh, if I'm like picking out produced to cook with, I could see like a good, fresh piece of produce and I attribute moral goodness to that, and I see like a bad, rotten piece of produce and I attribute moral badness to it. Do do you do you ever feel inklings of that kind of thing with rocks? Oh? Well, there's a certainly I don't know about the moral dimensions, and certainly a real aesthetic to it.

I mean, you know, I don't know if you're familiar with with Flint, but it's a beautiful rock and the the sound that it makes and the way that it breaks when it when it does what you wanted to uh, is just infinitely pleasing, you know. And Uh, I just got some some really nice bassualt as well, which is a very different kind of of rock and has different but also really just aesthetically pleasing And you get a

real pleasure out of out of working in. Yeah, so you said you can you can hear the difference between a good break and a bad break. Yeah, yeah, this is a question. I mean, I think it's important, and I've talked to people who are much more experienced stone toolmakers than I am that that really emphasized that, you know,

the sound is important. And in fact, we're just in the process of developing an online tests that people can take where we play the sounds of a stone flake coming off and you use a little slider to say how big you think it was. Uh So we're trying to see how much information is actually present in those sounds. Uh, I know, I know that when we're sitting around napping, everybody's looking napping being a term we used to talk about stone toolmaking, not to be confused with falling asleep,

but it's knocking, yeah, and napping. I don't know if it's German or something. They don't even know where it comes from, but yeah, knocking the flakes off. Anyway, we're sitting around knocking the flakes off, and uh, you know, all staring down at what we're doing, and then somebody will strike off a really nice large flake and it makes this flat, popping sound and everybody just looks up

over it. Then so all right, you know, uh so anyway, long, Sorry, the the we think the sound is is probably really important, and we're trying to probe that it. It keeps coming up also in uh some of the neuroimaging research that we do, or we look at uh stone toolmaking, and we get these activity in areas that are more classically auditory. And initially wasn't expecting that, but of course it makes sense.

That is interesting. And the stuff about the toolmaking process giving you all these sort of aesthetic values when you look at rocks or when you hear the sounds rocks make. Does that, um lead you to draw any connections between the origins of tool crafting in the origins of art um? Yeah, sure, you know, in a informal sort of way. Um. And and and you know people have have written about these ideas. And this is another area sort of of contention, particularly

with the hand axes. Uh. They're beautiful, right, they did. They're very appealing. Um. And there's some argument that in fact, there are much too beautiful and appealing from no apparent functional benefit, that this must be one of our earliest examples of you know, aesthetic sense. UM. But as I mentioned that, it's awfully hard to demonstrate that in a really compelling way to skeptics. Uh. Um, it's it's it

is hard to say. You do get these glimmerings of interesting things like, uh, you know, to make a hand act and will be a fossil impression of a shell that they leave right in the middle of the center of one of the sides. You know, it's sort of like they showed it off or was that an accident? Yuh Um, it is hard to say. Um, but certainly from our perspective, the symmetry and many of the aspects of these tools are very aesthetically pleasing, so we'd like

to speculate that there's some relationship. There is there any indication with any of the any particular hand axes that are particularly beautiful to modern eye that they were in any way merely ritualistic, that they I mean, they were not used. Yeah, So it's a it's a bit hard because it's actually not always possible to show that that many of the hand axes were used. You need particular preservation conditions and evidence to actually demonstrate that something was used,

so we rarely get that. On the other hand, um, there are examples of things that look like they couldn't have been used. Um. These are very rare where there would be like this really giant hand acts like the length of my forearm, you know, that somebody made, and in our imagination, it's pretty hard to come up with a functional reason to do that. So it seems to have been somebody showing off or just trying to produce a piece that is somehow appealing to them or something

like that. Yeah, it's it's it's elusive. Um, they're these these glimmerings of it. So we've already mentioned a little bit the possible relationships between tool use and UM and the development of human neuro anatomy. Uh, do you talk a little bit more about that, like what some of the leads are and what is the evidence directly for

those connections. I know some of it has to do with just like correlation of timelines, right right, Well, I mean, so there's a basic awareness so we've had for for a long time that you know, there's a broad general trend towards brain size increase over human evolution, with many

exceptions and side branches and so forth that we're discovering now. Um, but yeah, I mean, our brains are bigger than any of the brains were two millioneers, and there is a trend there also, you know, the tools over time with many exceptions and places where it didn't happen and so forth. But the most elaborate sophisticated tools around a hundred thousand years ago, we're much more complex than the most elaborate

sophisticated tools that were around two million years ago. So there's a trend there, and there there's two trends side by side, and you know, like think maybe they're related to each other. Um. Now exactly how they're related to each other is a more difficult question. You know, did the brain get bigger and for other reasons that then spill over into being able to make tools or where

the tools really important? So that like if you could make a if you're a little bit faster at making a tool, more reliable at making a tool, you had a little bit of a reproductive advantage, then you know, than than then maybe the tools drove it um And those are hard to uh discern exactly. So that's why we we try to do some of these experiments where we relate the actual process of making tools. We try to figure out, well, what does it demand cognitively neurally?

If there were pressure on being able to make these tools. These are the things then that would respond to it. So that's we're just trying to sketch out some of the basics still at this point, I think to make that link and to do that, You've done some research with the neuroimaging and and how that relates to thinking about tools to making tools. Could you tell us some more about that. Yeah, So, Uh, We've done a couple

of different things. UM. One is what most people are probably more familiar with, which is a functional neuroimaging, which typically works somehow related to to blood flow in the brain responsive neurons, so when they're active UM, and so we can isolate those areas of the brain UM that are more active when you make a particular kind of tool, you know, for instance, the hand actions that I was talking about versus the earlier, simpler, older one style tools,

and we can say, oh, well, this is the neural system related to these forms of cognition UM that is required to do that. So if there was something that changed in the past associated with this technology, is most likely to be those systems. Uh. Then the other thing that we do is actually structural stuff UM. And that comes in two flavors. Also, you can, uh, you can look at plastic changes in the brain that are caused

by a behavior. And this is something that in the past, I guess about twenty years or so, people really become aware that, even over short periods, doing things learning to juggle, actually changes the physical structure of your brain, especially things like white matter uh that sort of the cables that connect things in your brain. UM. And so we've applied that also to stone toolmaking uh and seeing that training to make hand access, for instance, will increase certain white

matter pathways in the brain. UH. Interestingly enough, these are also white matter pathways that are larger and modern humans versus chimpanzee. So we know that it's something that has evolved in our history and we can relate it to a behavior that also is observable to have come along at a certain time in our history. So we started to strengthen this sort of infrenial Well, maybe these things

are related to the evolution of that pathway. UM. The other thing that we can do that we're really just starting to look at is uh individual differences in structure and function of people. So if you get a large enough sample, there are small differences for instance, in the rapidity with which people learn uh different kinds of stone toolmaking, you know, and you can then correlate with starting differences in their brain structure or the way that their brain

changes over time. And I think that's really exciting because we can then also relate that to uh cognitive tests. So you know, some of the initial stuff that we're getting is you know, so if you're particularly good at uh planning. For instance, there's a task called the Tower of London, which you move sort of rings around on three pegs and you have to do it in a particular order. Uh. If you're good at that, you learn

stone tool making faster slightly. Uh yeah. I think that's really really fast because we're actually making these links between particular cognitive operations and kind of types of stone toolmaking that we can see in the archaeological record. Now, now that the test subjects who learned how to make stone tools and then you saw the changes in the brain, Um, were any of them engaged in any activity that was comparable to stone tool use or construction, like carp injury

or anything prior? Uh yeah, Um, so we actually have uh data on that that we haven't analyzed yet. We have people right about their other hobbies and activities. And actually we've got a big pile of stuff we've still

got to go through in that study. Um but you know, uh, sort of anecdotally, I do know that there were people from a bunch of different kinds of professions, like we had teachers, we did have one sculptor in the project, and so there we don't yet, um have any hard conclusions about that, because we need to work with the data.

But one general impression I got there was a little bit counterintuitive, is that if you have more experience with some of these things that you might think of as being you know, conducive to knowing how to make stone tools, you can actually interfere if you're sort of setting your ways. Um. Um So, but there's a lot more to be done

with that. And one of one of the things that it bothers me is we always do these studies, you know, with the the typical college undergraduates, and they're not really known for being particularly good with their hands. So, um, I would really like to expand into different populations in

different ages. And but you know, we're just getting started, because that's where you would find individuals who were, say, skilled craftsman craft people in other in other areas, right, yeah, yeah, yeah, and just just people that are more commonly doing work with their hands, you know. Um. Now, I work with people out when we go do excavations in Ethiopia and

the aar Um you know is there's their pastoralists. They have herds of animals and they you know, they make little walls out of stone all the time, and I mean they're a lot more handy. They might pick it up a lot faster. So obviously getting the population you want is one experimental challenge. I would imagine another one if you're if you're trying to do neuroimaging while people are engaging in tool tool making. The I mean, don't you have to hold still say for from R I, Yes,

for fm R I you do. Um. So there is you know, a couple kinds of workarounds. One of them is the the the the the earliest studies that we did, you know, about eighteen years ago or more. Now, we used a technique called f DG pet UM and positron emission tomography UM is something they don't use a lot

for research anymore, and brain activation. But one of the things that lets you do is we injected a radiological tracer UH into their bloodstream and this is a glucose analog UH and so it's taken up by basically hungry cells in the body like they think it's glucose. Happens in the brain and neurons UM and then it emits radiation small amounts, but this can be this can be detected by you know, a sensor array around the head.

So basically you can give somebody this injection, have them do anything you want really, like they could run around the block and but we have them sitting in a chair and make stone tools in an nonconstrained way. Then you walk them over to the scanner about half an hour later, I have I've been doing this for half an hour UH and you collect an image of where the gluco is built up right. UM. So this is great because you can do it UM and have them

do real tasks outside the scanner. UM. But it's limited because you know, you've got time averaged over half an hour, and you can only do a couple of different conditions because it does involve radiation exposure and you don't want to give anybody too much and so you know, UM, the fm R. I you mentioned you have to be still,

but we can take advantage of the fact that. Let's get a little theoretical, but neuroscientists have largely converged on the idea that one of the ways we understand what we see other people do is to internally simulated ourselves in fact using the same neural systems. UH. And this is probably an important way that we learn from others

as well, which is an important research question too. But we can take advantage of that, and we show people films of toolmaking in the scanner, and so this is most directly relevant to observational understand ending and learning from other individuals. UM. But it does pretty much use overlapping systems with execution, and we've shown that, so that's another

sort of work around. And UH, colleague of mine, Shelby Putt, is using something called functional near infrared spectrography ay F near as anyway is what I what I remember, UM, and that actually uses near infrared visible light that can penetrate the cranium and get some information on blood flow from superficial areas of the brain, and that you can

wear while you're doing something as well. So there's some a few workarounds that you can do to actually use neuroimaging techniques, and I wonder, um, are there I don't know if anybody's looked at this, but would there be differences in the brain between um, doing doing a task and stone tool creation and simply imagining the task because of all, you know, we've looked on the show a bunch of times about simply imagining doing something is very

similar in the brain to actually doing it. Yeah. UM, so it's similar in very interesting and important ways, but also different in important ways, and particularly in the context of stone toolmaking, where some of the things that were interested in are the actual skill to really deliver the right amount of force to the right place. Um, we

want to actually tap into that somehow. Um. We did do an experiment though, um, in which we were more interested in the uh, the kind of planning aspects and the evaluation aspects, and we had just people looking at stone tools and answering questions about what would be the good thing to do next, which is basically asking them to mentally imagine and simulate the actions, and you tap into different aspects of the task demands there. So we

can use both. But but there are aspects of stone tool making that are very reliant I think on actually doing it. All right, we're gonna take a quick but we're gonna jump right back in with our interview. Thank thank alright, we're back. Just recently, I happened to be reading a couple of papers in UM, I think Frontiers in Psychology. I believe about the possible role of UM,

possible role of tool use in the development of consciousness. Uh. The the idea under this new framework was that maybe consciousness has something to do with creating states of objectivity in the mind where you can sort of like imagine and correctly judge the properties of an object that is not yourself. UM. I don't know if you've read that, Mariano. No, this was Oh I'm sorry. I can't remember the guy's name, but he's from Europe somewhere. I think he might have

been mas streaked. Okay, yeah, I don't I don't know that, but um yeah, I mean there are potential uh links between consciousness. This is great for me. Actually, I I told you how I, you know, got into this. I thought I wanted to be a philosopher and all this certain I'd love to get around the consciousness. They say, you know, you wait till after you have tenure, maybe wait to get longer than that. You know, maytel you're

all the time. Um, but I do think there is a potential that there there might be some way we could gain insight there. You know, if you think about what are the things that actually require consciousness, Like what is consciousness actually good for? Um? And you know some people have said basically nothing, uh you know, but but if there is something that it's good for, it's for tasks that require attention. I mean, that's what consciousness is.

It's attending to things, uh, really getting the whole brain on board, uh, you know, and focusing on on this one thing. Um. And I think that uh, learning a skill like stone toolmaking is the kind of thing that demands that concentrated attention. And if consciousness is the way that you get that, if consciousness is the feeling that you have when you fully attend to things, then then

then maybe there is a relationship there. I mean some of the other things people you can as you know, you can get into a car and uh start thinking about something else and drive to work when you meant to go to the store and so forth, which is you know, this sort of zombie stuff is pretty scary. Actually the things that you can do without being aware of it, um. But things people can't do are sort of sustain hopefully conversations like what we're having here. Uh,

you know, the stay focused, um, very skilled activities. I mean, if you're like a race car driver, you wouldn't drift away and think about something else that demands your attention, demands consciousness. UM. So I think when we pick up tasks in the past UM that required people to really focus and attend UM, we might be picking up things

that are diagnostic of the need for conscious states. Of course, one of the interesting things about tasks like that, like work with your hands, is that it requires a lot of consciousness when it's new to you, and over time

requires less and less exactly. And that's why you know, unfortunately we we really have to focus on study being uh people who are learning um rather than you know, expert performance is still interesting in many ways, UM, but if you want to get at the real demands for something like conscious attention, that's going to happen when you're figuring it out later on. And I mentioned to some of the people that can make a hand act really well, and like, you know, twelve minutes, they don't have to

think about it at all. Um, Someone like me, I have to attend to it so much that what always happens is I, you know, I I give demonstrations of napping, and then I will always wind up cutting myself because trying to talk about it and do us you know, and you're not focusing on it. Um. So yeah, it is the more skills you get, the more you can ignore the low level stuff and think about something else, you know, like making it a really appealing hand ax

versus just trying to get something you can use. Do you happen to find that the most beautiful hand axes are also the best to like, the most functional, useful or those things generally aligned or not aligned. You'd be surprised the things that we don't know about stone tools because of the amount of time that it takes to do proper experimentation and actually test these sorts of things.

So that's something that people are interested in, but there's only been a handful of experiments, um that actually looked at you know, is the symmetry of the hand acts make it a more or less effective butchery tool? Um, does the straightness of the edge matter? Um? Do any of the things to the thinness of it matter? Uh?

And to the extent that has been shown, like the things like symmetry don't seem to really matter very much for the function uh the UH the evenness of the edge does seem to be important, and that might be aesthetic for some people. UM. The sort of extreme thinning of the hand axes that we find very appealing, I think because it's hard to do, is something that you know, maybe somewhat beneficial because you have the tool you're carrying

around is lighter. Um. But thus far, there's not a lot of evidence that things we think of is really aesthetically important about hand axes are particularly functionally important. So there is another question we may not know the answer to. But do you think in general, is it more widely assumed that people in the uh prehistoric times would make a hand axe and and that would be their hand accidentally carried around with them, or is it something that

would be made on site when it was needed. Yeah, I mean, I think it's important to uh, for archaeologists and for everybody to to remember when we think about the past that these is a huge amount of time over a large area. Um and they probably did just about everything at one uh time or another. Um I. It's some sites where you're sitting close to raw materials, you know, like there's a site of box grove. It's it's pretty close to these chalk cliffs where the flint

is coming right out. They seem to have used them lightly and discarded them, probably made them pretty close to the time that they were going to use them, and that sort of thing. Um elsewhere, they may have actually carried them around for when you don't have as much rock. You know, when you're going far from the source, you probably take the hand next with you, and when it gets dull, you re sharpen it and all these sorts

of things. Maybe you keep using it till you've whittled it down the way we do a pencil nub, you know. Uh So this is an area people try to understand, um basically the economics. This is sort of an economic question. Uh you know, when does it make sense to just toss the hand as versus you know, carrying it with you and resharpening it. And it seems to be driven by the things you would expect it to be driven by. Like distances from raw materials and the kind of activities

that you're doing. So you probably get asked this question a lot, especially this year since it's such a milestone year for the film. But we recently talked about the about two thousand and one of Space Odyssey on the show. UM what are your thoughts about two thousand one of Space audi specifically of course, these scenes of these these

ancient creatures engaging in tool used for the first time. Yeah, well, I mean, as you may you may be aware of that two thousand one was actually UH produced in consultation with archaeologists and paleo anthropologists, so it was informed by current UH speculations hypotheses about the origins of technology at the time. UM. I think that we have a a

different view now. UM. I think if you would ask most most archaeologists about the origins of tool use and technology, they get very excited about things like cooperation and collaboration UH as as being a real turning point for for humans, and we are very cooperative species and this makes a

lot of things possible. Whereas that vision UM was much more about the importance of killing each other UH and the sort of you know, the the killer ape basically, And if you want to take a step back from that, there's a lot of my my other colleagues and in anthropology and other disciplines who might point out that these things are heavily influenced by our own social views at the time about what's important, because some of it's is, you know, uh, myth make about human origins and what

we think human nature is, and after World War Two it seemed pretty obvious we're all about killing each other. Right now, we'd like to think it's about cooperation. Uh. I don't want to get too heavy on that, because there actually is uh empirical are there are empirical arguments that can be made about this, in particular looking at comparisons across species and the importance of cooperation versus competition in different contexts. So there is a framework for for

doing this. But it is interesting to think about our biases. But are certainly two thousand one fantastic film. I like, I wish the introductory segment we're a little bit quicker because I like to use it in my classes, but we have to sit there for like half a students aren't up for it. Um. Yeah, So I think it's Uh, they did their best to work with the current understanding at the time. It's a great movie. This is another realm where we might ask you to speculate if you're comfortable.

But one of the things we talked about with two thousand one was the idea that you know, so when the ape like creature is first encounter the monolith in the in the savannah, UM, they they are changed in some way. But it's often assumed that maybe this is some alien technology that goes in and changes something in their brain. But an interpretation we talked about in the episode is one that that's actually not what happens. That what happens is they see this object in their environment

that it's nothing like the rest of their environment. It looks completely artificial, and it's simply seeing that spurred something in their imagination that allowed them to to take up the tools. UM. And that makes me wonder about what what what would you imagine could be the role of simply seeing things in the environment to inspire the taking up and creation of tools. Yeah, I mean it's probably, uh,

probably very important. I think this is the kind of thing that that archaeologists are loath to actually talk about because you're talking about like, uh, you know, individual acts of invention um that happened in the past, whereas the sort of the record that we have is this really really high level, averaged sort of sort of thing. Um. So it's hard for us, I mean, but clearly, you know,

we shouldn't forget these things are inventions. They're not like mutations or just inevitable things that happened like somebody at some point had a new idea and did it. And then whether they were inspired by particular things in their environment. We like to think about, well, what kind of what were the kinds of things that they commonly encountered, and

we could have some leverage to talk about that. You know, if they moved into a bit of a of a foraging niche, then they may be around these animal bones, you know, if there are stones available. Uh, if they cracked nuts um occasionally, as chimpanzees do, you're going to accidentally fracture the rock and and you know you could imagine imagine an aha moment there. But those are things

that are very difficult to actually get to. Um. What I what I will say about the vision in in two thousand one is that it is an idea of a transformative moment um, and this is something that was also very current and maybe is to a certain extent, the idea that the invention of the earliest stone tools should be some kind of transformative, great leap forward that you know, that changed everything, and that doesn't seem to

be the case. Actually. I mean, we now have one site at three point three million where they made stone tools, the next one is at two point six million, with nothing in between. Now we're going to find eventually something, but it's not a lot. It didn't like take off and go crazy, and and even at the two point six there's just a few and it's not around two million years ago that they start doing this regularly in a lot of places. So there's this huge long period

of time where they're again stone tools. Maybe you could do it sometimes when it's worth it, I don't know. And so it wasn't like this sort of you know, gun that went off and everything changed, which is a different perspective than what we used to have. Well, it thinks it makes me think about even today and in

modern society. You know, you have a new business as a new type of product, and it's always losing money at first, right, Uh, it makes me wonder if, yeah, were these things um more trouble than they were worth to begin with, and how if that's the case, how would you get through that? You know, how would you trust it to keep making them? Yeah? I mean it's

hard to say. I think you know, my my favorite sort of pet hypothesis right now is that, yeah, it was just too too hard, in particular the investment in learning how to do this, uh, you know they did. Those were smaller brand individuals. They didn't have the same learning capacities that we have, and for whatever at the time,

I think there was too steep a cost. I mean, occasionally it seemed worth it, um, but only a few individuals would learn, and and then they had to spend so much time figuring it out that you know, it was didn't really give them that much of an advantage.

And then it was just lost in a small population, and nobody did it for however long you know, um, but you on long enough, and there may have been some selection either on the toolmaking or on other things that they were doing that eventually lowered the costs for them a little bit. It wasn't quite such a stretch to be able to do this, and that's where I have the chance of it actually paying for itself and

then it would take off. So that's currently because when it does take off around two million years ago, it's very close in time to the appearance of Homo erectus, which has a larger brain and body, So you know, coincidence. But they've messed around for a long time until something changed about the cost benefit equation. I think, Ye, so many tantalizing mysteries. I'm just imagining these sort of many

dark ages. Uh, and they're learning huh. Yeah, I mean if you think of these small groups very isolated, you know, I mean, somebody could have a great idea and then you know, they have a bad year and everybody dies, and that we think of it again for five years. I'm sorry, we keep asking you to speculate about stuff. Uh, these are the kind of questions we love to ask. But yeah, I mean, obviously people should understand that there there are tons of limitations on what we can know

empirically about things this far in the past. So besides what we've talked about so far, what else do you find most fascinating about studying Stone age technology? Like what really gets your gears going about it. I mean, I guess, uh one thing, maybe it's a bit a bit technical.

We we we started to talk about the relationship between stone toolmaking and language, and one of the ideas that we discussed is that it created selective pressures that benefit for being able to communicate better, which eventually led to language. But there's another idea that, uh, that there's a more direct connection between toolmaking language because they might depend upon

some of the same cognitive and neural systems. Right. Uh So this is an old idea, you know, relating to the idea that there's kind of a syntax of action, that the way we structure sequential actions is similar to the way we structure words and a sentence. In fact, words and a sentence are sequential actions. Uh. So there's

clearly some really important differences. Um. But there's also the possibility that some of the systems that we use just to put together complex sequence of actions and toolmaking are also important to language evolution, so that if you had selection acting on toolmaking, it would provide a foundation from

which then you could get language evolution. And you know, some of the work that we've done generally uh supports that idea that there is overlap, particularly in what people call Broca's area of the inferior frontal gyrus, which is related to language processing but also uh to putting together complex actions of other kinds. UH. And so currently what we're working on is actually putting a people in the scanner or showing them videos of toolmaking, have them listen

to language. UH. We use computational methods to to parse the structure of the language and the structure of the toolmaking, and we see if the kind of the syntactic structure that we see in the toolmaking and in the language produces the same responses in the brain. And UH, that's not done yet, but so far we have some encouraging

results along those lines. So this this idea that uh, basic action sequencing and statistical learning that you would have for putting together complex actions provided the foundation for language evolution is something that I would like to continue pursuing.

That's fascinating. I mean, if you even if you just think about your experience in there, there are ways that putting together a sentence can sometimes feel somewhat analogous to step by step activities with the hands, like the way that uh, you know if you're used to speaking, or if you're used to doing an activity, it can happen

like we were talking about, mostly unconsciously. But then there are those moments where you feel you're maybe ready to break the sentence or something, and you slow down and it becomes more conscious. Um. Anyway, that's just what made

that made me think of very much. So, Uh. You know that Morton Christensen is another colleague of It's written a bit about the concept of language as a skill, and you think about it, uh, trying not to think about it while I'm speaking, and that that's the point, because if you're attending to exactly how you're enunciating the words and so forth, you lose the threat of what you're trying to say. So you need to be able to very rapidly translate sort of a high level in

tension into very particular motor actions. And then when you talk to me, I have to very rapidly translate what you're saying into a sort of a loose summary. I mean, I can't remember exactly what you said five minutes ago, but hopefully I have a general idea of what we've been talking about. Uh. And so this is skill, it's It's just like when you uh, A famous example a is you know, skiing down a mountain slope. I mean, initially, if you don't know what you're doing, you're focused on

how you're positioning your feet and so forth. Later on you can ignore that and focus on, you know, skiing the slope, and and so your focus of attention moves. Um in this the same language and toolmaking, and I think the neural systems are related to each other. Yeah, it's kind of like how if you I think they're actually even studies of this that if you focus too consciously on, say like shooting a basketball, you get worse at it. Yeah, yeah, exactly experienced the flow. Yeah, you

have to, you have to. You have to automate a lot of it. Yeah. Well, Dietrich, this has been so great. Thank you so much for joining us today. Thank you, thank you. I really enjoyed it, alright, So we hope you enjoyed our conversation with Dietrich Stout. I know Robert and I did. Um. So if you want to follow up and check out any of the centers we mentioned, like the Center for Mind Braining Culture that's c MBC, dot Emery dot E d U but you can also we'll put a link to that on the landing page

for this podcast. You can also check out the Paleolithic Technology Laboratory site at scholar Blogs dot Emory, dot e d U slash stout lab. And then there was one more thing that Dietrich emailed me about. So he talked in the interview about the role of sound in toolmaking, and so he sent me actually a link to a study where you can be a participant in trying to uh.

It's a study where they ask you about your experience with certain types of you know, like playing a musical instrument or something like that, and then you get to listen to different stone napping sounds and estimate the size of the chip that was produced by the sound you're listening to. I guess, not produced by the sound, but that the sound was correlated with And we'll make sure the link for that is on the landing page as well. In the landing page for this episode, you will find it.

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