Dr. Smiti Nathan

Transcript

Smiti: Welcome to Curiosity Meets the Past, a podcast for curious minds who love learning about the past. My name is Dr. Smiti Nathan, and I’m an archaeologist and your host.

Smiti:  Welcome to Curiosity Meets the Past, a podcast for curious minds who love learning about the past. I’m Dr. Smiti Nathan, and I’m an archaeologist and your host.

In this episode, I’m speaking with Dr. Giulia Gallo, an archaeologist and paleoanthropologist. Her research explores the mineral and protein components of bone in Paleolithic contexts.

She’s currently a postdoctoral researcher, and her work brings new attention to some of the smallest and often most overlooked materials in the archaeological record. Giulia and I first met when we were both at NYU and I’ve known her to be a curious, rigorous, and enthusiastic scholar.

In our conversation, she shares how analyzing tiny fragmentary bones can lead to surprising insights from how Neanderthals and Homo sapiens use fires to the animals they interacted with. She also walks us through how cutting-edge scientific methods are transforming what we can learn about even the most fragile remains. And trust me, even I was surprised.

Her work is a fascinating look into how the tiniest materials can reshape our understanding of the Paleolithic past, and I’m excited for you to learn about it. Giulia starts us off by sharing why these tiny bones were often overlooked in the first place.

Giulia: So you have to imagine that you’re on an excavation, right? And you’re on your hands and knees. You’re clearing debris. You’re shooting in every artifact, every bone, or stone tool, or piece of pottery, or ornament greater than two centimeters. What happens to the rest of the dirt in your meter square? It goes in a bucket. 

And now you’re going to go to the sieving station. And this can be a lot of hard work. I don’t think it’s many people’s favorite. But you dump that bucket into usually nested screens. So for my sites, we standardize four millimeter, two millimeter, and if we’re collecting microfauna, like the mice and the wolverines, and the beavers, their bones are so small that you need to use an even smaller sieve to get the meso fauna and microfauna. 

So you’ve stacked those screens with the biggest grid on top, the smallest mesh on bottom. You dump your bucket in and you have to shake that. All of the dirt leaves. You’re left with the materials sorted in their size class. And usually for a lot of sites, you then have to go wash it off. So for me, I’ve done that in many rivers with many fire hoses across Western Europe and Asia. 

Now you have your screened material, clean and shiny, stacked by sizes, and you have to sort that. So a lot of times that does happen in the field as well as a lab component. And you have tables of students going through and pulling out the lithic debitage, which are like the small pieces of stone tools that shatter when you’re making a tool. You have your pieces of bone, your pieces of teeth. Sometimes organic material or minerals like ochre are also caught in these sieves.

And after all that tedious work, all that time sorting, which I actually quite find quite zen, it’s a meditative part of the lab work for me. You’re left at the end of the day with these bags of really, really tiny material. So, if this is the standard today, we have to ask, why would we go through the effort of sieving this material, of sorting this material, of cleaning this material?

And it’s because they give a wealth of information. I think typically even in the start of excavations, people didn’t screen at all. So maybe between, like, the 1880s and the 1980s screening was not included, or wasn’t included systematically. And I’m pretty sure in, like, the French archaeological lore, the sieving really started because they were missing all the small ornaments that if you were just excavating and throwing the dirt behind you and picking out the really big bones or really big stone tools, you were missing like really beautiful artistic symbols of personal ornamentation.So they started sieving. 

Now that we know that screening gives us, like, a lot of information, it is absolutely the standard across most excavations in most time periods. But with sieving, you get all these other tiny pieces often not included in analyses, bones. But they weren’t typically included in analyses because there was no morphological markers on them, right? You couldn’t tell if it came from a femur, or a cranio, or a vertebra ’cause they had nothing on them. They look like corn flakes.

And I wanna share with you some really good pictures. And by “good pictures,” I mean, it looks like a mess of crap. But because it doesn’t automatically lend itself to the typical zoological analyses or lithic analyses, they’re not heavily exploited. But that’s where I get to come in and use them for my analyses.

Smiti: That’s awesome to hear. And I’m curious, was there a moment in your work where you realized these tiny bones might be telling us something important?

Giulia: For many years before I started my graduate degree, I’m just helping out on excavations. It’s truly what I live for. I’m absolutely a field archaeologist at heart. And when you’re a student without a specialty, in the beginning you are heavily used on teams to go through these sieves. But when you see all the material in there and then you don’t see it being used afterwards, I really was inspired to make my project centered around this screened material.

But I do, I have a bone to pick. Actually. I think zooarchaeology as a discipline overall is also overlooked. And I would like to stand up for my sub-discipline. Zooarchaeology is the study of animal remains that humans interacted with. If it was just the study of animal remains, it would be more like paleontology, like the ecology of these animals. But when they intersect with the human sphere, when they have any anthropogenic influence over them, whether they be hunted or used for stone tools, uh, used for tools, excuse me. That means that they fall under an archaeologist’s purview. 

And I think bones are such a dynamic raw material, not only on the species level do you get to learn about the environment, the biome, the hunting strategies. From the bones that are brought back to site, like a lot of times, you know, when we look at an archaeological landscape, we’re only sampling little areas of how that landscape was used. But when we see what animal bones humans took with them, we can learn about their economic behavior, their social behavior. We can look for cut marks and artwork on bone, bone tools.

Even then, on my scale, bones themselves contain a lot of information within them. So for example, you can sample isotopes and learn about, again, the biome. From fetal bone you can learn the season that those animals died in and when humans hunted them. You can learn about the mineral and chemical component that can give you interesting information on what happened in the burial process. 

And I will speak more about my specialties, but on that level of bone, really considering what transformations have happened structurally and chemically as the influence of human behavior on this raw material, like that to me, is really exciting. And a lot of that information is coming from this screened material.

Smiti: Wow. Thank you so much for that. And I know that trying to analyze tiny overlooked bones, whether it could be human or animal, as you mentioned, is not an easy thing to do. And you’ve also given yourself, I guess, more hard work because you look into burnt bones.

Giulia: Yeah.

Smiti: Which are overlooked for sure, and have their own challenges. What makes burnt bone especially challenging to study?

Giulia: It’s so challenging. If I wasn’t obsessed with it, it’s hard to believe that I’m giving myself such a hard job. But again, these screened materials are often overlooked, ‘cause the bigger things, you know, that’s how you say what species they are. That’s how you can see the artwork, or see the tools. On the scale that I’m looking at, these are like gravel-sized assemblages coming from the screened. 

So not only are there multiple, multiple fragments that are really, really tiny, but also they’re highly fragmentary. So, sometimes when I’m even picking one up, it breaks into two pieces. Because burnt bone is really fragile. It loses a lot of that mechanical stability of the fresh bone, which makes it good for being in our bodies, by the way. Right? Bones are really flexible. They’re really strong, but when they’re burned and they lose the organic component, yeah, they’re, they really are crumbly. So it’s really challenging for me because you have this large amount of really tiny material that’s super fragile. 

And if I can add another layer on that, it is difficult to distinguish different coloration of burned bone, which is a major primary classification factor for archaeologists. Is it black or brown and carbonized, or is it gray and white and calcine, which means usually, typically that it has experienced the higher temperatures, but not always. And I think this is a fun example of, like, equifinality, which is a pretty, common concept that we as archaeologists have to deal with. The idea that there’s many pathways to getting this end result. So, you have to be very careful when building your hypotheses to not be biased of one of the pathways when it could be several. But these teeny tiny burn bones are colored in ways that some people could confuse for staining. And if you’re thinking about, like, the fire behaviors of different hominins, you do not wanna mistake staining from the sediment as burning, to say that they had fire technology. 

So there are a lot of challenges and I think how I address these is I collect a ton of data and it takes a lot of time, but you have to do it. And it’s important that things are sorted and sieved and screened really well. But also I check almost everything with analyses like spectroscopic analyses or diffraction analyses to confirm that the staining, for example, isn’t fooling me into thinking it’s burning. So it gives a scientific basis to my observations to then make and draw conclusions about ancient fire use.

Smiti: So that is a lot to contend with and I’m curious, can you give us an example of something surprising that you learned from studying burnt bones in the Paleolithic?

Giulia: I would love to share. I think these are the conclusions that keep you going, right? Learning this stuff about the past is so addicting. I think one of the coolest, more recent things that I have figured out or contributed to figuring out is Neanderthals are burning mammoth bone. [We’ll provide a link to these finds once it’s published (presented at conference). These results will expand on the findings of this paper.]

So when I find burned mammoth bone, you really are put in a mindset to consider, how did they get this mammoth bone? Why are they burning it? How are they burning it? 

And one of the conclusions after, you know, looking at other interdisciplinary results from this well-studied site, this is not a time period with a lot of vegetation. And again, if the mammoths are on the landscape, you can imagine, like, a steppe-tundra landscape. There’s not a ton of firewood hanging around. 

Like most bones, human bones, deer bones, horse bones, in the middle of our long bones is a cavity filled with marrow. And this is like a reservoir for the body. But you know, whales and mammoths have a different structure where the inside of the bone is all spongy, to simplify it. And this means that the entire bone was, like, permeated with oil, right? Stuff that would burn really well. So when we find burned mammoth bones, we’re speaking towards survival strategies of Neanderthals in these really cold periods.

Smiti: Thank you so much for that example about Neanderthals. That was absolutely fascinating. And maybe because I’m a bit species-centric, because I study later periods, I’m curious if we have any surprising examples from your work about Homo sapiens.

Giulia: I think this other example is also really exciting and it’s a cave that I’m working in. And in this period of the Paleolithic, this is the Upper Paleolithic of Western Europe. Neanderthals have now gone extinct. The modern humans that came into Europe are now found all around, but they’re heavily exploiting these deep cave environments for making art, actually. And maybe your listeners have heard of, like, Lascaux or Cave Chauvet. There’s really, really incredible depictions of how they saw their world and how they depict the animals around them. And the choices that we see in that art tell you a lot about their worldview, right? Like, why are they drawing some animals and not others? They’re not really drawing humans. Or if they do, it’s in very interesting, zoomorphic context. 

But I have the pleasure and opportunity to study one of the fires in these very deep, painted caves. And this fire is at the absolute back of the cave, like the farthest chamber from the entrance. It’s also a really confined small chamber. Like I can stand ’cause I’m a tiny person, but I think a very tall human would have difficulty. 

And in studying the fire in the back of this cave, the bones are all burned to what we would consider like a low-medium temperature. They’re carbonized, they’re not calcined, but bones burned to this temperature produce a lot of smoke, Smiti. And why would they be putting all this material, organic material, in a fire that would produce such smoke in a small, confined area, you know, an hour walk from the entrance of the cave in deep dark blindness. And maybe something that you find burnt could have been a natural lightning fire. But this is definitely not natural fire. Everything found in these fireplaces is an absolute choice. They desired and put it into that fire. 

And I can speak more about burnt bone and the properties that burn bone lends a fire, right? For example, it doesn’t really make fires brighter, but it makes fires last longer ’cause it’s a fuel that isn’t so quickly eaten. Also it only really contributes beneficial duration properties to fires if it’s fresh. If they’re dry bone and it doesn’t have any of that organic component in it, it doesn’t really add anything to the fire.

So, this example and having the opportunity to study this fire in this deep cave environment has been fascinating. And I, I do think it’s giving a lens on how this chamber was used, that just looking at the art, can’t tell you.

Smiti: That’s really awesome and thank you so much for that example. And please keep us posted as this research evolves.

Giulia: I will!

Smiti: Now you’ve given us so many fascinating examples about burnt bone, but you also study unburnt bone. And you’re using a really new technique called proteomic analysis. I was wondering if you could walk us through that.

Giulia: One thing that I think makes bones so dynamic, right, is that it’s primarily made of three components. So, you have your mineral component, which is the thing that’s transforming in the burnt bone studies that I really pay attention to. It’s called bioapatite or hydroxyapatite. There’s also the water in bone, and that’s incorporated both in the mineral and in the intercellular matrix. 

But also there’s a protein component. And usually in bone, the biggest protein is collagen. And I think collagen is having a moment right now, right? So I think everyone knows what collagen is. I think it’s in my kombucha for some reason. But it keeps our head healthy, it keeps our hair and skin healthy. But collagen turns out, is kind of species-specific.

So, proteomics is this exciting, new discipline in which we can use the protein component of bone, which is typically the collagen, that’s the most abundant protein, to say what species it is. Because it turns out proteins are pretty specific to genre and family. Sometimes you can get very, even more specific to species level. And this totally transforms how we can use little fragments for greater zooarchaeological studies.

Specifically, the method I use is called ZooMS, which is zooarchaeology by mass spectrometry. Because, how you, how you get the information, the proteins, out of these little bones, you use mass spec to get that data. And to simplify it tremendously, you isolate the collagen from the bone. You distill, you pull out, and you clean out that collagen. You put it on a tiny metal plate, you put that metal plate in a mass spec, and then you zap it. You ionize the sample. And as those molecules are hit, they fly. And the heavier ones don’t jump up so much and the lighter ones jump up really far. And the mass spec can actually collect all of that data and give you a spectra of the mass over time of the weights of these proteins, these peptides. So yeah, you can use this data to say what a bone fragment is.

Smiti: Wow, that’s pretty amazing that we can get that level of detail. Can you walk us through why you’re using it?

Giulia: If there’s no morphological features on the bone, for example, the tiny corn flakes that I’m finding in the sieve material, how are you supposed to incorporate this bone into larger studies? How are you supposed to know who it is? It could be coming from a tibia of a human, or the calcaneus of a deer, right? When they are so fragmentary and tiny, it’s very difficult to say much about them. But with the power of proteomics and the study of isolating the proteins, seeing the pattern of the proteins, and comparing them, we can actually say who it is or what family or genre it is. 

And it’s become very popular and interesting, not only to expand zooarchaeological data sets, but also to try to find humans because we don’t really have many representations of humans in a lot of sites. Without purposeful burial, bodies don’t hang around so well, and humans are on a low population density across these landscapes, archaeologically. But with these tiny little fragments, we now can take our level of data or analysis and expand it much greater. And it has been successful in many sites.

Smiti: So thank you so much for walking us through why you’re using proteomic analysis, and I’m curious, are there any early findings that you’re willing to share that might be a bit surprising or unexpected or just changing how you’re viewing the Paleolithic?

Giulia: Yeah, so I do wanna highlight, this isn’t my work, but it’s using the same method and the project is similar. But people have had success going back through old archaeological collections, unidentifiable tiny teeny bone fragments and finding humans. And I’ll absolutely share this paper with you so your listeners can find it. But they were able to identify a mother-daughter pair. Yes. It’s so cool. 

And this is in a Paleolithic context in Germany, and this is also a really early period for Homo sapiens to be entering Europe. So Neanderthals have their distinct evolutionary history. They were in Europe for a long time, but when Homo sapiens starts coming over and populating Europe, especially in Germany at the time period, it was frigid. This is like a really hostile landscape. But it’s actually such an incredible window, on such a small timescale, to have this level of data about who is at the site and their relationship with each other. And they’re also distantly related to another modern human, a fossil found further south. So like. It’s an absolutely stunning study done with proteomics. I will share it.

For my own work, my project because I get to do high-throughput, data analysis, which means instead of selectively taking samples for ZooMS, I’m Zooming everything. So I am building these massive zooarchaeological data sets about like every fragment, over two cm. I’m getting an interesting mesofauna representation. So things like wolverine and badger, which I didn’t expect. 

And at one site that I just finished, cave lion came up, and we have zero cave lion in the identifiable spectrum of the collection. So that is so surprising. And the human interactions with cave lion, for Neanderthals and modern humans as they enter Europe, we are so curious about that relationship and how they’re sharing these rock shelters and caves. Right? It’s making it all very exciting.

Smiti: That’s amazing. Thank you so much for those fascinating examples and sharing that paper and your early finds. And I’m curious, how has working with these fragile overlooked bones changed what you think about what counts as evidence and what’s considered valuable in archaeology?

Giulia: So, I am definitely happy to be mucking around in the screened material. It’s usually me and the mesofauna- or microfaunaists. We’re really the only people who are, like, super exploiting this, this size class of material. But I think the level of detail that I have been able to pull out of the screens, even especially for my burnt bone study, because burn bone is so fragile, you don’t get the big pieces.

So it’s a type of information about fire technology and presence of fire that is only found here. So it emphasizes to me that this size class should be taken seriously, should be done well, should be cleaned well, sorted well, sieved well. I think this means there’s a lot of potential in parts of the excavated materials that aren’t so heavily studied.

Maybe for me it’s sediment that’s standing out. I think we talked earlier about, like, how you have your bucket, and then you dry sieve it, and all of that sediment is usually just going into the river, or going into piles of dirt, or going into pits that people dig. There’s a lot of information in that sediment actually. And it’s not just like geological information, or the fabric analyses, or grain size analyses. 

I’m not sure how familiar your listeners are, but with, like, the sediment DNA advancements from taking samples of sediment, you can get DNA of those who are on the landscape. And it’s still highly debated. Like what type of DNA this sediment is. Is it hair? Is it spit? Is it excrement? There’s like a lot of ways our DNA can end up in the sediment. But it has been successful at many sites including an exciting site I’m working at. We just took, I think, 28 samples and nearly all of them were a positive hit for hominin. So these hominins that are heavily using these rock shelters are leaving their DNA behind and we’re getting it. And, and I wanna know how they’re related. I wanna know the population overturns. 

I think the sediment DNA is not only one of the coolest advancements to happen outside of ZooMs proteomics in the past, God, I guess the paper was 2017 when the method was really fully announced to the scientific community. So in 10 years, what archaeologists have been able to do with that has only been the start. And for the moment, usually I’m putting that sediment right in with the sieve pile, right? Hopefully, maybe keeping sediment samples and taking sterile sediment samples becomes commonplace even if you don’t have the funds to send them automatically for sediment dNA analysis.

Smiti: Gotcha. Thank you so much for that. And it just kind of shows why we don’t excavate sites fully, why we try to keep things for the future, especially with advances in technology. And to wrap us up here, what do you hope listeners take away about paying attention to things that are often overlooked?

Giulia: I love this question. As someone who is really curious about the past, it’s really easy for me to get excited about these tiny, tiny gravel burnt bone assemblages when most people roll their eyes and go, what are you gonna do with that?

I think a lot of public science makes it sound like the past is figured out, like, we got it. We figured it out. This happened, this happened. Don’t worry about it. 

It is so much more dynamic than that. So the fact that I can confirm that they had fire through my burned bone, it might not seem like the most exciting, but then I can tell you what temperature the fire was and we can probably try to use spatial analyses to say where the fire is in the cave. And that can help us understand how they organize their space. 

So, yes, saying like, oh, they had fire maybe is not the most exciting contribution, but we can take it so much further. I do think it makes a difference and I do think it helps add to our understanding of what happened, and where we came from, and who we are.

Smiti:  One of my biggest takeaways from this conversation is that by reexamining what we already have, especially the overlooked parts of the archaeological record, can completely shift how we understand the past. If you’d like to follow Giulia’s work, you can find her on Instagram and Bluesky. You’ll find those links in the show notes along with the link to a full transcript of this episode.

And if you’re curious to dig deeper, Giulia shares her favorite popular science book for learning about the past, as well as how you can support the next generation of student archaeologists. And this is all in our Patreon exclusive video.

Our Patreon is free to join and gives you access to all of our extra content if you’d like to support the podcast monetarily, that’s always appreciated too. Thanks so much for listening and cultivating your curiosity with us.

We’ll see you soon.

Credits

Giulia Gallo: Guest

Noor Hanania: Theme Music Creator

Laura Riveiro: Podcast Cover Art Creator

Smiti Nathan: Host, Video Editor

Patreon Supporters

Thank you to our paid Patreon members for supporting the creation of this episode:

Nancy Fulton, James D., Giancarlo Annese, Thomas Martin, Stuart A. Griffin, Tagg, Ann Brookens, Diana Madden, Cole Guinn, Seemingly Unrelated Podcast

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