What's a natural diet? (with Amy Styring)

Around 6000 years ago in Northwest Europe, our ancestors transitioned from hunter-gatherer societies to sedentary farming. How did their diets change during this time? The field of archaeological sciences and chemistry teamed up to shed new light on this question.

In this episode, we ask Amy Styring, archaeological chemist at the University of Oxford, what's her take on a natural diet, whether we overestimate the role of meat in our past diets, and what lessons can we learn today if we have a better understanding of how people produced and ate food in the past?

This is the first of a two-part series. Next week we hear from a meal historian on the role culture plays in informing what we eat.

For more info and resources, visit: https://tabledebates.org/podcast/episode59

Guests

• Amy Styring, Associate Professor at the University of Oxford

Episode edited and produced by Matthew Kessler. Music by Blue dot sessions.

Transcript

Amy

I think food and food production is a real leveler. We all have to eat. And so getting an insight into what people were eating, we're not just focusing on the people who have gold bracelets associated with them or buried in special places. We can understand what everyone was doing and what they were doing in order to stay healthy or to survive.

Matthew 

Can you first introduce yourself?

Amy  

I'm Amy Styring. I'm associate professor of Archaeological Science at the University of Oxford. 

Matthew 

And you're an archaeologist and also a chemist?

Amy  

So I studied archaeology and chemistry, and then I've managed to carry on, basically using chemistry as a tool to understand more about life in the past. So it's a little bit like, well, archeology is a bit like detective work trying to work out what people were doing, from the traces that they have left behind. And chemistry is a tool that can help with that. So using the actual molecules, or the chemistry of the things that people left behind to understand more about their lives.

Matthew

Welcome to the nature season of Feed, a food system podcast presented by Table. I’m Matthew Kessler. 

In our next two episodes, we're going to hear two different answers to the question: what’s a natural diet? 

Amy

The topic I'm interested in is what people were eating, and then also how they were producing their foods. So how they were growing their crops, how they were herding their animals, and then what impacts that those activities had on their environment.

Matthew

With Amy Styring, professor of archaeological science at the University of Oxford, we look for answers 6000 years ago. 

One of the things that this series is looking at is ideas around naturalness. And what's a natural diet? And there's a lot of claims about how different diets in the past are seen as a benchmark for how we should eat today. Do you have some views on this?

Amy  

Yeah, so I've been asked that question before. My answer is always well, yeah, how far back do you want to go? I mean, how far back is natural? We can talk about really ancient ancestors, evolutionary timescales. We actually don't know that much about what they were eating. I mean, it's very difficult to find out from their remains. 

We've been eating dairy products, maybe not just as milk, but as fermented milk, yogurt, cheese, since we've started farming, which is up to 10,000 years ago. But is that sort of far back enough?

I think there's been a bit of a focus on meat eating, for example, it's easier to understand what types of animals people are eating, because we find their bones, whereas we don't necessarily get to it, it's not so easy to find out, you know, different types of plants that they were eating. 

Matthew

Animal bones are bigger and they preserve more easily than plant material, which decomposes much faster and often doesn’t show up in the fossil record. So how might the way different food decomposes impact our understanding of past diets?

Amy

There’s definitely been a bias towards meat consumption, because it's easier for us to see. So we find the bones of animals on archeological digs. And so we can identify which species those animals were, and we can try and get an idea of how many animals and you know how important they might be in the diet. But actually, it's really difficult to recover the plant remains. Either they just don't preserve as well. Leafy plants will only survive 1000s of years in really specific conditions if it's very dry, if it's very wet. So we don't necessarily have those visible remains that we do for animal bones. But even then, they're just a lot harder to find. They're a lot smaller, so you have to sieve the soil in order to find those small plant remains, which hasn't necessarily been done on very old excavations, for example. 

Matthew

Amy Styring is a part of a group of archaeologists that apply chemistry techniques to older excavations as a way to learn something new about our past. Amy believes that the insights from this new research can reshape, or at least nuance, our understanding of past human diets. 

Amy

The newer methods - the chemistry that's been used to understand what people were actually eating. This, again, is sort of biased. We look at the collagen, which is the protein in bones, but this is biased towards - it's produced from the protein in the diet. And meat and fish contain much more protein than most plants do. And I think it's only recently that really exciting methods, which can actually look for specific molecules, which are specific to certain types of plants, even maybe species of plants. Seeing that actually it's not just about those main staples like meat, carbohydrates, fat, but actually, what plants did they exploit and the vitamins and minerals, the sort of wider antioxidants that come from a diverse range of plants.

Matthew

Of course these main staples, these high energy foods are important. But what else were people eating and how important were those foods in their diets? Understanding this whole picture leads Amy to offer a pretty clear answer on what constitutes a natural diet, and how that might guide what we should eat today.

Amy

I think there's a lot more to be done to understand what people ate in the past at different points, which is really relevant. But I think what really strikes me is actually the diversity of different things that people ate in the past. So even just talking about cereals. Today we rely very heavily on bread wheat, and a particular kind of very narrow sort of gene bank of that bread wheat. 

Well, actually, we're learning more and more that in the past, people weren't just growing one type of wheat, they were growing a mixture of different types of wheats. And even within different species, you know, different land races, which are kind of different variations on those species. And I think that, we've become quite niched. So I think that's, if I were to try and pick a sort of, what is a natural diet? I think it's diversity. Even when people started farming, they didn't stop hunting animals for a very long period, they didn't stop collecting the wild fruits and nuts and plants that they had before they were growing crops. So I think it's that sort of diversity in the diet that maybe has more of a nod towards naturalness, whatever time point we want to put on that.

Matthew

Amy Styring examines what we ate in the past. Specifically around moments of transition in human history, like the shift from hunter-gatherer to farming societies. And how our diets and food production changed when we moved into cities. 

So I want to focus on this transition from hunter gatherer to sedentary farming. So can you first set the scene? Where are we and when are we?

Amy  

I'm going to focus on, yes, as you say, that transition from hunting and gathering to farming, but focusing on Northwest Europe, so particularly Britain, and sort of southern Scandinavia. So this is because a lot of work, a lot of the kind of archaeological science work has been done here over the last few decades. So here, farming actually started relatively late. So we're talking about about 4000 BCE. So that's about 6000 years ago.

Matthew  

And I'm really excited to talk to you because, like you said, there's been decades of research, but there's also new research, which you've been a part of too, that challenges some of our previous findings. So first, what has been our understanding of what diets were like during this time?  

Amy  

The traditional way of trying to find out what people were eating was looking at, basically the rubbish that they left behind. So animal bones that they threw away after preparing the food, eating the food, the plant remains, hopefully, that you might get because they sort of fell close to the fire and they got toasted. And so you find them as kind of these little charred remains, fish bones, but again, these are really small, they break up very easily, so they're a bit more difficult to find. 

What was 30, 40 years ago now was revolutionary was actually we could look at the chemistry of the bones of the people themselves to actually find out okay, well, what are their tissues made of. 

So has to come from their diet, and actually using the chemistry. So looking at different versions of carbon, for example. They're called isotopes. And these are found in different proportions in different types of foods. So particularly useful for distinguishing between marine resources. So fish for example, seals and terrestrial, so yeah, herbivores, and also plants that have grown on the land. 

Matthew

Okay, so 3 or 4 decades back, archaeologists began not only to look at animal bones and plant remains to determine what we ate, but they started taking samples from the bones of humans, and analyzing what their tissues were made of. This method helped archaeologists better break down what animals and plants they were eating from the sea and from the land.

Amy

And so quite early work was done measuring these different isotopes of carbon, versions of carbon in these human bones. So from the Mesolithic context, which is the hunter gatherers,, before farming. And then also from the first farmers, in what's called the Neolithic. And they found, really surprisingly, that whereas there's evidence that the hunter gatherers are eating a lot of fish. Once you see other evidence that people were farming, so we get pottery, we get domestic animals, like sheep, goats, cows, and we get cereals like wheat and barley, they were no longer eating fish. Or at least you couldn't detect it in by looking at these carbon isotopes. And so there's this big discussion: people turned away from the sea. As soon as they sort of were able to produce their own food, they stopped fishing, and they sort of focused on the land. This was really controversial. And so it's kind of almost stimulated an ongoing impetus to almost challenge the idea work out whether this was actually the case. I think that's a lot of what of the sort of these new methods of doing is, is almost trying to add nuance to that to the overarching picture.

Matthew

So 6000 years ago in Northwest Europe, as hunter-gatherers gradually began living more stationary lives and changed they changed their diets. Previously they gathering more seeds and berries, hunting land animals, and fishing. And as they started moving towards farming, they were eating domesticated animals and crops, and they largely stopped eating fish, which is something we’re still learning about. Did they still hunt land animals?

Amy 

Not necessarily abandoning the hunting of the terrestrial animals. So we still find a lot of bones of wild animals. So things like red deer, elk, wild boar, on these early farming sites and lots of gathered nuts, for example, but it's the fact that they seemed at least in northwest Europe, they seem to have stopped fishing, stopped eating huge quantities of fish, and seals as they had done in the past.

Matthew  

Now there are some new methods available. So can you paint the scene? Are you still going on an archeological dig with your equipment? Is everything happening in a lab? How does this new data gathering look like?

Amy 

Yeah, so new data gathering is actually really exciting because it doesn't necessarily need new excavation. So it's actually so one of the new methods is actually looking at the fats that get absorbed into pottery vessels. So when people were cooking in their pots. For example, boiling away their stews. The fats from for example, the meat, would soak into the actual ceramic, the pottery matrix. And then that pot breaks, it kind of ends up in the soil, and then we can still recover the fats after 1000s of years. And I think that was so exciting, because actually museums, stores there are 1000s, hundreds of 1000s of broken bits of pots. That to be honest, people have studied and done lots of interesting studies to understand how their shapes changed. You know how the forms of those pots change and how that might tell us about society and different groups of people but it's kind of untapped a new side. 

So actually, people are going back through the archives and finding these broken bits of pots and being able to find something new about what people were eating. And so what was, again, what was a new development in this, was that they were able to identify the oils from oily fish. So in these pots, and so they were able to explore this transition. 

So in Scandinavia, for example, actually, the hunter gatherers did have pots. And so they're able to extract the fats from the pots of the hunter gatherers and see that yes, they were, they obviously had their processing lots of fish in these pots, find lots of these oily, oily fats. But that also the Neolithic farmers were as well. So actually, that challenges this idea in Scandinavia, at least, that people completely stopped consuming fish. That wasn't the case in Britain. So Britain, and this is why it's kind of adding nuance, you don't see any evidence for these oily fats from fish in the early farming pots. And so it does seem to hold that people stopped, stopped eating fish at this time.

Matthew  

Is there a hypothesis why those two regions took different paths.

Amy  

So Sweden, for example, southern Sweden, for a long time hunter gatherers, and farmers lived in close proximity. They were contemporaneous. We know they were interacting with one another. Whereas Britain, it seems at least from genetic evidence that early farmers came in to Britain. We're still trying to understand, but it seems like maybe there was more of a wholesale kind of transition to farming. Whereas in southern Sweden, people were very much hunters and gatherers, and farmers were very much living alongside each other. So maybe there was less of this kind of dichotomy between the fishing and the farming.

Matthew  

So the fish is one component, what else were you able to detect through these new methods?

Amy 

Well, yeah, as I said, there has been a bias, even with these new methods. There has been a bias towards the sort of protein rich foods like the fish and like the meats. But what's really exciting is very recently, people not myself, other researchers have looked at - they've been able to look at, for example, the proteins in. So the plaque of your teeth becomes mineralized, it becomes what's called calculus, it's basically your so much plaque, it becomes hard like tartar. But it traps molecules. So it tracks kind of everything that's been in your mouth. And so this is a new way to actually detect particular proteins that can be linked to certain types of plants. Now, there hasn't been that much work done on it, it's been mainly focused on trying to identify the milk protein. But more and more work has been done on plants. So I'm kind of excited about that. But what came up really recently, so literally a couple of months ago was a paper. There was a study that has actually identified seaweed in people's teeth. So they again, it’s this calculus, so on the teeth, they were able to identify specific molecules that come from seaweed. And this is just again, it sort of showcases the diversity of people's diet in the past. We don't think, at least in Western Europe, we don't think of seaweed as a kind of staple or, or even as a sort of a condiment, really. Whereas this study shows that in the past, people were eating seaweed. And so it was an extra part of the diet. So I'm really excited about where it's going. I think, you know, we've seen how this picture of what people were eating has changed already with different methods. 

I hope that that's the sort of next stage is really revealing more about what the diversity of the plants that these people are eating. And again, exploring whether there is more nuance to this idea that once people could grow their own wheat and barley, they narrowed down their dietary spectrum, or maybe maybe they didn't. Maybe they that sort of diversity lasted for a really long time.

Matthew 

I guess this brings the question that we introduced at the beginning, which is we have new methods. We have new understandings of this particular transition in time and I'm sure these methods will be applied across different time periods, in different regions, which will, as you say, nuance our understanding. What does this mean for you about the debates around what is a natural diet today?

Amy  

I think the more we know about what people are eating in the past and how they were producing their food, the more - I’ve had someone described this to me, and I think it's really nice, is that we “can expand the library of possibilities”. So today, we can only see a certain set of possible ways of eating, possible ways of producing food, whereas the past provides this library of, you know, different ways of doing things. And so it's only by refining the tools that we have to read that library, basically, to see that diversity, that we can really explore that. 

I think the other thing is that, for me, I find studying the past, so exciting, because I could set up an experiment today, you know, to see the effects of eating a particular diet, on people's health or on society, or, in particular, what I'm interested in is sort of the effects of farming in a particular way. What does that do to the soil? What does that do to the environment? What does that impact does that have on people's health? We can't, I can set that experiment up. But I won't be able to see the effects of that over hundreds or 1000s of years. Whereas actually, by going back to the past, we almost have - it's not an experiment, but we can almost observe how sustainable certain farming practices were, what effects they had on the soil, what effects they had on the environment. I think that's really important to understand. Yeah, the effects of different types of diets or, of cultivation practices. How they will affect our world, whether you see that as natural or not. 

Matthew  

The past is such an interesting thing to look at, because there's such a plethora of examples to draw from. And the conditions in the past are not always the same as the conditions today. Especially around population size and the environmental challenge that we are confronted with. Is there any sort of Flim Flam or common myths about the past when people cherry pick different examples from it that you would like to debunk? Or to speak to from being a archeologists-chemists who is, who is actually working on the science that's informing people's understanding? 

Amy  

Sounds bad, but maybe I'm not so tapped into what these myths are? That it makes sense, because we're so used as academics to always be looking for the nuance and always having to caveat what we say. And so actually, being really aware of what these myths are. Maybe I take it for granted that they're not true, if that makes sense. Not that they're not true, but they're always be more nuanced than maybe it appears. So I mean, it's just reiterating the point. But I think, from me, not necessarily a myth, but I think this focus on meat, because it's easy to see in the archaeological record. Easier to see, it's not easy, but it's easier to recognize meat consumption, as opposed to plants. I think that is a preconception that most people have, when they think of paleo, they think of the kind of paleo-diet, they sort of think of the red meat and not necessarily about the diversity of potential plants that people would have been supplementing, would have been having in their diets hundreds of 1000s of years ago, if that's how far you want to go back. When talking about natural diets.

Matthew 

Just to name two examples. So I've been very immersed in this in the Meat: the for futures project that I've been working on. So I've been hearing all these different arguments and people use the past as you know, as precedent. We’ve had some guests who have said, who have pointed to some older societies that have eaten, you know, a largely meat diet like way more meat than people do an average day and they were living healthy lives. And then I know also that there's civilizations going on for quite a long time eating largely or exclusively plant diets. So, yeah, I don't know if there's anything to kind of reflect on with these people drawing from these very different examples of the past?

Amy 

I think it would be: how do we know that? We've got lots of methods and the new methods developing . But actually, we're still relatively limited in terms of what we know. So if we go really far back, hundreds, 10s to hundreds of 1000s of years ago. We don't have this, the bone isn't really preserved, it's fossilized. And so actually, the insights that we get into the importance of meat from the chemistry is very limited. So really, new work is being done to try and get this from tooth enamel. So we do have teeth preserved. Tooth enamel contains the tiniest amount of protein, absolutely tiny, but people are actually managing to analyze this protein now. And so then maybe we will get more advances into sort of how important meat was in the diet. So I think it's, how do we - where are we getting this information from? And I would suggest that maybe if it's coming from looking at the animal bones that are found on sites, where it's very easy to dismiss or to not, not be aware of because it's very hard to find the plant component of the diet. And so I think it's really difficult to actually really get a handle on how important meat was versus plants in the past.

Matthew 

Thank you so much for speaking with us, Amy.

Amy 

Thank you. It's yeah, it's been fun, and I really look forward to hearing how it comes about.

Matthew

Digging into the diets of our ancestors, you probably can't help but wonder: how are these old eating habits relevant for our modern lives? One thought I had since chatting with Amy was thinking about dietary trends of today, like the paleo diet. I think one of the attractions to the paleo diet is not just about what we should eat, but what we shouldn’t eat. But it’s always strange for me to see some combination of cauliflower rice and organ meat. It’s a weird take  on a natural diet. But anyway, there’s this modern fascination, that goes beyond the paleo diet - to avoid processed foods, grains, and whole categories of other foods like dairy, despite the fact, that as Amy points, some of which have been part of human diets for anywhere from 1000 to 10,000 year old..

Conversations with experts like Amy highlight that we’re still learning about what we ate in the past - and with new research challenging some ideas of what we ate, or how much of something we ate, we can maybe be a little more humble about claiming what a natural diet is. Especially given the range of what people ate around the world across different cultures and time periods.

Next week, we’ll hear a very different take on what is or what informs our understanding of a “natural diet”. We talk to a meal scientist Richard Tellström on how diets have changed in Sweden over the last 100 years.

Richard

And it's still very difficult to find a good horse meat in the shop. They don't have horse meat on the menu. Why not? It's such a good meat

Matthew

A big thanks to Amy, professor of archaeological science at the University of Oxford for speaking with us. 

We’ll link to her work and other reserach mentioned in this episode on our website: https://tabledebates.org/

TABLE is a collaboration between the U of Oxford, Swedish University of Agricultural Sciences Wageningen University in the Netherlands, the University of the Andes in Colombia, National Autonomist University of Mexico, and Cornell University in the US. This episode was edited and produced by Matthew Kessler with special thanks to Rye Hickman, Tamsin Blaxter and Tara Garnett. Music by blue dot sessions. Talk to you next week.