Speaker 1: All right, So I have a follow up question there.
Speaker 1: First of all, am I correct in interpreting your answer
Speaker 1: is saying that bitter tastes are learned tastes and therefore
Speaker 1: more sophisticated, And therefore we have scientific evidence that dark
Speaker 1: chocolate is better than white chocolate, for example.
Speaker 2: That may be a stretch.
Speaker 1: I'm taking that as a yes, and we're moving on.
Speaker 2: Hi.
Speaker 1: I'm Daniel. I'm a particle physicist. And I remember the
Speaker 1: first time I smelled California. Hi.
Speaker 3: I'm Kelly wider Smith. I'm a parasitologist. And I remember
Speaker 3: the first time I felt the wind on my feet
Speaker 3: as I put on my sandals when I got to
Speaker 3: California for my PhD interview, And I remember thinking, I'm
Speaker 3: never going to leave here because it was snowy and
Speaker 3: cold and miserable in Ohio, and I just loved that
Speaker 3: I could wear my chockos. But I did end up leaving.
Speaker 3: But I don't remember the smell. What was the smell
Speaker 3: of California?
Speaker 1: And now I'm worried the smell is wind from other
Speaker 1: people's feet.
Speaker 3: Well, that doesn't sound very nice, and I wonder so
Speaker 3: many people are leaving California No.
Speaker 1: I used to visit my grandfather in Los Angeles when
Speaker 1: I was a kid, and I remember walking out of
Speaker 1: the airplane into Los Angeles and smelling it, and in
Speaker 1: my memory it's got sort of floral notes to it
Speaker 1: and a little bit of sea salt or a little
Speaker 1: bit of something from the ocean, because I learned in
Speaker 1: this interview you can't actually smell salt, but there's definitely
Speaker 1: something about California. And when I returned later to interview
Speaker 1: for a job, I remember getting off the airplane, this
Speaker 1: time in Orange County and having that same scent memory
Speaker 1: transporting me back to my childhood in those summers in
Speaker 1: Los Angeles and being like, hey, this could be a
Speaker 1: place I live. I like it here.
Speaker 3: Yeah, I remember when we lived in Santa Barbara. I
Speaker 3: did love the smell of Santa Barbara. But I think
Speaker 3: that's mostly the smell of the ocean.
Speaker 1: And what is the smell of the ocean. What are
Speaker 1: we smelling in the ocean? Is it fish? Is at
Speaker 1: al g Is it fish poop? What's going on there?
Speaker 3: It's probably algae dia. Tom's Yeah, I don't know. Maybe
Speaker 3: I don't want to know. Maybe I enjoy it more
Speaker 3: not knowing what is your favorite scent?
Speaker 1: My favorite sent that's a great question. I'm not sure
Speaker 1: what my favorite is. But up there is the smell
Speaker 1: of onions and garlic in olive oil. You know, when
Speaker 1: you start cooking something delicious and that smell hits you,
Speaker 1: I'm like, hmm. Sometimes I feel like they should make
Speaker 1: up perfume, you know, because if I want on a
Speaker 1: date with a lady and she smelled like onions and
Speaker 1: garlic and olive oil, I'd be like.
Speaker 3: Ye, marry in a very wholesome way, right right, right,
Speaker 3: here's the ring. Yeah, that is a good smell. That
Speaker 3: always laughs because whenever he cooks I come in and go, oh,
Speaker 3: it smells great. He's like, every time you say it
Speaker 3: smells great, it's the same thing. And I'm like, well,
Speaker 3: I'm consistent. It just still smells great. I love it.
Speaker 1: There you go, And so what are your favorite smells?
Speaker 3: Kelly love the smell right after a rain, and I
Speaker 3: think that has something to do with bacteria and some
Speaker 3: other stuff. I don't need to know. It just smells great.
Speaker 3: And then I'd love the smell of rosemary. One of
Speaker 3: the things that I loved about the place that I
Speaker 3: lived in Davis, California. Is that there was a rosemary
Speaker 3: bush and every day before i'd go to school, I'd
Speaker 3: pull a bit off and snap it and smell it
Speaker 3: before I went out. And then lavender and eucalyptus. Those
Speaker 3: are very relaxing smells for me.
Speaker 1: We have a whole hillside that's been colonized by a
Speaker 1: rosemary bush, and when the sun hits it in the afternoon,
Speaker 1: that wafts over. It's like overpoweringly amazing.
Speaker 3: Oh, that's fantastic. Life is really good.
Speaker 1: Sometimes life smells amazing.
Speaker 3: Sometimes it does. It didn't in grad school when I
Speaker 3: was jumping into dump trucks full of dead fish. But
Speaker 3: there have been plenty of good smelling parts of my
Speaker 3: life and I'm in one of them now, which is great.
Speaker 1: I'm very glad your life doesn't stink.
Speaker 3: Thanks. Yeah, I'm glad your life doesn't stink either.
Speaker 2: Yeah.
Speaker 3: So on today's show, we have my friend Steve Munger.
Speaker 3: He is an expert on smell and taste, and I
Speaker 3: have asked him all sorts of stupid questions in the
Speaker 3: like five plus years that I've known him, and I
Speaker 3: am super excited to do that again today. So let's
Speaker 3: go ahead and bring Steve on the show. Today's show
Speaker 3: we have doctor Stephen Munger. He's professor and co director
Speaker 3: of the Center for Smell and Taste Disorders at the
Speaker 3: University of Virginia. Welcome to the show.
Speaker 2: Thanks so much, really join the invitation.
Speaker 3: I'm excited that I get the chance to chat with
Speaker 3: you again. We've interacted a couple times about all sorts
Speaker 3: of weird smell and taste topics, and I'm excited to
Speaker 3: bring to our listeners your sort of weird knowledge on
Speaker 3: smell and taste, weird and wonderful.
Speaker 2: Thanks. Yeah, it was one of those instances back in
Speaker 2: the day when Twitter was a lot more about finding
Speaker 2: each other and getting interesting information. So it's a good result.
Speaker 3: Yeah, yes, yes, Back when I used Twitter, we met Steve.
Speaker 3: I had a question for him for our book soonish
Speaker 3: and we've been in touch since.
Speaker 1: So, Steve, You've got to ask do your family and
Speaker 1: your kids describe your work as a professor of everything
Speaker 1: stinky and delicious?
Speaker 2: No, No, they don't, or at least they haven't until
Speaker 2: this point.
Speaker 3: But I always love getting the chance to ask you
Speaker 3: about smell and taste stuff. And let's start with sort
Speaker 3: of a very basic question, how well do we understand
Speaker 3: smell and taste? Like, do we understand it microscopically?
Speaker 2: We do, I would say we're still a bit behind
Speaker 2: vision and hearing as far as our understanding of a
Speaker 2: lot of the basic biology of it. But it's come
Speaker 2: a long way, especially in the last thirty years. We
Speaker 2: know what sells in the nose, which sells in the tongue,
Speaker 2: detect odors and taste. We have a good sense of
Speaker 2: everything from the protein receptors on their surfaces to the
Speaker 2: way they connect to the brain and start to organize signals,
Speaker 2: so that we can actually make sense of our detection
Speaker 2: of all those chemicals that are in our food or
Speaker 2: in our environment. But it's still a lot left to
Speaker 2: be worked out, particularly in the way that one distinguishes
Speaker 2: different types of odors or tastes, or conversely puts them together,
Speaker 2: because of course, you don't really encounter single odor molecules,
Speaker 2: which we call odorant or single taste molecules, except yeah,
Speaker 2: vicetherian cotton candy, you're getting pretty much pure sugar, But
Speaker 2: usually you're encountering them as mixtures. A flower has hundreds
Speaker 2: of different compounds that you're smelling at the time foods
Speaker 2: have tastes and odors that your brain is trying to
Speaker 2: put those signals together. So how we pull apart the
Speaker 2: different components and then put them back together so our
Speaker 2: brain can make sense of them and we can then
Speaker 2: react in an appropriate way. There's still a lot of
Speaker 2: questions in those areas.
Speaker 1: And so for vision, we have something of a cartoon understanding,
Speaker 1: at least I do of how this works. You know,
Speaker 1: photons hit these proteins in your eye, they get absorbed,
Speaker 1: they flip some switch, they send a signal of your
Speaker 1: optic nerve. Your brain gives you an experience of a color.
Speaker 1: Do we have an analogous picture for smell and taste?
Speaker 1: Can you walk us through microscopically what happens from when
Speaker 1: that cotton candy molecule hits your nose or your tongue.
Speaker 1: What's going on?
Speaker 2: Of course, it depends a little bit on whether you're
Speaker 2: talking about vertebrates or in vertebrates. There are amazing amounts
Speaker 2: of similarities in the organization, but a lot of the
Speaker 2: molecular players are quite different.
Speaker 1: Do invertebrates like cotton candy.
Speaker 2: Most insects and others like sugars are attracted to at
Speaker 2: least certain types of sugars, and they will avoid compounds
Speaker 2: that we perceive of is bitter. But how they do
Speaker 2: that can be a little bit varied. If we think
Speaker 2: of smell, what we're working with are millions of cells
Speaker 2: in our case and sort of the roof of the
Speaker 2: nasal cavity. These are neurons nerve cells that have one
Speaker 2: end projecting out into the environment, basically within a mucous
Speaker 2: layer within your nasal cavity. So when you sniff something
Speaker 2: or when odors come back from your throat while you're
Speaker 2: eating and get up into that nasal cavity, they bind
Speaker 2: with receptor molecules that fit into the family known as
Speaker 2: G protein coupled receptors. So these are ones that recognize
Speaker 2: the odor molecule and then initiate a biochemical cascade within
Speaker 2: the cell that changes the electrical activity of that sell.
Speaker 2: Those nerve cells then send messages back through the skull
Speaker 2: to the brain where they interact with nerve cells of
Speaker 2: the brain and create this process.
Speaker 1: So folks like me who are not adept to chemistry,
Speaker 1: I want to understand what you mean when you say
Speaker 1: recognize those molecules, Like I'm imagining some molecules sticking up
Speaker 1: above the mucus and another molecule comes along, and if
Speaker 1: they have the right sort of shape and electrons in
Speaker 1: the right places, they can bind together. Is that what's happening,
Speaker 1: Like they're interacting chemically.
Speaker 2: Exactly, So we'd call it docking or binding, where the
Speaker 2: odor molecule actually fits within a pocket that is formed
Speaker 2: by the protein strands of the receptor and causes a
Speaker 2: conformational change. The receptor protein changes its shape, which allows
Speaker 2: it basically to flip a switch inside the cell, so
Speaker 2: it's working across the membrane to initiate this cascade. And
Speaker 2: then one interesting thing about how we perceive ots, there's
Speaker 2: not a particular receptor just for this molecule and just
Speaker 2: for that molecule. In humans, we have about four hundred
Speaker 2: of these receptors. In rodents could be one thousand, fifteen hundred,
Speaker 2: depending on the species. But even with those numbers, you
Speaker 2: can imagine that would be a pretty limited repertoire of
Speaker 2: chemicals you could detect if it was really that one
Speaker 2: to one thing. What it turns out to be is
Speaker 2: that each receptor generally can recognize a number of different molecules.
Speaker 2: Oftentimes they may even be chemically distinct in their structure,
Speaker 2: and each individual odorant molecule can bind two multiple receptors,
Speaker 2: and so what you're getting is really a pattern of activation.
Speaker 2: The molecule A may turn on receptors one, five, and six,
Speaker 2: molecule B may turn on receptors three, five, and six,
Speaker 2: and that, because of the way those receptors and cells
Speaker 2: that express them are connected to the brain, gives you
Speaker 2: different patterns of activation that you then learn to associate
Speaker 2: with molecule A or molecule B.
Speaker 1: So let me see if I'm understanding The picture I
Speaker 1: was imagining before was something sort of like a lock
Speaker 1: and key mechanism, where you know, the dog poop molecule
Speaker 1: floats up and connects with something in my nose and
Speaker 1: is able to connect in and activate that and as
Speaker 1: you say, actually change the shape of that which triggers
Speaker 1: some signal down the brain. But now you're telling me that, like,
Speaker 1: there are lots of different keys that can turn that lock,
Speaker 1: and that one key also can turn multiple locks, so
Speaker 1: that everything in our environment can turn on several signals,
Speaker 1: and that each signal can actually be turned on by
Speaker 1: several different kinds of things. So dog poop and cat
Speaker 1: poop might turn on the same signal, but they also
Speaker 1: might turn on a different combination of signals.
Speaker 2: Absolutely, you got it.
Speaker 3: Yeah, So you know when I look around my room,
Speaker 3: there's lots of different wavelengths, lots of different colors hitting
Speaker 3: my eye. Is smell more complicated vision? And does the
Speaker 3: brain process it in different ways?
Speaker 2: I don't know if i'd say it's more complicated, but
Speaker 2: it is a little different, particularly because there's a bit
Speaker 2: of a learning aspect. You're not born knowing what the
Speaker 2: utterance of pizza is. You smell the pizza and your
Speaker 2: brain certain number of receptors are activated by those odor
Speaker 2: molecules that come from the pizza your sniffing, and you
Speaker 2: learn that that pattern of activity means pizza, while another
Speaker 2: one that may have some but not all of the
Speaker 2: molecules in common means rotting fish. And you know what
Speaker 2: to do with the mind because there can be.
Speaker 1: Overlaps, especially if you're a baby in Iceland and they
Speaker 1: like rotting fish pizza.
Speaker 3: Right, My PhD involves a lot of rotting fish.
Speaker 2: Yeah, just in Iceland. This summer for our conference, which
Speaker 2: is fout, I did not eat in any of the
Speaker 2: rotting fish there though.
Speaker 1: Beautiful country, the beautiful country, wonderful people.
Speaker 2: Yes, oh it's stunning, stunning.
Speaker 1: So, Steve, you know that there's a common philosophy question
Speaker 1: which is also a staple in dorm rooms at three am,
Speaker 1: which is like, when I see red, do you see
Speaker 1: the same red? How do we know? And what you
Speaker 1: just said suggests a similar question about pizza, like when
Speaker 1: I'm smelling pizza, is somebody else experiencing the same thing?
Speaker 1: And my understanding is that the qualitya of seeing red,
Speaker 1: or the quality of experiencing that signal from your nose
Speaker 1: is something we don't have a great philosophical handle on.
Speaker 1: We don't know how to compare. We can't experience somebody
Speaker 1: else's internal subjective experience. Is there an equivalent question for smell?
Speaker 1: You know? Is there this sort of marry in the
Speaker 1: red room philosophical study about smell and taste?
Speaker 2: I think from a practical point of view, you can say, indeed,
Speaker 2: people have different perceptions of the same odor mixture, and
Speaker 2: one of the classic ones is slantro. Some of you
Speaker 2: might really like slantro and like sort of that green grassiness,
Speaker 2: of a brightness of it that it can add to foods,
Speaker 2: and others may hit it and say nope, that's soapy.
Speaker 2: That ends up being less likely a genetic difference in
Speaker 2: one particular odent receptor that seems to be changed in
Speaker 2: its responsiveness to those soapy odor components. Those people who
Speaker 2: get the grassiness as the primary b versus get the
Speaker 2: soapiness is the primary odor component, are differing in the
Speaker 2: ability of their odor receptors in their nose to respond
Speaker 2: to that array of chemicals. So the chemicals are the same,
Speaker 2: but the way someone's perceiving it, and of course the
Speaker 2: way that impacts their interest in ingesting that changes quite
Speaker 2: a bit. They're also what we hit a variety of
Speaker 2: other genetic variants we call specific anosmias, and these are
Speaker 2: ones where you may have a mutated odent receptor that
Speaker 2: is the primary receptor for particular compound and you just
Speaker 2: can't smell it and someone else can't. So endosternone, which
Speaker 2: is a pig pheromone from male pigs, but there are
Speaker 2: related chemicals in it they're using cleaning products and other things,
Speaker 2: is a classic of that. There are a lot of people,
Speaker 2: myself included. You can put a big vat in front
Speaker 2: of my nose. I have no ideas there, and there
Speaker 2: are other people like my wife who get even remotely
Speaker 2: close to it, and you know, oh my god, that's awful.
Speaker 2: And there are those types of genetic differences. We did
Speaker 2: a thing with a bunch of winemakers recently and spiked
Speaker 2: identical wines, one unspiked one with another compound called rotundo in,
Speaker 2: which is a black peppery odorant, and there were maybe
Speaker 2: twenty percent of the people in that room that could
Speaker 2: not actually tell the differences between the wine, even though
Speaker 2: in that case I could, and it was quite pronounced pepperiness.
Speaker 2: From that respect, there are differences now that is a
Speaker 2: little different than what you brought up with the are
Speaker 2: we seeing the same red wavelength getting the same perception
Speaker 2: of what red is? Although if I recall, there is
Speaker 2: a fairly common mutation in the green cone option that
Speaker 2: actually shifts the wavelength response a little bit in that
Speaker 2: and so in that case you can imagine two people
Speaker 2: seeing slightly different shades of green. But still I go,
Speaker 2: that's the grass on.
Speaker 1: And so as somebody who is director of a center
Speaker 1: on smell disorders, would you categorize somebody who can't appreciate
Speaker 1: cilantro as having a variant or like an issue, like
Speaker 1: a disorder. I mean, this is something we need to treat.
Speaker 1: All these folks out there are like missing out on
Speaker 1: one of the joys of life.
Speaker 2: Colleague of mind Doron lance At once made the statement,
Speaker 2: no one is norma osmic. We all different. That there
Speaker 2: are four hundred potentially active odent receptor genes in the
Speaker 2: human and all of us probably have one or two
Speaker 2: or maybe more that are mutatd in such a way
Speaker 2: that that changes the way that we respond to the
Speaker 2: molecules that those receptors would normally spawn to. So we're
Speaker 2: all seeing something a little different. And I do think
Speaker 2: that that is distinct from people who have a smell
Speaker 2: or taste loss, or distortions or phantoms that disrupt their
Speaker 2: ability to really more globally interact with food, interact with
Speaker 2: each other, perceive the world around them, or have sort
Speaker 2: of underlying long term off tastes or equal smells or
Speaker 2: other things that their brain is constructing. Those are the
Speaker 2: ones where I put them into the category of disorders,
Speaker 2: as opposed to we have blondes and brunettes and blue
Speaker 2: eyes and brown eyes and that's more of what I've
Speaker 2: put a specific in osmia.
Speaker 3: So you mentioned wine. I enjoy wine, but when I
Speaker 3: read the descriptions on the back, I call both. When
Speaker 3: I read the back, I'm like, what percent of people
Speaker 3: who drink wine can taste all of the notes that
Speaker 3: are listed on the back? Am I in my or
Speaker 3: the majority of not being able to appreciate a complex
Speaker 3: flavor profile.
Speaker 2: I don't know if you are in the minority majority.
Speaker 2: I can't say that. I am certainly is hugely skilled
Speaker 2: as people that do that professionally, But part of it
Speaker 2: is also training. I mean, certainly a summer or winemaker
Speaker 2: or brewmaster or whatever generally going to have a pretty
Speaker 2: functional sense of smell and taste in order to be
Speaker 2: able to get most of the signals that they want
Speaker 2: to be able to perceive. But the ability to sort
Speaker 2: of pull out strawberry and lead pencil and black current
Speaker 2: and whatever others. Part of that is because there's been
Speaker 2: a standardization of the naming of certain odor perceptions. In
Speaker 2: the context of wine, beer has its own beer wheel,
Speaker 2: coffee has its own coffee wheel, so that when someone
Speaker 2: says lead pencil, they are describing pretty close to the
Speaker 2: same odorant molecules present there that someone else is. They're
Speaker 2: trying to make it a common language using more descriptive
Speaker 2: things rather than saying Islam molassatype or whatever other chemical
Speaker 2: name you might want to come up with. The other
Speaker 2: thing that people are really skilled is they practice a lot.
Speaker 2: This is a attention to detail, This is memory, This
Speaker 2: is like learning the language. All those aspects go into
Speaker 2: it too, that allow you to sort of focus on.
Speaker 2: So if you get someone who trains you that, Okay,
Speaker 2: these six ones all have this flavor of characteristic and
Speaker 2: those six ones do not, it becomes a lot easier
Speaker 2: to start to pick them out, and then once you've
Speaker 2: done that, it's easier to recognize it as well. So
Speaker 2: I think it's more practice.
Speaker 3: Than anything I need to switch jobs.
Speaker 1: I think that probably also tells us something about the
Speaker 1: experience of these smells. You know, you're training somebody to
Speaker 1: recognize as certain responses. You're helping distinguish between black paper
Speaker 1: and current and whatever. There must be a lot sort
Speaker 1: of in the neurobiology of smell behind you know, the
Speaker 1: actual chemistry of the receptors as well.
Speaker 2: Yeah, which is an interesting contrast with taste in some ways.
Speaker 2: And that taste is much more innate. You give babies sugar,
Speaker 2: they're going to smack their lips, and if they're old enough,
Speaker 2: they're going to smile and they're going to want to
Speaker 2: eat more. You give them something that's plain bitter compound,
Speaker 2: they're going to scrunch up their face and put their
Speaker 2: tongue out and try to sort of spit it out.
Speaker 2: And they're born with that. I mean, we learn over
Speaker 2: time to give context to that. We learn that in
Speaker 2: some cases bitterness is not definitely poison. If it's our
Speaker 2: French rose coffee or our ipa beer or Belgian and
Speaker 2: dive or whatever it might be. We learn that we
Speaker 2: can appreciate that as part of a complex flavor profile
Speaker 2: in a safe way, but innately bitter being spitted out
Speaker 2: and sweet meaning go ahead and adjust it. There's an
Speaker 2: energy source.
Speaker 3: There, all right. So here we have a question from
Speaker 3: a listener that actually inspired this whole episode. So let's
Speaker 3: go ahead and listen.
Speaker 4: Hi, Daniel and Kelly. I had a question growing up
Speaker 4: and going into the woods. I was always told that
Speaker 4: if you put a plant in your mouth and it's bitter,
Speaker 4: spit it out, because it's likely poisonous as an adult.
Speaker 4: This raises questions in my mind, why are poisonous plants bitter?
Speaker 4: Did humans evolve the taste of bitterness exclusively to the
Speaker 4: tech poisonous plants? But then you got the question of
Speaker 4: coffee is bitter and we all know how that goes
Speaker 4: in the morning, But how bitter is too bitter to
Speaker 4: be poisonous because we know everything in moderation. And then
Speaker 4: there's the did the boy scout leader just tell me
Speaker 4: this because he didn't want to see what all of
Speaker 4: us were trying to put in our mouth because we
Speaker 4: were super kids. But I have this question. I was
Speaker 4: hoping you could help me out and figure out why
Speaker 4: are we able to detect poison as bitterer?
Speaker 2: Thank you very much. We think that the sense of
Speaker 2: bitterness has evolved in order to avoid toxins. That seems
Speaker 2: to be common that compounds that we would perceive of
Speaker 2: as bitder are also aversive to a lot of other animals,
Speaker 2: even if they're not using the same protein molecules to
Speaker 2: detect them that mammals are. So that's very common. But
Speaker 2: obviously we can learn in context that bitterness may also
Speaker 2: be something that can be attractive if it's put together
Speaker 2: with other things that we like. Coffee is a good example.
Speaker 2: There are a lot of compounds in coffee, including caffeine,
Speaker 2: that on their own are bitter and you would not
Speaker 2: like them. No one would like them. Put in the
Speaker 2: kind of coffee, not only do you have the appealing
Speaker 2: aroma of coffee, the pharmacologic buzz of the caffeine. The
Speaker 2: fact that you enjoy going to the coffee shop with
Speaker 2: your friends is a part of a ritual every morning.
Speaker 2: The fact that you don't see a bunch of dead
Speaker 2: people laying around that coffee shops they've just been poisoned.
Speaker 2: All these things give you context that tells you that
Speaker 2: in that particular situation, the bitterness is positive and a
Speaker 2: lot of people learn to like better. I like darker
Speaker 2: roasted coffees and I like highly hopped beers. That it's
Speaker 2: appealing to me. But if I took those compounds in
Speaker 2: and of themselves, out of that context, I wouldn't. So
Speaker 2: that's definitely the case. It's interesting that both for the
Speaker 2: receptors that respond to sweet and umami or savory tastes
Speaker 2: amino acid tastes as well as to bitter tasting compounds
Speaker 2: They're not restricted to the taste cells of the mouth,
Speaker 2: the ones that actually lead to taste receptions. They're found
Speaker 2: all over the body. Bitter receptors are in the gut,
Speaker 2: they're in the heart, they are in the thyroid gland.
Speaker 2: And there's a lot of question if are these proteins
Speaker 2: potentially responding to ingested toxins and then allowing for some
Speaker 2: sort of physiological protective response if you start to build
Speaker 2: up too much, or could they be just repurposed in
Speaker 2: a way that allows the same protein to respond to
Speaker 2: indigenous signaling molecules within the body and also be used
Speaker 2: when it's connected up to the taste system, to be
Speaker 2: used for detecting bitter tastes.
Speaker 1: All right, follow up questions there. First of all, am
Speaker 1: I correct in interpreting your answer is saying that bitter
Speaker 1: tastes are learned taste and therefore more sophisticated, and therefore
Speaker 1: we have scientific evidence that dark chocolate is better than
Speaker 1: white chocolate for example.
Speaker 2: That may be a stretch.
Speaker 1: I'm taking that as a yes, and we're moving on.
Speaker 1: My real question is a comment on the idea of
Speaker 1: having smell receptors in the gut and in the heart.
Speaker 1: And other places in your body as it relates to
Speaker 1: the experience of smell. Is there a possibility that we
Speaker 1: are experiencing those flavors in our gut or in other
Speaker 1: parts of our body and it's contributing to our experience.
Speaker 1: Are we tasting inside our body?
Speaker 2: That's a very common question. The answer is quite conclusively no.
Speaker 1: Oh man.
Speaker 2: So I'll give you example. So the sweet taste receptor,
Speaker 2: this is a protein. It's actually a protein complex called
Speaker 2: T one R two T one R three two members
Speaker 2: the type one taste receptor family. These in the mouth.
Speaker 2: They are responding not only to sugars, but to anything
Speaker 2: that you perceive of as sweet. It actually activates this
Speaker 2: protein complex. It has lots of different binding sides differently,
Speaker 2: so synthetic sweeteners like aspertain so the blue packet saccharin,
Speaker 2: the pink packet, sucrolos, the yellow one proteins that are
Speaker 2: found in a number of tropical berries and fruits that
Speaker 2: are highly potent, thousands of times more potent than sugar. Lead.
Speaker 2: One reason the kids eat lead paint is lead acetate
Speaker 2: taste sweet, and that activates that same receptor. So all
Speaker 2: of those compounds are giving you a perception of sweetness
Speaker 2: because they turn on that receptor. That same receptor is
Speaker 2: in your gut and specifically in a population of cells
Speaker 2: called ntraantigrin l cells that are involved in glucose responses,
Speaker 2: allowing your metabolic systems to respond to the ingestion of
Speaker 2: the sugar load. So let's go back to cotton candy.
Speaker 2: You eat that cotton candy, the sugar goes through your
Speaker 2: digestive system down into your small intestine. Those glucose molecules
Speaker 2: now interact with the sweet taste receptor, the sitting inside
Speaker 2: surface of your intestine. That triggers a response that elicits,
Speaker 2: amongst other things, a peptide hormone called glp one glucagun
Speaker 2: like peptide one, which probably everybody now knows about because
Speaker 2: of ozembic and govi, which is basically mimics of that peptide,
Speaker 2: and that pep pi can then act on the brain,
Speaker 2: It can act on the pancreas to adjust the insulin
Speaker 2: release and satiety and things like that. So the receptor
Speaker 2: is mediating that physiological response in the gut, it's mediating
Speaker 2: the detection of taste in the mouth. But why is
Speaker 2: it not giving you taste in the gut. It's because
Speaker 2: the nerves that connect that part of the gut to
Speaker 2: the brain go to a different area than the nerves
Speaker 2: that connect the part of the tongue. So how you
Speaker 2: are detecting it is the same. It's the same lock
Speaker 2: in those two different places, but the doors that they
Speaker 2: are in are very different.
Speaker 3: So Daniel and I will asking you questions have been
Speaker 3: alternating between saying smell and taste, and we haven't been consistent,
Speaker 3: But those are different. How does our body respond to
Speaker 3: smell and taste differently? Or is it okay that we're
Speaker 3: being sort of loose with those terms.
Speaker 2: No, I think it's something we do want to distinguish,
Speaker 2: and maybe it's good to briefly define them explicitly. So
Speaker 2: smell is going to be at least in humans. The
Speaker 2: detection of volatile chemicals, whether coming through the nares of
Speaker 2: your nose the front, or as you sniff, that would
Speaker 2: be called that orthonasal faction, or as you're chewing food
Speaker 2: or drinking drink. Otor molecules that volatize can come up
Speaker 2: back through your throat and enter your nasal cavity. That way,
Speaker 2: we call that retro nasal olfaction.
Speaker 3: From the back, and volatile just means it goes into.
Speaker 2: The air, and volatile just means it is light enough
Speaker 2: to go in the air. Okay, the receptors are all
Speaker 2: in the nose. In lower primitive mammals, you're going to
Speaker 2: have also another variant called the vomer and nasal organ.
Speaker 2: This is part of the accessoril factory system that can
Speaker 2: not only respond to some volatile chemicals, but also peptides
Speaker 2: can serve as olfactory stimuli.
Speaker 3: There So the vomero nasal organ. When snakes are sensing
Speaker 3: their environment, they stick it into the romero nasal organ
Speaker 3: to like figure out cent trails. Is that right? Can
Speaker 3: we go a little more into detail about what that does?
Speaker 2: Yes, so snake's doing it a little differently. It tends
Speaker 2: to require contact in mice. In rants, the mouse will
Speaker 2: generally stick its nose right in whatever that odor source is,
Speaker 2: whether it's the glandeurth, secretions of a mate or a
Speaker 2: fool of urine or what might be. These are often
Speaker 2: social signals that can be sex or aggression, pheromones or
Speaker 2: predator cues or such. There's within the vomer a nasal organ,
Speaker 2: which is just adjacent to the nasal cavity. There's a
Speaker 2: blood vessel that will pump those molecules into the organ
Speaker 2: where they can interact with these specialized olfactory neurons in
Speaker 2: that goes back to a slightly different part of the brain.
Speaker 2: Humans don't have that organ, so it's a little bit different.
Speaker 2: So you have all those and those are all located
Speaker 2: in the nose and they project to specific areas of
Speaker 2: the brain. Taste is very specifically the detection of non
Speaker 2: volatile compounds like sugars and salts, and acids and amino
Speaker 2: acids and a variety of compounds that can be perceived
Speaker 2: of the spinner. They activate cells that sit within taste
Speaker 2: buds for the most part, which are basically just little
Speaker 2: onion like collections of cells, and those are on the tongue,
Speaker 2: certain taste papillo, some of the bumps in your tongue,
Speaker 2: and they're also in the soft palate in my favorite
Speaker 2: German word, the geschmack Strifen, which is the taste strip,
Speaker 2: which a bunch of taste buds in the soft pealet
Speaker 2: and then there also are some in the varyingx throat.
Speaker 2: Those are connected to different parts of the brain. Specifically
Speaker 2: to the brain stem, and that's carrying taste information. There's
Speaker 2: a third chemical sense both smell and taste or detecting chemicals.
Speaker 2: The third chemical sense is known as chemisthesis, and chemos
Speaker 2: thesis is one you probably haven't heard the name of,
Speaker 2: but you've experienced, and that is when chemicals that are
Speaker 2: often in spices or herbs will sort of hijacked sensors
Speaker 2: for temperature or pain or vibration. So capsayasin and a
Speaker 2: hot chili pepper, menthol in, mint, santial in, sesshue, peppercorns,
Speaker 2: these are going to basically be naturally current chemicals that
Speaker 2: make this is generally trigeminal nerve sensors feel like they've
Speaker 2: been activated. So capsaicin makes it feel like there's warmth
Speaker 2: there even though there's no change in temperature because it's
Speaker 2: turning on a heat receptor. Menthol is cooling because it's
Speaker 2: turning on a cold sensitive receptor.
Speaker 1: Did you say there was one that triggers a sense
Speaker 1: of vibration.
Speaker 2: Yeah, the sansial in such one peppercorns, which are actually
Speaker 2: flower bites, give see this little tingling aspect to it.
Speaker 1: I see, So it's different from capsas and it's not
Speaker 1: a warm.
Speaker 2: It seems to have a bit of a warmth aspect
Speaker 2: to it as well. So some of these can be
Speaker 2: working across but their compounds in ginger and compounds and
Speaker 2: eucalyptus and all these types of that will do this
Speaker 2: type of thing.
Speaker 1: And is the chemical mechanism the same, the sort of
Speaker 1: lock and key structure the same for all these different
Speaker 1: kinds of experiences.
Speaker 2: They are, although in these cases they're primarily attaching to
Speaker 2: ion channels, which are proteins that can be bound by
Speaker 2: an external chemical But then they open up and they
Speaker 2: let charge particles fly across the rent, so they're not
Speaker 2: triggering an intracellular biochemical cascade. They're actually changing the electrical
Speaker 2: properties of the cells directly. So just different families proteins,
Speaker 2: but they do all come together in this all comes
Speaker 2: together in the brain, and that's what we call flavor.
Speaker 2: So flavor is smell plus taste. You can bring chemosthesis
Speaker 2: into that. You can also impact flavor by site. For example,
Speaker 2: if either you remember crystal pepsi or any of these
Speaker 2: clear colas that came out a number of years ago.
Speaker 2: One of the problems was is you looked at it,
Speaker 2: you expected a seltzer or a sprite or whatever or not,
Speaker 2: and then you drank it and there was a real
Speaker 2: disconnect between your expectation and what your taste and smell
Speaker 2: was telling you. So sometimes those visual cues temperature, and
Speaker 2: other things can impact how your flavors perceive. But one
Speaker 2: of the big term confusions is how I would say
Speaker 2: the general population uses the word taste versus how we
Speaker 2: face as smell scientists use it. When we as scientists
Speaker 2: use it, we mean just those limited sweet, sour, salty, bitter,
Speaker 2: umami tastes happening in the mouth. Patient comes they've lost
Speaker 2: their sense of smell. They may say, I can't taste anything.
Speaker 2: It all tastes really flat. If you were to test
Speaker 2: them with putting sugar on their tongue or salt on
Speaker 2: their tongue, it probably would work really well. But what
Speaker 2: they've lost is the complexity of flavor that comes from
Speaker 2: the odors that arise from those foods. The ability to
Speaker 2: distinguish a lemon from a lime if you're not looking
Speaker 2: at the color of it, is not because one is
Speaker 2: sour and one's not sour the most sour, but one
Speaker 2: has a different complement of ettererant molecules than the other
Speaker 2: that gives it a subtly different perceptual flavor.
Speaker 1: You distinguish smell and taste in terms of whether or
Speaker 1: not the things can volatilize. Is that just because it
Speaker 1: determines where it lands, like on your tongue or on
Speaker 1: your nose, or is there fundamentally different sweet receptors there?
Speaker 1: For example, to make a concrete is there a smell
Speaker 1: of salt? Like salt doesn't volatilize. You're sitting in front
Speaker 1: of a crystal of salt. You can't receive any salt
Speaker 1: molecules on your nose. Obviously, you lick it, you taste it,
Speaker 1: But is there a smell of salt if you could
Speaker 1: like pulverize the salt and sprayed against your nose, would
Speaker 1: you notice anything?
Speaker 2: Basically, no, there's not. I mean people often if you
Speaker 2: ever looked at Terminado sugar, you know that's a raw sugar.
Speaker 2: This hasn't been really refined. It has an aroma to it,
Speaker 2: but that's sort of the leftover molasses and stuff. If
Speaker 2: you were to get pure sucrose or pure sodium chloride,
Speaker 2: and you do, there are no contaminants. They're really not
Speaker 2: going to give you a smell. I mean, if you
Speaker 2: could somehow create a spray of individual sodium chloride molecules,
Speaker 2: I guess there wouldn't be anything specific, because that would
Speaker 2: be a molecule that would probably impact every single receptor. Wow,
Speaker 2: I'd just give you a background blur.
Speaker 3: So if you had to lose your sense of taste
Speaker 3: or your sense of smell, which would you rather.
Speaker 2: Lose smell easily?
Speaker 1: Wow?
Speaker 3: Really?
Speaker 2: And that's not because any way just diminished. I don't
Speaker 2: want to lose either of them. Yeah, people who I
Speaker 2: would say I would probably rather lose sight, er hearing
Speaker 2: than smell or taste. Once again, I don't want to
Speaker 2: lose any of them. The reason that I put taste
Speaker 2: at sort of the top of the list of not
Speaker 2: wanting to is because the people who really cannot taste,
Speaker 2: it's much less common than people losing the sense of smell.
Speaker 2: I've actually met someone who actually born without a sense
Speaker 2: of taste, and one thing that they sort of routinely
Speaker 2: describe is just how hard it is to eat. I mean,
Speaker 2: even to swallow food. Everything becomes very texturally driven in
Speaker 2: the mouth, so soft foods are really hard to get
Speaker 2: down and it just seems like a real challenge for
Speaker 2: them for whole life.
Speaker 1: Wait, so soft foods are unpleasant without taste, is that
Speaker 1: what you're saying.
Speaker 2: Yeah, there's something about without having that taste, but it's
Speaker 2: just purely the texture impact. The yogurts and cotta cheese.
Speaker 2: I mean, not that I want to eat cottage cheese anyway,
Speaker 2: but oh, these things aren't just very difficult. So usually
Speaker 2: what they will do is they'll try to add texture
Speaker 2: to it, which is to make any time with a
Speaker 2: sensory loss, if you can make things multisensory in other
Speaker 2: ways that help to offset some of those losses. We
Speaker 2: say that for people with smell disorders, explore adding different spices,
Speaker 2: adding textures, adding color to your food to make it
Speaker 2: more palatable, enjoyable. You're never going to hundred percent offset
Speaker 2: the loss of the ability to smell the aromas, but
Speaker 2: you can get it closer. A lot of South Asian
Speaker 2: food oftentimes are very popular with individuals who have lost
Speaker 2: their sense of smell because of the spices.
Speaker 1: So you're saying, crunchy blue cottage cheese is a better
Speaker 1: experience than white, soft cottage cheese.
Speaker 2: Yeah, but that's a low Baruch.
Speaker 3: Let's take a break and we'll come back and talk
Speaker 3: more about smell and taste.
Speaker 1: So this helps me understand a question I wanted to ask,
Speaker 1: which was about what happens when we get a cold
Speaker 1: and our nose is plugged up and things taste like cardboard.
Speaker 1: So I'm guessing now from your answers before that my
Speaker 1: taste hasn't changed because I can still put my tongue
Speaker 1: on things, but my sense of smell has decreased, and
Speaker 1: so my flavor experience has changed. So I can still
Speaker 1: technically taste things when I have a cold, but I'm
Speaker 1: not getting the full experience exactly.
Speaker 2: You're losing You're having diminished flavor perception while your taste
Speaker 2: is the same. But that's being technically how we use
Speaker 2: it as opposed to the way most people would colloquially
Speaker 2: describe it. So that's having diminished taste. But yes, taste
Speaker 2: and smell are differentially affected. There are a variety of
Speaker 2: reasons that people could lose sense of smell, sometimes very temporarily,
Speaker 2: like just having a head cold where you're just clogged
Speaker 2: up and so the outer molecules can't get to where
Speaker 2: they need to go. Sometimes it's because of shorter or
Speaker 2: longer term damage, everything from viruses to inhale toxins or pollutants,
Speaker 2: sino nasal disease. It may cause inflammation, allergies, head trauma,
Speaker 2: early stages Alzheimer's, Parkinson's, and other neurological generative diseases.
Speaker 1: Exposure to the swamps of Virginia Daniel.
Speaker 3: If I could just intruct it, are those things like
Speaker 3: messing up the shape of the receptors, are messing up
Speaker 3: the connection between the neurons that talk to your brain,
Speaker 3: or maybe it's a combination of these things.
Speaker 2: They differ. So for example, loss of smell is one
Speaker 2: of the earliest signs of what we call idiopathic or
Speaker 2: typical Parkinson's disease, even before some of the motor symptoms.
Speaker 2: While we don't know exactly how it's happening, what seems
Speaker 2: to be the case is areas of the brain that
Speaker 2: are affected by Parkinson's. Some of the earlier areas to
Speaker 2: be affected are ones that are important for dealing with smell,
Speaker 2: So that's happening in the brain, not in the periphery
Speaker 2: within the nose. Contrast that with COVID nineteen, so we'd
Speaker 2: known for long time that a variety of viruses, common
Speaker 2: coronaviruses that can cause common cold, rhinoviruses, abnoviruses, influenza, they
Speaker 2: could in some people will lead to temporary or permanent
Speaker 2: smell loss. In COVID was really striking how many people
Speaker 2: were losing their sense of smell very rapidly, and the
Speaker 2: large number of them, probably about ten percent, may never
Speaker 2: recover that spell that they lost, which is really hard
Speaker 2: for them to deal with. But we do know something
Speaker 2: about how that virus is causing this disruption. And so
Speaker 2: in the tissue in your nose where those sensory neurons
Speaker 2: are sitting that detect the odors, that's called the olfactory epithelium,
Speaker 2: there are other cells there that support those neurons actions.
Speaker 2: There are supporting cells called sustentacular cells that are sort
Speaker 2: of balancing the environment. They may be putting out certain
Speaker 2: molecules in the area. They're providing support to the whole tissue.
Speaker 2: There are glandular cells, there are stem cells that are
Speaker 2: allowing the tissue throughout your life to constantly regenerate. It
Speaker 2: turns out that the virus doesn't directly attack the sensory
Speaker 2: neurons tacks the supporting cells and the stem cells, and
Speaker 2: in some people that attack, that disruption of those cells
Speaker 2: is going to be temporary enough the cells, some of them, survive.
Speaker 2: The neurons aren't damaged indirectly enough to not be able
Speaker 2: to recover. Maybe the neurons are wiped out, but the
Speaker 2: stem cells are intact and they're able to regenerate the
Speaker 2: tissue in a few days or weeks. But in other
Speaker 2: people the damage is extensive enough that that does not
Speaker 2: seem to be the case. But it is a sort
Speaker 2: of an indirect attack by the virus on the olfactory neurons,
Speaker 2: rather than the neurons.
Speaker 1: Themselves be dead.
Speaker 2: Other viruses may work differently, but it is that peripheral
Speaker 2: damage that's the issue. Now we also know that in
Speaker 2: a small number of people there seem to be true
Speaker 2: taste effects and even chemosthesis effects. You may have send
Speaker 2: videos of people saying, oh, yeah, I'm chewing an onion,
Speaker 2: or I'm going to just shovel garlic into my mouth,
Speaker 2: not perceiving.
Speaker 1: It at all. We don't know why or how.
Speaker 2: The virus was affecting taste or chemosthesis. Those losses did
Speaker 2: seem to be temporary. I'm not aware of long term
Speaker 2: losses in those senses.
Speaker 3: So I have a friend she lost her sense of smell,
Speaker 3: and then when it came back, she was smelling things
Speaker 3: that weren't there. Is that common and what causes that?
Speaker 2: That actually is very common. So if we think of
Speaker 2: smell disorders, we can break them into two different categories.
Speaker 2: One we'd call quantitative disorders, So this really a reduction
Speaker 2: or complete inability to detect or perceive odors, and the
Speaker 2: others are qualitative someone changing the quality of the smell.
Speaker 2: And we can break those into two different groups. Parosmia
Speaker 2: is distorted smell. So someone put a flower in front
Speaker 2: of your nose, you smell, and it smells like garbage,
Speaker 2: and that's you can imagine not good. Phantosmia is the
Speaker 2: perception of smells when nothing is there. I smell smoke,
Speaker 2: I smell sometimes luckily those are pleasant smells, but more often,
Speaker 2: like with the prosmea, they are unpleasant smells as well. Well.
Speaker 1: You mentioned fecal phantoms earlier that I have to follow
Speaker 1: up on.
Speaker 2: Yeah, equal smells, garbage smells are ones that are very common.
Speaker 2: These often not exclusively, but often will come sort of
Speaker 2: as the system is trying to potentially repair itself. We
Speaker 2: see someone's getting they've lost their sense of smell, so
Speaker 2: they have an osmia with no ability smell, or hyposmia
Speaker 2: reduce smell, and that sense of smell is coming back.
Speaker 2: But during that time, parosmia or phantosmia emerges. And while
Speaker 2: we don't absolutely know the cause, it may be as
Speaker 2: the system's trying to rewire itself whenever the brain is
Speaker 2: getting miss signals or creating signals looking for them when
Speaker 2: they aren't fully coming from the nose. So that is
Speaker 2: unfortunately pretty common.
Speaker 1: And why don't we understand the cause? What's hard about
Speaker 1: these studies is it that we're talking about humans and
Speaker 1: brains and you can't just do whatever experiments you want.
Speaker 2: I think there are a couple of reasons. One is
Speaker 2: that the senses of smell and taste were very much
Speaker 2: neglected from a medical point of view for many, many years.
Speaker 2: The loser sense of smell, you go to the doctor
Speaker 2: if they even knew anything about it, because they don't
Speaker 2: get taught about it in medical school to any meaningful extent.
Speaker 2: They might say, oh, that's too bad, You're just gonna
Speaker 2: have to live with it. Or nothing we can do
Speaker 2: about it and sort of getting passed off of that
Speaker 2: there wasn't a lot of attention to it. The other is,
Speaker 2: for those qualitative disorders parosmi and phantasmia, we can't measure
Speaker 2: them in any objective way. We have tools to measure
Speaker 2: smell loss, the variety of psychophysical tests that we can
Speaker 2: do that can allow us to quantify how sensitive you
Speaker 2: are to particular odors. With parosmia and photosmia, we are
Speaker 2: entirely relying on the patient being able to describe it
Speaker 2: and sort of related. We just don't have the tools
Speaker 2: to investigate it nearly as well as for smell loss.
Speaker 3: You mentioned that the phantom smells tend to to be
Speaker 3: like garbage or feces. Is there any hypothesis for why
Speaker 3: bad smells are what comes first? Does it represent anything about, like,
Speaker 3: you know, evolutionarily, smells that clue us into the presence
Speaker 3: of like disease causing agents are more important, so we
Speaker 3: put those online first, or who the heck knows?
Speaker 2: I think it's both of those that you gave. What
Speaker 2: I'd say, it's probably the leading hypothesis about it that
Speaker 2: avoiding bad is more important, So it sort of faulse
Speaker 2: to that, but there's really no evidence to support it,
Speaker 2: just as the one that seems to make more sense.
Speaker 2: But yeah, we just don't know.
Speaker 1: And what about on the other end of the spectrum.
Speaker 1: I remember hearing when I visited a perfume factory once
Speaker 1: in France that there are people who are like super smellers,
Speaker 1: and you know, their job is to like distinguish these
Speaker 1: smells and design new perfumes. And there's like a very
Speaker 1: small number of these supernoses. And also that their noses
Speaker 1: get tired, so they can only work for a few
Speaker 1: hours during the day and then that's spend the rest
Speaker 1: of the day on the beach recovering from all this,
Speaker 1: you know, difficult smelling work. Are these people real? Oh's
Speaker 1: the whole thing a scam? And how does your nose
Speaker 1: get tired?
Speaker 2: They are real? Yeah, Generally their professional term is a
Speaker 2: nose professional nose. And much like we were talking about
Speaker 2: earlier about Sammie's and others, they've been trained. They certainly
Speaker 2: have a good sense of smell. They probably are if
Speaker 2: we look on the bell curve, they lean towards the
Speaker 2: better end of those abilities. But they've also really learned
Speaker 2: to recognize all these things. But the reason that they
Speaker 2: get tired is what we call it adaptation or desensitization
Speaker 2: and habituation, depending on where along in the nose and
Speaker 2: brain this happens. But basically, when you're having something stimulated
Speaker 2: over and over, you can sort of oversaturate a particular
Speaker 2: information channel in the brain and it will dial down
Speaker 2: the gain and come less. So you have to take breaks.
Speaker 2: Even when we're smell testing people, we work in breaks
Speaker 2: within it so that they don't get sort of overwhelmed
Speaker 2: and saturated, so they're attuned to the next Like you
Speaker 2: all experience adaptation. You go into a bakery and smell
Speaker 2: the cookies and the breads and everything, and then you're
Speaker 2: there for a few minutes and it just there goes away.
Speaker 2: You don't really notice it anymore. Part of that is
Speaker 2: the gain of the system being down. Part of that
Speaker 2: is your brain attending to novel stimuli and all of that.
Speaker 2: I don't know if they head out to the beach,
Speaker 2: probably most of them are in Paris or Geneva, but yeah,
Speaker 2: there's a real physiological reason that they need to have
Speaker 2: those breaks.
Speaker 1: Well, I used to know a guy who lived downwind
Speaker 1: from the Nilla wafer factory in Houston, and he said
Speaker 1: he had to move away because he was gaining weight
Speaker 1: because it just made him eat all the time. And
Speaker 1: it makes me wonder about the sort of subconscious effect
Speaker 1: of smells. I mean, are there smells that affect our
Speaker 1: behavior that we don't consciously experience? Are there, for example,
Speaker 1: human pheromones that you know attract you to somebody or not.
Speaker 1: Do perfumes actually do that to people?
Speaker 2: There's no good evidence of human fairmonts. And by a
Speaker 2: pheromone specifically mean a odoor that's given off by one
Speaker 2: number of a species, that acts on another member of
Speaker 2: a species to change its behavior, or some physiological response
Speaker 2: like a hormonal response. We don't use those, but certainly
Speaker 2: smells can affect our interactions with each other. You talk
Speaker 2: about two young mothers who lose their sense of smell.
Speaker 2: One of the things they'll bring up very early. So
Speaker 2: you know my baby's head, I love smelling his hair
Speaker 2: after you got to wash your stuff. There definitely is
Speaker 2: a link between smell and emotion and sort of that
Speaker 2: bonding and all those types of things. Romantic partners will
Speaker 2: often talk about enjoying the smell of their partner and
Speaker 2: things like that, But these are not innate triggering fair
Speaker 2: aomones in that way. But similarly, it can be if
Speaker 2: your friend had the nil away for experience and that
Speaker 2: triggered you know, intensity, maybe around front baking all the time,
Speaker 2: whatever it is. But people who live near hog farms
Speaker 2: that have these large pools to deal with the waste.
Speaker 2: There are a lot of studies about the increased depression.
Speaker 1: Ecal lagoons cause people to get depressed or saying.
Speaker 2: Yeah exactly wow, so yeah, those aspects are very real.
Speaker 3: When I was in college, I remember in my evolutionary
Speaker 3: psychology class learning about these studies where like men wear
Speaker 3: shirts and then the women smelled the shirts and then
Speaker 3: rated which men were the most attractive. So that's not pheromones.
Speaker 3: Has that study since been debunked or was there something
Speaker 3: else that they were picking up on?
Speaker 2: There certainly are questions about the extent of that mean.
Speaker 2: Certainly the concept of women's menstrual cycles coordinating in dorms
Speaker 2: and things like that that may be spell related. I
Speaker 2: would say they haven't always been replicated to the sense.
Speaker 3: So I thought that one was fairly debunked. That it's
Speaker 3: more like a statistical you're just going to overlap twenty
Speaker 3: five percent of the time.
Speaker 1: By chance or something.
Speaker 2: Yeah, exactly. It's also not something I think a lot
Speaker 2: of people are spending a lot of time studying at
Speaker 2: the moment.
Speaker 1: And if we have some understanding of the chemical mechanism
Speaker 1: of this, can we make progress towards things like recording
Speaker 1: sense digitally and then manufacturing them. You know, can I
Speaker 1: create an artificial nose with all of these receptors, write
Speaker 1: down the signals and then create something which puffs out
Speaker 1: those molecules on the other side, or I could like
Speaker 1: email somebody a smell.
Speaker 2: There are a lot of efforts in this area, and
Speaker 2: you can imagine artificial noses being used as sensors for
Speaker 2: all sorts of things, biosecurity types of questions. They put
Speaker 2: them in fields to know when the props are ready
Speaker 2: to harvest, or if there's been an infestation, things like that.
Speaker 2: A lot of these it could be more specialized. You'd
Speaker 2: certainly love to have. You know, there's a lot of
Speaker 2: evidence that the aromas that an individual gives off if
Speaker 2: they have cancer or if they have some other disease
Speaker 2: might be unique. If you could identify those chemicals there
Speaker 2: are dogs that have been trained, although that's really hard
Speaker 2: to make a regular part of it because just the
Speaker 2: amount of training and how you have to go through that.
Speaker 2: But if you can have a sensor a wand you
Speaker 2: could wave over someone to detect that, that would be
Speaker 2: a miracle. But there's also commercial ways for trying to
Speaker 2: replicate this with food or with other types of aromas
Speaker 2: you might like to recapitulate. For example, a lot of
Speaker 2: the flavor houses now will usually go around and sample things.
Speaker 2: They put a dome to capture the odor headspace over
Speaker 2: a plate of food at a particular food truck that
Speaker 2: you like, or you put over a borneo forest and
Speaker 2: collect all the volatives coming off a particular group of
Speaker 2: plants or whatever. Take those back, use modern biochemical chromatographic
Speaker 2: mass spect types of techniques to define not only every
Speaker 2: single molecule but also its relative concentration, which is very important,
Speaker 2: and then they can recapitulate these. They can do this chemically,
Speaker 2: but then can you also send it a lot long
Speaker 2: to have a production apparatus on the other end of
Speaker 2: that email that that can then puff it out. People
Speaker 2: have been trying that to various degrees for decades now,
Speaker 2: and I think the technology is catching up to be
Speaker 2: able to do that in a much more sophisticated way.
Speaker 1: So I could email California to Kelly so she can
Speaker 1: also enjoy the sense of the ocean and the floral notes.
Speaker 3: You know, I'm going to try to be nice and
Speaker 3: not mentioned that right now, you'd probably be sending me
Speaker 3: the smell of burning home. But Virginia's got some perks. Man.
Speaker 2: Yeah, this seems like maybe a running.
Speaker 3: This is a running debate.
Speaker 1: So my question is, I hope a question you haven't
Speaker 1: heard before, which is about smell and taste on other planets.
Speaker 1: Given the usefulness of smell and taste and our knowledge
Speaker 1: of the evolutionary history on Earth, what do you think
Speaker 1: the chances are that aliens, when they evolve on their
Speaker 1: planets smell and taste or don't smell and taste. How
Speaker 1: likely do you think this is to be ubiquitous to
Speaker 1: life in the universe.
Speaker 2: I would think it would be more ubiquitous than other senses.
Speaker 2: They are chemicals everywhere the universes, chemicals just arranged in
Speaker 2: different forms, and so being able to sense that is
Speaker 2: really integral. You look at unicellular organisms, whether they're bacteria,
Speaker 2: protozoans or whatnot. They can all sense the chemicals around them.
Speaker 2: These are fundamentally primitive forms of smell and taste. So yeah,
Speaker 2: I think that is clearly going to be a thing.
Speaker 2: Whether it is put together the same way then we have.
Speaker 2: It's interesting that while the receptors in a fruit fly
Speaker 2: and a human, the receptors for odors and for tastes
Speaker 2: are molecularly completely distinct from each other those two families.
Speaker 2: It's not a single evolutionary origin of the odor receptors
Speaker 2: across those different phila, but the arrangement of what the
Speaker 2: sensory neurons look like, how they're arranged connected to the brain,
Speaker 2: and how they arranged is actually remarkably similar. And those
Speaker 2: that independently evolve, so there seem to be some strategies
Speaker 2: that have benefited from that conservation or at least limited
Speaker 2: repertoire of options, while other ones are free to to
Speaker 2: sort of evolve independently and come up with more than
Speaker 2: one solution to the problem.
Speaker 1: Do aliens like cilantro a question we don't yet have
Speaker 1: an answer to.
Speaker 3: Maybe one day, all right. As someone with anxiety, I'm
Speaker 3: still dwelling on the fact that I called your research
Speaker 3: weird at the beginning. What I meant was, I asked
Speaker 3: you weird questions because of what you do.
Speaker 2: I don't remember that.
Speaker 3: Oh good, good. So then the lead in is you
Speaker 3: just started this new center for smell and taste disorders.
Speaker 3: Tell us a bit about your new center that you're
Speaker 3: co directing.
Speaker 2: Well, thanks for that opportunity. It's something that we've seen
Speaker 2: over the last decades that there's a huge need for.
Speaker 2: And what that need is we have massive underserved population
Speaker 2: of people that are experiencing the disorders, but the amount
Speaker 2: of research that's going into trying to better diagnose them,
Speaker 2: better support them, and eventually better treat them is really small.
Speaker 2: One of the small bright spots of COVID was because
Speaker 2: of the prevalence of smell loss and taste loss that
Speaker 2: associated with COVID. It brought a greater attention and understanding
Speaker 2: of the broader population about how impactful these disorders can be.
Speaker 2: But we still have a long way goo and we
Speaker 2: don't want to lose the momentum of that knowledge and
Speaker 2: appreciation from it. So the center is really trying to
Speaker 2: areas within its mission, and one is patient care, So
Speaker 2: being able to make sure that someone who has a
Speaker 2: smell or taste disorder has a place to go to
Speaker 2: get diagnosed, perhaps identifying underlying cause that might be treatable,
Speaker 2: as well to get support such that they better understand
Speaker 2: how to improve the palatability of the food, how to
Speaker 2: be safer with gas leaks and fires and spoiled food
Speaker 2: and things that they may be hard to detect, how
Speaker 2: to get emotional or therapeutic support if they're being depressed,
Speaker 2: which is very common, where's changing their social relationships. We
Speaker 2: also want to facilitate research, and that's everything from the
Speaker 2: very fundamental building blocks of smell and taste and how
Speaker 2: it works, so that we can better understand how it
Speaker 2: may not work when it's spent, but also clinical studies
Speaker 2: looking at dignostics and treatment. One of the studies we're
Speaker 2: doing right now is trying to answer a very simple
Speaker 2: question is how much does your sense of smell normally
Speaker 2: vary morning versus night day to day, if you're pregnant
Speaker 2: during menstrual cycle, if you have other types of disorders,
Speaker 2: so that you can have a base line to understanding.
Speaker 2: So if you're going to get your sense of smell
Speaker 2: regularly tested, do you actually know what's just normal variation
Speaker 2: versus an actual pathologic change that needs to be dealt with.
Speaker 2: So we want to train doctors and scientists in this
Speaker 2: field to a better degree than is often the case.
Speaker 2: And then we want to reach out to the community
Speaker 2: education and engagement to kill people every whether it's with
Speaker 2: a disorder or whether it's for people who chefs, mind makers,
Speaker 2: and who or not that are using smell and taste
Speaker 2: as part of their livelihood and how they make their
Speaker 2: way through the world, to help them better understand that
Speaker 2: as well.
Speaker 3: Awesome, Well, congrats on the new center. I learned a
Speaker 3: lot today. I think I'm going to appreciate the next
Speaker 3: piece of food that I eat even more and appreciate
Speaker 3: how complex it is. I love that we learned the
Speaker 3: thing about vibrating. The next time I go to a
Speaker 3: Chinese restaurant, I'm definitely going to order something with extra
Speaker 3: session one. So yeah, thank you so much for coming
Speaker 3: on the show.
Speaker 2: Thanks so much for having me. It is fun.
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