 Okay, so today I have a pleasure to introduce AJ White, who is brave enough to give up that much as a part here. Congrats to him. And thank you very much for doing that. Thanks. And this is basically from what I've heard. It's your MA thesis in geology. Yeah, that's right. My MS work. Cal State Long Beach. And I have friends who study chemical analysis at Cal State Long Beach. So I know that the university has a reputation for doing really good scientific analysis. It is my pleasure to introduce AJ's talk. It's titled Everybody Poops. Using physical standards to track cohocia region population change and evaluate ideas on cohocia's decline. So please welcome AJ. Thank you everyone for being here today. I'd like to start by apologizing because I know somebody brought your lunch and food is really kind of at odds with poop. So I'm sorry about that. I hope it's not too disgusting. But if you brought meat, you will be actively converting cholesterol to coprostinol, which is very much at the heart of this. So it's kind of participant learning maybe. I don't know, trying to spin it positively. But we'll just get right into it. So as Jinko said, I'll be presenting what I did as part of my master's work in geology at Long Beach State, which is basically investing the use of fecal standals in archaeology. So I'll first give you an introduction to these molecules, give an overview of its use in our discipline, and finish with an application to cohocia. So a good place to begin is just what are fecal standals? So this term refers to a suite of lipids that are produced in the guts of humans and several other animals that result from the microbial degradation of a parent sterile molecule. Now there are many different types of sterils. The most recognized one is cholesterol. So that's an animal sterile that's found in every animal. And when we eat cholesterol, which is what you see here to the right, the meat that contains that cholesterol gets broken down by microbes in our gut to the form of coprostinol. And that's something that doesn't happen in every animal. So dogs, for example, do not produce any coprostinol because their gut biome is different in us from ours that they break it down a completely different way. So because of that and the fact that it's the most prevalent standal in human feces, we use it as a human biomarker. And lastly, as is probably obvious by now, it's introduced into the environment as a form of fecal waste. So that's why it's called fecal standals and why we had the poop emoji and all that fun stuff. So I'd like to now sort of take a look at the pathway of these molecules out on a landscape. And so we discussed how cholesterol gets converted to coprostinol in our guts and then gets introduced into the environment as a component of feces, but can also happen just through the person actually dying. But since we all go to the bathroom a lot more than we die, really feces is the chief sort of mechanism for all of this. Once out on the landscape, oh, there, there it goes. Once out on the landscape, it can either be buried in situ or transported some distance to a basin like a lake. But once out in the soil itself, it will persist for a very long period of time. And the reason is that it's a very unattractive molecule to microbes out in the environment. The microbes in our gut already got the low hanging fruit, the easy part of the molecule. And what's left is a very complex molecule that's very difficult to break down, doesn't net a lot of energy, so it's ignored for hundreds, even thousands of years. It just sits there. Now eventually though, they'll get desperate enough to convert it to the second derivative of cholesterol, which is called epicoprostinol. But we can find either of these molecules and when we do, we can kind of link that back to a human presence on the landscape, possibly thousands of years before the present. So that's sort of the foundation of all of this. So the use of fecal snails in archaeology really began out of modern sewage studies. And so coprostinol is used today as an indicator of sewage pollution in waters. So it could mean that there's a leaking sewage pipe or something, and we send environmental scientists out to quantify it. So the same laboratory applications were used by archaeologists starting in the 80s and 90s. And it was originally used as sort of an indicator of a human presence on a landscape. So it was used to indicate the presence of agricultural fields that would have received manure or the presence of things like privies and cesspits, areas where people were actively defecating. But it wasn't until 2012 that Dianju et al. made a publication that made a link between varying amounts of fecal snails over time as a proxy of population change of humans. And so when I first started my master's work in 2014, my advisor thought this was a really cool idea, but there wasn't that much follow-up work on this method to see really how viable it is in all sorts of places, what are its advantages and limitations. So that's really what I wanted to set out and determine through my master's work. So a good place to begin is why would we use fecal snails in the first place? What are the advantages of this method? I believe that it can provide a more direct record of human population change because we're quantifying molecules that actually originate in human beings themselves. Unlike some rather traditional methods in archaeological demography that rely on estimations such as the amount of rooms in a play-blown room block or shells that a person would need to consume in a day, I think that this is one step closer actually to human beings themselves. Additionally, it is the advantage of not being very intrusive. You don't need to excavate the entire site to do this. You simply need small sediment samples that can be taken from a core. So it really doesn't require a whole lot of work out in the field. And lastly, from that same sediment you can do a lot of comparisons between other proxies such as paleo-environmental proxies on hydroclimate things like that and make direct comparisons between a population proxy and environmental events from the same core without having to really rely on a strong technology. So despite its advantages, there's really a lot of considerations and even limitations that we need to be upfront about this method. So one of them, when we first started, was will this method work everywhere? Or did it just work because Dianju et al. did their study in the Arctic Circle like way into northern Norway where it's really cold all the time and it would have made for enhanced preservation. So who knows if this method would work in a lot more warm environments where there's more microbial activity. So we set out to test that by applying the method in a temperate climate. This is Horseshoe Lake in Illinois. And we'll get into later what that means for Cahokia. And we also tested it in a tropical setting on Kwan Laan Island in Vietnam. And so unfortunately we don't have a good chronology for Kwan Laan yet and so this is kind of on the back burner. But the point is it worked in a tropical setting, in a temperate setting, and in an Arctic setting in three very broad climatic regimes which lead us to believe that this probably works anywhere and climate is not a major limitation. And I encourage you to go out and test that and see if that's actually true. I think the more that we investigate this, the more sure we can be about that. A second consideration and one that turns out to be a major limitation of this method is the fact that other animals, not all but a select few, do produce fecal stanels, the ones that we're interested in a small amount, but one that still might be of significance. So here we see in blue, caprosinal levels for modern stool samples across various animals including humans. And as we see and what we expect, humans produce by and large the most caprosinal, which is great. But at levels underneath about a tenth of what humans are making, but still some, we find animals like pigs, cows, even sheep, possum and cats produce minor amounts of this molecule. So that makes the problem of how do we know that the area we're studying has a fecal stanal record dominated by a human presence or maybe there's some lost city of pigs that is controlling all of this. And the answer to that is I cannot say with a hundred percent certainty that it is completely human controlled. We need to make assumptions in this case and going forward. So what Danjou had all did in their studies, they basically acknowledged that there were large domesticated animals present at their site in northern Norway and they assumed that those animals would only be there because those humans were there as well. They brought them and so that indirectly that indicates a human presence, that those animals represent that humans were there as well. Now for our study in prehistoric North America, we had the advantage of not having these large domesticated animals present. So we can simply just kind of X them out. However, I do concede that there were probably populations of deer producing very, very small amounts of this because deer are herbivores so they don't ingest a lot of cholesterol, but it still could be a little bit, maybe an occasional bear that's contributing to this. But my assumption is that we know that Cahokia's region supported thousands of people and that it's really people that are controlling the fecal-stamble signature that we get. But again, I cannot actually scientifically prove that. It is assumption and also a limitation of study that I got to just be real about. Okay, so another consideration to discuss and one that seems a lot easier than it actually is to figure out is where did people poop? And it's a question that I don't think is answered enough or at least asked enough in archaeology because, yeah, I couldn't find a whole lot of information out there at all. It's almost like people didn't give a shit. Okay, there we go. I had to get the poo joke, the pun out of the way. Okay, so the answer is very easy to get to in a modern sense. So our poop all goes to very predictable places like treatment plants, assuming you lose a toilet. But in an archaeological sense, in areas that didn't have sewage, it's a lot more complicated. So I've been forced to kind of look at sort of anecdotes to kind of see how the range that people travel basically to poop from where they live. And there's a large range from what I found. So I was speaking to a German researcher who was looking at Powell dwellings in central Europe from the Neolithic and she was telling me that they find copper lights right underneath the settlements themselves. So in that case, there's zero distance traveled as people, they literally wake up and they just do their business right off the side of their house. So in that case, that makes for a very easy study and one that I actually might want to do one day. You just sink your core in right there, you know where the site is and it's wonderful you're in the Alps and it's a very easy time. However, outside of there, it's a little more complicated. So and perhaps a hunter-gatherer sort of perspective. I looked at some ethnographic research on the Hadza in Tanzania and it was noted that people will defecate about 40 to 50 meters away from where their primary activity location and their sleeping area is. It's kind of balanced between the convenience of not having to walk too far but also going some distance so that it's not very unpleasant. And so you get this diffuse kind of ring of feces around the site, if you will. So under that context, you might want to sample close to where most of the artifacts are but not too far at the same time to actually find the poop. And then for Cahokia, I couldn't find any information at all about how Mississippian people defecated. And so I looked to modern medical research of open defecation practices across the world particularly in India where there's a lot of work done on rural farmers and it was found there that people will do most of their defecation out while they're working in the fields. So away from where they're spending time, you know, in their settlement at night and so in this case it's actually quite a distance away from where you think the site might be. The poop is actually perhaps far removed from there. So again, there's a whole range of where to look for when using this method and you really have to think hard on where people would have used the bathroom because once you find that then you can really begin the study. By the way, if anyone in their study areas throughout the world and times, if you know any information about where your people went to the bathroom please talk to me because I'm trying to really assemble more information really compile this together because there's a lot of work to be done. Okay, so those are some of the major considerations I'd say need to be taken into account before going forward with this line of work. And so now that we have that down, I'd like to show you an application of the method. In this case at Horseshoe Lake which is right outside of the massive site of Cahokia. So Cahokia is in southern Illinois as I imagine most of you are aware just across the Mississippi River from St. Louis. And here is our study area sort of zoomed in. This is the lake that we sampled Horseshoe Lake. It's an oxbow of the Mississippi that separated about 3,000 years ago. It's rather nice. It's a big large lake but it's also very shallow. It's only about a meter throughout its entire area so you can stand up pretty much anywhere in here. Anyhow the reason that we sampled this lake is because right to the southeast about I don't know maybe a kilometer or so to the southeast is the site of Cahokia. And so what we assume is that as I just mentioned you know farmers were probably going some distance a foot to actually defecate and so my hope is that the ring if you will of feces would be confined within or mostly contained by the watershed of the lake which is shown by this dashed line. So the idea is although we're getting trace amounts of it it's hopefully is catching a pretty good representation of you know different activities going on at Cahokia and washing in with time into Horseshoe Lake. So to do that we got two sediment cores from the lake. The first one I actually didn't obtain myself. It's from a study that was done by Sam Munoz and his colleagues and he published this in 2014 and 2015. So I got easy sediment that was just sent to me. It had already been dated so that wasn't a problem. But we wanted to make sure that the fecal-stamble record that we're getting here was representative of the entire watershed and not just the lakeshore closest to the core. So I got a second core with the idea being that if those two cores agree in their fecal-stamble record then that's more likely to indicate that it's happening on a watershed scale and not something super local to that coring location. Now a brief word on Cahokia. Again I'm just going to assume that most people are very well educated on this site but just briefly it is one of the most significant archeological sites in this country. It's one of the largest mound building Mississippi Insights, a series of which were built up and down the Mississippi River Valley from about 1,000 to 1,400 AD. And Cahokia is just particularly massive. It hosts the Monks Mound, the largest prehistoric earthwork on the continent. And without getting too much into its rich background in history, its demographic history is of particular interest to me because what is generally agreed upon is that around the 10th century AD, Cahokia was a relatively small site. There was very few people there. But by the following century it really exploded into an area, a city, that was bustling with thousands of people. However by the 1100s and into the 1200s population was declined and it's thought by the 14th century that this area was pretty much abandoned. So the reason why I wanted to target Cahokia as well for this study was because here is a site that has a very sort of sudden increase and decrease in its demography. And so if I want to see how well the fecal stanol method works, I can see how precise it is and how able it's able to pick up sudden demographic events. And in addition to that I would be able to check the method against pretty well established archaeological population reconstructions with the idea that if we get a similar pattern then this method probably works. So this is also the first application of this method in a very well-known archaeological context. So in order to do all of this I had to first go out and get that second core, which was really hard. We were using a Livingston hand core and as you can see, I'm just letting the big strong guy, Joe, do the work. I'm just like, I could not get it in there, man. It was rough and when we finally did get our core we were so happy but then the engine on our boat went out and we had to paddle just very pathetically about a half mile upwind. The sun went down, as you can see it's quite dark. We were just holding a boat through a swamp at night covering mosquitoes. But we got the sediment and that's what science is all about. So anyway, once we had the sediment we could go into the lab and really work it up. I won't go into much detail here. The basic strategy for this is that we need to get the fecal stanols out of the sediment and into a solution and we do that through solid to liquid extraction. We used a Soxlet system but I'm hoping to hear you something a little more modern. Then we then derivotized the solution and we do that in order to make basically what's a controlled chemical reaction that artificially makes caprostil and epicaprostil slightly different from each other because they are almost the exactly identical molecule in terms of their structure. It's very difficult for GCMS to distinguish between them. So that's why we have this derivation step to improve our detection through gas chromatography mass spectrometry. And that is what gives us our data. A brief word on the chronology before getting into this just to state how we obtained time here. So the first core that I mentioned to you that was obtained by Sam Munoz and he had two publications out of this, actually three, one that doesn't pertain to this work as much. But here's his chronology. It's based off of 10 radiocarbon dates. And in his 2015 study he noted that there were multiple significant flooding events. And I was able to find the same flood events in my core and they happened at a very similar depth. So we basically linked the cores in time through these flood events and that's how we were able to apply the chronology to both cores. Moving on to actually looking at our results. Here is the results of our fecal-stanal analysis between the two cores. And the first thing I'd like to point out is that they're pretty much in agreement for most of the time. And that leaves me to believe that they are representative of the larger watershed and not just showing what's happening right at the shore next to where we got them. There is a slight divergence in the historic period. I thought a lot about that and I don't have a good answer for why that might be. However, since our focus is really much earlier than this, it's a good thing that we have this agreement on a fecal-stanal maximum around 1,000 AD and a fecal-stanal minimum just after 1,400 AD. Now I'd like to mention, you'll see here that I have the data presented as a ratio and I haven't discussed how we present our data yet. But the reason I do this is because if we were to show just the sheer concentration of these fecal-stinals over time, it would look like a decay curve because although coprostal is very recalcitrant and it persists for a long time, it does decay and so we get less and less of it. And it makes these really important distinctions that happen in the past muted. So to really emphasize that we use this ratio and what that ratio is, is a ratio suggested by a British researcher Ian Bull, a ratio of the human fecal-stannals, coprostal and epicoprost, epicoprostal to the same standals plus five alpha-cholestinal. I haven't mentioned that molecule yet, but what it is, is the breakdown product of cholesterol that occurs in the environment, not in our guts. So that's something that's just consistently happening in the environment as cholesterol just decays out in the open. So what we have is basically a ratio of the human input versus what's happening on the environment, but the idea being the higher the ratio is, the more sort of human input and the lower that ratio, the lower input, the lower population. That's the idea that we're getting at with this ratio. So now to put our data to the test and see how well they do against those population reconstructions, let's have a look at that. So here are the population reconstructions from Pocateye Lopinot and Milner. And as you can see, in a gross sense they agree. We do get our population high slightly before those of the traditional reconstructions, but once we're in decline, they're very much in agreement and we actually extend our population record out a little bit further on either end. So we find that our actual population is population minimum is past the sand prairie phase and actually around 1400 AD and a time period where this is actually not that well understood in the region. So we're kind of contributing, I'd like to argue, to that period. In addition, I've been thinking a lot about why we have the high a little bit earlier and I think it's because what we're showing here is what's happening on the entire watershed. So it's well known that prior to Pocateye really taking off, there was a lot of people in the region to begin with. So I think what we're seeing is that there's a lot of people in the region that are coming together to produce this high that we see here that archeologically kind of shows up a little bit later. And then also, last thing to note on this is just that it's very obvious how there's a lot more people in the Pocateye region before Pocateye proper was really established than if you look at that net change afterwards, it really crashes. So this is a net loss and it's a big one, I'd like to argue. And then we can kind of just more for fun at this point than anything, kind of look at the timing of various cultural events in regard to what we see in the fecal stanels. Something that I found interesting that I don't know a whole lot about so I won't speak to it very much is just the timing of Mound 72 and the associated human sacrifice happened during our population maximum which I think is kind of interesting, might be interesting to look into that more but this is just a sort of side idea I have right now. I'd like to pursue a little bit more. What is quite important to understand is that right when we're in our decline you'll see these peas that show up as these arrows which stand for palisades. There were a series of palisades that were constructed around Cahokia that are traditionally thought of to be as an indication that things were going bad at the site. And so we sure enough we find them right about when we're really starting to get into a decline which makes sense, that really holds up and leads me to further believe that what we're seeing here is real human population. And lastly to note, we actually have a population rebound, a modest one before European contact with the DeSoto expedition in the 1540s occurred. So it's been said that when Europeans arrived this 8th area was abandoned but I'd like to say that actually this area was starting to receive more of a rebound and there's definitely people here, definitely not Cahokia level but there's some rebound going on. So far what I've basically done is just showed that here's this method and it seems to work but we haven't really contributed that much new information to the understanding of Cahokia. So what I attempted to do for sort of the last part of my thesis work was show how we can use these fecal stanels to assess ideas on demographic decline or increase for that matter, but in particular in regards to environmental events because like we can see with the fecal stanels in soil and sediment, sorry Lisa, I'll think more closely about which term I use there, in Lake Settlement we can also see paleo environmental events in Lake Settlement as well and make direct comparisons so that's what we'll attempt to do. So there are many ideas as to why that dramatic decline at Cahokia happened. Many of them are societal explanations involving political collapse or economic problems and I cannot directly address those through these data. That's a problem that I actually hope to think more about now about how to bridge that gap but what I can really get into and by the way I'm not trying to not acknowledge those. I very much think that they're real. It's just a problem of trying to make direct comparisons. Where I can make those direct comparisons is with these environmental explanations. There it is. So of the environmental explanations that I've put forward, some of them involve multi-decadal drought, there's also changes in seasonal precipitation, massive flooding and environmental degradation. And so my hypothesis on all of this is that if a certain environmental event had an impact on Cahokia's decline, it would occur stratographically at or near the peak fecal stanel concentration and that if that did have an impact it could have perhaps then kicked off that decline. So what we can do is look to the stratigraphy to see where these events occur relative to our fecal stanel data. So that's what I hope to do. And one last note on this too is a lot of these researchers have kind of formulated their arguments in terms of it was this in a very not a comprehensive sense and what I'm hoping to do too is perhaps use these data to unite some of these ideas as well as opposed to saying this one's wrong, this one's completely right. So let's start with flooding. And I apologize, I have like a big figure that goes down, it looks great on paper but on PowerPoint, not so much so I had to kind of cut it around so just ignore that brown color right there. But many of us at all hypothesized that flood event five, which they noted is this increase in median grain size right here, occurs, they had by the size that this had a impact on Kogi's population. It was a big unexpected flood event and there hadn't been any floods for several hundred years before that. So what we find relative to the fecal stanels is we have this flood event immediately after the fecal stanel maximum. Now it might seem like there's a gap in time right here because it's this width compared to that width but note that that's 20 centimeters that happened instantaneously. That was a single depositional event that occurred immediately after these more elevated values here. So I believe that this actually supports Munozada's idea that this flood may have contributed to the problems that Koki may have had. We can't go out and prove that causation but I do think that it is a pretty strong correlation. Moving on now to environmental degradation. It's been suggested as well that perhaps people at Kahukia deforested the region which led to problems with erosion control and that forced people to kind of just pack up and leave. So if there was increased deforestation we would expect there to be increased watershed erosion which would lead to a greater mineral content in our lake sediment. And so what we actually see is that we find mineral content decreased during the fecal stanel population maximum. So it goes down and to me that indicates that the fecal stanel data do not support the idea of environmental degradation occurring based on these data. So we don't see a strong correlation there in my opinion. And in addition to that Munozada in 2014 actually demonstrated that a lot of tree pollen really declined much earlier around 400 to 500 AD. So he argued that that deforestation occurred a thousand years almost before Kahukia was a thing. So moving on to the idea of multi-decadal drought. This was an idea put forward in particular by Benson et al in 2007 and he basically found evidence of a large-scale multi-year drought that occurred in the mid part of the 12th century. And so although I could not use the same methods he used which were based on tree ring data I figured that we could use oxygen isotope data as a proxy for hydroclimate and make a direct comparison between those isotopes and our fecal stanel data. So that's what we did. And so we would expect that if there was a large-scale drought what would happen to the oxygen isotopes is that these delta-18 values would become more positive. So you'd expect these isotope data here in orange to be more positive during a drought and more negative during wet conditions for a very large drought with a lot of evaporation. But instead what we find is that there's positive delta-18 during the stanel high and negative delta-18 during the low which does not support Benson's idea. That's saying that there was a drought when most people were there and that things got wetter when people started to leave which is kind of the opposite of what he suggested. I do think though that Benson was definitely on the right track in the idea that hydroclimate and rainfall in particular played a big play or was a big player in Kokia's decline. So sort of an amended theory on that was put forward by Burt et al. just this year. And their data comes from Indiana. They're looking at delta-18 values of carbonate material from a lake over in Indiana and they suggested that it's more of changes in the seasonality of rainfall and that what was happening was there were times of more summer season precipitation which is great for maize agriculture and then there are times where that precipitation shifted to more winter rainfall which doesn't do that much for you in terms of maize agriculture which would be bad for people who really relied on that. So what we'd expect then is that there'd be a more positive delta-18 values during the warm season as we're getting like positive delta-18 water coming up from the Gulf of Mexico and being dropped in the summer. And then we'd expect more negative delta-18 values during the cold season as we're getting more rainfall coming in from the north from water that is characteristically lower in its delta-18 values. And that's exactly what we see. We see that during the fecal stanol high here we have our relatively higher delta-18 values which may indicate that during this time there's more summer precipitation, good for growing maize and then we lose that around right here and it shifts to a more negative value. So this could be a large change in climate controlling this. And we actually find too that our delta-18 values match up quite well with those of birded ales and you'll see that there's this area that's positive, an area that's positive and then an area that's negative and an area that's negative and we find that in our lake that's much closer to Kokia. So I think this is definitely a regional phenomenon, not something specific to just the lake in Indiana. So to tie it all together, and I apologize because this is a very, very tall graph, not good for PowerPoint, but what I believe happened is that we have this change in seasonal precipitation. I believe it occurred around 1150 A.D. right here. There was also this flood event that happened around the same time on our age model at 1159 A.D. And that kind of corresponds to this drop in stanols that happened right there. So it is my opinion that there was not just one large environmental event but several environmental stresses, one affecting agriculture in a sort of longer trend and one in immediate event in terms of a flood, that might have put increased stresses on the people living here who may have already been dealing with economic and political problems on top of that. So in order to really get people to leave, if you have all these problems happening all at once, I think that really is a good case for what might have been going on. And it's through the fecal sale data that allow us to do that, that allow us to really unite the flood and the changes in precipitation. It's because that's what kind of ties us all together. And all even since I feel this is a friendly environment, I'll take it a leap further. So I was talking with Drinco in class about this other day about the effective climate and so I'm going to show my true colors here. So I also plotted North American temperature change over time here. And again, I'm sorry that I had to kind of cut this awkwardly. And what we see is that there is actually warmer medieval climate anomaly sort of level temperatures earlier on, closer to Kokia's maximum population. And we do get this kind of decrease in temperatures as we're transitioning to little ice age conditions. And I do wonder, I'm not going to say that this is what happened, but I wonder if that might have been manifesting itself in this sudden increase in flooding and change in the seasonality of precipitation in the context of more almost global level climate change. So that one I'm less a little bit ready to take and run with. But I do wonder if there's some sort of relationship here atop what's happening at a societal level. Again, which I wish I could talk more about. I just haven't find a way to make that jump yet. So that is what happened at Kokia for my data, I think. And in terms of new directions and ways that I want to take it here at Cal, Lisa and I are looking at trying to test this method in an epipaleolithic context from a burial, which as far as I can tell will probably be like the oldest this method has really been attempted. So that's kind of seeing how far back in time we can go. Additionally, in targeting a burial, I haven't heard of people doing that. So that's kind of a new direction for it as well. I'm also really excited about using biogeochemistry in archaeology. And I'm going to keep an eye out for other approaches that we can be using to get at the past coming in this kind of way. And then also, I'd really like to hear any sort of new ideas anyone might have or possibly even collaborations or even just advice about how this all works, what you think of it. And again, if you have any information on where people pood, tell me. So yeah, so thank you very much for your attention and yeah, thank you. Hey Felicia. That's a good question. So the movement of the molecules right in the sediment. So I mean, we're in like sediment and at times you do get these kind of big pulses like those floods that might be kind of stopping some bioturbation. At the same time, these molecules are hydrophobic. So they do want to latch on to the sediment that's near them. So I think that would probably prevent a lot of movement. But I have not really investigated what happens to these in soil with time. Do they stick in place or not? I frankly don't really know a whole lot about that. But I think not too much. Yeah. That's a great question. So if you have someone ingesting more cholesterol than others. I don't think that has been investigated formally. I've considered maybe changing my diet and trying this out myself. And just like eating barbecue all the time versus going vegan. Because I think that might have an impact. I think there's an assumption that I make that the diet across time is pretty consistent. Which is probably not the case. There's probably some changes I think. It might not make a huge difference. But that's yet to be investigated. Yeah. You finished up by saying later, a community member saying, hey, the corn's growing really tall over there. But we have high school students doing hardware store soil tests and survey patterns across the valley of some of these communities that we work in. Would those tests help you narrow in? Or would there be a parallel test that you would run or suggest for us to run as we do these valley-wide surveys, doing these hardware store, you know. They're saying, oh, this is really high. These kinds of nitrates are really high in these kinds of phosphates and we think they're bringing these kinds of crops because of these surveys. Would there be a parallel test that would be affordable and something that our high school kids could actually run? That we could be doing to kind of answer your questions. Where did people poop or were they using that so it would serve their lives? Yeah, I think that's an excellent idea. That could be relatively done easily in the field. The laboratory methods of quantifying this stuff can be more advanced and can be a little expensive as well. For my master's work, each of those dots was $50. So that, yeah, it adds up. So I'm not sure what the price will be when I get that. I'd really like to get a relationship with the lab here. Maybe it will be more cost-effective. But that's just something to consider in terms of actually going for fecal snails. I am familiar with some work looking at phosphorus and nitrogen and things like that. That's a lot cheaper to analyze for. And that might give you a better idea on just fertilizer in general, not specific to a certain animal or human. So yeah, but if you're looking for fertilizer in general, yeah, I might suggest what you kind of had mentioned for those elemental sort of studies. Yeah. Just from the archaeology, I've asked some formal remains, for example, are they primarily eating deer or what would be the major kind of vein in that? That might also affect your Jordanian example if it's, you know, release of cyclolygazelles. But related to that, is there then possibility a dietary difference between elites and commoners? Where the elites may be getting more of the deer or other meat proteins compared to others and how might that affect your generalizations? Sure, yeah. I can only speak somewhat anecdotally to this, since I really cannot consider myself an expert on Kogia. I mean, that takes decades. But what I can say is what I've read is that there's surprisingly not a large variation from what we can tell and what people with more hierarchy were eating compared to the more average person. There's not seemingly a huge difference. There was feasting. Do you want to jump in there? Okay. So there you go. As to how that might affect the data, given that, you know, the lead are a relatively small group of people, as long as, you know, we have something that is pretty consistent across a large group of people, I think that's what we need to really establish what's happening in large-scale population. And, you know, what a few people might be eating and a small difference, I don't think would make a huge impact on, you know, our ability to distinguish large-scale population change. Yeah. We would have some sense about how these chemicals are made in the gut, right? And so a cholesterol is pretty obvious. We know what kinds of plants and animals cholesterol occurs in my data on that. Your standals are not necessarily coming from cholesterol. I haven't looked up here on that. Are they coming from other things? Is it all about cholesterol? So what I did not get into today is that archaeologists also use other types of standals that come from plant sterols. And so if you're looking at, like, so I mentioned that there's some domestic animals, like cows that produce this molecule. Cows produce way more cytosterol, sigmasterol, because they're eating primarily plants. And so people can use those molecules for that study. However, for Caprocinol, that does drive only from cholesterol. And so cholesterol produces Caprocinol. And it can be degraded in various ways, but Caprocinol itself only comes from the parent molecule of cholesterol. Right. I mean, we make it in our body. You can be a vegan, and there will still be some amount of Caprocinol in your feces. A lot less though, because you don't have that additional input. Not so much a symbol of meat eating, just a symbol of this is a molecule that's produced pretty uniquely in human guts. And that's what we're using to try to link back to this. Right. Diet has not been investigated in a large sense in regard to this method. And there could be a lot of important differences there that might matter. But as of yet, I don't really know what they are. But then it also is the issue that with a little bit of refinement in the technique and the particular samples that you would actually get at, it's a diet. Or like in your burials, I mean, a burial is really different than a watershed. Right. No. For sure. In person. Exactly. And that will be... You said that the preservation condition didn't really matter if it's temperate zone or anything. Your core was still a lake core. Right. Does it have to be waterlogged? Does it have to be waterlogged? No. So the first studies were not in water. They were just on dry land as someone going across a modern farm and looking to see has it always been a farm and just getting soil. However, I think with the advantage of some sort of catchment such as a lake, is that you do get past a wider net. And so that's why we went for water, not for some sort of preservation reason was to catch that. And also because I think that lakes are great records of other events that make you able to say a lot of things about climate and things like that. So they actually utilized human species as fertilizer. Oh, well. So they actually transported a big challenge outside of the city of Edel. And that was part of the reason why agriculture in the summer worked very well. They also shipped a whole bunch of herring and sardine all the way from Hokkaido to mainland. Obviously this requires a big boat. But in your case, imagine if they were utilizing species as fertilizer to agriculture. That kind of thing could be potentially detected? Absolutely. Yeah, I think that would be a wonderful study. And a similar study was done on Mycenaean farms in Greece by Ian Bull, who I mentioned earlier. And so he was looking at 3,000 year old farms that had human feces as the fertilizer. And I think for this case, it sounds like it might be more widespread than an obvious change. You might be just in the soil, probably full of no-cabroson-cabroson, and bam, you know, a sudden pulse of it. So that actually might be really interesting to look at. Yeah. A tiny little thing to say. Please. I'm talking about Arctic environment, cold all year round. That's not okay. Okay. Yeah. Very well. Which is even better for you because it's not frozen. True. Yeah. No, it's a summer climate in the summer. Okay. North. Oh, absolutely. Wow. Okay. Cool. Beautiful. Beautiful. Awesome. All right. Okay, thank you very much.