World's No. 1 Exercise Professor: "Our Comfortable Lives Are Causing Cancer", "The Truth About Running", "Hand Sanitiser Is Making You Sick!

**Daniel Lieberman** (0:00)
Cancer, violence, aggression, obesity, stress. If you want to fix all your complex problems, well, this is controversial, but the vast majority of the evidence suggests that Daniel Lieberman, a Harvard professor who uses the information of our evolutionary past to understand the health crisis we are in today and educate people on how to live a long, healthy life. The vast majority of us in the Western world will die from a mismatched disease. Chronic stress, that's what we call a mismatch. Obesity, heart disease, many cancers are mismatches. And it's because we now live in a world where we're able to have incredible levels of comfort with all this choice. For example, the number one medical complaint is back pain. Because I'm sitting in this comfortable chair, I don't have to use any of the back muscles. So we develop weak backs that don't have any endurance. We know that people who sit a lot at work, but then also sit a lot in their leisure time, run way more risk of disease. And if you aren't physically active, you don't grow as much skeleton. And then when you hit 25 to 30, for the rest of your life, you're going to start losing bone.

**Steven Bartlett** (0:55)
Oh, sugar.

**Daniel Lieberman** (0:57)
Even in this highly sanitized world, we're much more likely to develop allergies and various kinds of autoimmune diseases because our immune systems are so unchallenged, they end up accidentally attacking us. Also, famous studies show that the richer the country, the higher the rate of cancer. Bangladeshi women who move to England, their cancer rates go way up because of diet and physical activity and stress, things that have changed in our modern world, for which we are very poorly adapted.

**Steven Bartlett** (1:19)
There's a lot to take in. Is there an actionable conclusion that I can do today that is going to reduce my chances of getting one of these mismatched diseases?

**Daniel Lieberman** (1:26)
Yes, I think there's two. The first is...

**Steven Bartlett** (1:38)
Daniel, what is your job title?

**Daniel Lieberman** (1:41)
I am a professor of human evolutionary biology at Harvard University.

**Steven Bartlett** (1:46)
And what does that mean?

**Daniel Lieberman** (1:48)
It means I get to have a lot of fun. I study, well, my department studies how and why humans are the way we are, and we're also interested in how and why that's relevant to humans today. My particular specialty is I study the human body. I'm interested in how and why the human body is the way it is and how that's relevant to health and disease. I'm most interested, most of my work is on the evolution of human physical activity, but I'm also interested in the Indian diet and other ways in which we use our bodies.

**Steven Bartlett** (2:18)
Why does it matter?

**Daniel Lieberman** (2:20)
Well, because we weren't designed, we weren't engineered, we evolved. If you want to understand why we are the way we are, you have to understand that evolutionary history. If you want to solve problems, if you want to deal with big issues that we face today, obesity, heart disease, cancer, violence, aggression, all of these things have an evolutionary origin. An evolutionary origin is crucial to helping us come up with solutions.

**Steven Bartlett** (2:48)
Does what we eat play a role in the starting point of our stories and how we began to eat and thinking about farming, hunter gathering, and all those things? Because when I look at human beings versus a lot of animals, and you talk about this in the book, we are remarkably fragile and inadequate in comparison. Our eyesight isn't that great. We're super weak. I think you say that most monkeys are stronger than we are. Squirrels can run faster than us.

**Daniel Lieberman** (3:13)
Well, I think we actually exaggerate our fragileness and weakness to some extent. Chimpanzees, our closest relatives, are probably about 30 percent stronger than we are. You would not want to arm wrestle a chimpanzee. Most quadrupeds can run way faster than we can. Right. We have this story about human evolution, that it's been a triumph of brains over brawn, right? That we have tools and language, and that has enabled us to conquer the world and become the dominant species. There's some truth to that, of course. Technology, language, communication, cooperation, all are essential parts of the human success story. But I think as athletes, we're pretty impressive. We can outrun most animals over long distances, so we're really impressive in terms of endurance, both men and women. We can throw, we can kick, we can do all kinds of things that my dog can't do. As far as diet is concerned, we're the ultimate omnivores. We can eat anything. I mean, most animals have a very constrained diets. There are certain things they can eat, most of the things out there they cannot eat. We've managed to figure out because of technology, cooking, food processing, but also because of the nature of our digestive system, we can eat just about anything on the planet. People can be vegans. They can eat all meat diets.