Behaviors That Alter Your Genes to Improve Your Health & Performance | Dr. Melissa Ilardo

**Andrew Huberman** (0:00)
Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life.
I'm Andrew Huberman, and I'm a professor of Neurobiology and Ophthalmology at Stanford School of Medicine. My guest today is Dr. Melissa Ilardo, Professor of Biomedical Informatics at the University of Utah. Dr. Ilardo is a world-renowned expert in human genetics and epigenetics. She conducts pioneering studies on how our behavior and the environment can modify our gene expression. Today marks the first time on the Huberman Lab podcast that we really explore human genetics, epigenetics, and how behavior shapes gene expression across generations. We talk about the inheritance of physical traits like eye color, and we dive deep into fascinating mechanisms such as the mammalian dive reflex, a physiological reaction to breath holding and cold water that, as Dr. Ilardo explains, can dramatically alter the physiology of your spleen to allow significant increases in red blood cell count and oxygen availability to your brain and body. And by the way, the mammalian dive reflex can be activated outside of free diving, and you can even do it at home. We also explore how mate preference and selection in humans relates to the immune system. That is, if you were given a choice of many, many different mates, as most people are, the mate you would select is the mate who has the immune system composition that is most different from yours. And you would know that on the basis of their smell and how attractive their smell is to you compared to the smell of other people. We also talk about how differences in external traits signal important variations in organ function, hormone levels, and even brain physiology. Toward the end of our conversation, we discuss the current state and ethical considerations of gene editing in humans, something that's apt to be an increasingly important topic in the years to come because gene editing in humans is now possible and is happening. As you'll soon learn, Dr. Ilardo does incredible real-world experiments that reveal the remarkable interplay between genes and behavior, and she's an absolutely phenomenal teacher who makes complex genetic concepts accessible and practical. The conversation is sure to change the way that you think about mate selection, your parents, their parents, and what you can do to optimize your physiology and health through behavioral practices that influence gene expression. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, this episode does include sponsors. And now for my discussion with Dr. Melissa Ilardo. Dr. Melissa Ilardo, welcome.

**Melissa Ilardo** (2:38)
Thank you.

**Andrew Huberman** (2:40)
Nature versus nurture. Super big question that we all wonder about, you know, how much of our capabilities and potential and just general themes of life, everything from how we look to what we're capable of doing or not doing in the moment or where we might be able to improve or not improve. We hear some of its nature, some of its nurture. So if we take a step back and we just ask a big question about human genetics, how much of our DNA is modifiable by our environment and what we do, what we choose to do in particular, because that's most of what we're going to emphasize today.

**Melissa Ilardo** (3:19)
I think that's something we're still understanding at this point. I think every day we're getting more and more information about the ways that we can actually modify gene expression and these things that we thought were totally predetermined in the past.
I think we're still learning with epigenetics and all of these new fields just how much we can actually change things. There are of course things that are kind of written in our genes but I think we're learning that there's a lot more that we can change.

**Andrew Huberman** (3:45)
Most of us at some point in high school learned Mendelian genetics. Mendel, the monk and his peas in his garden. Most people probably don't remember the details of that. But we also learn about eye color. You know, it's, you know, commonplace for people to understand that if both your parents have dark eyes, with very rare exception, it's unlikely that you're going to get light eyes as a child. But it's possible. But if you have one light-eyed parent and one dark-eyed parent, then you start to enter the probability game. And then at some point, your parents dictate a lot of your appearance, your phenotype.
And yet that there are aspects of our parents that are not seen in us at all and vice versa. And so I think for most people, when we think about genes, we think about heritability. But your work focuses a lot on the aspects of genetic expression that are subject to change based on what people choose to do or are forced to do in order to survive, something we call selection. So could you tell us about selection in terms of how quickly a given behavior, for example, can change our gene expression? I'm not aware of any way to change one's eye color without putting in like a colored contact lens. Now there's some esoteric things showing up online about people using these bizarre treatments to change their eye color. But for the most part, people accept that you're not going to change your eye color by behaving differently. But what are some examples where we can change our gene expression quickly, relatively quickly, by doing something differently?