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More Projectile Ballistics with Dr. Devin Pettigrew - Ep 170
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On this episode of ALiRP we are joined again by Dr. Devin Pettigrew to talk about his three recent publications. All three discuss experimental archaeology methodologies and the need to revisit the accuracy and precision of previous research under modern techniques.
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Transcripts: https://www.archpodnet.com/ruins/170
Links
- Basketmaker Atlatl website: https://basketmakeratlatl.com/
Literature Recommendations
- Terminal Ballistics of Stone-Tipped Atlatl Darts and Arrows: Results From Exploratory Naturalistic Experiments. By Pettigrew et al., Open Archaeology, Vol 9, Iss 1, Pp 799-820 (2023).
- On the (Non-)Scalability of Target Media for Evaluating the Performance of Ancient Projectile Weapons. By Pettigrew & Bamforth, Open Archaeology, Vol 9, Iss 1, Pp 799-820 (2023).
- Reassessing the terminal ballistic performance of trilobate and quadrilobate arrow points on Iron Age battlefields. By Pettigrew & Taylor, PLoS ONE. July 26, 2023, Vol. 18 Issue 7, pe0288483 (2023).
Guest Contact
- Devin’s Instagram: @ar.atlatl
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Transcript
00:00:00
Speaker
You're
Introduction of Hosts and Guest
00:00:01
Speaker
listening to the Archaeology Podcast Network. Welcome to Episode 170 of the Life Ruins Podcast, where we investigate the careers of those living life in ruins. I'm your host Carlton Gover, joined by my co-host, David Ian Howe. Connor cannot be with us today. He is not dead. He's unzipped.
00:00:22
Speaker
Yep. Yep. But for this week, uh, we are joined by Dr. Devin Pettigrew, who is actually realized like one of, uh, the leading guests on the show and actually debuted on episode 18.2 as like a, as a guest host, not even as a guest proper. We came in, interviewed, I think that's 18.2. All we are is Donnie dust in the wind, uh, had him back on immediately after episode 19 episode 75 and also episode, uh, one 12. So we've like,
00:00:50
Speaker
Devin appears in very pivotal points of this podcast.
Dr. Pettigrew's Recent Work and New Position
00:00:54
Speaker
He's been evenly spaced. And we have him on now to talk about, he just had three articles dropped this year recently, all on weapons ballistics regarding the archaeological record. And he is also an incoming professor to what university, Devin? Soul Ross. It's in Alpine in West Texas.
00:01:18
Speaker
That's gonna be a fun time. I'm really happy for you. Yeah, I'm excited. They have a really strong wildlife management program. And so a lot of what I do is hunting focused and they have really incredible archeology down there and they want to open up an experimental archeology lab potentially. So it's going to be cool. I think that sounds awesome and pretty suited for you. Yeah. Surprisingly well suited.
00:01:44
Speaker
Yeah. And I hope you definitely argue for these three papers to be on your tenure packet because your first year is golden. If you have these three, like you're definitely on track. So the titles of these articles, we're going to put these in the episode description. We have reassessing the terminal ballistic performance of trilobite and crotch, crotch lobe bait.
Discussion of Published Articles
00:02:03
Speaker
arrow points in the Iron Age battlefield. That's by Devin and Dr. William Taylor who's been on the podcast. Terminal ballistics of stone tipped adelital darts and arrows results from exploratory naturalist experiments. And in that one, you can see a very great picture of me.
00:02:16
Speaker
with my belly hanging out, looking through a cannon, through a camera, not a cannon. And then the last one is on the non-scalability of target media for evaluating the performance of ancient projectile weapons. And that's with Devin and Dr. Douglas Banfforth from CU Boulder. It was really fun for me just to look through your illustrations, Devin, because I recognize a lot of these things. I recognize rolled office space where you had a crossbow set up in the lab.
00:02:43
Speaker
And you've been talking about this on the podcast since you've been on. You kind of watched the beginning, like your research back in 2019 as you defended. I mean, now we're looking at like these published peer reviewed results outside of the dissertation defense media. So
00:03:04
Speaker
I mean, just kind of walk us through. So one of the big ones, well, we'll kind of wait for the Iron Age stuff last. But when we're talking about, prior to your work on weapon ballistics, how were archeologists studying the effects of projectiles on past human populations, but also in hunting practices?
Controlled vs. Naturalistic Experiments
00:03:28
Speaker
Yeah, sure. So there's a couple different ways. And I think on the last episode I was on, we talked about the differences between a controlled style experiment and a naturalistic experiment, the controlled one being where you're like in a lab kind of setting, you're trying to isolate some variable or variables of interest. And so it's very kind of artificial, you know, like it's,
00:03:55
Speaker
Imagine a bunch of guys standing around in the lab coats. That's not the past. The naturalistic style experiment where you can imagine being out of doors. You have actually human users launching weapons. It's really hard to control for variables in that setting. So they both kind of have their strengths and weaknesses. Prior to my work, archaeologists have been doing both for some time.
00:04:23
Speaker
And I would say it seemed like as I looked through the literature that controlled experiments were becoming more and more popular. And so a big issue I ran into is that in a control type experiment where you're in a lab kind of environment, one of the ways that you control variables of interest is through the targets that you're using. And so people tend to try and use these artificial
00:04:53
Speaker
Target media like ballistics gelatin is probably the best known. And so I discovered more or less that those target media aren't working that well for studying the type of projectile that we're studying. They're really quite different from bullets. And so you just can't assume that the same target media is going to work the same way. And in fact, you get pretty astoundingly different results, shootings,
00:05:21
Speaker
an arrow into ballistic shelter than you do into actual flesh. So that's really the big difference. And then the naturalistic types of experiments I carried out are carcasses. The big difference there is that the way I employed high-speed cameras allows you to track the projectiles that's coming in, track its velocity, and then track how it decelerates as it penetrates through the carcass, and then you get like a force feedback. So that was pretty
00:05:51
Speaker
Pretty interesting. So, I mean, it just kind of seems like, I mean, I use ballistics gel in my experiment just cause it seemed like ballistics gel is the medium you use to test penetration. So I see my archaeologists before us just kind of assumed the same. And so did I, yeah, for my usage as well, for my master's research. Okay. It's just, yeah, it's a totally a flush to me. I mean,
00:06:16
Speaker
Yeah. No, it makes sense. I think I might've mentioned this last time you were around, but frizzen like chewed me out for using those six gel and not like, and like a practical experiment. And I was like presenting to the board. I was like, well, I mean, if you want to pay for me to get an elephant to shoot at, like I'd love to, it's like all I could really say, but yeah, you got to buy some. So that's the next best thing. Yeah. It took a lot of work, but we've done three different bison experiments now.
00:06:46
Speaker
still hoping for an elephant sometime in the future, but things are going to have to play out just right for that. Yeah. The seventies were definitely a different time. They were.
00:07:01
Speaker
Well, the logistics alone, like you have to one, be on a list for the, what, the Denver zoo or the Bronx zoo and then San Diego zoo. And then a day later be able to fly out fully stocked with atlatls ready to be experimented with or else that thing's going to start to rot. Yeah. Everything's got to be ready. Exactly. There was a paper I read. It was never published or was one of the most useful outlet, all elephant carcass experiments.
00:07:29
Speaker
I read about because the guy said, I threw together my kit the day before and it was like sharpened wood points and stuff and got pretty lousy results in the take-up messages. Be ready in case an elephant drops dead at your doorstep. I was like, okay, so now I have like 40 close points on standby for just in case. But you know, the way prison did it, he went to Africa.
00:07:59
Speaker
during a cooling operation and He actually wasn't that well prepared He kind of threw together his kid a little bit and then in the field he had to break it down To get onto the plane and then the field he had to reconstruct it and had he ran into a bunch of issues with that and I think he had seven total close points with him and he made a few shots that convinced him that the weapon would work and
00:08:26
Speaker
But his results aren't that well documented. So it couldn't be done again. But it's important to get all the ethical issues lined out and find a good source for a fresh carcass. Absolutely.
00:08:45
Speaker
What I really like about these three articles is how they really come as a package deal. They came out close enough together. You can tell there's different aspects of your dissertation.
00:08:59
Speaker
in each one, right? So like one is basically like the most recent one. I don't know if it's the most recent, but it was accepted in May of 2023, the target media. So you're basically just like, here's a whole article on, and what you've discussed on this podcast, why ballistic gel and these other variables, we need more control over these things, why they're not necessarily adequate. Then you move into
00:09:23
Speaker
with your terminal ballistics, a stone tip to add a little darts and arrows. Your actual experiments, the target velocities, and introducing more methodology. How do you do this in a very naturalist experiment? And then the third is kind of a case study of doing this on
00:09:39
Speaker
Iron Age battlefields. Like that one kind of threw me for a loop because when I think of you, I don't necessarily think of Mongols and Iron Age points. I was like, wow, okay. And then when I saw Dr. Taylor as a co-author, I was like, oh, I wonder where the data is coming from here on this one.
Open Access and Feedback on Articles
00:10:01
Speaker
So that, I mean, I just think it's just absolutely fantastic. But yeah, so since these, before we kind of like dive
00:10:09
Speaker
Well, and it is what's, what has the reception been to your articles? If, if any, so far I'm not hearing a lot. So hopefully people will get out there and read them. They're, they're all open access. The first two, the one about targeted media and the one about carcass naturalistic experiments are in open archeology. And then the third one on iron age, your appoints as a plus one. But so far I'm not seeing.
00:10:39
Speaker
direct responses. And I mean, could you say that some of the ones you were doing were in response to the, I forget the author of came out last year about the, um, where they were shooting into pottery points, more in effect. That's right. Yeah. There have been several experiments at Kent state university in Ohio, shooting into pottery clay is a, uh, flush stimulant.
00:11:07
Speaker
So I did tests on pottery clay as well as ballistics gelatin. I used a synthetic ballistics gelatin that you can melt and recast. And then I tested a variety of different skin simulates because skin simulates, although in firearms terminal ballistics, they're, they're mainly focused on flesh simulates, flesh being like muscle tissue mixed with blood vessels and little bits of fat stuff. It's mainly muscle.
00:11:37
Speaker
Skin stimulants are used primarily in studies of knife stabbings, which is a whole body literature I got into. I think most of the work is done in England, but they're researching the efficacy of different knives, thrust into people as a way to have another line of evidence if you're evaluating a crime scene, or if you're trying to protect your police force,
00:12:06
Speaker
with body armor or stab protective body armor, that sort of thing. So they use skin thingals because skin is the most resistant soft tissue on the body. And so the first thing that the knife has to do, aside from clothing or body armor, is it has to defeat the skin. And once it gets through skin, it can penetrate into less resistive flesh. And then especially the internal organs tend to be a lot less resistant. So I try and evaluate dark scenarios.
00:12:35
Speaker
in those three different categories of media, the two flushes, you know, it's clay, it was just ultimate skip. So yeah, the testing, all those was in direct response to a number of papers that have come out that have used those types of media. And I guess to follow up with that, I didn't get a chance to read the Iron Age paper.
Iron Age Arrow Points Study
00:12:55
Speaker
Would you be able to tell just like a quick synopsis of what that paper was before we dive in?
00:13:02
Speaker
Sure. Yeah. There was a prior experiment that shot trilobate and bilobate. That's simply bilobate is two blades and trilobate is three blades, bronze arrow points that were collected from Neo-Assyrian sites. So around seven to 600 BC, shot them into pottery clay and discovered that the bilobate points, the two bladed points penetrated better.
00:13:32
Speaker
into clay. And so it was confusing because around 700 BC, trilobate points enter into the Near Eastern record. They're coming down from the North because they were invented in the North on the Eurasian steps by presumably precursors to the Scythians or the Scythians themselves. But any event they entered into the Near East,
00:13:59
Speaker
And then they spread throughout the ancient world. So it was confusing as to why it would cause them to spread or become popular. So I essentially reran that test in clay and then I did an additional test in a really thick, heavy, stiff tooling leather because people were wearing body armor.
00:14:21
Speaker
and soft body armor specially made of leather primarily but also fabrics like linen that was very popular in the ancient world and people continued to wear it into the medieval period so on a battlefield event a lot of times the arrows are probably going to be having to defeat body armor before they can
00:14:41
Speaker
enter into the body of the combatant. So the leather was just an analog for body armor. And I got pretty much the opposite results shooting into leather rather than clay. And those results being that it was tougher to shoot into the leather? Yeah. So, uh, stiff leather is unsurprisingly, it's very resistive and it's resistive when the broad head penetrates it. And then it continues to be resistant as the arrow passes through it. So we shot into clay.
00:15:11
Speaker
And when the previous experimenter shot it in the clay, you're capturing more friction on larger surface areas. So if you attach additional blades, you're just attaching more surface area to your arrow and it creates more drag and it penetrates less. In the weather, you do get a little bit extra resistance when a broadhead with an additional blade goes through the letter.
00:15:38
Speaker
But it dramatically reduces the drag on the trailing shaft of the arrow. Okay. So you get a significantly better penetration after that initial, you know, defeating of the weather. Okay. So, so the idea is like, when these points enter into the near East from the North, we can't just assume that they are
00:16:01
Speaker
representative of an ethnic group. That's been done. Archaeologists were doing that. I think mostly earlier on, but apparently this has been a continual problem. If you're not looking at a battlefield doing battlefield archaeology, you can't just assume that one arrow point represents one ethnicity.
00:16:21
Speaker
Right? There's all sorts of problems with that. First off, how do we even identify an ethnicity and their ecological record when we have enough trouble doing so today? I mean, you know, do people want to? It's a tricky problem. But this just adds another line of evidence that, hey, this is a technical functional, it's a technological innovation.
00:16:43
Speaker
on the battlefield. And it's not necessarily just that you're going to want three blades at three blade arrow points from now on, because if you shoot at a different target media, you get different results. So if you're defeating, attacking points with shields or different kinds of body armor, maybe in different cases, two blades will be better than three. But certainly three blades became really popular and were just completely adopted by the Roman military and a lot of other, a lot of other folks.
00:17:13
Speaker
Well, we're going to wrap this segment up. I have plenty of questions regarding that stuff into the next segment, but yeah, Carlton, you got anything? Yeah, we'll be right back with Tim and Pettigrew after these messages. We're going to get into more of the math and have him explain a couple of these very colorful tables. So we'll be right back.
00:17:30
Speaker
Welcome back to episode 170 of a Life and Ruins podcast. I'm David Howe. I'm here with Carlton Gover and Dr. Devin Pettigrew. Also Dr. Gover should add that. So we want to move on to the other papers, but I do want to ask when I typed in trial of eight points, the second thing that comes up is your recent paper. So
00:17:50
Speaker
My question would be, one, I'm assuming these were used by horse archers, if they're precursors to the Scythians. And two, do you have any idea why that style took off around the ancient world? Or was it designed for shooting other horses or something? Well, yeah, if you had additional blades and they, and the arrow penetrates well, you get a much worse wound, you know, especially like a three bladed wound. It's really hard to treat that. And it's, it's just more deadly. So.
00:18:18
Speaker
So if you're shooting at horses, yes, certainly a horse is on the battlefield. You want to use a big broad head. And people talked about that in the medieval period in Europe. Actually, the long vote is extremely, could be extremely effective at defeating horses. So if you have a Calvary charge at a good group of archers, I mean, that can go very badly for the Calvary. It was the French learned at Ashmore. Yes, exactly.
00:18:46
Speaker
So yes, broadheads are effective there and three blades can make worse wounds. But what's interesting on the northern steps, and I can't get into too much detail, but these bronze points are essentially copying bone points that came about towards the end of the Bronze Age. I think they were used certainly earlier in the Bronze Age, but by the end of the Bronze Age,
00:19:16
Speaker
on the steps, the bone points, the socketed triangular and trilobate bone, bone points were becoming really popular and then they were replaced in their early iron age by bronze points, which is interesting that they switched over to bronze. But one of the ideas in the iron age, one of the ideas here is that to make a three-bladed point from iron is actually very challenging and it takes a lot of effort.
00:19:45
Speaker
The Romans were using three-bladed iron points, so it shows how important it was for them to make that style of point from iron. But earlier on, they were casting a amount of bronze, and so the idea is it's easier to cast them from bronze. And if they were working better on the battlefield, that helps explain why they spread relatively rapidly.
00:20:13
Speaker
Okay. No, that's pretty fascinating. I was watching kingdom of heaven the other day and I was thinking too, just when you were talking like the sheer amount, not even the dead bodies, but you got to pull all of those dead horses off the battlefield as well. And that probably took much more labor or you just left the horses to rot. I don't know, but
00:20:34
Speaker
Wow. My thought assumption before that was that you just tried your best not to shoot horses because it's extra money for you when you get those, the other army's horses, but it's kind of unavoidable when you're, you're in stirrups attached to one. Yeah. I think the tactics just, you know, changed and evolved it during the time to whatever they did is it do if you got to shoot the worst out from other, the guy to get the guy, then that's what you do. Yeah. If he can capture the worst, then that's what you do. But.
00:21:04
Speaker
It just, you know, it depends on the moment. And so, yeah. And then speaking to when, uh, when Dr. Pettigrew was talking about triangular points, do more damage, uh, triangular bayonets are like banned by the Geneva convention. Cause they are like impossible to stitch up, like lessons we learned for world war one, you know, so just kind of showing the efficacy of those things.
00:21:25
Speaker
But this is another example. Your work continues to show, here are all these assumptions that archaeologists in the field have made about projectile weapons, how we measure them, how we can tell things about the past, and they're systematically through the scientific method, deconstructing their arguments, using the math, and being like, this is actually how this works, right?
00:21:45
Speaker
Iron age stuff you're looking at like, well, the first guy simulated with this clay. This is why clay is not a good indicator for this. Right. And then kind of shifting gears here. I wanted to talk more about the terminal ballistic system to add a lot of darts and arrows. So that is the conglomeration of several different experiments. It's what I was looking for. So the three bison, the goats is the pig data included in this too.
00:22:15
Speaker
Yes, the hog, two goats and two bison. The third bison is brand new. Okay. So if Devin was on Noah's ark, there wouldn't be any animals left on the planet. No one gets at least. And I was very fortunate and privileged enough to take part in those experiments, whether just like holding a camera,
00:22:36
Speaker
I'm getting to throw darts myself and just being a part of that whole fun process across the West. But I want to kind of pull everyone's attention to this paper on figure seven on page 13 of Pettigrew at all 2023, the figure momentum and was it velocity as predictors of penetrant? Yes, we're looking at a term of ballistics of stone tipped out little darts and arrows figure seven shows
00:23:06
Speaker
kinetic energy and momentum, fit it out against the wound service area and the total penetration depth. And you have a couple different indicators here. So we're looking at arrows, basket, make it darts, different types of cane. So I imagine, so what does cane L, cane M and cane H stand for? Just the weights. So cane H is cane heavy, cane M is cane medium, and then cane light.
00:23:34
Speaker
Oh, okay. And then you have composite. Yeah, those are the composite darts are these very heavy darts I started making to try and increase the sample and improve the projectiles because the thing about projectiles that people need to remember and that we keep screwing up is that they're extremely variable. The same projectile technology
00:24:02
Speaker
will be extremely variable and you're going to have a significant amount of overlap in their ballistics. So a huge amount of overlap in the kinetic energy momentum of an arrow relative to a dart because you happen to have arrows that are, according to the English from the medieval, from the Tudor period, half pounds and they're being shot by bows pulling up to 180 pounds of draw.
00:24:30
Speaker
on the battlefield. Right. And they're penetrating a plate metal armor. So you have that arrow and then you have an arrow that's shot by a little bitty 20 pound Bushman bow. That's just tiny. And the point is to get poison into the bloodstream of the animal. Those are going to leave entirely different signatures in the archaeological record, those types of bows and arrow, you know, but that's one weapon technology. So that's a problem for us because
00:24:58
Speaker
because we tend to kind of essentialize projectile technology as if you can, you know, boil them down to these kinds of essential features. Yeah. And like everybody, even in like within the same culture, I'd imagine somebody has their own specific way of wanting their atlatls. And like when we were shooting the ones on that mountain top, like you gave her that really, really thick happy one, I'm assuming was your composite.
00:25:25
Speaker
And like that felt really good to throw, but it was too big for the at-lateral itself. Right. But I'd imagine even if the points are pretty ubiquitous throughout like a region in time period, the at-lateral shafts could be way longer or thicker depending on what the person wanted to. So yeah, I mean, you can have extreme variability in that level shaft and hold the point or less constant, or you can do the opposite. You can have a bunch of guys, people throwing at-l darts are all very similar, but.
00:25:53
Speaker
The points are all hugely different in size. All that works. It's all acceptable. So the problem here that we're trying to deal with in these naturalistic experiments is we're trying to assess the performance of projectile points against that backdrop of variability. So we're trying to use different sizes of dart shafts primarily.
00:26:19
Speaker
that we could do the same with arrows. Our arrow sample is much smaller for this, but the focus was mainly on darts, and we wanted some arrows just for comparison. So that's why there's all these different sizes of darts in this graph. I know the answer to this question, but I just wanted to...
00:26:37
Speaker
I'll have you answer it for the audience, but like the extreme variability of these graphs and why they're so, not to say why they're so colorful, but what are the importance of these graphs and like why they're complicated and complex? Cause in your experiment, they need to be. Right. So the point of all the different colors and shapes is to allow the reader to
00:27:02
Speaker
pull in a lot of data with one little figure, right? And to try and figure out what's going on to see the differences. So as you're looking at this graph, you see kinetic energy and you can actually see that the projectiles are grouping pretty well in how much kinetic energy they're carrying. As the darks get bigger, they carry a lot more kinetic energy. That's not surprising at all because
00:27:27
Speaker
We know from past work that as projectile thrown projectiles get heavier, they become more efficient for people to throw up to a point of dimension returns where you hit that point of dimension returns depends on the skill and strength of the thrower.
Kinetic Energy in Archaeological Studies
00:27:43
Speaker
But as a general rule of thumb, they're going to carry more energy as they get bigger. And that's true for single throwers.
00:27:51
Speaker
as well as for large groups of throwers. So just for me, a heavier dart carries more energy than a really light one. And what this is showing is that as that kinetic energy goes up, they're penetrating better. Big surprise, but kinetic energy is the number one variable capturing the penetration and the size of the wind in the wind surface area in our data.
00:28:14
Speaker
So, so if you're going to hunt a big animal, you're probably, and you do that for a living, you're probably going to adapt a heavier weapon kit. Sure. The, uh, figure six as well. Like I just want to commend you on the.
00:28:29
Speaker
Like the adding the, like the spearheads or the at-lateral parts, like with the graft is really, really helpful. And this is like a beautiful figure. And not to mention like you're showing all your work on the side. And yeah, I love how the bottom one is covered in bison crap. Like I remember that point. Cause even though it was a gut shot, I looked at that. I was like, Oh, that's the poopy point. And you got that. Continue work here.
00:28:55
Speaker
Yeah, you had two shots right in the row Carlton. So actually these shots were three apart, two 90 shot, number two 90 shot, number two 93. They hit really close together. They certainly didn't hit the same wound channel, but they, they hit pretty close together and there are two different points, but they're on the same dark. So that was a really good comparison. So yeah. Well, I'm glad I can help.
00:29:22
Speaker
But one of the more early on table one, right? Where you're looking at the bow hunting requirements. That's a very big part. And we talked about that with the met and all, um, Aaron at all. Sorry. Paper were there just like, well, you can't hunt elephants with these Clovis points cause they're firing them off like a 30 pound bow and blah, blah, blah. And you know, we talked about that in that episode, but you have like the list of like, these are the requirements, the kinetic energy and the, uh, force and jewels that you need to be able to hunt these different classifications of game. And you have the very large game.
00:29:52
Speaker
which is between 227 and 998 kilograms. Now, does a mammoth or mastodon fit within? I don't know what a kilogram is. I speak Merck and I do my weights in orders of Big Macs. So I don't know what a kilogram is. Let's see. Yeah, I know, uh, let's do a commercial real quick. Cause I know that Fred Barrett killed an African elephant, a four ton African elephant. At least that was the estimate with a 75 pound bow.
00:30:22
Speaker
So not a terribly heavy drop open. He killed in one shot and so 1800 kilograms. Yeah. So interesting. That's the outside of the, the kilogram range, but these, I can tell you that these ballistics, these recommendation recommendations apply to elephants. Yeah. So I'd have to go back and look at Tom cause article as to why he drew the, the upper range in 98, 998 kilograms, but in African countries,
00:30:51
Speaker
these ballistics associated with this very large game category are what they recommend for elephant honey with a bow. Cause you have in that you do have two heavy darts composite number 13 composite number 16 composite number 13 is only able to do 83 joules of energy, which is below that recommended 88 threshold. But the, yeah, but I stuck it in that, that heavy darts category just
00:31:20
Speaker
Yeah. But then composite 16 is at 112, which like very well exceeds that limit. Right. And that's one, um, it's like what me and Donnie got similar values on the heavy dart. I remember that thing. I think suck to throw. Well, the one use you threw at Donnie's house, you said you enjoyed. It sucked to throw. It was one to throw, but it was weird. Okay.
00:31:48
Speaker
Well, there's the one you threw up on the mountain and then there's the one you threw at his house. So the one you threw at his house, you told me at the time that, that, uh, you liked it. That's not correct. I think I'm thinking about the mountain one. One of those wasn't a fun day to throw that thing. That was the mountain one. Yeah. It wasn't as it wasn't tuned as well. So I improved it. And that's the one you threw at Donnie's house. So 112 joules of energy.
00:32:18
Speaker
is absolutely the, the mean that you were getting down range at Donnie's house. And then we were getting some higher values above that 120, 130 joules. But your mean, your average was, was above the necessary recommended energy for an arrow to kill an elephant. And the arrow that Fred Barry used to kill that 410 elephant had to have been
00:32:45
Speaker
down in like the 60 or 70 joule range or lower even. So these are just recommendations. Gotcha.
00:32:55
Speaker
I remember trying on the mountain top, trying to shoot the target while also keeping it in range of the sheet you had on the side so you could track it with the slo-mo camera, but I kept like throwing them over that. Still hitting it sometimes. You were just laughing over the backdrop. Made it hard to get any kind of good readings. I wish I had the radar gun.
00:33:24
Speaker
I mean, because later we got a really sweet radar again. For our second bison, we crowdsourced it. And one of the things I wanted to get with the crowdsourcing was a radar again so we could compare the velocity from a really high quality radar again with the high speed camera.
00:33:42
Speaker
So we were able to do that. And, um, subsequent velocity experiments, we use the radar data and it was, it's phenomenal. It works so well. Oh, that's good. Well, uh, we need to wrap this segment up, but when we come back, uh, we'll talk about the other paper and we're back. So real quick, cause that, uh, paper included an experiment that none of us were a part of. So the first, so since you arrived at Boulder, I think I took part.
00:34:11
Speaker
in your experiments and David and Connor and others were able to join in one of them. And so that when you're able to crowdsource that other bison, did you do anything different prior to the other experiments? For the second bison, the idea on the second bison was to test, first we wanted a more robust younger animal because you helped out with the first bison, which was a cow, and we wanted to test a young bull.
00:34:41
Speaker
We also wanted to focus on heavier dart shafts. So I did a lot of prep work up to that experiment crafting these dart shafts. And then for the third bison, the one that we just did, we pretty much continued that protocol with some improvements. So what was different about the second one, we actually had a really small crew. So we had to kind of try and optimize our output with a small crew.
00:35:09
Speaker
We used two of the kind of older Casio cameras. One was observing from behind, observing the impacts, the exact location of the impacts. The other one was observing from the side. And then in the third bison, we used a really powerful camera called a Chronos 1.4 to observe from the side. And that's capturing the dark coming in and impacting the bison. And the results there are just astounding because
00:35:37
Speaker
You can use this auto tracker function and tracker, follow a specific mark on the dart shaft, and it just goes automatically. And then you get this force readback as the dart penetrates, and you get some really sweet data. So it was definitely really useful to see how those heavier darts were performing, but also to test
00:36:00
Speaker
more robust younger bison and, and just to try out those different cameras. Yeah. No, your equipment's always been pretty, pretty sweet for all this. Absolutely. Now I'm curious.
00:36:13
Speaker
Like what's the next step with the data, right? Cause we see, you know, generally we're talking about the heavier darts are we believe are used first, right? Cause that's what people are hunting places in megafauna with. And as time progresses, then we get lighter darts. Then there's a transition. There's a time where darts like basket maker darts and arrows are being used together. And then especially in like the United States,
00:36:36
Speaker
Indigenous nations within the United States begin just using bow and arrow technology. So what is that transition tracking? Or is there something going on in the environment or the type of game that's being hunted that's kind of shifting this practice? Yeah. I mean, so you're bringing up all the questions that we have because we don't know what people were using. I mean, we can see what LLS and darts looked like in it. The later cake that are coming out of the Southwest.
00:37:06
Speaker
We don't know what paleo-indo nap models and darts look like. Always hear the points. And we have a problem, like we mentioned earlier, where archaeologists, not always, but they tend to be essentializing these weapons, so they're just saying, oh, this is a nap little dart point, and nap little dart is XYZ, and that's what it looks like, and that's that. What we suspect, if people are hunting really big animals and applies to seeing, they're probably using a heavier kit.
Evolution of Projectile Technology
00:37:31
Speaker
And then later in time, these lightweight basket maker darts that we're seeing in the Southwest, these are adapted to hunting a sweeter prey, smaller prey, probably. And they're, they're hunting, you know, desert big horns and that sort of thing. So those are the kinds of questions that we have. And how do we see all that just from stone points alone? When you pick up a stone point, you don't know how it was used. You don't know what the dart it was on looked like.
00:37:58
Speaker
But if you can make replica stone points and use them and see how they perform and see how they become damaged and see how bone becomes damaged with these different ballistic profiles, that gives you something to work with that you can then bring that to the archaeological record and try it and draw your data set out a little bit more and make some approximations of what a hunting kit looked like in the past. So that's a big part of what we're trying to do here.
00:38:27
Speaker
Would you ever, given the chance, do a live bison hunt, or would you be opposed to that? You don't have the answer if you don't want. I mean, I would hunt a bison with an ant level, but, um, I think ethically it's just, uh, it's something you have to tiptoe around. You know, I might do it for, for my own hunt. Now, having seen how these points perform, I definitely, one of the good reasons to do this kind of experiment is it gives you a sense of how efficacious the hunting weapon is.
00:38:57
Speaker
And then you can bring that data to try and determine, you know, is this still something we want to do or not? You know, you want to do that first on an animal that has just recently died a very rapid death.
00:39:11
Speaker
And, you know, I would also point out in these experiments, we're going ahead and we're consuming these animals. So, so nothing is really lost that wouldn't have been, yeah. I'm skeptical. I would be really careful, really cautious. Yeah. Definitely tasted the edge in that first place and holy shit, was that she rugged.
00:39:31
Speaker
I met a guy this spring that had done a bison hunt, I believe with the hunt primitive guy. He had said like he wouldn't do it again because you just felt so like I don't think gross was the word but that was kind of like what he was getting at that you know it's in a confined area it's not like a real hunt and they got a great shot and it died like pretty quickly but he was like it's just not
00:39:56
Speaker
Not worth it, yeah. Yeah, a farmed animal is, it's not really hunting. And unfortunately, we haven't recovered bison yet to the extent that you can go find, easily find a big wild population that you can legitimately hunt. Right. So yeah, we have a lot of work ahead of us to recover those animals on the landscape.
00:40:20
Speaker
Absolutely. Man, dude, you just do such cool shit. I'm so fucking happy that you got this new job. It's just really awesome to see all this turn out in this published form. I think you're part of a trend of this generation of archaeologists in their fields and in their folk eye.
00:40:44
Speaker
really going after a lot of this assumed knowledge and like showing like, you know, this is the work that's been done for the past 40, 50 years is not necessarily accurate because we just assumed the nature of the record and what these tools were used for. Like my colleague here at IU, he's a zoarchaeologist.
00:41:03
Speaker
And he's like quickly realizing a lot of times specimens that are in a box aren't actually what's labeled on the box. And like he was trying to get samples from like Harvard and they wanted 15 rabbits and like even Harvard sample, like five of the 15 were squirrels. They weren't even rabbits. And it's just like, and those are comparative
00:41:24
Speaker
samples that the world uses to identify remains in the archeological record. Like, oh, we know, you know, so it's just like, and you're part of this, like, well, how do we actually know what we know? And we're in this really interesting transition where we had the post-procestral critique in the late, in the early nineties that said, well, we need to look at things differently, but you're a part of this generation that's
00:41:47
Speaker
still very much rooted in quantitative methodologies to really go back, re-analyze a lot of our understanding of the archaeological record and be like, no, no, no.
00:41:58
Speaker
if we're going to be scientific, we actually have to use the scientific method and you can't assume when doing that. And like, it's just in the fact that, I don't know, man, like some of my favorite moments of being a grad student are with you in random places on a farm. While you guys were in grad school, like just being there for part of this was like, damn dude, this is, to piggyback off what Carlton was saying, like,
00:42:24
Speaker
When you explain archaeology is a science, like your papers are like the gold standard for like, you know, not just experimental, but like legitimate science. Like it's a myth busters type thing. Looking at everything. Yeah, it's just, it's cool. Yeah, man. Rightfully. You know, ballistics gel that they use all the time. It's like, well, yeah. Yeah. You can use it for firearms. Okay. And I should, I should just,
00:42:54
Speaker
clarify really quickly why that is because if you think about leather if you think if you imagine you have three strips of material you have a strip of leather that's kind of thick and then you have a strip the same size of ballistics gelatin and you have a strip of clay if you pick up those strips in your fingertips and pull them apart you can imagine that the gel just like gel would come apart really easily in your hands
00:43:19
Speaker
the clay would too, but the leather, you would probably have a hernia right before you pulled it apart. So the ballistic gelatin, and it's been tested for quite a long time for firearms, it's mimicking the density and viscosity of muscle tissue. It's not mimicking the fracture toughness, but for a bullet, because it's traveling at such high velocity, and it doesn't defeat a target using a sharp tip and edge,
00:43:47
Speaker
The fracture toughness isn't the main part. You can model a bullet penetration using a fluid model as if it's traveling through a fluid medium like atmosphere or water. And so one of the two main variables in a fluid penetration model are density and viscosity. But we are studying low velocity projectiles that defeat targets using sharp tips and edges. And so they're defeating tough targets.
00:44:17
Speaker
Like skin is a very tough target. Leather body armor is a very tough target. They're defeating that using those sharp tips and edges. So that's why ballistic gelatin just is not working. And the same is true of clay. Yeah. Because there was one moment that you were speaking about how in the high speed, you can see that the some, the ballistic shell was like bending before it broke, like it was absorbing. Yeah. Like grow heads in particular before it even penetrated. And then it kind of, there's,
00:44:46
Speaker
the, uh, an elasticity to it where it kind of gets stuck back in. Like it wasn't even act late and just like you said, right. It's, it's not doing what it's supposed to do with the tension. So it's like fucking with the penetration depths because it's acting like flubber. Yeah. Yeah. I mean, it's just like, it doesn't have any of the structure, you know, to make it you, if you want to make a college based gel, you're rendering college and out of these, uh, tissues, uh, tendon.
00:45:16
Speaker
bone, skin, you're rendering that out in a hot water acid bath, and you're mixing that collagen gel with water. None of this structure, like the collagen fibers and skin, none of that is preserved. So the toughness just isn't there. It's capturing friction. So if you use a smaller point, it can even be a dull field point. If it's smaller than a larger sharp broadhead, it's going to tend to penetrate.
00:45:46
Speaker
Whereas you're going to get entirely the opposite result in an animal carcass. What do you, how, how deep do you think a heavy adult dart would penetrate a Russian consquip wearing nerf. We could take a plane trip and go test this quasi legally.
00:46:08
Speaker
No, so body armor that protects on a battlefield against a ballistic attack isn't necessarily designed for something like a knife. That's why now that the body armor that's being manufactured from the police forces
00:46:24
Speaker
They're trying to have to try and balance body armor that's going to capture both a knife, thrusting attack, and a bullet. So if you didn't have that kind of body armor and you had a sharp rod head on the end of a dart, it might go right through the body armor into the body.
00:46:44
Speaker
Yeah, I don't know how, I can't tell you how deep, but I suspect it would defeat the outer layer of body armor and go through the torch though and probably stop at the back, the back layer of body armor. And at lateral with the stone point? I'm not sure about a stone point on a short broadhead, but the result we tend to get on a bison is that when they get through the skin,
00:47:07
Speaker
And resistance is far less through the torso. They're going all the way through and they're actually stopping and skin at the back of the torso, or in some cases they're penetrating through the skin on the back of the torso. But usually they have shed the large amount of energy that they need to punch through that tough hide on the bison is shed by the time they get to the back of the torso.
00:47:32
Speaker
So I must've missed it then, but like, how, how is it that a body armor could stop a bullet, but couldn't stop like a broad head from going through it? Is it just surface area or like pressure?
Modern Armor vs. Projectiles
00:47:46
Speaker
It's the fibers of the body armor because, uh, Kevlar body armor, you know, it's a fabric it's, it's stopping kind of a blunt, but very high velocity projectile. If you take sharp edges.
00:48:00
Speaker
They're able to cut through the fibers. So to make a body armor that protects against both, they're using this armor that becomes hardened at higher velocities or at a certain high velocity. You want the armor to move with your body, especially if you're having to wear it all day as a police officer. You're getting hot and sweaty and you need to move around.
00:48:24
Speaker
You don't want it to be stiff, hard material, but that's what you need to shield against a sharp object. You want a hard material that's going to dull the edge.
00:48:36
Speaker
So it's like why a trampoline can bounce a bowling ball, but gets cut by a knife. That makes plenty of sense then. Yeah. Yeah. Okay. So just hire a bunch of city and mercenaries to go to car heaver. Yeah. Yeah. Lightsaber would work too, but what's your favorite result or what's the favorite thing you've learned?
00:49:05
Speaker
Which is his favorite thing from these papers. The force data that's coming out of the high velocity or the highest speed video impacts. That's really fascinating. We're seeing peaks in force at different moments in time. So the main peak generally occurs when the point is penetrating the skin. Because again, it's the most resistant soft tissue. If you have like a lot of wool, a thick wool coat, it becomes even more resistant.
00:49:34
Speaker
So we're seeing these high peaks in force, but oftentimes those peaks are occurring when the hafting area of the projectiles penetrate. Especially on the third bison that we tested, it still had its winter coat. It had this very thick wool coat that was full of sediment, and a lot of the points
00:49:55
Speaker
we're actually getting hung up the hafting area and the, like, wool was getting lodged in there. Or if you just have a hafting area that's kind of bulky going through, that's generally where the peak force occurs. And what that means is that, unsurprisingly, a bulkier haft or a haft that isn't very smooth or that the point is hafted to the foreshaft, that tends to be a big inhibitor of penetration depth.
00:50:20
Speaker
So we don't see the haves in the archaeological record, but we do see the bases of the points that correspond to how they were hafted. And so we should be thinking about how to most efficiently haft points, when really efficient hafting would be called on, namely if you're hunting really big prey, and how that's going to be, that information is going to be passed down to us generally through stone points alone.
00:50:47
Speaker
Oh, that was cool, man. I mean, I've known you for what, five years? No, it's 2020. So yeah, you've been at this a minute. When did we record Donny? That was 2019. No, that was 2020. That was right before COVID. I remember like people wearing masks at the airport on the way back and I thought I had it. But don't you meet Devin at, he was there for the Helga. Yeah, you were at Albuquerque. That's where I met you. Yeah, that too. But then the Helga.
00:51:17
Speaker
Dedication. I wasn't there for that. Anyway, yeah, you've been working on this stuff for a while and it clearly you're passionate about it and it just look at it. I'm still stuck on this figure with the points or figure six. Yeah, clearly passionate about it. So looks great. You're starting a new job soon, but where can people find you? I still post occasionally on Instagram, AR and F at all.
00:51:43
Speaker
And we have the website. I want to start putting some time into that website, asktomakerathletle.com is the website that Justin and I run. So I think we should start updating that a bit more. But on social media, look for me on Instagram.
00:52:00
Speaker
Okay. It's AR dot at ladle or AR underscore. Yeah. All that will be in the episode description, dude, Devin, as always, thank you so much. Thank you for continuously agreeing to be on the podcast. I'm really excited to see you at a university. You absolutely deserve a tenure track position. I'm think you're only like 12 hours away by car ride still. Yes.
00:52:30
Speaker
I know I have the same distance from my home in Arkansas to, to so Ross as I was from to Colorado. So there's that. Yeah. Life of an archeologist. Well, then West Texas would be fine. I'd visit you there. It's a cool environment. Yeah. You got the big band national park is right there. Yeah. Absolutely. Cool.
00:52:53
Speaker
All right, when we just interviewed Dr. Devin Pettigrew, you can find him on Instagram at ar.adalatal, as well as his website, Bescamaker something. Bescamakeradalatal.com. I don't know why I thought that was it. Bescamakeradalatal.com. I thought you froze. I thought your video literally froze. My brain did. I blue screened in the brain.
00:53:13
Speaker
All right, well, yeah, this has been great. Appreciate you coming on and guys waiting to review the podcast. Do whatever you want. The all shows feed thing. Subscribe on our our thing and whatever. Anyway. All right. See you guys later. Bye.
00:53:34
Speaker
Thanks for listening to a life in ruins podcast. You can follow us on Instagram and Facebook at a life in ruins podcast. And you can also email us at a life in ruins podcast at gmail.com. And remember, make sure to bring your archaeologists in from the cold and feed them beer.
00:54:01
Speaker
This episode was produced by Chris Webster from his RV traveling the United States, Tristan Boyle in Scotland, DigTech LLC, Culturo Media, and the Archaeology Podcast Network, and was edited by Chris Webster. This has been a presentation of the Archaeology Podcast Network. Visit us on the web for show notes and other podcasts at www.archpodnet.com. Contact us at chris at archaeologypodcastnetwork.com.