PSYC 123: The Psychology, Biology and Politics of Food

Lecture 2

 - Food Then, Food Now: Modern Food Conditions and Their Mismatch with Evolution


This lecture explores how the mismatch between evolution and the current food environment has changed people’s relationship to food. Ancient societies had a vastly different food environment compared to modern day societies, which was characterized by unpredictable food supply, the threat of starvation, and a high priority to bank energy. The human brain evolved for this ancient food environment, which creates challenges in the modern food environment where people have unfettered access to the high sugar, high fat, high variety foods that they are programmed to find appealing.

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The Psychology, Biology and Politics of Food

PSYC 123 - Lecture 2 - Food Then, Food Now: Modern Food Conditions and Their Mismatch with Evolution

Chapter 1. General Housekeeping for the Course [00:00:00]

Professor Kelly Brownell: Is this tolerable for you guys, bright and early in the morning like this? Yeah, just barely? Well, I’m glad you were able to make it. How many of you are here for the first time who weren’t here for the — okay good. I’m going to talk about some class logistics and I’ll talk about the course website which you’re welcome to visit. Most of the information that we covered about requirements for the class and things like that were — are on the course website. Everything should be pretty self-explanatory and if you have any questions you can just contact me or ask me questions after class. By the way, after class, I’m more then happy to stay as long as needed to answer any questions you guys have or to talk about whatever issues you’d like to bring up, but probably what makes sense is for me to power down the computer and pack up and then we can stand out in the hallway and I can answer questions out there, that way the next class can get in and the instructor can work unimpeded.

A couple things I’ll do during the semester routinely is talk to you guys about research opportunities. In case any of you would like to get involved in research there are very often colleagues of mine or graduate students who are doing interesting projects who will ask me to alert you to the possibilities of working with them. If you’d like to do that you’re more then welcome too. These are completely optional, not required for the course, so there’s no obligation for you guys to get involved in these things, but I’ll mention these things as we go along in case anybody would like to get involved in working with professors or graduate students.

The first one that I’d like to mention today is Christina Roberto who is a grad student who is working at The Rudd Center, who’s right here, a teaching fellow for the class, is going to be doing some very interesting work on health policies and people’s food intake. If anybody would like to work with Christina her email address is right there. By the way, as you probably know already, in the afternoon after each of these lectures we’ll post the day’s lectures, so if you come back and want to get in touch with Christina or anybody else, you don’t have to have it now because it’ll show up on the course website, this slide. Christina’s doing very interesting work. You want to stand up so people can see who you are? Okay, if anybody has questions about this one in particular you can ask Christina after class or at a different time.

The next one is a colleague of mine, William Corbin, who’s doing some very interesting work on alcohol intake and gambling, and sometimes how they go together. There are very interesting research opportunities in his laboratory, and if any of you are interested in that you can go to one of the two email addresses that you see on the bottom. Then in addition, one of the other teaching fellows here, Ashley Gearhardt — Ashley would you mind standing up — is very active in this research. In fact, is doing some work with Professor Corbin and me jointly on the issue of food and addiction, and she’ll be doing some lecturing on that later in the class. In any event, this is some interesting research opportunity, so again, no obligation, you don’t have to do this, I won’t even know if you are or not, but I just thought I would present these in the case you might find them interesting things to do.

A few things about logistics of the class to help you guys navigate through various electronic things that the class has at the moment. First of all, there are two ways to get to the course website. You can go through the class’s server. There will be an option when you pull up the tab for this particular course if you go to the course website and that will link you right to the course website. Then secondly, you can go directly to the website of the course itself that way. If any of you haven’t been to the website I urge you to do that, because it has all the information about requirements, the order of readings, a lot of supplementary information that may be helpful, interesting links to other resources and things like that, so please see the course website.

Second, well we’re not getting to the second one; let’s see what — okay as I mentioned the lecture slides will be posted almost always the same day after the class. Now some of you may be wondering, and you’ll find out this for yourself about how important it is to come to class. The — what I tend to do is not discuss the readings all that much in class. I’ll cover them of course and go over what I think the key points are, but if I don’t discuss the readings in class please don’t take that as a sign that the readings aren’t important. What it means is is I don’t want to take unique time that we could be discussing other things in class by covering things that you could have read already. There will be things in the class that are not covered in the readings, and may or may not be apparent from looking at the slides online, so coming to class is probably a good idea. I mean I’m not going to try to trick you or throw in things just to make sure you come to class, but it’s usually a pretty good policy.

I’m going to show you some slides on how to get at the course readings, and then we’ll talk also about doing the first concept sheet. For those of you here for the first time, I mentioned that the first time you’ll actually have an assignment that you’ll have to turn in, will be next week. These are called concept sheets and they’re one to two pages of things that you write about what’s going on in the class. They’re your interpretation of what’s happening in the class. Not a repeat of what’s happening in the class; I don’t want to hear what was in the readings, I don’t want to hear what was in the lecture undigested. What I’d rather have is your interpretation of things like I thought this thing was really interesting and here’s why, or I remember back in week two of the class we talked about this issue and it links up with what we’re now talking about in week eight, or I just saw something on the news and here’s how it relates, and all those sort of things are the way the concept sheets go. If you go to the course website there is a sample concept sheet that you’ll be able to read. The first one will be due next week. You can turn it in on either Monday or Wednesday, and typically with the exception of the first week, which I’ll explain in just a minute the concept sheet should deal with the information that’s relevant to that week, so the readings, the lectures, or something that’s going on in that particular week. Again, I’m happy to answer any questions you guys have about that, but the first concept sheet has to do with this website and I’ll come back to that in just a minute.

Just a little bit about navigating the information that’s available for the readings of the class: everything is available electronically. It used to be that you had to big thick course packets that cost a lot of money, but now everything thankfully is available electronically on the course website. If you go to the Yale classes server and you pull up this particular class — which by the way has this designation as the first thing on the tab, because it’s cross listed as a course in epidemiology and public health and that’s the first alphabetical cross listing there happens to be — if you pull up the tab for this course and you see over here that under the course reserves, if you click on that button then you’re going to get something that looks like this, which is a list of readings for the class.

The question is how do you get those readings and how do you access them? Well first is, you go over here to the right hand side for each one, and it says click here for the full text article. Pretty self-explanatory so far. Then you’re going to get several different looking versions of articles when you click on that particular tab. In this case, this is one of the articles, in fact this was today’s reading, I got here a little early so it was this particular article was assigned for today and — but what shows up when you click on the initial tab is just the abstract of the article not the whole article itself. Then you go over here to where it says PDF and you click on that and that will allow you to download the whole article, which will look something like this. Again, these slides will be posted so you can refresh your memory later on this. There will be — here’s another example of a different kind of article where when you click on the click here for full text option, you get something that looks a little bit different. In this case it’ll look like this, but again, it’s not really the full article. It takes you to the link of the place that publishes the article, but then you have to look a little farther to download the entire article. In this case it would be right here where it says PDF or also download PDF over on the right. If you click on that then you pull up the whole article and then you’ll have it and you can store it, or just read it and do whatever you wish. It’ll be there for the whole semester. Does that make sense? Okay, it should be pretty obvious I think.

Now let’s talk about the first concept sheet that’s due. As I said, for every subsequent week of the class you’ll be doing a concept sheet that will be your interpretation of what’s going on, but we’re going to do something a little bit different for the first concept sheet that’s due next week. I wanted to tell you about early because I’m going to ask you to do something for three days and then write about that. What I’m going to ask you to do is track what you’re eating, and to go to a website that will allow you to enter all your eating, and then it will print out a dietary analysis of that. Then what I’d like you to do for your first concept sheet is to write about that. Now we don’t care what you’re eating so nobody — we’re not going to attend to that at all; I mean you could eat Twinkies four times a day and that could be your total diet, or you could eat something else; it doesn’t really matter so much. It’s going to be your way of analyzing your own diet and trying to make sense of it.

What we’re going to do is ask you to go to this particular website,, and at no charge you’re going to be able to enter information from your own diet and then the program will do a dietary analysis and you can print it out, and I’d like you to do this for three days and then print out three days worth of dietary analysis of what you’re eating, and then write a concept sheet about it, and it says well I didn’t realize this about my diet, or I see now that I’m getting calories from this source and not that source, and things like that, so this will be an interesting experience for you if you haven’t done that. Usually people find it a little bit surprising. It also is a good lesson in how difficult it is, and we’ll talk about this in a subsequent class, to actually measure what people eat.

Chapter 2. What Do We Know about the Food We Eat? [00:10:43]

A huge amount about what we know on diet and health — like is too much sugar bad for you? What about fat? What about Trans fat? What about salt? What affect do these have on our health? — comes from flawed reports of what people eat, because in order to know what people eat you have to ask them, and even if people are really trying hard to be truthful, it’s not the easiest thing to do. You’ll find that out when you do your own dietary assessment. That will give you insight into how these studies are done on diet and health.

When you pull up, you’ll get this website. The first thing to do is to go over here where it says, My Plate Calorie Counter, you’ll actually get more information then just calories, but if you go over here, click on this, then the next version you’ll see will be something like this. In this blank area over here next to the search tab you can type in any food that you’re having, and then the program, unless it’s something really unusual, the program will recognize it and then give you a series of options of things it thinks it might be. Then you can choose one of those for the specific food.

Let’s say, for example, if you happen to eat Frosted Flakes for breakfast one morning. What you would do is type Frosted Flakes over here into that blank area, so you’d enter it here and then click. Then what the program will do will give you a series of things it might potentially be because it recognizes that you could be entering more then one thing, and then you have to take the one that you think is closest to what you’re actually eating. Let’s just say it’s the Kellogg’s Frosted Flakes and three quarters of a cup is about how much you had, and so these serving sizes are listed here. Like here would be one small — I guess these are the small boxes, but the serving sizes are listed and the brand, and then you could click on that particular food if that’s the appropriate one. You confirm your selection after you click on it. It’ll say is this really what you ate, and if you ate it, then you say yes I ate this, and then it adds to the electronic log. I guess this means you ate it with enthusiasm.

It’ll also give you a breakdown of the particular nutrients of that food. You click there, and you have to pay attention to how many services you have of something, because if it says that a serving is three-quarters of a cup and you ate a cup and a half, then the program has to recognize that or it won’t be able to make an adequate judgment of what you’re eating. Then you go over here and it’ll ask you how much you consumed. I sort of blocked it out with the circles, but then you can go put in two servings, and you put what time of day you had it and then the program will be able to do its work.

Now this will be — as I said it’ll be an interesting exercise and you get a printout that will be pretty interesting. So you printout — you enter everything you’ve had for the day. Now that doesn’t mean that you have to carry around your laptop and every time you eat something enter it at the moment, but carry around at least a little piece of paper that you can write down everything you ate, because it’s hard to remember later in the day, and it’s hard to remember exactly how much you had of things, it’s hard to remember condiments that you might have put on something, and so it’s very easy not to remember everything, but it’s very important to try, because as I said, this will be instructive for you, but also instructive for how this sort of happens with the course in general. Then you’ll get a page that looks like this that will talk about — given that you’ve had that particular food how many additional calories you have for the day, given an average person, and it gives you the breakdown of what you’ve eaten so far. Now that may interest you at the moment, or what you may want to do is to get a printout of the whole day after that. Of course, if you have cereal with milk, then you’ve got to enter the milk as well because it wasn’t just the cereal that you had.

Write down everything so you don’t forget it, we don’t forget anything that you have at all. Don’t forget drinks, condiments, things you snack on and stuff, late night pizza of course would get entered and other things. If you guys want a seat there are plenty of seats over here scattered about. Try to be as accurate as you can about how much of something you eat. Now if you’re not in a kitchen it’s going to be hard to measure a cup, or an ounce, or things like that so you’ll have to be estimating. But how carefully you estimate will determine in part how good your ultimate records are so please try to be as careful as you can, and then pick the closest option if you can’t find the exact food that you’re eating at that time. Then at the end of the day what you’ll get is something that looks like this which will be a whole day’s worth of food intake and then this is what I’d like you to print out and then write about in your concept sheets.

Again, do three of these and then write about them in your concept sheets. They’re not due — the first one’s not due until next Monday or Wednesday, so you can pick any three days to do it during that period of time. Then when you’re done you print the page, and we have a special instruction for that in just a moment, and then you’ll what you need for the concept sheets.

To do your concept sheets, as I said, do any three days, attach the printouts to when you write the concepts sheets. Then what I’d like is your reaction to having done this exercise. What did you learn about how easy or hard it is to keep track of what food intake is? It’s also nice. by the way, that there are these electronic programs that immediately figure out the nutrient breakdown of what you’re eating. It used to be case that trained people like dieticians would have to sit down and go through one by one, by one and nutrient analysis, but of course the computer helps with that. How hard did you find it to estimate how much you were eating of something? How hard did you find it to figure out what food it was to begin with? I mean sometimes if you have things that are a mixture of foods, like you go out for Chinese food or you have a casserole somewhere, or you have some dish of vegetables mixed together, how do you make sense of that when it comes to entering these things into a record. Were you surprised by how many calories were in some foods? Surprised on the high side or the low side? Where are your calories coming from? What about sources of protein, that and carbohydrate for you, and how do those look and where are you getting those from?

Then you could also think about whether there are changes that could be made to improve diet. Now again we’re not — the purpose of this class isn’t to have you improve your diet, if that happens that’s fine, but that’s not the purpose of the class. We’re not asking you to change anything; in fact it’s best for this particular exercise to eat as you typically would so you get a sense of what an average day would be like for you. But it’s also helpful to think just for health and well-being in general, what might be done to improve the diet and this will be a good way to try to get at that.

Several notes, the website will never ask you for identifying information. This particular website has this free nutrient analysis that we talked about here as sort of an entrée to other options. On the website people may choose to get involved in and there may be charges for those things, I don’t really know, but there may be and then they may ask you for identifying information, but it’s your option to do that. You don’t need too, if you want to take advantage then you can, but you don’t need too. Then also you’ll be asked to do identifying information if you print it out from the program itself, but if you go up to your web browser print option and print from that particular thing then you can do it and no identifying information will be necessary. Any questions about that? Okay good, this should be a very interesting exercise and fun to think about a dietary analysis like this.

Chapter 3. Food and the Evolution of Humans [00:19:08]

Now let’s get onto the course topic for today, which is food and evolution. There have been major changes of course in the food supply. It’s happened over the course of millions of years of human evolution, but it’s happened also in a relatively recent time frame when we think about the American diet and what people are eating, but also the world diet of course. Here is a picture of a cover from the journal — the magazine The Economist who were writing about food and nutrition in modern times and they created this graphic for the website to show the evolution of humans. They show these as some of the first stages and then intermediate changes they depict it as this, and then the final one is this. Notice the large beverage in this fellow’s left hand.

This is a really pretty dramatic change in human evolution and the question is: what happened? What made things go so awry that people and food used to be more in sync in terms of health and well-being, although there were problems in some ways. Why did this happen? What’s the impact? What is all this doing to us? Now several lectures down the road we’ll talk about modern food and epidemiology; that is what the research on food intake and human health, and what do we know about our health and well-being based on diets.

Let’s talk about more ancient societies and how food got started and what sort of phases we’ve gone through and how does that shape what’s going on today. If you look at the percent of time people in society were involved in various activities and broken into agriculture versus everything else, in ancient Egypt it looked like this. Basically, the whole society was spending all of the time raising enough food just to support life and there was only 5% left over and that ended up being used in ways like this. Obviously with this sort of partitioning of behavior, and activities, and effort, there’s not a lot of time leftover for leisure, for development of new technologies and things like this. So agriculture pretty much overwhelmed everything else.

If you think about what ancient food gathering habits used to be like, you see things like this where people are out gathering food that is growing naturally, and you can think about what would — what sort of conditions this would create and what kind of hardships it would create. Well first, you’re subject to the food not growing. If there are droughts, pests, other things that interfere with the growing of the food you’ve got problems. That made some populations mobile because they had to move from place to place to find food, but of course, it made starvation a very real possibility. In different parts of the world you would see this sort of activity for finding food. But again, the elements were harsh, finding food may not have been easy, and certain sorts of diets would prevail over others, where there would be a lot of certain nutrients and few of other ones. Humans suffered as a consequence from nutritional deficiencies in almost all parts of the world because there weren’t complete diets.

Then you see way back in human histories figures like this where people had to go hunt for their food, and of course there was danger involved in this, uncertainty of the food supply and the like. This is all pretty well known. This is captured in this little quote by Woody Allen. We get to modern conditions where we something like this. Now here we have a situation where you have a completely concocted food, you have something like Twinkies to begin with, not something found in nature. And then we concoct them even further by deep frying them and then having them with a sugared beverage and that’s certainly different than ancient times. We see what the environment has become and here you see something where there’s deep fried Twinkies, deep fried candy bars, deep fried onions, and deep fried Coca-Cola. Has anybody ever had deep fried Coke? How is it?

Student: [inaudible]

Professor Kelly Brownell: It tasted like Coke with a lot of oil. Yeah because I — it’s like fried dough isn’t it? They make it like that, but instead of water or whatever, they put Coca-Cola into it? Interesting. One brave soul admitted to having fried Coke, thank you for doing that. There’s a lot of frying going on at this particular place and this is something that’s not typical of ancestral human diets.

If you think about the modern food environment compared to the ancient one, so let’s say somebody getting something at a fair compared to the old days. Well, how do these two humans differ in their relationship to food? What type of different foods were they eating, and how much effort went into getting them? Here you have somebody who’s happy, at ease, and completely secure that there will be food around the corner. There’s never any question at all about whether one can eat. Now it could be that you’re hungry but you’re working hard, and so you may not get your food for an hour until after you’re hungry. There may be a little bit of uncertainty about that. There may be a little uncertainty about whether the pizza place is still going to be open late at night when you get hungry.

There may be uncertainties of that nature but certainly not the uncertainties of early humans. You have somebody like this who would be frightened to death about getting the food; and you have somebody over here who has a completely different relationship with it. What does that mean? Does it change how humans appreciate food, what it does to their relationship with food, and of course what it does to their health and well being. So things have changed a lot. You also have to factor in here how much physical work is involved in getting the food. On the left, you see somebody expending enormous physical effort to secure the food. Here are humans who had to walk long distances potentially to find the food, kill the food at great risk to themselves; inspiring a cascade of physiological effects that have to do with fear and arousal and things like that, not to mention all the calories one would burn doing this kind of activity. And then there would be the butchering of the animal, there would be the — securing the crops from the fields, and then bringing it to wherever you were going to eat it, which burns more calories and requires more physical effort, compared to the person on the right that really doesn’t have to do much at all. This shows part of the changed relationship with food.

Now if any of you are interested in exploring this issue of food and history there’s an awful lot written about it a number of books that have been written about it that are quite good. One that I found most instructive is called The Cambridge World History of Food, which is this very — two very large volumes. Edited volumes with a number of smaller chapters in them on food and history and they’re really very good. I’m not sure if the Yale Library has this or not, but if they don’t you could ask the librarian to get it. It’s an excellent resource that talks a lot about the history of food. Some of the things that I’m about to talk about are drawn from chapters in that particular volume.

Now we’ll go back further then 10,000 years to talk about the history of food, but in those — but at 10,000 years ago several very important changes happened that have shaped to a great extent what our modern relationship with food is. That was the planful growing of food and the domestication of animals. So we’ll loop back to this in just a moment, but start by going back earlier in history. This Cambridge History of Food talks about three separate primary phases in human food evolution: one beginning a million and a half years ago, another about 700,000 years ago, and then the 10,000 year ago one that I talked about just a moment ago.

Phase One, the million and a half years ago, in the early — in the late — Miocene and early Pleistocene phases, there was shift where people were less likely to be just going out and gathering foods from every place they could find it. To some, some planting of food, although not a lot, but also dealing with food in different ways. Instead of just eating them at the time there would be processing of it. There would be some sort of cooking, some attempt to store food for when people may have been hungry later, etc. Then going from a plant based diet to a diet that included meat. Now these were important changes because humans of course can — are omnivores and can eat both plants and animals, and therefore, the ability to secure nutrients from these different sources became very appealing to humans.

Phase Two, in the middle Pleistocene phase — 700,000 years ago. Then we got into more deliberate hunting of animals, larger species were hunted and then you started to see humans eating things like mammoth, deer, horse, bison, and reindeer. Humans banded together instead of working more as individuals and started hunting animals in groups, groups of animals hunted by groups of humans. The plant diet at this point was still quite important.

Then the Phase Three that I mentioned, the 10,000 years ago had several things occur that were very important in shaping our current situation. We have modern patterns of climate, vegetation, and fauna so the climate conditions were somewhat similar to today. Several large animal species had disappeared so people had to find other animals and so this changed from going to find animals to domesticating animals, and shift from collection of plants to production of plants. Because of the climate and because of certain things growing in different parts of the world — and by the way, I see some of you kind of struggling to keep up with some of the things I’m doing on the slides, but I’m hoping to make broad points here, and again, the slides will be posted on the website so don’t worry so much if you’re not able to get everything down.

Chapter 4. The Implications of Single Cereal Diets According to Location [00:30:27]

In certain location things were dominated by certain cereals; rice in Asia, wheat in Europe, sorghum and millet in Africa, and maize in the New World. These then became the objects of trade, of commerce, and of course of human diets and these had nutritional implications for people in different parts of the world. The people who write about food history have called these things superfoods, not necessarily because they’re super rich in all nutrients, but because they were super available. The ubiquity, not the nutrition, was what got them called superfoods. They became dominant foods in different parts of the world. You can see in the New World with maize being important how America has become a corn dominated society, even though it’s still true that we raise wheat, we raise other things in the United States, and we can import different foods, corn has become an incredibly important constituent of the diet in the U.S. What we’ll — later in the course we’ll talk about how much of your body has been influenced by corn; how much of your diet is influenced by corn; how many products you touch in a given day have been derived in some way from corn. It’s really quite amazing. That would not necessarily be true in other parts of the world but it is true in this part of the world.

Now the fact that people were so reliant on certain foods led to deficiencies of certain nutrients, so people that were dependent on a rice based diet tended to have problems with deficiencies in protein, Vitamin A, and thiamine. Now I’m not — again, this is the kind of detail I’m not expecting you to remember, but it’s just an exemplar of this broader issue about how dependence on certain foods leads to nutritional deficiencies that have to get remedied somehow or else people have health problems. Either people in these populations were malnourished or they had to find supplementation for these super foods in order to survive. This is an interesting quote about maize from this particular book called Prehistoric Food Production in North America and if you have trouble I’ll read it.

‘By the time of Columbus maize had already become the staff of life in the New World. It was distributed throughout both hemispheres from Argentina and Chile northwest to Canada and from sea level to high in the Andes, from swamp land to arid conditions and from short to long day lengths, and becoming so widespread it involved hundreds of races, or types of corn, each with special adaptations for the environment including special utilities for man.’

Now what’s — a lot is hidden in this particular quote. Number one is because was so — or maize was so important during this period of time but it was grown in many, many different conditions, high altitude, low altitude, short days, long days, hundreds of species of maize developed and that led to great biodiversity. That meant that people growing corn were less — less vulnerable to having things wipe out entire crops because there were different types of crops planted around the world, so the world corn supply would never be threatened by anything.

As we’ll talk about later in the class, the biodiversity has shrunk so what used to be hundreds of varieties of corn is now just a few. As I’ll explain later in class, in Florida there used to be many, many, many varieties of oranges and now there are about four and there are commercials reasons for this occurring. The biodiversity has shrunk for various reasons of profitability and as a consequence of that things like corn crops, and the orange crops in Florida are particularly susceptible to certain environmental conditions, certain pests, and certain types of blight. Because of that large amounts of particular types of pesticides and fertilizers and the like have to be used to defend against these outside threats; and those bring their own series of environmental consequences, so we’ll go into that in some detail.

It’s interesting how humans and plants have evolved together, and there’s a very interesting book on this by Michael Pollan called, The Botany of Desire. Now we’re reading another book for the class by Michael Pollan, not this particular one, but this book is a pretty quick read and it’s extremely interesting and his premise in this book is that humans have become dependent on plants and animals, and animals have become evolutionary dependent — -evolutionarily dependent on humans at the same time, and so this idea that the human body has evolved to be able to take in certain sorts of foods and that the foods have evolved at the same time and they’ve become dependent on one another is an extremely interesting premise, and Pollan writes beautifully. So this is an interesting book worth exploring and I urge you to read it if you get the opportunity. This idea that humans have evolved, that physical changes have occurred in humans as a consequence of their food environment, has led us to where we are now. I alluded to this a little bit in the first class about how humans have evolved to seek out energy because famine was the largest threat is one example of this.

Chapter 5. Challenges to a Plant Based Diet [00:36:15]

Now there are challenges to a plant based diet which made eating meat important to humans in human history. Some of the challenges that you see here I mentioned before, so there are problems with drought, with pests, with temperature changes and the like. There were also issues about nutritional adequacy and meat turned out to be a better overall food then most plants. Now that seems counterintuitive now because we think that a plant based diet may be more healthy for people then a meat based diet, but remember, that we’re fighting off overnutrition and these folks were fighting off undernutrition. The plants can be deficient in certain things, especially fat soluble vitamins that come from meat and from essential amino acids.

In order to have a completely balanced diet that’s completely plant based, one has to be very careful about having a wide array of foods. A narrower array of foods is necessary for nutritional adequacy if people are eating meat. Now that’s not to say that this has implications for what people are eating now, but it certainly did at one point.

There are changes in food and agriculture that made a number of things possible. Once it became true that people could raise food or gather food, or produce food for more then just themselves or their families, meant that people were free to do other things. Not everybody had to be involved in creating food, and so that gave people more time to trade, to develop other products, to be involved in non-food pursuits and many, many more things.

So it was a major change in human evolution where people started raising animals in large groups or started growing plants in large amounts. There were some landmarks along the way. The plant based economies began in the Middle East and then they spread to the rest of the world. This was thought by many to be a positive change but in game rich environments where there was a lot of meat available, people could actually get many more calories per hour — that is secure more food that would help fend off starvation compared to what they could get for people cultivating food. So economically it meant more — it made more sense to eat meat under those circumstances, but of course the meat didn’t exist in all places of the world, so some people were dependent on plants.

Change comes from necessity. People have to evolve to have biology that tolerates the subsistence that they access to, and that varies in different parts of the world, so again, humans evolve. This quote from Larson, in the Cambridge World History of Food, captures this.

Virtually every major anatomical change — think about that for a minute — every major anatomical change that has existed in humans can be related in one way or another to how foods are acquired and processed by the human body.

Quite a remarkable statement and I was reminded of this when I saw this cartoon. There’s an anatomical change for you.

Chapter 6. Human Evolution versus the Modern Food Environment [00:39:51]

Things of course have changed since those early times in so many ways. Iif you go back to this particular graphic, the interesting thing is how have humans changed and what are they like now. Well now the food environment is things like this. Instead of hard labor to go get food all it requires is a little drive-in to the window. It used to be the case — I forget how long drive-in windows have been around, certainly as long as you guys can remember — but there was a time when drive-in windows didn’t exist. When that was the case if you wanted fast food you had to at least spend the calories to get out of your car to walk into the place to buy the fast food. Now you’re saving a few calories because you don’t even have to do that, so the food environment’s changed in a lot of ways.

People even get coached on how to do it, so when drive-in windows were introduced recently in Malaysia, these little graphics went out to show people how you actually used a drive-in window. McDonald’s created these. You drive your car in, it shows you by the arrows where you go, you stop at window one to make your order and pay, and then you go to window two to collect your food, and they’re open twenty-four hours. Again, it shows how much things have changed during that period of time. Even if you’re a moose you can get fast food. Here’s another example of that.

Back to this graphic again: unpredictable food supply occurred on the left but doesn’t occur on the right. Starvation was a major threat on the left but not on the right, and the top priority on the left was to bank energy. The top priority on the right has become to spend energy. So a completely different way humans are interacting with food.

Now these changes, these human evolutionary changes, have created some very interesting metabolic things inside our bodies. We talked about the strong biological drive in the last class for sugar, fat, and variety. People need fat, and they need sugar, and they need variety — at least what their brain thinks. But the brain thinks that you exist in climates or conditions where food is likely to be scarce some of the time, and so the brain hasn’t evolved fast enough, through periods of evolution, to keep up with the rapidly changing food environment, and that’s what creates problems.

If you have a brain, and a body, and a metabolism that wants calories, it wants fat, it wants sugar, it wants a broad variety of food so you can survive, that would be good if you lived in certain parts of the world today. Now these parts of the world are shrinking in the number; but let’s say you lived in Ethiopia or Somalia, or places where food really is scarce way too much of the time, then having this particular biological drive, having a brain that wants you to seek out these foods would be highly adaptive. But in cultures where the food environment doesn’t represent the conditions the brain expects, you’ve got a mismatch. That’s where we have problems.

As I mentioned in the earlier class, most of you would probably rather have some high fat food like French fries or ice cream, or some type of a dessert than have cauliflower or have broccoli or have brussel sprouts. Why does your body experience one food as highly pleasant, highly reinforcing, highly comforting, highly soothing even, and experience those other foods as bitter and unpleasant? Now some people can — some people may be turned off by those high fat foods. You might have trained yourself to do that and then maybe — there may be cultural reasons why you like broccoli better then Haagen-Dazs lets say. Some people can train themselves to do it, but it’s contrary to the way the brain wants you to behave. If you were unfettered by all those environmental things that make people eat different kinds of foods, most of you would probably like the high fat, high sugar foods better; most of you probably still do. Now you might be able to resist them and not eat them in abundance but they’re still there and the brain likes those sorts of things. Well, that’s thanks to your ancestors and thanks to the conditions that they’ve inherited, that you would seek out a diet that has those particular conditions.

There’s also something that scientists have talked about called the thrifty metabolism. Now thrifty metabolism means you make very good use of your calories. Now if you think around to the people you know, you probably are aware that there are pretty important differences between people and how much they eat, and then how well those calories get banked. Now the bank for calories is body fat. If you take in more calories than you consume, it gets stored in the fat cells, that’s the energy bank that you can draw upon if you don’t have enough food and starvation or famine were an issue. People do that with differing levels of efficiency.

Each of you probably know, some of you may be in this category yourself, people who can eat like crazy and still not gain weight. Those people are the envy of many other people. You eat, and eat, and eat and those people don’t gain weight. Then there are other people who are pretty careful about what they eat and they’re still prone to gaining weight. Well those are differences in metabolism. Calories go in, food gets consumed, the body metabolizes or makes use of those particular nutrients. In that process there is a metabolic engine at work, and some people have an efficient engine so that the calories in get banked in the fat, other people have an inefficient engine, that is the calories get wasted as body heat and things like that, and they tend not to gain weight. That efficient metabolism that banks calories is highly efficient, highly important, highly adaptable, under circumstances where food is scarce, but not efficient and not adaptive under modern food conditions in the developed world.

Chapter 7. Evolution’s Enduring Impacts on Human Behavior [00:46:22]

The behavior that comes from this hard-wiring manifests itself in several different ways. It means that we want to eat when there’s food around, and it doesn’t matter so much whether we’re really hungry. I mean, think of going out to a nice dinner, you’re completely full, your body doesn’t really need more calories necessarily, your stomach has had enough, and then the dessert cart comes by, or there are the mints on the way out of the restaurant or something. People have those, they want them, why?

It’s because food is there. Not because you necessarily need it at the moment but your brain tells you you may need it later and so eat, eat, eat becomes the priority. Satiety, or the feeling full, having enough, being sated gets trumped by the presence of food. I just mentioned examples of that, so the organism seeks out fat, sweet, and variety and eating large amounts of food becomes a priority, at least according to the brain.

Some people can fight the brain off in this case, and control their food intake, maintain a healthy diet, and maintain a normal weight, but the number of such people in the population is shrinking by the day. As we see prevalence of obesity and diet related diseases going up around the world, country after country, year after year, you can see how the environmental conditions are trumping people’s thoughts about what they should eat, knowledge about what’s healthy to eat, and the like; and so the brain and the environment are mismatched at this time and that’s created havoc in a lot of different ways that we’ll talk about.

We can think about this in an evolutionary way, as I’ve alluded to a lot, but if you think about it from a completely Darwinian point of view, and you think about these food conditions where food would be scarce in ancient times. Who were the organisms that would survive those conditions and then contribute to the gene pool? Well they’re the ones who would do these things — the behavior things that we mentioned before. They’re the ones who would seek out high fat, high sugar diets because then they would get calories to seek out a variety of food, to eat in — eat above what immediate hunger might dictate. Those people would bank their calories, survive the next famine, contribute to the gene pool, and thereby create what we have today which are organisms, humans, who very much like the kind of diets that are creating problems.

So it makes sense from an evolutionary point of view. If the food environment had evolved very slowly, as it had in earlier human history, the body would have a chance to adapt. Natural selection would create people who were in sync with their environment. But as I said before, the food environment has changed very quickly and people have not. The ones who would seek out calories, the ones who could store and not waste energy, those with an efficient metabolism — that is those people who took in calories and banked them into their body fat and stored against subsequent famine — are the ones who would do the best under these circumstances. The ones who would conserve energy, that is they were sedentary when possible, other then when they had to go get food would again not waste their calories but would save them and contribute to the gene pool. Doesn’t it make sense then that being sedentary and seeking out high fat, high sugar, high calorie foods has become a priority woven into our biology? But we’re mismatched with environment?

Here’s a little video clip that I’d like to show you that talks about evolution and how humans have evolved in relationship to their food. This was a series put together by a British filmmaker who’s actually narrating this named Antony Thomas who did a terrific — I think six or seven part series for British television and several of those got collapsed into a one hour special on Nova that was shown in the United States. He sent me this because he interviewed me for this series of films and sent me some clips, so I’d like to share this one in particular with you. Actually I have three that I’ll show you.

[video playing]

This fellow who was just interviewed on this is a man named Philip James who’s in London and runs a group called The International Obesity Task Force, and probably more then anyone in the world, knows the world situation about food and food policy. In this case, he’s talked about fat and talked about the survival mechanism that’s so important for fat. Now another clip from that same Antony Thomas series I’d like to show you here. In this case one of the people being interviewed is a woman named Susan Jebb, who is a prominent research in the UK.

[video playing]

So something about fat is driving people, and as I’ll explain in a subsequent lecture, what would it be about fat that makes it more reinforcing then protein or carbohydrate? Anybody guess? Go ahead.

Student: [inaudible]

Professor Kelly Brownell: Okay, the higher caloric density. Fat has twice the calories per unit weight that protein or carbohydrate sugar has, as a consequence, has the greatest survival value. So that music, the sort of seductive feel that was in this video is how humans feel about fat. You can smell the bacon when people make it in the morning, the idea of French fries cooked in fat becomes appealing to people. Things that are high in fat and then high in sugar too like ice cream, become very appealing to individuals and so these foods become incredibly powerful for people. Incredibly powerful. People in the United States and increasingly in other countries around the world, are eating way too much fat. They’re also eating way too much everything else, but they’re eating way too much fat. Most of those people know they shouldn’t. When there’s this disconnect between what people think they should do and what they actually do do, and so many people are involved in this, so many people are affected by it, it gives you a sense of how powerful biology can be and how it can override people’s common sense, education, and knowledge and all part of evolution. So counteracting those things becomes pretty important.

Chapter 8. Food Then, Food Now [00:55:32]

Now the paper that was in the readings by Boyd Eaton talked about this. There are some people who have talked about returning to an ancestral diet. Now we’ll talk in a subsequent class about what the ideal diet is. Experts differ on this and people have their favorite nutrients, and this gets played out in diet books. So you have the low fat diets, you have the low carb diets like Atkins, etc., and so — and even the experts who aren’t out there trying to make a fortune on diet books have their own favorite foods and things. So what to eat, what the optimal diet is has become a pretty controversial issue.

Some people have said let’s go back to what our ancestors ate. It worked for them, they didn’t have all these chronic diseases like we have, now they had other challenges, infectious diseases primarily, but they didn’t have the chronic diseases like we have, like cancer, heart disease, hypertension, hyperlipidaemia, etc., and Diabetes particularly. Let’s go back to the old diet, and Eaton is one of the main proponents of that sort of philosophy. Now you can come to your own conclusions about whether that makes sense and we’ll go over different dietary approaches as we go through subsequent classes but its interesting philosophy.

If you compare ancient humans to what modern people eat, let’s look at different constituents of the diet. Fat is not all that much different, but one thing that’s happened is the type of fat has changed a lot, and so people are eating less fat from plant sources and more fat from animals sources and that’s where the saturated fat comes in and high saturated fat intake is not a good thing. Carbohydrate has really shifted, and so people are eating more calories from carbohydrate before, sugars primarily, and that is coming primarily from added sugar, or that’s at least one of the primary contributors. Now the added sugar before, does anybody remember from the Eaton article how ancient humans added sugar to things? Honey. Honey was the one place where it may have come from, but of course, now there are lots of ways to add sugar to things, and sugar is everywhere and added to foods you wouldn’t expect.

We did a little study once in our group testing the following hypothesis. Now we never completed the study so we never wrote it up, but we did find some interesting preliminary things. Our hypothesis is that in the United States it’s less expensive to sweeten things then it is elsewhere in the world, and part of that is because of high fructose corn syrup that we’ll talk about later in the class. It becomes very inexpensive to sweeten things. Why would you sweeten things in the United States? Well because you can, because it’s less expensive to do so then it is elsewhere in the world and people naturally like sweet tastes. If you have a product and your competitor has a product and you put sugar in yours, people are going to like it better. Sugar shows up in all sorts of interesting places where you wouldn’t expect it necessarily. Large amounts of sugar in peanut butter, large amounts of sugar will go into things like stews, and soups, and things like that where you wouldn’t necessarily expect to find it. And that’s because you can add sugar. People will naturally like it better.

Our little study hypothesized that foods that you could buy in the United States would be sweeter and have more sugar in it than the same foods that one could buy in other countries. So we started collecting cereals and things like that from various countries, and found in this preliminary study, that it was the case, the American foods were sweeter. But again, pretty preliminary and not a complete study.

Protein was a lot different in this period of time and many health authorities think a higher protein diet would benefit humans. Fruits and vegetables of course were much different. This is one of the most striking findings. It’s not surprising, therefore, that people should be eating more fruits and vegetables, and our ancestors were eating much more. Then fiber was tremendously different as well. Fiber is related at a risk for some diseases, particularly some cancers, and therefore the low fiber intake that we have now compared to what our ancestors had is a factor. The fiber intake is affected not only by what particular foods people pick but how much processing is done of the foods they have, where some of the fiber in foods is specifically processed out. So we’ll talk about that later in the class.

Chapter 9. Genes Mismatched with the Modern Environment [01:00:18]

The question is: why do people eat so much? This is pretty much the answer: because they can! Because humans want to eat a lot, they want to bank their calories, they want to seek out foods that are high in sugar, fat, and variety, and if those are available then they’re going to be eaten and we’ve got problems.

This is a normal weight laboratory rat given much more then it would — could necessarily eat of standard laboratory food. Now in this particular case, these animals will not overeat on the healthy balanced food and won’t gain excess weight, they’ll maintain a normal weight. But if you throw off the environment, in this case, the animal’s biology, it’s drive for certain nutrients is in concert with the food it has access to. So this diet, although its processed by a company and sold for people doing animal studies, it more or less mimics what these animals might be eating under natural conditions.

If you change the animal’s environment and you give it access to these sort of foods, and these are the pictures that I showed in the first class, and you remember I asked you what constituents of this diet promoted obesity and you said it was fat, sugar, and variety that was correct. This normal weight animal like this has its whole equilibrium thrown off, its homeostasis thrown off when its dietary conditions change. What you get is quite a heavy animal. That looks like a pretty happy rat, doesn’t it?

Well why would it be happy? Well it doesn’t have to go out and search for food, it’s right there, it can eat whatever it wants, whenever it wants. In this case banking energy trumps good nutrition because the pellets of the healthy diet are in the pile, and if nutrition trumped conservation of energy the animal would eat those pellets and maintain a normal body weight, but the animals under these conditions pretty much ignore this, they ignore the healthy food, they seek out the foods that are higher in sugar, fat, and variety, and become quite overweight.

Now as I mentioned in the earlier class, variety becomes interesting, because if you could somehow put these piles of food and take each of the foods separately and put them in separate piles, and find out which food the animal preferred and then gave it just that, instead of a mix of foods, even less preferred foods, you wouldn’t get nearly the degree of overweight that you get if you mix up the foods. The variety is important.

What better mimics modern human conditions than fat, then sugar, and variety? Those foods that you see there, that throw off the animals homeostasis, and their hunger equilibrium are the same foods that are marketed very heavily. I don’t know if any of you watched tennis recently, but the U.S. Open has been shown and there’s an Oreo advertisement with the William sisters and so you — that’s why people know about these foods. Not that particular one, but in general. These foods are heavily marketed, they tend to be sold in schools, there tend to be mini markets right outside the schools so people can get them on the way to and from schools at many places, and this is the food environment.

When the animals respond by doing this how can we be surprised that humans do it? It starts to teach us some lessons about if we’re going to change the food environment for the better, if your job let’s say as a public health official, and you’d like to help people change their diets, how are we going to do it? Are you going to focus on willpower, restraint, and personal responsibility, and try to educate people, give them the skills and the knowledge it takes? Or are you going to say that that will only take us so far, and it’s the conditions that are messed up, and we have to do something about the conditions to make it easier for people to make healthier choices? We’ll talk about those two different approaches as we go through the class.

Now it’s not uncommon, by the way, for laboratory animals in these studies to triple their body weight. Take your own weight in your mind and multiply it by three. Again, there’s no advertising affecting this, there’s no parents being irresponsible and buying sugary cereals for the poor little animals. There’s none of this. This is raw intersection of biology and environment. Again, when we see this evidence, then it starts to help guide us about what we might do to make changes in society in general. Again, to show you the difference, a different perspective, from a different point of view about the impact of this diet you can look at something like that.

What we have is ancient genes are mismatched with the modern environment. Here’s another video clip from that same series that speaks to this issue, this one’s beautifully done.

[video playing]

Now this is a very striking visual display of how much difference an environment can make. Now one could say that there’s something peculiar about the — biologically about the Pimas who live in Arizona, who put that — makes them so much at risk for diseases like Diabetes. However, their biological relatives in Mexico would presumably have that same risk, but it would never be manifested if they’re not exposed to what some have called a toxic food and physical activity environment. Because of that, we have a set of environmental conditions that have enormous impacts on people. Some people in the population are more biologically vulnerable then others, and the Pimas appear to be one of those groups. It’s all different degrees of terrible, if you will, because so many people in the population share that biological vulnerability and when the environment changes, we have the problems.

Again, we have to ask ourselves, we have to start thinking of the question about what does this mean for doing something about changing the world’s diet, changing the nation’s diet, changing the world’s diet? Do we rely on the individual behavior and education, or do we try to do something about the environment? Food has changed in a lot of ways from the early ancestral days. The amount of food available is striking, I mean in the period of time I was — since I was a child there are a lot of changes that have occurred, and I mentioned some of this in the last class — but when I was a child you didn’t have rows and rows of food at a drugstore. Gas stations sold gas and that was it. There might have been one Coke vending machine at my high school, if any, I don’t even remember. And that’s just in my lifetime. Think about how grossly things have changed starting in those earlier times.

Food is basically available to people all the time in many different forms, coming in many different ways. The calorie density has changed because food is processed, so the calories and the fat, and the sugar that can get squeezed into things made possible by technological changes has shifted things a lot. Portion sizes, and we’ll devote a class to this later on, have gone way up and that’s a big problem. The amount of processing I mentioned, we’ll talk specifically about how many calories people are consuming in liquid form which has gone way, way up. The number of calories you guys consume as a part of your diet, if you’re the average person, is much higher then used to be the case and that has very interesting biological implications that we’ll discuss. Your body interprets liquid calories different then it does calories in solid food. Of course the physical work of securing the food has changed a lot. These are very profound changes, and it has led to the humans that we are today. It’s important to understand the ancestral diet to see why we’ve evolved, the biological reasons we are the humans we are today, but it also helps instruct us about what we might happen to do.

That will end the lecture, I’ll show you the comedy clip in just a moment. If any of you guys have questions after the class we can meet outside and talk about those.

[end of transcript]

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