Essentials: How Smells Influence Our Hormones, Health & Behavior | Dr. Noam Sobel

In this Huberman Lab Essentials episode, my guest is Dr. Noam Sobel, PhD, a Professor of Neurobiology at the Weizmann Institute of Science and an expert on the human sense of smell. We discuss how the brain processes odors and how smell shapes our lives more than we realize, influencing everything from who we become friends with to how we experience emotions, hormones and aggression. Dr. Sobel also shares his lab’s groundbreaking work on digitizing smell and future technologies that could enable noninvasive disease detection through body odors. Read the full episode show notes at hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman Eight Sleep: https://eightsleep.com/huberman LMNT: https://drinklmnt.com/huberman Timestamps (00:00:00) Noam Sobel (00:00:20) Biology of Smell (Olfaction) (00:04:32) Human Smell, Social Interaction, Handshaking (00:08:31) Sponsor: LMNT (00:10:03) Friendship, Body Odor (00:14:04) Human Chemosignals, Smell of Fear & Contagion (00:15:48) Aggression, Chemosignals, Men vs Women, Babies (00:20:38) Sponsor: AG1 (00:21:51) Tears, “Chemical Blanket”, Testosterone (00:25:37) Digitizing Smells (00:28:25) Sponsor: Eight Sleep (00:29:48) Creating Digital Odors; Future Medical Diagnostics (00:33:43) Acknowledgments Disclaimer & Disclosures Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Andrew D. Huberman?

  Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. And now for my discussion with Dr. Noam Sobel. Dr. Sobel, Noam, welcome.

• 0:22Speaker 01

  Thank you.

• 0:23Andrew D. Huberman?

  Must say, I am extremely excited for this conversation. I've been a huge fan of your work. And today, I'd love for you to share with us all about the amazing landscape of chemosensation, in particular olfaction, our sense of smell, and some related perceptual abilities or subconscious abilities, including pheromones, et cetera. To get everybody on the same page, I'd like to just start off by asking, what are the major components of our ability to smell? Obviously, where I like to think it involves the nose at some level.

• 0:53Speaker 01

  It does.

• 0:53Andrew D. Huberman?

  If you could just give us the top contour, or even deep contour, if you like, of the parts list and the various roles they play.

• 1:03Speaker 01

  Primary olfaction is referred to as ortho-nasal olfaction. That is, through our nose, we sniff, and sniffing is a big thing. Well, I have a sense we might talk about that a lot today in all sorts of contexts. So we sniff in through our nose. And to answer your general question of the organization of the system, so molecules, airborne molecules, travel up our nose, a distance in the human of about six or seven centimeters to about here, where they interact with, I will use the word sheet of receptors, but sheet is a bit misleading here. It's not a sheet, it's very convoluted. We have about 7 million such receptors lining a structure known as the olfactory epithelium.

• 1:46Speaker 01

  This is the sensory surface of the olfactory system, the olfactory epithelium. Again, about, probably about 6 or 7 million receptors in the human. In the human, probably of about 350 different kinds. So that's amazing. That means a meaningful percentage of your genome is devoted just to this, just to the kinds of olfactory receptor subtypes you have in your nose. So odorants interact with these receptors here in our epithelium, where they undergo what is referred to as transduction. That is, the odorants are docked a receptor and turn into a neural signal. And this neural signal, in fact, action potentials, not gradient potentials of any kind, propagates via the olfactory nerve

• 2:31Speaker 01

  through the thinnest part of our skull, which is perforated. It has a lot of holes. The nerve goes through those holes and synapses at the first target in the brain, which is the olfactory bulb. The pattern of that synapsing follows what's referred to as the most extreme case of convergence in the mammalian nervous system. More specifically, what happens is that all the receptors of one subtype converge to one location in the bulb. And this location is referred to as a glomerulus or an imploroglomeruli. And that may be a slight oversimplification. It's in fact two glomeruli. The textbook view of how things work is that every such receptor subtype

• 3:12Speaker 01

  is responsive to a small subset of different molecular shapes, what's sometimes referred to as odorotopes, the molecular aspects of the odorant. And each odorote will activate a different subset of receptors. Then, because of this convergence, you end up having on the bulb, in a way, a map reflecting receptor identity. So let's say this coffee activates receptors of type 1, 3, and 7. So the glomeruli of receptors 1, 3, and 7 will light up, quote unquote, "when I smell the coffee." And if you could take a snapshot of that, theoretically, you would have the map of coffee. This is sort of the textbook view of how the system works. And then information goes from the bulb to several targets in the brain.

• 3:56Speaker 01

  I mean, what is referred to as primary olfactory cortex is piriform cortex and anterinal cortex. This is on the ventral surface of the brain, the lower portion of our temporal lobe. And information goes there directly, but it also goes directly to the amygdala. It probably goes directly to the hypothalamus. It may go directly to the cerebellum. It goes all over the brain. So information projects widely from there. And as far as people understand, the map that may exist on the bulb doesn't exist in the rest of the brain. And the understanding of how coding occurs in the rest of the brain is murky. Again, in our lab, we already said, you know, yeah, we know this. This is old news. But to people who come from different worlds, we have to reiterate this.

• 4:40Speaker 01

  Sometimes when I give, you know, public lectures to non-olfaction audiences, I reiterate this. Humans have an utterly remarkable sense of smell. We look at human behavior a lot. We try to look at it through our nose in the way we look at what people are doing. You know, we try to think, you know, if I was a dog, what would I think of this? And, you know, if you look at dogs, right? They've, you know, when they interact, they visibly sniff each other. It's very obvious. They walk up to each other and they sniff each other. And yet, humans don't typically walk up to a stranger and carefully sniff them, right? I mean, it's, we're sort of obliged to sniff our babies.

• 5:22Speaker 01

  That's considered almost something you're supposed to do. And it's not culturally taboo to sniff our loved ones. It sort of doesn't seem like an odd thing to do. But we don't sniff strangers, right? Well, or do we? So we're finding more and more mechanisms where we do this. And the one I'm referring to now, for one example, is we started looking at handshaking. There's really poor understanding of how this behavior evolved. Like, where did this thing come from? You know, if you look for the Wikipedia version, right? Then they'll tell you that it's to show that you're not holding a weapon in your hand. But there's really no good evidence for that. And we started looking at people handshaking. And we noticed, or it seemed to us that we're noticing that,

• 6:07Speaker 01

  you know, people will shake hands and then go like this and like this.

• 6:11Andrew D. Huberman?

  For those of you listening, not watching, Noam is taking his hand and wiping it on his face. Grabbing his nose or touching the side of his cheek.

• 6:20Speaker 01

  These things, these things that we do all the time.

• 6:22Andrew D. Huberman?

  After a handshake.

• 6:23Speaker 01

  Well, so first of all, we do them all the time, just period, right? The baseline here is really high, and we'll get to that in a second. But, but, but these behaviors that, you know, you could easily not notice, right? And so we, we asked whether that's a real thing. And this was a study led by Dan Froome in our lab at the time. So what we did is we brought in participants to our lab, and we sat them in the room, experiment room, and told them the experiment would start soon, and they should wait for us there. They didn't know what they were coming from. Unbeknownst to them, they were already being videoed. And they would sit there for three minutes. And during those three minutes, we could later quantify how much indeed they, just by baseline, how much they touched their nose, or their forehead, or their chin,

• 7:08Speaker 01

  or how many times their hand reaches their face. And by the way, that baseline is not low. And then three minutes later, an experimenter would walk into the room and would share a consistent text. It would be, you know, we're still setting up our equipment in the other room. And so just wait here, and we'll be right back with you. But in the meantime, just wait here. And in half of the cases, it included a handshake. This was a new experimenter, not the one who put them in the room. So that's the first time they met. So it would be, hello, I'm, you know, so-and-so. They would put out their hand and shake their hand, or not. And so you had handshake and no handshake conditions. And then you can quantify that behavior of the hand going to the nose after handshake. And there was a remarkable increase in the hand going to the nose after handshake. It's unreal.

• 7:52Andrew D. Huberman?

  So interesting.

• 7:53Speaker 01

  So the hand goes to the nose. Now, we did a few controls here to verify that this is an olfactory behavior. One is unbeknownst to participants, we measured nasal airflow. And people not only bring their hand to their nose, they sniff it. So, and this is perfectly timed. They go like this, okay? So they're sniffing their hand. So this was an olfactory behavior, no doubt about it. I mean, we're quite confident. And there's an interesting thing going on here, too, because people didn't only smell the hand that shook. They also smelled the other hand. And we think that there's something going on here comparing self to other. And we think a lot of self-sampling might reflect that.

• 8:31Andrew D. Huberman?

  I'd like to take a quick break and acknowledge one of our sponsors, Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the electrolytes, sodium, magnesium, and potassium in the correct amounts, but no sugar. Proper hydration is critical for optimal brain and body function. Even a slight degree of dehydration can diminish cognitive and physical performance. It's also important that you get adequate electrolytes. The electrolytes, sodium, magnesium, and potassium are vital for functioning of all the cells in your body, especially your neurons or your nerve cells. Drinking Element dissolved in water makes it very easy to ensure that you're getting adequate hydration and adequate electrolytes. To make sure that I'm getting proper amounts of hydration and electrolytes, I dissolve one packet of Element in about 16 to 32 ounces of water when I first wake up in the morning.

• 9:16Andrew D. Huberman?

  And I drink that basically first thing in the morning. I'll also drink Element dissolved in water during any kind of physical exercise that I'm doing, especially on hot days when I'm sweating a lot and losing water and electrolytes. Element has a bunch of great tasting flavors. I love the raspberry, I love the citrus flavor. Right now, Element has a limited edition lemonade flavor that is absolutely delicious. I hate to say that I love one more than all the others, but this lemonade flavor is right up there with my favorite other one, which is raspberry or watermelon. Again, I can't pick just one flavor, I love them all. If you'd like to try Element, you can go to drinklmnt.com/huberman, spelled drink L-M-N-T dot com slash huberman, to claim a free Element sample pack with a purchase of any Element drink mix. Again, that's drinklmnt.com/huberman

• 10:01Andrew D. Huberman?

  to claim a free sample pack.

• 10:03Speaker 01

  There's a study we published by Balra Vravi in our lab.

• 10:09Speaker 01

  Where Inba came with this basic interest in this phenomenon that's loosely referred to as click friendships. So people you meet and you click right away. Everybody experienced this in their life, you know, to some extent. And the question is, what was there, right? What was it? Was it because you looked the same? Could be. Was it because, you know, you had the same sports team that you liked? Or is there something deeper here? And Inba's theory was that a similarity in body odor may contribute to this, that people who smell the same will click in some way. And so to address that, she actually recruited click

• 10:53Speaker 01

  friends from all over Israel. She posted all over social media to identify pairs of friends. So these are same-sex, non-romantic dyads. So these are friends, men and women, whose friendship started as a click. And then she sampled their body odor. And we have a protocol for this. They're given, you know, odorless shampoo and soap to use for three weeks or something. And then they sleep two nights in this T-shirt where they have to sleep alone. And then we extract the body odor from the T-shirt. And so we have a way to extract, a method to extract body odor. And then she first asked whether indeed click friends are more similar in their body odor than you would expect by chance. And she

• 11:37Speaker 01

  first tested this with a device, a machine we call an electronic nose. So an electronic nose is sort of a very poor effort to mimic what the mammalian nose does. Basically, it's a bunch of sensors that respond to airborne molecules. In this case, sensors referred to as moxers, as metal oxide-covered sensors. And so she used an electronic nose to sample these body odors. And she found that click friends are indeed more similar to each other than you would expect by chance, by random dyads. And this was a significant difference. And after she found that a device could do this, she had other participants do this. So she had people smelling the click friends versus non-click friends, and they judged

• 12:20Speaker 01

  them as being more similar to each other than not. Now, again, you might wonder, is this causal or not, right? Because maybe click friends go to the same restaurant together all the time, or whatever, or live in the same neighborhood, and that's why they smell the same. So to address causality, she recruited total strangers and first smelled them with the electronic nose, and then engaged them in a social interaction, something called the mirror game. So in the mirror game, one person moves their hands, and the other person is really close to them, like, right here, so they can smell each other, and has to move their hands with the other person. And one prediction there panned out, but

• 13:01Speaker 01

  another didn't. The one that didn't, so she predicted that people who would smell more similar to each other would be better at the mirror game. That is, they would follow each other better. That did not pan out. However, she then also had, the interaction was completely nonverbal. They were not allowed to speak with each other. And she did an entire round robin. So everybody played with everybody else. This was an insane experiment to run. She then, at the end of the experiment, each person rated each other person as to how much they think they would want to be their friends, and also on a bunch of ratings, how nice they think they are, how affectionate they think, a bunch of ratings, okay? All of this was predicted by the electronic nose. So people who smell more similar to each

• 13:41Speaker 01

  other think that the other person is more likely to be their friend, is more likely to be a nice person, et cetera, et cetera. So we could actually predict friendship using the electronic nose. So this is not a result of friendship. It plays into the causal elements of building friendship. People are constantly smelling themselves, constantly smelling others.

• 14:04Andrew D. Huberman?

  I want to touch on some other so-called pheromone effects, whether or not it's a classic pheromone effect, or whether or not it's olfaction or something else. This is chemosensory signaling between individuals.

• 14:15Speaker 01

  It all becomes semantics.

• 14:16Andrew D. Huberman?

  Yeah, sort of like nerdy inside ball.

• 14:18Speaker 01

  It's all semantics. So I don't, in our publications, we don't use the term pheromone, you know, because it would not help me, and it would probably only hurt us. And so, you know, we talk about chemosignals, and humans definitely emit chemosignals from their body. And these chemosignals influence other humans and influence their behavior. The flavor of the month for the past 10 years in this field is what's referred to as the smell of fear. Humans emit a particular body odor when they're in a state of fear, and this body odor influences other humans, in effect, increasing their autonomic arousal, their sympathetic state. So in effect, you could say that fear is contagious a bit. So

• 15:01Speaker 01

  the smell of fear is contagious. By the way, culturally, we know for ages that dogs can smell fear in humans, but actually, that was only really shown about a year and a half ago in a study. So it was always said, but it wasn't really shown effectively. It was shown about a year and a half ago in a study, that dogs indeed can smell human fear. And humans can smell human fear. So several labs, starting from Denise Chen and Havilin Jones, and then in our lab and in other labs, if you collect body odor from people in a state of fear, and collect body odor from the same people when they're not in a state of fear, other people can determine which is the state of fear or not, and this

• 15:42Speaker 01

  influences their behavior. And they just highlight, again, you know, that we're incredibly olfactory animals.

• 15:48Andrew D. Huberman?

  We had a guest on this podcast, who I'm sure you're familiar with, Charles Zucker.

• 15:51Speaker 01

  Yeah.

• 15:51Andrew D. Huberman?

  A professor at Columbia, has done incredible work in vision and olfaction and thirst sensing. And I talked a little bit about this, that there's something in the breath of romantic partners that's hopefully appetitive, not aversive, as well as in children, he was talking about the smell of his grandchild's, the nape of their, the back of their neck, and how he misses that smell, because when he thinks about missing his grandchild or children, it's that smell that's associated with that feeling.

• 16:22Speaker 01

  Hexadecanol.

• 16:23Andrew D. Huberman?

  Hexadecanol?

• 16:24Speaker 01

  Yes. This is a study ran by Eva Mishor, who was a graduate student in our lab. Eva was interested in aggression. And so when she started off, we said, okay, let's do chemosignaling of aggression. She actually was going to like MMA clubs and collecting body odors. And we had all sorts of ideas going, and she worked on that for quite a bit. It never went anywhere, really. At the same time, Heinz Breier, he was studying in his lab, a molecule, hexadecanol, that was a chemosignal in mice that promotes social buffering. So when lots of mice are together, they feel good about being in a

• 17:04Speaker 01

  group, and that's social buffering. And it's promoted by hexadecanol, which they emit in their feces. So Breier and his colleague Stortman, they discovered the receptor for this. And then they went and discovered that the receptor is very highly conserved throughout mammalian evolution. And therefore, they hypothesized that maybe this is a universal mammalian signal. Now, which is unusual, because in chemosignaling, typically, you tend to think of things as being very species-specific. So he approached us and said, look, you've got to study this stuff in humans, right? Because he knows us as the human people, right? I mean, we go to these olfaction conferences where lots of people study mice

• 17:45Speaker 01

  and zebrafish and whatnot, and we're the human group. And eventually, he just FedExed us, hexadecanol. And Eva was not going anywhere with her aggression studies with sweat from human participants. And yet, she built the entire paradigm to study human aggression. So they're standard paradigms. This is a paradigm known as the TAP, the Tyler aggression paradigm. And what's nice about this is that then allows you to quantify aggression. And so you have a measure of aggression. Again, the Tyler aggression paradigm, obviously invented by Tyler, very well-validated, studied all over, you know, a very standard

• 18:24Speaker 01

  protocol. So we brought in participants and had them play the Tyler, the TAP, either under exposure to hexadecanol or control. And I'll first tell you the result with men, which is that hexadecanol consistently reduced aggression. People were less aggressive under hexadecanol. The effect size was quite meaningful compared to the effects seen in the aggression world in research, really, really strong effects, so unusually strong. So hexadecanol lowered aggression in men, and we were like, cool, this is, you know, sort of what we were hoping to see, consistent with the hypothesis, and consistent with

• 19:06Speaker 01

  what it seems to do in mice. But then we looked at the data from women, and hexadecanol increased aggression equally significantly.

• 19:14Andrew D. Huberman?

  Is this thought to be something related to maternal protectiveness?

• 19:17Speaker 01

  We're getting there. So she went and did the entire experiment again, and this time, she did it within the fMRI magnet, so that we can also track brain activity while this was happening. And first of all, it replicated again. So once again, hexadecanol made men less aggressive and women more aggressive. And yet, I was telling Eva, you know, but, you know, this makes no sense to me. And then her insight, which of course afterwards is like, duh, is, no, there's a place where this makes perfect sense. And that is if you're a mammalian offspring. Because paternal aggression is often directed at you. There's infanticide all over, and sadly, there's male aggression towards human children as

• 20:01Speaker 01

  well. And maternal aggression is often protective. So if you're an offspring, if you have a molecule that will make your mother more aggressive and your daddy less aggressive, both of those are good for you. So you're winning. So the bottom line of all this is that hexadecanol is the most abundant semivolatil in baby hits. It's tons of it coming out of baby hits. Babies are conducting chemical warfare, right? They're reducing aggression in their fathers or males around them, and increasing aggression in their mothers or females around them. And both of those things are good for them.

• 20:38Andrew D. Huberman?

  I'd like to take a quick break and acknowledge our sponsor, AG1. I'm excited to share that AG1 has just launched their newest formulation, AG1 Pro. AG1 Pro takes the clinically-backed AG1 formula, which is a blend of vitamins, minerals, probiotics, and adaptogens, and adds three important new ingredients: creatine monohydrate, calcium HMB, and zinc carnecine. Each serving has five grams of creatine monohydrate to support muscle strength and performance, as well as brain health; calcium HMB to support muscle recovery and reduce muscle breakdown; and zinc carnecine to support and improve the lining of your gut. All three of these ingredients have compelling science to support them, and therefore, I love seeing them added to the existing AG1 formula.

• 21:19Andrew D. Huberman?

  As most of you know, I've been taking AG1 every day for nearly 14 years now. I started taking it long before I even knew what a podcast was. It's a great product, and it's now made even better with the new AG1 Pro formula. If you would like to try AG1 Pro, you can go to drinkag1.com/huberman to get a special offer. AG1 is giving away a free bottle of omega-3 coenzyme Q10 with your first subscription. Again, go to drinkag1.com/huberman to get a free bottle of omega-3 coenzyme Q10 with your first AG1 subscription. What is the relationship between odors and hormones, and in particular, crying?

• 21:58Speaker 01

  Tears are bodily liquid, emotional tears, that we emit in emotional situations where these are situations where nonverbal communication is critical and key. The most influential text, I think, till this day in emotion research is Darwin's book, The Showing of the Emotions in Man and Animals, I think is the full name of the book. And an entire chapter, chapter six, is devoted to tears. So Darwin systematically went through the expressions of emotions, and for each one, went to their functional antecedent and explained everything very nicely. And then he got stuck with tears, right? Because tears are an obviously emotional expression, and he could not find a functional antecedent.

• 22:43Speaker 01

  So he ended up saying, this is an epic phenomenon. So we thought, well, maybe the function is a chemical signal. So with that in mind, we harvested emotional tears. So we collected tears, and we exposed participants to these tears. First of all, the tears are completely odorless. You cannot detect them at all, completely odorless. And yet, when you sniff them, you have a pronounced reduction in testosterone within about 20 minutes, half an hour.

• 23:18Andrew D. Huberman?

  This is men and women smelling women's tears?

• 23:20Speaker 01

  Men.

• 23:21Andrew D. Huberman?

  Men smelling women's tears, but not perceiving any odor?

• 23:24Speaker 01

  Nothing, just sniffing them. And you have about 14% drop in free testosterone. And people who studied testosterone, which is not me, but they tell me this is a really strong effect. Like, it's hard to even pharmacologically get an effect like that that fast. I mean, no in pharmacology.

• 23:43Andrew D. Huberman?

  Yeah, years ago, I spent time studying endocrine effects of this sort, and that's a tremendous, resized effect.

• 23:49Speaker 01

  And so here, I'll point out in passing that one of the concerns we had because of the effort to run this study is that nobody would ever try to replicate it. And to our joy, about two years later, an independent group from South Korea, Ohit Al, who I don't know at all, replicated the testosterone effect to a T. I mean, like, same numbers. So it lowers testosterone. And we then also looked, using MR, at the effect on brain activity, and saw pronounced

• 24:32Speaker 01

  effect on activity, a dampening, a lowering of activity under an arousing state, a lowering of activity both in the hypothalamus and in the fusiform gyrus, for whatever reason, I don't know.

• 24:47Andrew D. Huberman?

  Face recognition area.

• 24:48Speaker 01

  Amongst other things, yes. And we don't know why, but pronounced. So usually in our chemosignaling work, we look at what happens in rodents, and we see if the same thing is happening in humans. This was a rare case where, after we did this work, more or less identical effects were discovered in rodents. So a paper published in Nature two years later found that mouse tears, mouse pup tears, lower aggression in male adult mice towards them.

• 25:16Andrew D. Huberman?

  In a smell-dependent way?

• 25:18Speaker 01

  Yeah, yeah. And they also actually found the actual component in tears that, so the tear pheromone, that lowers aggression, right? So, you know, this has us thinking of tears as, you can think of tears as like a chemical blanket, in a way, that you're covering yourself up again with, you know, to protect against aggression, right?

• 25:37Andrew D. Huberman?

  Smell being such a rich source of behavioral and hormonal and other sorts of deep, deep information, what is your experience with generating smells in silicone in computers? And here, folks, for those of you that aren't catching on to this, and I don't expect that everyone would, because what we're really alluding to here is the idea that you'll look at, you'll put into a search engine, "blueberry pancakes recipe," and that not only will you get photos of those blueberry pancakes and a recipe, but you will get the, hopefully, validated odor of those pancakes and that recipe coming at you in real time through the computer.

• 26:20Speaker 01

  So, Google had an April Fool's spoof.

• 26:23Andrew D. Huberman?

  Oh, right.

• 26:24Speaker 01

  And they put out this video of Google smell, okay? And it had all these, like, classic, like, sales images of, you know, holding up your phone to a rose, and it generating rose, and all these things, right? So Google is now trying to do that, you know, to digitize smell. And there are other companies that are trying to do this as well. And recently, in our lab, we've had, and I hope this doesn't come across as overly arrogant, but we've had a sort of mini-breakthrough on this front.

• 26:56Andrew D. Huberman?

  To call something a mini-breakthrough is far from arrogant.

• 26:59Speaker 01

  And this is a paper led by Arun Raviya from our lab, and Kobe Snitz, also a major contributor there, a paper published in Nature. And in this paper, we develop an algorithmic framework where we can predict the perceptual similarity of any two molecular mixtures with very, very high accuracy. So if you give me two molecular mixtures, I can predict how similar you will smell them to be, okay? Not only could we predict that, but we could design it, so we can generate mixtures with no insimilarities.

• 27:40Speaker 01

  The result was highlighted, and you'll appreciate this coming from Vision, is that using our algorithmic solution, we generated olfactory metameres. So we measured mixtures completely not overlapping in their molecular structure, but they smell exactly the same, okay? Now, if you would come to a classic perfumer, or most classic perfumers, and tell them that you can generate two mixtures with zero molecules in common, but smell exactly the same, they would tell you, no. And yet, we did, and anybody can recreate them. This is simple, actually. And in the paper, we do a few things, like, we generate a metamere for Chanel number five, with no component from Chanel number five in it.

• 28:25Andrew D. Huberman?

  I'd like to take a quick break and acknowledge our sponsor, Eight Sleep. Eight Sleep makes smart mattress covers with cooling, heating, and sleep-tracking capacity. Eight Sleep just launched the Pod 6, which is their most advanced sleep system. The Pod 6 is half the size of their previous models. It's 20% faster with its cooling and heating, and it has nine times as many sensors for tracking your sleep. The reason why Eight Sleep is so effective at improving your sleep quality and duration is because it helps control your core body temperature. And the reason for that is that in order to fall and stay deeply asleep, your core body temperature has to drop by about 1 to 3 degrees. And to wake up feeling completely refreshed and energized, you actually want your body temperature to be increasing in the final hours of your sleep.

• 29:09Andrew D. Huberman?

  Eight Sleep automatically regulates the temperature of your bed throughout the night, and is monitoring your sleep and dynamically adjusting the temperature of your sleep environment, so you get the maximum amount of deep sleep and rapid eye movement sleep. I've been sleeping on an Eight Sleep mattress cover for nearly five years now, and with each new iteration of Eight Sleep, it gets better and better at figuring out what my body needs in order to get the best possible night's sleep. If you would like to try Eight Sleep, go to eightsleep.com/huberman to get up to $200 off their new Pod 6. Eight Sleep ships to many countries worldwide, including Mexico and the UAE. Again, that's eightsleep.com/huberman to save up to $200.

• 29:48Speaker 01

  In a way, we've generated the infrastructure for digitizing smell, because, again, what our algorithm predicts, our framework predicts is similarity. But in a way, that's enough for you. Why is that enough? We have a map of 4,000 molecules. For each one, we know their perceived smell. Now you can make up any mixture you want for me. I can project it into that map and measure its pairwise distance from all the points in the map. If it falls on lemon, then what you generated smells like lemon. And if it falls, you know, on tomato, then what you generated smells like tomato. So we now solve that problem. We can predict the odor of any molecular mixture.

• 30:33Speaker 01

  We can say how it's going to smell. What we can do is then find a set of components, which we call odor primaries, that can be used to mix any odor that you can perceive. And that's what we're working on now. So this is in collaboration with a lab of Jonathan Williams and Max Planck in Munich. Jonathan Williams is an atmospheric chemist, but he's really good at using GCMS, these tools that measure molecules. So Jonathan Williams measured odorants in Germany, transmitted the information to us over IP. We fed that into our algorithmic framework and recreated it from a device that mixes primaries.

• 31:16Speaker 01

  And we tried to do four different odorants in our proof of concept test. One of them was rose, and we failed at recreating rose. We in fact recreated something that had a percep, but most people perceived it as bubble gum. The second one we tried to do was anise, and we failed at recreating anise. And most people said it was cherry, which is not very far, but it failed. The third was gasoline, and we were slightly but significantly better than chance at recreating gasoline. And the fourth was violets, and 15 of 16 people said violets. So the first odor ever transmitted over IP is violets.

• 32:00Speaker 01

  You know, don't hold your breath for this to be on your table tomorrow. You know, all we have in hand is this very initial proof of concept, but we're on the path. We're talking now of trying to achieve the olfactory equivalent of circa 1956 black and white TV. Okay, basically, right? I mean, you know, I'm not dreaming, let's say, of being able to transmit to you the difference between a Cabernet or Armerol, right? But if I can generate something that's vaguely wine, that will be an amazing success from my perspective, right? But jump ahead in your imagination to 4K odor transmission, then medical diagnostics is what you want to be talking about.

• 32:43Speaker 01

  Because this is over extension, but you can almost say that every disease will have an odor. I mean, every disease is a specific metabolic process. Metabolic processes have metabolites, metabolites have a smell, olfaction, once it's digitized, and high resolution, which again, in our hands, it's not going to be. I mean, we're talking, you know, in my retirement, maybe I'll read about this one day if I'll still have vision. I mean, this is not close. But when olfaction digitization is brought to the equivalent of 4K vision and audition that you have now, then it will be in medical diagnosis.

• 33:24Speaker 01

  Excuse me for the imagery, but you will have an electronic nose in your bathroom. Each one of us will have in the toilet, and it will be doing diagnostics all the time. And that's where it's going to go. But again, not anywhere in the very close future.

• 33:43Andrew D. Huberman?

  Noam, I want to say thank you for your time today. First of all, this was a tremendously interesting conversation. And we touched on so many things, hormones, smells, the architecture of the olfactory system. I know that people listening to this are realizing, but I'm going to say it anyway. What an incredible gift you've given us.

• 34:03Speaker 01

  Thank you.

• 34:04Andrew D. Huberman?

  As a expert in this field, giving us this tour of the work that you and others, who you credit so generously, have done, and the spirit that you bring to it. Whatever drives that spirit, as the great, late Ben Baris used to say, keep going, because we are all benefiting tremendously. And I also just want to say that, you know, for people listening to this, the spirit of science is one of, as you mentioned, there's complex politics and all these things. But it's absolutely clear that you delight in the work you do. And so I delight in it. I'm grateful for it. I'm grateful for your time today. And so on behalf of me and many, many people listening to this, I just want to extend a huge debt of gratitude. Thank you so much.

• 34:48Speaker 01

  Thank you so much for very warm words.