How Hormones Shape Sexual Development

**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. 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. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink. I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or twice a day is that it helps me cover all of my basic nutritional needs. It makes up for any deficiencies that I might have. In addition, it has probiotics, which are vital for microbiome health. I've done a couple of episodes now on the so-called gut microbiome and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With Athletic Greens, I get the vitamins I need, the minerals I need and the probiotics to support my microbiome. If you'd like to try Athletic Greens, you can go to athleticgreens.com/huberman and claim a special offer. They'll give you five free travel packs plus a year supply of vitamin D3 K2. There are a ton of data now showing that vitamin D3 is essential for various aspects of our brain and body health. Even if we're getting a lot of sunshine, many of us are still deficient in vitamin D3. And K2 is also important because it regulates things like cardiovascular function, calcium in the body and so on. Again, go to athleticgreens.com/huberman to claim the special offer of the five free travel packs and the year supply of vitamin D3 K2. Today's episode is also brought to us by Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the exact ratios of electrolytes are an element and those are sodium, magnesium and potassium, but it has no sugar. I've talked many times before on this podcast about the key role of hydration and electrolytes for nerve cell function, neuron function, as well as the function of all the cells and all the tissues and organ systems of the body. If we have sodium, magnesium and potassium present in the proper ratios, all of those cells function properly and all our bodily systems can be optimized. If the electrolytes are not present and if hydration is low, we simply can't think as well as we would otherwise. Our mood is off, hormone systems go off, our ability to get into physical action, to engage in endurance and strength and all sorts of other things is diminished. So with element, you can make sure that you're staying on top of your hydration and that you're getting the proper ratios of electrolytes. If you'd like to try element, you can go to drink element, that's lmnt.com/huberman, and you'll get a free element sample pack with your purchase. They're all delicious. So again, if you want to try element, you can go to element, lmnt.com/huberman.
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Take a three-minute quiz, and Thesis will send you four different formulas to try in your first month. That's takethesis.com/huberman, and use the code Huberman at checkout for 10% off your first order. It's a new month, which means it's a new topic here at the Huberman Lab podcast. For the next four or so episodes, we're going to be talking all about hormone effects on the brain and body. So that's a huge number of different topics. We're going to talk about sex. We're going to talk about reproduction. We're going to talk about puberty a little bit more. We talked about that in the previous episode. We're going to talk about menopause. We're going to talk about birth control. We are going to talk about aggression, competition, winning, losing. Basically, we're going to cover as much about hormones as we possibly can in this month. And in doing so, we are going to go deep into tools and protocols. We are also going to talk about a lot of tools that relate to things that you might not want to do in order to optimize hormone health, regardless of stage of life or your goals, et cetera. So it's sure to be a month rich with discussion, rich with tools, and you're going to learn a lot of neuroscience and endocrinology. There's actually a field of neuroendocrinology. It's actually where I started my graduate work. I did a master's in it, which is only to say that I love the topic. I have a lot of friends that work on this topic, many of whom I've consulted for these episodes, and I'm really excited to share the information with you. Before we dive into today's episode, all about emotions and sex, I want to just have a few announcements that are designed to point you to some useful resources. Last episode, talking about the science of emotions and relationships, I mentioned the Mood Meter app. The Mood Meter app was developed by people out at Yale University who study the biology and psychology of emotions. It's a really wonderful app. However, many of you quickly told me that the Mood Meter app isn't available in your area. You went to the link we posted, and it just was saying not available in your area. The situation was actually a lot worse than that. The situation was that when we recorded the episode, the Mood Meter app was working, I know, because I downloaded a fresh copy of it to my phone. And then in the ensuing weekend, they took the Mood Meter app down for some repairs. The Mood Meter app is now up. It is available. I want to be really clear. It's not an app I'm affiliated with. I'm just mentioning it to you. They don't know me. I know them, but they don't know me. So we don't have any kind of business relationship. They do charge 99 cents for the app. I think the free version has disappeared in the last year or so. So that's Mood Meter app will provide the link again and the link should be working. Hopefully they won't take it down again in between this announcement and the release of this episode. Also just want to take a step back for a moment and talk a little bit about the logic of how to make the most of the information on the Huberman Lab podcast. I tend to throw out a lot of information about a given topic. Many of you have pointed out, however, that I don't cover certain things. And once again, I'll just say, the goal is always to be accurate, but there's no way I can be exhaustive. There's no way I can cover everything for a particular topic. The good news is we have time. My goal, at least in the first year of the Huberman Lab podcast, is to give you a basis, a foundation in these different topics of neural plasticity, focus, sleep, hormones, et cetera. And of course, to provide tools along the way. We are going to host guests. I've actually started recording with some of these guests already. And even those episodes will include a little, what we call primer, a little description of the basics of a given topic so that you can get more information from those topics. My goal really is to educate you in these topics, give you a foundation in these topics and allow you to start exploring them here in the episodes with our future guests, but also in other podcasts and books and other sources of information. So for those of you that are saying it's too much information, I just encourage you to remind yourself that you have a pause button, you can return to it, everything's timestamp. For those of you who feel it's not enough information, I'm not covering enough, just know that this is just the beginning. We intend to do this for a very long time and we will be thorough over time. So thanks for your patience and please be patient with yourselves. There's no reason why you have to digest all the information in one swoop. The other thing is that I've been told both that I speak too fast and speak too slow. So there's a wonderful solution to this. If I speak too fast or too slow, you can adjust the speed in YouTube. If you're listening in a different format, I think you also can adjust the speed of playback. So that's something that wouldn't be possible in the classroom, but you may find useful. And then last but not least, I want to point people again to this NSDR, non-sleep deep rest protocol that the folks over at made For have put out as a free resource. It does, as many of you pointed out, bear resemblance to things like yoga nidra, other forms of meditation. But what we've done is we've stripped out intentions or any kind of the verbiage related to what some people might perceive as kind of related to the yoga community or specific to kind of new agey type techniques, not because we don't like yoga nidra. In fact, I've done yoga nidra daily for almost the last goodness, eight years of my life. I love yoga nidra. But sometimes the complicated language can be a separator and can discourage people from taking on these protocols that are extremely useful. So NSDR is intentionally generic. It's designed to bring you into a state of deep relaxation through a combination of breathing and body scan. There's the YouTube script over at made For, which is linked in the caption. And many people find that they prefer that to scripts like yoga nidra scripts where they're doing intentions and they're hearing a lot of kind of unusual language around the process. This is just very basic and I hope you'll enjoy it. And if you prefer the more typical yoga nidra scripts, then go with those. There are many of them available on the internet and elsewhere. And last but not least, I want to point out that all our episodes now are subtitled both in English and in Spanish. So for those of you that prefer to digest this information in Spanish, that's now available to you in the subtitles. Today, we're going to talk about the science of sex, in particular, sexual differentiation. Now, that's a complicated topic because sex is both a adjective, a noun and a verb depending on the context. Today, we're going to talk about the hormonal effects and the neural effects of particular events that happen during development and how those guide adolescent and adult behavior, including sexual preference. It's an area that's fascinating and for which there are actually very solid textbook findings. So textbook findings means that there are many studies that have been aggregated over decades that point to what we now know to be absolute truths in terms of how hormones affect brain development, how the brain impacts hormonal development and how those interact to control behavior, for instance. We are also going to talk about reproduction, the verb sex. And of course, sex, the verb, can also be carried out independent of reproduction. It's not always in particular in humans, just to produce offspring. So that's going to be covered in the next episode, but you absolutely need to understand the information in this episode in order to make sense of the information in the next episode. So today we're going to explore hormones, what they are, how they work, what leads to masculinization or feminization of the brain and body. I'll just throw out one really interesting fact that perhaps most of you didn't realize that hormones have direct effects on the body. Most people know that because there are hormone differences and sex differences in bodies in terms of genitalia and body hair, distribution of body hair, et cetera. But there are also effects of hormones on the brain directly. And believe it or not, there are also effects on the spinal cord, on the neurons and structures within the spinal cord that impact in a very direct way what sorts of behaviors are possible. So it's a fascinating area. You might notice I'm going to go a little bit more slowly through this topic than I normally do. I want to be extremely careful with my language. Some of these topics, some of you may be thinking are extremely sensitive, right? And of course, any discussion about sex and reproduction is a sensitive one. But today we're just talking about the biology. We're not getting into the cultural constraints or the cultural dialogue. What we're trying to do today is really get to the biology, the physiology, the endocrinology and the behavior. So let's start by talking about what hormones are, just to remind you, and what they do. Hormones by definition are a substance, a chemical that's released in one area of the body, typically from something we call a gland, although they can also be released from neurons. But they're released often from glands that travel and have effects both on that gland, but also on other organs and tissues in the body. And that differentiates hormones from things like neurotransmitters, which tend to act more locally. So that's important. A hormone is a substance secreted at one location in the body travels and has impact on things elsewhere in the body. Examples of tissues that produce hormones would be the thyroid, the testes, the ovaries, et cetera. And then of course there are areas of the brain like the hypothalamus and the pituitary, which are closely related to one another and release hormones that cause the release of yet other hormones out in the body. So we're going to cover all this. If you don't know anything about endocrinology, you're still going to be able to understand today's discussion. And we're going to start with a discussion about what hormones actually do to create this thing that we call masculinization or feminization. So let's start with development. Sperm meets egg. Everything that happens before that is a topic of the next episode. But sperm meets egg. This is mammalian reproduction. And that egg starts to duplicate. It starts to make more of itself. It makes more cells. And eventually some of those cells become skin. Some of those cells become brain. Some of those cells become muscle. Some of those cells become fingers. All the stuff that makes up the brain and body plan.