What Should We Eat? Evolution, Diet, and Health

Meredith Johnson (0:03)

This is Origin Stories, the Leakey Foundation podcast. I'm Meredith Johnson. What should we eat? It's a simple but confusing question, and there's a lot of contradictory advice. Should you eat vegan, paleo, low-carb, low-fat, high-protein? Do we avoid saturated fats or put butter in our morning coffee? With so many diets claiming to be the key to better health, weight loss, and longevity, it's hard to figure out what to do. Today on the show, we welcome back paleoanthropologist and author Daniel Lieberman to talk about food, health, human evolution, and his new book, Fed Up, What Evolution Reveals About Food, Diet, Health, and Eating Well. The book brings insights from evolutionary science, physiology, anthropology, medicine, and history to help us make sense of the world of diet and wellness advice and give us some tools and knowledge so we can make more informed choices about what we eat. Dan is a professor at Harvard University and a founding chair of their Department of Human Evolutionary Biology. He's a Leakey Foundation grantee and a member of our Scientific Executive Committee. Dan, it's great to have you back on the show. It's a pleasure. Thank you. So why don't we start with the question you start your book with, what should I eat? I mean, that's really what the book is about. How many times a day do you or I, or like people listening, ask themselves, what should I eat?

And I really started the book because that's a very modern question that we never evolved to ask, let alone answer. I mean, when I walk into a supermarket, a typical American supermarket has about 40,000 different kinds of food. And a large percentage of those foods are pretty weird foods, right? They've been boxed and packaged in factories and processed in all kinds of ways.

And so we're actually choosing foods we never evolved to eat. But if I was a hunter gatherer, and of course we were hunter gatherers for most of our existence, hunter gatherers, they don't ask themselves what they're going to eat. They eat what they hunt and what they gather. And if you're a farmer, you eat what you grow. So this modern industrial problem of what should I eat is something entirely novel for which we never evolved. And obviously, we do a pretty bad job in many parts of the world. How does an evolutionary perspective help us figure out or do better with the question of what we should eat? Well, I mean, evolution doesn't answer the question entirely. But my favorite saying, and I say it all the time, is that nothing in biology makes sense except in the light of evolution. And that's because we weren't designed, we weren't engineered, we evolved. And if you want to understand how and why our digestive systems work and our nutrition works and the association between what we eat and our health works, an evolutionary perspective is an important element. But of course, you need to combine that with other kinds of data, with biomedical data, with nutrition, with physiology, with studying the microbiome. There's a lot of other forms of information, but evolution gives us the framework with which to interpret it.

One way people kind of take the framework of evolution and try to answer questions about health is to look at living hunter-gatherers, people living that lifestyle now.

In your work, you've spent time with hunter-gatherers. How does what they need to know about food compare to what people who get their food from grocery stores need to know? If you're a hunter-gatherer or farmer, you need to know a lot to get your food, right? I've had the privilege of going out with hunter-gatherers. You don't just walk out and just pluck berries. You need to know a lot in order to hunt and gather food, to find out where it is and know what to eat and how to process it. I mean, that's their job and it requires an enormous amount of knowledge. We don't need to know anything these days about how to get our food, right? What we need to know in the modern world is how to choose our food, because that's the problem that we face.

And so I tried to put in the book all the information I think anybody in the modern world needs to know about how to choose their food. And also for the book, I thought it would be sort of fun to try a lot of these diets. And I sort of matched diets to the kind of the history of diets. So I started off with a raw food diet, did a paleo diet, et cetera, et cetera. Not so much to test their effect on my health, because I didn't want to eat them for years and years. I couldn't. So I'm not pretending this is biomedical data, but rather to kind of get a sense of what these different diets are like, because I don't know, I'm curious. And just like I tried barefoot running when I was studying evolution of running, I thought I should try different diets. I like participant observation. I think you should try what you study. I like that. And you got your wife, Tonia, to go along with it. I really enjoyed that in the book. Yeah. My wife tried the diets with me and that added a lot of, I mean, first of all, I made it because we eat dinner together. So that was important, but also she's very funny. Very funny. So what was it like for you to eat these diets? Some of it sounded pretty not fun. I mean, some were okay and some were a challenge. I mean, the raw food diet was by far the hardest.