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The Gift of Food | The Science of Food

We follow the journey of food through the body and discuss the role eating and cooking had in making us into the species we are today.


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Cut peppers with spices

Photo by Colin Hoogerwerf

We follow the journey of food through the body and discuss the role eating and cooking had in making us into the species we are today.

Description

Taste is a sense that sometimes gets overshadowed by sight and sound, but it has played a crucial role in the development of our species. Some expert guides help us understand what is happening in our brains when when we eat. We also talk about food and cooking and the roles they have played in making humans what we are today.

This is part three of a five part mini-series.

Theme song and credits music by Breakmaster Cylinder. Other music in this episode by High Street Music, Klimenko Music, Northern Points, Tiny music, Glory House, Vesper Tapes, Liam Mansfield, Klaus Hergersheimer, Babel, and Nick Petrov, courtesy of Shutterstock, Inc. 

 

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Transcript

Stump:

Welcome to Language of God. I’m Jim Stump. 

Hoogerwerf:

And I’m Colin Hoogerwerf.

Stump:

Let’s do a little recap. 

Hoogerwerf:

Sure. In episode one we talked about how food has the possibility of being a great connector, connecting us better to our own materiality—

Foster: 

[clip from previous episode] Matter, in terms of the food, matters.

Hoogerwerf:

—connecting us to the world where the food comes from—

Weston: 

[clip from previous episode] So often we don’t think of the steps that it takes for food to get from the place where it’s grown or raised or manufactured to the table.

Hoogerwerf:

—connecting us to each other around the table—

Holmes Curran:

[clip from previous episode] I might want to share all that I have learned that I’ve learned to love and so I invite my friends and family, those who do not have enough to my table.

Colin 

—and finally connecting us to God, the giver of the gift of food in all its abundance and flavor. 

Wirzba: 

[clip from previous episode] Food is God’s love made delectable.

Stump:

Episode two picked up on that last one, though it’s pretty hard to be connected to God without being connected to the world and ourselves. We looked at how the ancient Israelites might have thought about food and the role of food in several bible passages, but we spent a lot of that episode talking about communion. All of it, though, led us back to this idea of food as a gift. 

Hoogerwerf:

I’m tempted to say this episode is going to do the opposite thing—that we’re going to make a full turn from faith to talk about science. I think that’s how we’re often trained to think of these things. We are going to focus on science, but it’s not a turning away from all the work we did in the last episode. Naming food and its material and physical and chemical properties will be informed by the fact that this is all a gift from God. 

Stump:

We’re going to start inside the body and take some time to look at how the brain registers what we put into our mouths. This will get us to one of our favorite topics, because there’s some good evidence to show that how humans have interacted with food has played a big role in what it means to be human. 

Hoogerwerf:

It’s no big surprise that food is pretty closely tied to evolution. How creatures find sustenance is probably one of the biggest factors in what traits will be passed on genetically. Finches with bigger beaks survive longer and have more offspring in seasons when seeds are growing bigger. Their offspring will have bigger beaks. Humans who are better able at finding food in their environments will pass those food-finding abilities on. And humans have gotten pretty good at efficiently getting calories. 

Stump:

Maybe too good. That has led to health problems and has had environmental costs, which we’ll explore a bit. So we’ll be heading toward that big picture, but we’re going to start very small. 

Dus: 

So in principle, taste is very simple. But in practice, like everything in biology, is fairly complex. 

Hoogerwerf:

This is Monica Dus.

Dus: 

I am a tenured professor of molecular, cellular, and developmental biology at the University of Michigan.

Hoogerwerf:

So the basic idea here is that there are receptors— 

Dus: 

—on specialized cells on the surface of our tongue that can essentially interact with different nutrients or molecules present in food.

Bebej: 

You know, the proper term for taste that I would use when I teach my classes is gustation.

Hoogerwerf:

And this is Ryan Bebej, who some of our listeners might know from a couple previous episodes, one on fossils and he was a guest on our Uniquely Unique series about what it means to be human. Ryan has been teaching anatomy and physiology classes to future physicians and nurses for as long as he’s been teaching. 

Stump:

Both Monica and Ryan are going to help us understand what is happening—biologically speaking—when we put food into our mouths. 

Hoogerwerf:

Yeah, so starting with this very basic level of sensation of the molecules in the things we eat, which is called gustation

Bebej: 

These are molecules in things that we’re eating, ingesting. We call them tastents. 

Hoogerwerf:

And those tastents dissolve in your saliva. 

Bebej: 

And when they dissolve in your saliva, they’re able to get to little receptors that are on cells within taste buds. And depending on the type of receptor, and depending on the type of molecule that’s there, right, they have kind of a hand-in-glove, or lock and key relationship. And so if you’re able to activate one of those cells, that’s going to initiate a signaling pathway, sent to your brain to say, hey, this molecule’s in my mouth, basically.

Stump:

So this is where we hear about the different taste receptors we have, right?

Dus: 

And people know that so far, we have these five basic tastes, which is sweetness, bitterness, sour, umami, and salty.

Hoogerwerf:

So each of these receptors can detect different kinds of chemical compounds, so starting with sweet cells— 

Bebej: 

Which are going to have receptors that bind to simple sugars, bind to alcohols, and some things like that. You’re going to have salty cells that have a different type of receptor there that responds to sodium and metal ions like that. You’ve got sours, sour cells that are going to bind to hydrogen ions, which are what acids produce. This is why orange juice, lemon juice are sour to us. We’ve got bitter cells that have receptors that bind to all kinds of different molecules, including things like caffeine and nicotine, aspirin as well, so they have a very bitter taste. And then we’ve got these umami cells, which are the savory or meaty flavor, which bind to things like monosodium glutamate when that’s added to food.

Hoogerwerf:

So Ryan described these receptors as being like keyholes. Different classes of molecules have different shapes which can fit into the different receptors and send messages to the brain. And each of the five different types of receptors can pick up a variety of different molecules in different classes. So there’s not just one molecule that would fit with the bitter receptor. And they aren’t distributed evenly, at least in humans. We have more of some receptors than others. 

Bebej: 

So we are 1,000 times more sensitive to acids, to sour things, than we are to sweet and salty things. If you think about that, acids can damage tissue if they’re concentrated enough, right? Especially mucous membranes and things like that. And then we are 100 times more sensitive to bitter things than we are to acids. So we’re 100,000 times more sensitive to bitter things than we are to sweet and salty things. 

Stump:

And when we go to animals, things start to vary even more. Lots of animals don’t have some of these particular receptors at all. Cats, for example, don’t have sweetness detectors. Pandas have lost their umami receptors, presumably because they stopped eating meat and lost the need for it. 

Hoogerwerf:

Right, and most birds don’t have sweetness receptors either.

Dus: 

One thing I really love is bird watching and backyard bird watching. I have a lot of feeders. And of course, we have a hummingbird feeder where we put sugar water. And notice that there’s only pretty much one bird that I see there, is our hummingbirds. You know, all the other birds, the sparrows, the cardinals, the bluejays, they don’t go close to it; they go eat the other things put out for them. And so that’s because actually, most birds lost the ability to sense sweetness. But hummingbirds turned essentially one of the receptors that senses protein or amino acids, through some molecular changes, it changed from proteins sensing to sweetness. And so hummingbirds essentially found a different way than we do to sense sweetness. And that’s why now they drink sugar water.

Stump:

So gustation is this ability to sense different chemical compounds in the food we eat. But there’s a lot more going on when I put food into my mouth than simply detecting whether it’s one of five different things. 

Hoogerwerf:

Right. So next we can add in olfaction. Smell. 

Bebej: 

When you smell something that you really like, there are tons of odorants in there. And they’re going to activate a whole particular group of olfactory receptors. And you learn through experience that when I activate these six or seven or eight just to make up numbers, when I activate those receptors, that’s the smell of bacon that I’m smelling, right? And when I smell my grandmother’s freshly baked apple pie, it’s activating a different subset of those receptors, and I recognize that that’s the apple pie. So we’re able to distinguish something like 10,000 or so different kinds of odors, whereas we can only distinguish like five different gustatory tastes, if you will.

Hoogerwerf:

But when it comes to food olfaction, it’s more than just what you get when you inhale odorants through your nose. I really like this term I learned, retronasal olfaction, and I’ve been trying to work that phrase into more conversations recently. 

Stump:

How has that gone? 

Hoogerwerf:

I think people are pretty interested. Anyway, retronasal olfaction is when you pick up odorants, not through your nostrils, like when Ryan’s grandma’s apple pie is on the window sill and you take a big sniff. But through the opening in the back of your mouth, when the apple pie is where it should be—in your mouth—those oderants go up to your nose while you’re chewing and swallowing. And a lot of what we think of taste actually comes from that retronasal olfaction.

Stump:

But there are other factors still. Texture and mouthfeel. Temperature. Plus add in things like memory.

Hoogerwerf:

Which is also closely tied to smell in the brain. 

Stump:

So all this together is taste? 

Hoogerwerf:

It seems like there is some different terminology to distinguish between taste and the more complex combination of signals.

Dus: 

Okay, so we have to differentiate between taste and flavor. So a lot of what we call taste colloquially, it’s actually a combination of taste, and those different kinds of smells.

Bebej:

So I often will distinguish between gustation and taste in my class. But in some of the places I’ve read, they say gustation and taste are the same thing. And so they make that elevated concept flavor. Maybe I should even take a step back. When I teach you about sensory physiology, I always distinguish between sensation and perception. Sensation is detecting that something is there and something about that quality. But perception is like your conscious awareness of what that is, what it’s like, a little bit more about its characteristics.

Dus: 

That information that now is very complex, it’s a flavor, and also gets incorporated and integrated with memories of past food, with signals from the gut, for example, and other parts of the brain of how filling the food is, with our emotions, especially as it connects to memories. I think we’re all seeing Ratatouille. And then all of this has the effect of affecting our food choices in the moment when we’re eating, you know, that plate of food in front of us, but also in the future, because it’s essentially also making a memory of how much we’d like to food, the situation’s we have, who were we eating with and so really goes beyond just making food choice or deciding how much to eat in the moment. And that’s why it’s so complex.

Stump:

So our experience of food in our mouths, our perception, is a combination of sensory signals, gustation, and olfaction, but also some other things like temperature—

Hoogerwerf:

And Ryan also talked about something that senses water or other liquids, and also our sensation of spiciness, which is actually a pain receptor on our tongue. 

Stump:

—and all that is sent to our brain and mixes with other signals from our brain about our hunger levels and our emotions and memories and experiences with similar foods in our past. These are all electrochemical signals that originate from the interaction of food with our tongue and nose.

Bebej: 

What we think about when we’re thinking about gustation initially is just sending that information from the taste buds on your tongue to the gustatory cortex of your brain. But that part of your brain has these connections to other parts of your brain as well, which are going to all impact that perception and that experience.

Hoogerwerf:

This idea of the complexity of taste and that it’s more than just a one-to-one chemical sensation makes a lot of sense to me. This explains why the same food might not taste the same every time you eat it. 

I think of this burger I had once during a summer vacation several years ago. I’ve been chasing after a burger as good ever since, and it seems by now I would have at least replicated the quality of the ingredients if it was simply that. But clearly there’s a lot more than just getting the right mix of physical ingredients. Maybe it was something about my hunger level and the sunshine and my mood and the people around the table with me. 

Stump:

Yeah, so this is the difference Ryan was pointing to between sensation and perception. Philosophers have typically said that perception involves the conceptualization of the sensory input. So two different people—or as in your story, the same person on two different occasions—could have the identical sensory input, but they could perceive something different based on their other background beliefs and experiences.

Hoogerwerf:

And since taste is such a complex sensation, it makes me think that in order to perceive something as tasting really good probably means paying attention to a lot of other things besides just the food itself. 

Alright. Let’s continue on with the food journey through our body. After the food passes through the sensory fireworks of our mouths, it moves into our digestive tract, and we become less aware of the food. We don’t taste it anymore, but there’s still a lot going on. 

Stump:

Obviously this is where we actually start to turn the food into energy. Fats, carbohydrates, and proteins all have slightly different systems for how they work in your body; but they all turn into energy to allow your body to function. Some of that energy goes to ongoing processes and keeping organs working. For humans the brain takes about 20 percent of that resting energy cost. Beyond that are things like thermoregulation, immune function, growth, and reproductive processes. 

Hoogerwerf:

All of this happens in our guts, which is a non-scientific way of saying our gastrointestinal tracts.

Stump:

Another non-scientific understanding of this is Leonard Cohen’s description—which I brought up in our first episode—that we’re all just “brief elaborations of a tube.”

Hoogerwerf:

Let’s talk a little about the tubes that Cohen says we are. Even if we are nothing but tubes—and I think we make a good case for in our first episode that we are more than tubes—I’m not sure Cohen gave enough credit to how sophisticated those tubes are. 

Stump:

This came up, coincidentally, a while back when we were touring a lab at Stanford. A chemistry professor named Guosong Hong was showing us a bunch of his lab equipment and one of the toys was a camera of sorts that was used in experiments and he got talking about the gut-brain axis.

Hoogerwerf:

Yeah the gut-brain axis is this term used to talk about the communication between the gut and the brain—obviously. But it turns out there are a bunch of nerve endings in the gut and two-way communication between the brain and the gut.

Stump:

Yeah, but isn’t the brain connected to everything in our body? There are nerve endings in our toes too, right? 

Hoogerwerf:

Yeah, but the gut is different. It’s way more complex, for one thing. The gut has its own nervous system called the enteric nervous system, which operates somewhat independently from the central nervous system. The enteric nervous system has about the same amount of neurons as the entire spinal cord, so that’s pretty telling. 

So the gut is receiving sensory input and sending messages to the brain about the chemical composition of the food and even affecting mood and emotion. And the brain is sending messages back about things like what hormones need to be released for digestion and the contraction of muscles that move food through your gut. 

Stump:

And a lot of this is happening involuntarily, which is different from what’s happening in our toes and limbs most of the time.

Hoogerwerf:

And there’s another thing that’s really different which is that when we talk about our guts, we probably have to stop being quite so possessive.

Al-Attas Bradford: 

We eat and digest, but it’s not exactly we who do it on our own.

Hoogerwerf:

This is Aminah Al-Attas Bradford. We heard from her last episode about the metaphor of levain. Aminah is a theologian, but she works in an ecology lab and a lot of her work has been looking at microbes and the role they play in making us what we are. And microbes play a big role in our processing of food. 

Al-Attas Bradford: 

Microbes push us, challenge us, to think about the world out there in a very different way. And it demands an attentiveness, whether you’re working on a bread loaf, or you’re working with a pathogen, or you’re trying to make a really good tempeh, it requires an intimate cooperation and humbling of oneself to really pay attention and to experiment with what the microbes want to do. 

Stump:

The gut microbiome has gotten a bit of attention over the last few years as we’ve learned more about it, but let’s start with a broader definition of what microbiota are.

Al-Attas Bradford: 

Microbiota is the plural for all of the critters and creatures that make up the subvisible—so microscopic microbes, the sub-visible creatures that live in and on our person, if we’re talking about human microbiota. And then the microbiome, to be technical, is both the microbiota but all of the entire ecology. So all of the genetic material that may be alive or may no longer or ever have been alive, depending on how you categorize life and viruses and those kinds of things. The whole web of microbial and human DNA that makes up what it takes for me to walk around and think and digest and those kinds of things. So really the little bugs that live in and on us, if you’re not being too scientific about it.

Stump:

And these little bugs play a really important role inside our bodies.

Al-Attas Bradford: 

The presence of certain microbes, in our guts and in our brains will influence what we crave, will influence whether or not we feel satisfied. So just about 95 percent of the neurotransmitters that you and I need, in the form of serotonin to feel happy, to feel satisfied and content with what we’ve eaten, and to feel even just good in a day, are actually the waste of our gut microbes that then travel to our brains through this gut-brain axis. So my ability to know what feels like enough is influenced by the presence of these creatures.

Hoogerwerf:

There are some really fascinating studies about this and scientists are starting to look at whether changing the microbiome can help solve psychiatric disorders. Things like schizophrenia and depression seem to have connections to the gut microbiome and there are studies looking at whether changing diet or introducing certain microbiota can alleviate symptoms. This is really new and complicated but it seems pretty promising. I would guess we’ll be learning a lot more in the next decade. 

Stump:

So what we eat, even after we taste it, is still profoundly affecting our bodies in direct ways, by affecting our microbiome. This is really interesting because these creatures are not us. They don’t have our DNA, and yet we are completely reliant on them to live healthy lives. 

Hoogerwerf:

And to add even more importance to microbes, they aren’t only doing the work of digestion in our bodies, in a lot of cases they actually starting to do that work before we eat the food.

Al-Attas Bradford: 

If you’re thinking about something that’s fermented, that’s been pre-digested for us, it makes the nutrients more bioavailable to us, but then they’re also in our mouths and on our hands and in our guts, actually doing the further work of drawing out the nutritional resources and doing the magic, if you will, to help us be nourished from the things that we eat. 

Hoogerwerf:

And that’s the case with the elements of communion. 

Al-Attas Bradford: 

I always talk about bread and wine at the Eucharist. Not only do we need microbes—there’s no wine and there’s no bread without the microbe, and there’s, of course, no grape and no wheat without the microbe because of all the work they do in the soil—but also we’re not fed as well by the bread and wine if there’s no microbe. And we might not even be as fed as well in our faith if we’re thinking about fencing the microbe from the table.

[musical interlude]

Stump:

Okay, before our journey of food through the body comes to its inevitable end let’s shift directions. As we’ve talked about how food registers in the brain and about how food is processed in the gut, it seems clear that there’s a direct line you could draw between those processes and evolutionary success. 

Hoogerwerf:

So going back to just the simple idea of gustation:

Bebej:

The thought is that for a lot of the animal world, like these, this sense of gustation is going to allow for, “Is this thing going to kill me or not?” or “Is this thing something that would be really nutrient dense and healthy for me to eat or not?”

Dus: 

A more fundamental way to think about taste is essentially, it’s truly a detection system that tells us about different properties of what we’re eating, either to encourage us to eat those things, and to seek them out and to pick them at the right time, or in order just help us avoid them and not die from eating them.

Stump:

For any creature, if it can detect some level of toxicity in a plant and that sensation sends a message to the brain that says “spit,” then it’s going to have a better chance of passing down the genes that detect those chemicals, through those receptors.  

Bebej: 

Why do we have two dozen different kinds of receptors for bitter cells and only one or two for all the others? Because most of the toxins that plants would create to protect themselves from being eaten are going to elicit a very bitter sensation. And all we need is a teeny, tiny bit of that for us to spit it out and realize that we don’t want to be eating that.

Hoogerwerf:

It’s pretty easy to imagine how that idea could expand and cause evolutionary ripples. Foods that are nutritionally rich are going to elicit good feelings because creatures that are rewarded for eating those foods will survive better. Creatures with very specific diets are not going to maintain a bunch of sensory traits for food they don’t encounter or don’t bother with. 

Stump: 

Things get even more complicated with humans, and there are several theories out there that have to do with eating being a major factor in humans becoming the creatures we are. 

Hoogerwerf:

To see some of those dietary changes, let’s start at seven million years ago, about the time when our species’ ancestors broke away from the ancestors of chimpanzees. Before that, evidence points toward a heavily plant-based diet. Paleontologists look at things like teeth shape, and fossils show body structures that point toward tree climbing, which probably meant gathering of fruit and other plant food. There may have been some meat eating, maybe more similar to chimpanzees today that eat termites and hunt other small animals occasionally.

Stump:

One development that might have happened during this time was that we started eating tubers, which is something that is rare in primates today. But it’s not until about two and half million years ago that we see a really dramatic shift to the beginning of hunting and gathering. The signs in the fossil record here are things like cut marks on bones and the remains of stone tools. The introduction of meat to the diet becomes more and more obvious in the fossil record as time goes on. For example, Neanderthal sites that are littered with bones of mammoths and other large animals. 

Bebej: 

Once we started to eat animal, right, that’s a very calorie-rich source of nutrients. And that influx of nutrients might have helped propel or allowed our body to use some of those excess nutrients for brain development, rather than for other things.

Hoogerwerf:

Eating meat is a more efficient way of getting calories if a body is built to handle those calories. Scientists have put some actual numbers to this. Herman Pontzer is an evolutionary anthropologist and studies human energetics. In his book Burn, he says, “Our digestive tracts are 40 percent smaller and our livers 10 percent smaller” because of the switch to eating meat. 

Stump: 

Having a smaller gut and liver means that instead of putting energy to those organs your body can divert energy toward the brain. Human brains take about 20 percent of our energy when we’re at rest, compared to a chimp’s brain, which takes only about 8 percent. 

Hoogerwerf:

So introducing meat into our diet was probably an important part of becoming human. But I think it’s also important to point out that there’s no evidence our ancestors switched to a completely meat diet. The fossil record might at first look like that, but there’s an important bias there to acknowledge, which is that the fossil record tends to preserve the meat-eating aspects—the bones of animals and the stone tools it takes to kill them—where it does not preserve plant material and the wooden tools it takes to gather plants. There have been studies that look at plaque from fossil hominid teeth that point toward plants being an important and consistent source of food. And all the evidence points toward diets of early hunter-gatherers being similar to the diets of modern-day hunter-gatherers, of which there are a few left. Their diets are usually a balance of meat with grains, starchy tubers, fruits, and nuts.  

Stump:

And it’s worth noting that there wasn’t just one diet of ancient people. People in different climates and different landscapes ate vastly different diets. Meat eating was almost always paired with the gathering of plant foods, though in northern climates, where plants are hard to find, some cultures did—and still do—eat nearly an entirely meat diet.

Hoogerwerf:

What all this means about how we should eat today is a complicated question and one we’ll devote to our next episodes. For now it’s enough to say that the introduction of meat to our diets and the invention—can we call it an invention?—of cooking our food gave humans some serious evolutionary advantages. 

Stump:

Estimates for when we started controlling fire and using it to roast meat vary pretty widely, from as long as 1.8 million years ago to just 700,000 years ago. And again, cooking probably started in different places at different times. No matter when it happened, cooking our food gave us a big advantage over other creatures.

Hoogerwerf:

It does the same thing that microbes do during fermentation, which is that it makes the food easier to digest. It also makes it easier to chew. Both of those things save energy. When we digest food, we break it down into its basic parts—proteins to amino acids, complex carbohydrates into simple sugars. Cooking does a lot of that work for us. We can put that saved energy towards other things. 

Bebej: 

You could maybe think about it in the sense of your pre digesting the food. You’re prepping that food to be able to be easily handled by your body. When that food is easier for you to digest, your digestive tract actually doesn’t need to be as long either. And so that’s fewer resources that need to be dedicated to maintaining this long digestive tract in your body, which also makes more calories available for other things. So we’re simultaneously looking at increasing our efficiency of extracting the nutrients from the food that we’re eating, and there’s less of it that needs to be used for certain parts of our body. So if you’re increasing the amount of calories you’re bringing in, you can dedicate it to brain growth and brain development, there could certainly be sort of a tie there to this exceptional brain size that we see in humans and other closely related primates.

Stump:

Besides saving energy, these new eating habits also save time. If we don’t have to spend six to eight of our waking hours foraging for food like chimpanzees do, that allows us to develop a very different way of life. Of course, there are a lot of other things that go into this, like becoming bipedal and developing language, but this change in diet seems like it’s right there at the beginning of these very significant changes to what it means—or at least would eventually mean—to be human.

Hoogerwerf:

Okay, so we’ve been hanging out around two million years, one million years ago. So this is pre-Homo sapiens, in the time of Australopithecus and Homo erectus. Let’s move way forward, then. We can imagine these new diets slowly changing us, our tastes changing and digestive systems evolving along with our diets and let’s zoom up to only 10,000 to 12,000 years ago. 

Stump:

Now it is just us Homo sapiens; all the other hominids having been long gone. 

Hoogerwerf:

Another change to our diet happens, a big one: the agricultural revolution. Humans start to grow their food. 

Stump:

This leads to more efficiencies. When you grow your food, you don’t have to travel as far to get it, and you can start to select and cultivate crops that hold more nutrition. 

Hoogerwerf:

More numbers from Herman Pontzer. He found that the Hazda people, modern hunter-gatherers, get about 1,000 to 1,500 calories for every hour they spend foraging compared to modern day foraging-farming communities that get around 1,500 to 2,000 per hour they spend. 

Stump:

Once again there’s more than just an energy savings. This leads to lots of other societal changes too. People stay put instead of constantly moving to where the food is. And we don’t yet have hard evidence of this, but it seems as though cultivating crops would be another step up in cooperation with others.

Hoogerwerf:

There are some downsides to this new system though too. These are some of the things Charles Foster talked about in our first episode. The move away from hunting and gathering meant a less diverse diet which was probably a less healthy diet. And there was an introduction of new diseases that came from keeping lots of animals close together and close to humans. 

Stump:

10,000 to 12,000 years ago counts as pretty recent history when it comes to the length of time that evolution works over, and in many ways our diets over that relatively short time have changed faster than our bodies have time to adapt.

Hoogerwerf:

That’s not to say there’s been no evolutionary change in humans in the last 10,000 to 12,000 years or that evolutionary changes aren’t still happening, but many of our biological systems are still tuned to a world where food is hard to come by. 

Bebej: 

So what’s happened now in our Western culture, with all of these things so ubiquitous, we are still hardwired to like those things, to want those things. But now, it’s not being able to come across an animal that you can track down and kill for your family or your tribe once a week. Now, you could have Burger King for breakfast and McDonald’s for lunch. It’s available all the time. And so we’re still hardwired to want those things. 

Hoogerwerf:

We’ve come to a point where the calories easily available to us are way more than we need to burn for energy. And while the agricultural revolution definitely played a role in leading us here, it’s only the last couple hundred years and the industrial revolution that really made the biggest difference with a huge influx of calories, and specifically of calories that come in the form of processed foods that have been created in ways that take advantage of some our biological systems.

Bebej: 

I also think it’s important to point out that there are food scientists that work for these companies and work for these restaurants who are trying to make these things as addictive as they can be so that we want to keep going back and buying more and more.

Stump:

Monica gave an example of this that isn’t quite so sinister sounding, and I’m afraid strikes pretty close to home for me.

Dus: 

So you can buy the peanuts like my grandparents did in Italy, just by buying the whole bag, and you have to shell each one of them, and it takes a while and it makes a mess, but it takes a lot longer to eat half a cup of peanuts when you’re eating it from the whole peanut. And then now, take a jar of peanuts that you buy at the grocery store. It’s really fast to eat a half a cup; it just takes me 30 seconds or less. Plus, they’re salted, which makes them a lot more delicious, so it’s easy to eat them. And they are roasted, which makes them crunchy, which also changes the way we perceive the salt. And also now we might perceive a different mouthfeel of the different fats that are in the peanuts. And so it becomes even more compelling and faster to eat them.

Stump:

I eat a lot of peanuts…I’m a victim of the “Big Peanut” industry, I guess. Though in the last year I’ve changed to the “slightly salted ones.”

Hoogerwerf:

Well, regardless of the intentions behind creating food that is easily available and delicious to the point of addiction, there are some serious problems that come from it. 

Stump:

Chronic conditions like heart disease, diabetes, and cancer continue to kill people at staggering rates around the world. Many of these diseases are preventable through changes in diet. New evidence is beginning to show a link between highly processed foods and bad health effects, including a higher rate of early death.

Hoogerwerf:

The other major change that happened as a result of the agricultural revolution and then the industrial revolution is that we changed how we grow food and who grows food. Yet another statistic from Dr Pontzer: in 1840 farmers made up 69 percent of the workforce in the United States; today it is only 1.3 percent. 

Stump:

So there has been a huge reduction in the number of people growing food, and yet the amount of food we produce has dramatically increased. 

Hoogerwerf:

A lot of that is the result of agricultural science. Selective breeding and genetic engineering of crops has led to higher yields, as has the use of chemical fertilizers and pesticides. 

Stump:

This is sometimes called the green revolution, back in the middle of the 20th century when crop yields dramatically rose. It is often credited as the change that allowed us to effectively feed the growing population of earth and reduce huge amounts of suffering. There’s absolutely some truth to this. There is more than enough food for everyone. If any place in the world suffers from lack of food, it is not because of the biological systems of food production. But it’s important to see that there are costs to this system too, and to explore whether there might be ways to feed people without some of the disastrous effects that this increase in crop production has led to. 

Here’s Norman Wirzba

Wirzba: 

Right now we’ve got people in agricultural sciences and economics. They’re talking about feeding a world for another 10, 20, 50 years. That is not the measure we need to be looking at, because it’s very clear that we’ve moved from, say, 50 bushels an acre to 250 bushels per acre in, say, corn. But we’re doing it at tremendous natural costs or ecological cost, in the sense that we’re still eroding soil at unsustainable rates, we’re still denuding soil of its microbial, microorganismic life. We’re poisoning depleting our water systems, right? Think about the Ogallala Aquifer, which is irrigating lands in the high plains. That aquifer, it doesn’t have a long lifespan. And so to think that we have to continue an agricultural system that is premised on the drawdown of fertility and water, that’s just a losing scenario. We just cannot accept it. So that’s, I think, a non-negotiable. So the calorie production that we’re getting right now, it’s simply—to use a term I don’t care for very much—it’s unsustainable; it’s actually self-undermining. So we don’t have a choice about thinking differently; we are going to have to do this. And this is, I think, where natural systems agriculture comes in because we’re now seeing that with intensive forms of agriculture that pay attention to the to the fertility of soil, the cleanliness of water, animal contentment, adequate compensation for farm workers, right, that these systems they can produce yields that rival, what conventional industrial methods, but the big difference is this, putting people back on the land and putting them to work.

[short musical interlude] 

Stump:

There’s one more stop to make.

Hoogerwerf:

Is it time to talk about nutritional science? 

Stump:

Yeah. One thing we have always tried to do at BioLogos is to defend science as being trustworthy. We talk a lot about how science works, and that science is a process that involves repetition, and that scientists, even groups of scientists, sometimes get things wrong. Science itself is not truth, but it’s a really good way at getting as close as we can with the evidence available. 

Hoogerwerf:

Nutritional science doesn’t seem like it helps us a lot in building that trust. Maybe more than any other form of science, it seems like things are always changing. One day salt is good for you; the next day it’s killing us. But maybe we can defend nutritional science a bit?

Stump:

We could start by saying that there are a lot of things that make this kind of science really hard. Of course, quantum physics is hard too, but for different reasons. 

Dus: 

It’s also legit hard to do human studies. It’s very costly. It’s hard to measure what people are really eating, if you do it for a short term and do a truly controlled, randomized, double-blinded study, beyond being wildly expensive, you can only really do it for a little bit, because you have to ask people, for instance, to come to the lab so that you know what they’re eating, and you’re controlling 100 percent what they’re putting in their mouth. So those are hard to do. And then also, we rely on observational studies, where we ask people where they’re eating, and we know that’s not very reliable. We are not really great at remembering what we eat. I can barely remember what I had this morning, and I’ve been awake for four hours.

Stump:

Some studies show that people regularly underreport their calorie consumption by between 20 and 40 percent. 

Hoogerwerf:

For large nutritional studies, self-reporting is pretty much the only option. It’s pretty hard to find participants for studies that will be locked in a room and only eat what they’re given for long periods of time, though it does happen. 

Stump:

So there are some understandable drawbacks to studying nutrition in humans. There is another problem which lies in the translation of the science through popular media. 

Dus: 

Because there is, you know, chemistry and physics and neuroscience and cell biology, it’s really one field that contains many different fields with many different organs. And so there is a certain fuzziness there, because of the complexity. So in this fuzziness in the space, a lot of voices can proliferate.

Hoogerwerf:

Some of those voices have commercial interests. There are people who are really invested in selling certain kinds of food and so would be keen to share any kind of information to show that those foods are healthy. There is a lot of money to be made in the selling of food products. And corporations will often fund nutritional studies, publicizing them widely when the results favor their products and burying them when they don’t. 

Stump:

Not all those voices are malicious. Food is important to all of us and most of what we learn about nutritional science comes not from our own reading of nutrition journals but from popular media. When a study comes out that shows that red wine might actually make us live longer, that might be more interesting for a media company to do a story on than the study that shows that red wine has no effect at all.

Hoogerwerf:

So the takeaway here is that for nutritional science, just like with any science, it’s important to look at consensus across scientists who are studying within their fields and to not take the findings of one particular study—and especially not the reporting of one particular study—to be absolute truth. 

Stump:

Ok, we’ve covered a lot here, and not nearly to the depth that they could be covered: Things like food and the role it played in evolution and is still playing in evolution, nutritional science and how it works, neuroscience around food and taste and flavor and our gut microbiome.

Hoogerwerf:

These are cutting-edge scientific topics, and people are writing whole books on things we dealt with in a few sentences. So this definitely is not meant to be a comprehensive overview of all the scientific topics related to food. We’ll have some resources to lead to more in-depth reading and listening in some of these areas if you’re interested. Check the shownotes or our website for that. 

Stump:

But all the science textbooks and science podcasts can only bring us so far in answering some important questions that come out of all this. 

Hoogerwerf:

Anything in particular that jumps out to you here that science can’t answer?

Stump:

Yes, I’m not sure what to do with this knowledge of how our ancient human ancestors ate. Scientists have learned a lot more about what ancient diets might have been, and that’s great and interesting, but I’m not sure it determines how we should eat now. On the one hand, following more closely to ancient diets might be a healthier option, since our bodies evolved in that context. But on the other hand, first of all, science also tells us there are a lot of different kinds of ancient diets; and also we also have to acknowledge that following traditions of the past isn’t always the right way forward. We’ve gotten better at some things over time. We are human, after all, which means we have a lot more to guide our decisions than simply what calories our brain has been wired to tell us are good for us. 

Hoogerwerf:

That makes the decisions harder. Following our biological inclinations is often pretty easy. That’s why we work so hard to create good habits to counter some of our less acceptable desires.

Stump:

Do you have any take-aways from all this? 

Hoogerwerf:

Well, I think all this science is fascinating. I love to learn about how all these signals from food turn into my perception of flavor. There are points where the science starts to take away from some of the mystery of food—this idea we’ve talked about in previous episodes that food is a miraculous gift—and instead can all start to turn into a tidy explanation. So we heard from Jen Holmes Curran last episode. 

Stump:

She was your pastor, who gave a homily about a carrot. 

Hoogerwerf:

Yeah, she also talked about how food shows us something about the creative nature of God.  

Holmes Curran:

God did not have to give us texture or taste or like, there’s like 7500 different varieties of tomato. And like, each one, you know, and you can use tomatoes in so many gazillion different ways. And like God didn’t have to give us that. It was just, it’s just completely unnecessary. We could be solid blobs, without digestive tracts without needing the community of the world to survive. And God chose instead to give us like, oranges grow on trees, and they come apart in little sections. And, and they’re so beautiful. And like, every part of it is beautiful and useful for delicious things in different ways. And it’s so unnecessary. 

Hoogerwerf:

I really love this. But I could see how this could stand in some tension with the science. You could tell the scientific story that shows how things like taste and texture might be totally necessary, and how our perceptions of flavor all just come out of a process of natural selection. 

Stump:

We need to be careful about thinking there is only spiritual value to things if they aren’t explained. Science could explain why there are so many varieties of tomatoes or why oranges come apart in sections. But that doesn’t need to undermine Jen’s point or God’s lavish creation of tastes and textures. God did create those things and did make them beautiful and flavorful, even if we now scientifically understand how they work.

Hoogerwerf:

That reminds me of an interview we did for an episode on prayer, way back in our first season. Barbara Bradley Hagerty was telling us about an experiment someone did that highlighted certain parts of the brain during a spiritual experience. This scientist’s goal was to show that prayer wasn’t real, just something that happens in your brain. But then Barbara told us about another scientist.

Hagerty: 

I remember speaking to Roland Griffiths at Johns Hopkins. 

Hoogerwerf:

And his point was that just showing how something works doesn’t make it not real. And the example is fitting for this series:

Hagerty: 

He said, when you eat a piece of apple pie, there will be certain predictable brain activity, right? So as you lift the fork to your mouth, the parts of the brain that mediate smell will light up. The parts of the brain that mediate taste will light up the parts of the brain that mediate memory that remember the last time you had a piece of apple pie that was this good. That part of the brain lights up too. But the fact that there is predictable brain activity, does that mean that there is no apple pie? That the apple pie is a figment of your imagination? Of course not. 

Stump:

We have two layers here. This scientific layer of food as substance and nutrition and how it works inside us and as a driver of evolution. And then we have the layer of food as a gift. And the key here is to lay them together. And it’s only by doing that that we’ll be able to start answering that question I brought up about how we should eat. 

Hoogerwerf:

That is the question we’ll ask ourselves in the next two episodes….

Credits

BioLogos: 

Language of God is produced by BioLogos. It has been funded in part by the Fetzer Institute. Fetzer supports a movement of organizations who are applying spiritual solutions to society’s toughest problems. Get involved at fetzer.org. And by the John Templeton Foundation, which funds research and catalyzes conversations that inspire people with awe and wonder. And BioLogos is also supported by individual donors and listeners alike you contribute to BioLogos. Language of God is produced and mixed by Colin Hoogerwerf. That’s me. Our theme song is by Brakemaster Cylinder. BioLogos offices are located in Grand Rapids, Michigan in the Grand River watershed. If you have questions or want to join in a conversation about this episode, find the link in the show notes for the BioLogos forum. Or visit our website biologos.org, where you’ll find articles, videos, and other resources on faith and science. Thanks for listening.


Featured guests

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Charles Foster

Charles Foster is an author and a Fellow of Exeter College, University of Oxford. His books include the New York Times Bestseller, Being a Beast, and many others - many of which have won or been short- or long-listed for various literary prizes. He won the Ig Nobel Prize for Biology in 2016. He lives in Oxford and a remote part of the Peloponnese.
Derrick Weston Headshot

Derrick Weston

Derrick Weston is the theological education and training coordinator for Creation Justice Ministries, an ecumenical organization equipping Christians to live in right relationship with God's creation. He is the co-author of the recently released book "The Just Kitchen: Invitations to Sustainability, Cooking, Conection, and Celebration" and co-hosts the Food and Faith podcast. He, his wife, and four children live outside of Baltimore, Maryland.
Jen Holmes Curran headshot

Jen Holmes Curran

Rev. Jennifer Holmes Curran serves as one of the co-pastors at Sherman Street Christian Reformed Church.
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Monica Dus

Monica Dus, Ph.D. is an Associate Professor with Tenure in the Department of Molecular, Cellular, and Developmental Biology at the University of Michigan and a 2023 Guggenheim Fellow in Biology. She is also affiliated with the Michigan Neuroscience Institute, the Obesity and Nutrition Research Center, the Diabetes Research Center, and the Prechter Bipolar Research Program. Her lab’s research focuses on nutrigenomics, or how dietary components interact with genes to shape neural plasticity and behavior. The Dus lab is funded by the NIDDK (K99/R00, DP2, and R01) and NSF CAREER, as well as private foundations such as The Klingestein-Simons, Rita Allen, Sloan, and the Brain and Behavior Research Foundation. Dr. Dus teaches Genetics and Neuroepigenetics to ~500 students every year and is passionate about communicating science and making it accessible to the public. She has organized museum workshops, published SugarBuzz, a children’s comic book about food, hosted her own podcast, and written for The Conversation. Dr. Dus was chosen as a 2023-24 White House Fellow working with the Secretary of the Navy to work on science and technology in higher education.
Ryan Bebej

Ryan Bebej

Ryan Bebej is a professor in the Department of Biology at Calvin University, where he was selected as professor of the year in 2017. He earned his Ph.D. in ecology and evolutionary biology with a focus in paleontology from the University of Michigan. His research focuses on the evolution of aquatic mammals from terrestrial ancestors, including cetaceans (whales, dolphins, and porpoises) and pinnipeds (seals, sea lions, and walruses). He is especially interested in the earliest stages of these large-scale evolutionary transitions and the anatomical modifications that facilitate changes in swimming mode. He has excavated skeletons of fossil whales at Wadi Al-Hitan, a UNESCO World Heritage Site in Egypt’s western desert, and he routinely spends time working in collections at world-renowned museums. Ryan is also deeply interested in the relationship between science and Christian faith. In addition to being a member of BioLogos Voices since 2016, he has been a Scholarship and Christianity in Oxford (SCIO) visiting scholar in science and religion and a participant in SCIO's Bridging the Two Cultures of Science and the Humanities II program. When he isn’t working, he loves spending time with his wife and two sons, playing German tabletop games, and rooting for the Michigan Wolverines and St. Louis Cardinals.
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Aminah Al-Attas Bradford

Dr. Bradford is an Arab-American theologian and research scholar at NCSU where she works in the department of Applied Ecology's Public Science Lab for Ecology, Evolution and Biodiversity of Humans and Food, blending issues of science and religion and hosting cross-disciplinary conversations. She is currently writing her book on a theology of the microbiome. Dr. Bradford has worked in higher education for eighteen years and in Chaplain’s offices for more than eleven years. She is a fellow at the Berggruen Institute where she serves as an ethics and religion consultant on projects related to the future of humanity and non-anthropocentric ways of governing. In her spare time Dr. Bradford loves to walk in the woods, work in her ceramics studio, best her husband and two daughters in Farkle Championships, and start reading books, which lately include Thích Nhất Hạnh’s How to Sit, Sandor Ellix Katz’s Fermentation as Metaphor, Halldor Laxness’ Independent People, When Women Were Birds by Terry Tempest Williams, Gathering Moss by Robin Wall Kimmerer, and The Ministry for the Future by Kim Stanley Robinson. She will not finish any of these…but she will try.
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Norman Wirzba

Norman Wirzba is the Gilbert T. Rowe Distinguished Professor of Theology at Duke Divinity School, and a Senior Fellow at Duke’s Kenan Institute for Ethics. He is the author of several books, including (most recently) This Sacred Life: Humanity’s Place in a Wounded World and Agrarian Spirit: Cultivating Faith, Community, and the Land.
Barbara Bradley Hagerty

Barbara Bradley Hagerty

Barbara Bradley Hagerty is a New York Times best-selling author and journalist. Her most recent book, Life Reimagined: The Science, Art, and Opportunity of Midlife was published by Riverhead/Penguin in March 2016. Fingerprints of God: The Search for the Science of Spirituality, was published by Riverhead/Penguin in May 2009. Barbara was a correspondent for NPR for 18 years, most recently covering religion. She received the American Women in Radio and Television Award (twice) for her religion reporting, as well as the National Headliners Award, and the Religion Newswriters Association Award. Before the religion beat, she was NPR’s Justice Department correspondent, where she, along with her colleagues, won the George Foster Peabody and Overseas Press Club awards for their coverage of the September 11, 2001 terrorist attacks. Barbara has a master’s degree in legal studies from Yale Law School, and a bachelors degree from Williams College.