Stuff You Should Know - Selects: Does the body replace itself?

Episode Date: May 6, 2023

Does the human body really replace itself every few years? The answer is yes, but different parts of the body do so at different rates. Learn all about which parts of your body are the speediest, and which take the longest to regenerate, in this classic episode.See omnystudio.com/listener for privacy information.

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Terms and conditions apply. Hey everybody, it's your old pal Josh. For this week's Select, I've chosen, does the body replace itself every seven years? Sounds like a medical episode and it kind of is. But after a little while, it turns into a brain buster of a head scratcher of a philosophical bent that I think you're going to love. I hope you enjoy the living heck out of it. Welcome to Stuff You Should Know, a production of iHeart Radio.

Hey and welcome to the podcast, I'm Josh Clark with Charles W. Chuck Bryant and guest producer Noel. Noel is in the house. Yes he is. In the new studio. Yeah. And his place is comfy and cozy. I like it.

I wish there was a chair version of a water bed. I know. This is a nappish little place. Yeah. Especially today. I think I'm dragging. Oh, apologies. Yeah.

Same here. So if we're talking kind of slow or low or we just stop talking for a little while, we're just tired. Yeah. Bumped into you at the Hawks game last night. I know. Hey, how's it going? How funny is that?

You know? Yeah. Just did the bump in. You gave me in the Hawks one. Didn't even know we were going. No. Look over in line. There's Josh and Yumi.

Yeah. That's great. There's Chuck and Eddie. Yep. Bumped into each other. Bast Eddie. And an arena of 18,000 bumping into someone. Is that it?

That's all it holds. I think it's something like that. Yeah. It's a lot of people. It's a good arena. Yeah. But you had box seats because you're special. They were free.

Mine were free too. And the nosebleeds. Yeah. I like just about every seat in that place. Yeah. It's not too bad. I was laughing about the nosebleeds going in. But then I got up there.

I was like, this is great. Yeah. You can see everything. Did your nose actually bleed? Just twice. Yeah. Once out of sheer excitement. Right.

And then once from the altitude. And that was more of a spray. Right? Yeah. Yeah. Just covering everyone. Yeah. I was like, go Hawks.

Boy, what a weird intro. It's a little weird. I mean, it kind of jibes a little bit because we're talking, yeah, you were mentioning blood. Sure. I was shedding cells and blood. You were. Like blood is made up of cells and we shed tons of cells.

But before we get to that, right, there's the fact of the podcast, you shed cells. I want to mention this one thing I read. It's called, I think the title of the article is the self is moral. It's about like where we get our identity of self from. Where it's rooted. It was written by a person named Nina Strohmeyer, I believe is on Aeon magazine. Just type in the self is moral Aeon. It'll come up.

That'll get you there. And toward the beginning, the author says there's this very famous philosophical exercise, which you know, philosophers love to do like mental exercises. Yeah. That's all they have. Imagine you have like a ship, right, like a boat, a nice Yankee clipper. And this Yankee clipper is slowly over time, kind of salvage for parts. But rather than just being stripped, like every time a part is taken out, it's replaced.

And then over the course of like 50, 100 years, as each plank, as each bolt, as each like mast head, even the thing that carved lady in front, eventually just gets replaced with something else. Yeah. A new carved lady that speaks of the time. Right. You know. Is it still though, after every single part has been replaced, the same ship that it was

before? Yeah. I see what you mean. I don't think that can be possible. Why not? Especially if it has the same name and it's the same ship in the same place as before. It was just slowly over time moved out. True.

Where does the self lie? Yeah. That's a good point, man. Like redoing a house, same thing. Yeah. I mean, place all the floors and the walls and the windows. Like when does it cease to become that same house that was built in 1930? Exactly.

Isn't that cool? Yeah, it is really cool. And the reason that it applies to this episode is because over the course of your lifetime, a significant portion, pretty much all of the cells in your body are going to be replaced. So that the person, even after you reach your adult self, physically, by the time you die, assuming you're going to die much later, you are essentially a different person, at least on the cellular level. Yeah.

37 trillion cells ish. That's how many we have? Yeah. That's what they estimate. And I did a little looking into lifespans too. That sounds like an estimate. 37 trillion? Yeah.

What do you want? They're like give or take. Yeah. I did a little research into lifespans just because this all sort of comes back to like your death basically. Yeah. And what that is, is your cells dying little by little? Well, yeah.

I mean, if you think about it, Chuck, one of the things that... Like why do we die if we'll get to all that? Oh, okay. But it's intriguing. It is. It started, questions started popping up. So apparently we gain about three months of life, humanity, every year that we progress. Like the average lifespan expands by three months?

Yeah. Like if you were born in 2012, the average lifespan is now, and this is the United States, is 78.8. If you were born in 1901, it was about 47 and 50 years for men and women, respectively. But if you look at the ratio, it's still about three months, despite all our technologies, three months a year. Every year. Every year.

Just slowly creeping along. Because I think the article was when we're going to live to be 100 by average, and they say by the year 2100, if things hold, then the average American will be about 100 years old. I thought that... So I guess that's just... If things are steadily progressing, I had heard that our generation would be either the last or the first, the last to not hit triple digits or the first two.

On average. Yeah. So I guess those were all... And these are all guesses, you know. So who knows? Plus, if you believe in things speeding, science speeding up. Yeah. What is that?

Moore's Law? Yeah. Is that it? Yeah. Applied to computers though, in that case, right? Right. Right. But I mean, you can extend it to other stuff.

Yeah. Then you might think, but they say it's not increasing like that. No. At least not so far. Moore's Law is exponential growth, just adding three months over years, non-exponentials, geometric. I think we're still at non-exponential growth. Definitely.

Yeah. We're just adding three months. Yeah. It's not bad though. That's a pretty good average. Every four years, that's an extra year. Yeah. Well, and it's interesting to think about people that were born, a lot of our colleagues,

like eight years behind us, are going to live an average of two years longer. Yeah. That seems unfair. Sad. Yeah. I know. We're thinking about our own deaths today, and Chuck, there's this rumor theory legend, maybe, that your body regenerates itself, 95% of your body regenerates itself every year.

Yeah. That's not true. No, it's not true. But it was a very long-standing rumor, and it was actually based on science. Not just the idea that, oh, yeah, our cells regenerate, so back of the envelope estimate is that we regenerate 95% or 98% of ourselves every year. It was early experimentation by injecting radioactive isotopes into human beings and then following their course and then making estimates based on that led to this idea.

It's called pulse labeling. Is it? Yeah, it's like tagging an animal in the wild, basically. Right. But you're just tagging a cell. Yeah. They don't do that to humans anymore. No.

They do it to animals, I think. It's a very dumb thing to do. Sure. Injecting radiation. Exactly. Yeah. Unless, of course, it's radiation treatment. That's true.

Which is still a really weird thing if you think about it. Yeah. I have a feeling it's going to be one of those things we look back on. It's like a primitive treatment. Yeah. Yeah. I hope so. But there was this long-standing science for decades or this idea, scientific idea

that we regenerated ourselves by 95, 98%. Finally, and I think 2005, there was a researcher named Dr. Jonas Friesen. He's Swedish. He's awesome. He said, this whole urban legend is really bringing me down. I want to figure out a way to really track how often the human body regenerates itself. Yeah. The biggest question has been the brain, specifically the cerebral cortex and the heart and the

heart muscles. I mean, they want to know all this stuff, but those were the two biggest mysteries, I think. Right. There's still the mysteries, but if you went back to prior to 2005 and Dr. Friesen's research, it was all a mystery. He figured out, he basically put a very accurate time stamp on how often human tissue and human cells regenerate themselves.

The way he did this is very clever. For a long time, botanists knew that the trees around the world contained a spike of carbon 14 radiation. Yes. Thanks to humans and nuclear bombs. Exactly. From 1954 to 1963, tree growth around the world show a big spike in carbon 14. Carbon 14 is naturally occurring, too.

Cosmic rays from the sun bombard Earth's atmosphere and create radioactive isotopes by knocking electrons from particles in Earth's atmosphere. Those radioactive particles become carbon 14, which is radioactive. In the atmosphere, carbon 14 binds to oxygen and creates carbon dioxide, which comes to Earth. Every living thing breathes this stuff in, whether it's a plant, whether it's a human. We just have C14 in our bodies. We also eat plants.

Exactly. Contain the C14, besides breathing it in. We also eat the animals that eat the plants in just C14. We got carbon 14 in our bodies. That's right. Because of the spike in carbon 14 that was introduced to the atmosphere from nuclear testing, there is a spike in humans as well. You can roughly age a human compared to another human if they were born in, say, 1959, and

one who was born in 1970 after there was that spike of carbon 14 had gone away. That's pretty cool. What Dr. Friesen did is even cooler. He basically went back to those tree trunks, those tree rings that show a spike in carbon 14 and created a calendar of carbon 14 decay and basically said, okay, on this date, this is how much carbon 14 was on Earth. If I take this cell and compare it, knowing that carbon 14 decays at a constant rate, I can tell you exactly how old the cell is.

Exactly. He used it to date cells and tissues and all sorts of cool stuff. He went looking for a marker and he found one due to our atomic testing program, which is pretty weird. Just released all that junk in the atmosphere and now, all these years later, it has a nice use. You know? It does.

So we now know when we're going to die. Right. Sort of. The reason he was able to use this as a marker, Chuckers, is that when you take a breath of life, your first breath of life, and you get some of that C14 into your DNA and a steady amount stays in there. You don't keep ingesting C14 as far as I understand, as far as your DNA goes. Once it's in your DNA, as your cells divide, that original amount becomes divided evenly.

So the less C14 that's in tissue, the older that cell line is, or the younger the actual cells are. Is that right? I think so, which would mean the new cell, the marker, would be a fresh batch of the C14? No, it would have less C14. Oh, really? Yeah. That's a cell divided, yes.

Exactly. Yeah. You have 10 grams of C14, which you don't. I can't imagine what that would be like. Let's say your one cell that's never divided has 10. When it divides into two, each of those two cells is going to have five grams, and then two and a half, and then 1.75, and so on, and so on. So since you know that C14 is generated at a constant rate, you know that it decays at

a half-life of 5,730 years, you can look at the amount of C14, and then also the decay of it as well. You can date things that are no longer living, too, to see when they ingested that C14 was. Yeah. He's a little like a bingo card. He just from the calendar that he made with the trees, and he holds it up in the light, and that's how he determines it. That's not true.

But what he did determine though was, which is really cool, and this is sort of what we've been building toward, is that most of your cells are about 7 to 10 years old in the body, and there are variances, and of course we're going to talk about all that, and right after this break, we're going to give you a little primer on cells so you know what all this means. Right. Hey friends, maybe you've stayed in an Airbnb before and thought to yourself, this actually seems pretty doable.

Maybe my place could be an Airbnb. It could be as simple as starting with a spare room you're not using. Instead of just letting it sit empty, you could Airbnb it. Maybe your roommate's going to move out and you're thinking about what to do with that space. A spare room could be that Airbnb, or maybe that spare bedroom where friends and family stay every few months. You could Airbnb that too.

Whether you could use a little extra money to cover bills or for something a little more fun, your extra room or extra space might be worth more than you think. Find out how much at airbnb.ca slash host. Hey, it's Megan Devine, host of Here After with me, Megan Devine on the Amy Brown Podcast Network. There's a lot going on lately, which is a massive understatement. From personal losses to bigger, collective sweeps of a lot of awful things, everything is a lot.

We have to start telling the truth about how hard it is to be here sometimes. How absolutely sideways life can go. In a culture that's often afraid of big emotions, it's a radical act just to let things hurt. Hereafter with Megan Devine is the show where everyone's allowed to talk about what's real in the service of a more connected and supportive world. It is also the place where I get to have conversations with interesting people about difficult things. With bestselling authors and a collection of artists and actors and activists, it's

how you'd imagine the coolest dinner party ever might be. Listen to new episodes of Here After with Megan Devine every Monday on the Amy Brown Podcast Network, available on the iHeart Radio app, Apple Podcasts, or wherever you listen to podcasts. Hey, it's Alec Baldwin. This past season on my podcast, Here's the Thing. I spoke with more actors, musicians, policy makers, and so many other fascinating people like actress and director Sheryl Hines.

They were looking for an unknown actress to play Larry David's wife. I said, well, how old is that guy? Isn't he old? And author David Sedaris. I feel like when you meet somebody and they'll say, well, I want to be a writer or I want to be an artist. And I say, well, is it all you care about? Because if it's not, it's going to be pretty hard for you if you're not on fire.

It's like opening the door of an oven and it's like, wow, you know, you take a step back. It's all they think about. It's all they talk about. It's all they care about. They don't have relationships. They're not good friends for other people. This is just what they're focused on. Man.

Listen to the new season of Here's the Thing on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, Josh, we were promised to sell primer and we like to deliver on those promises, weird stuff you should know. So I guess we started off by saying there are 37 trillion cells about in the human body. Yeah, give or take. Give or take. And water makes up about two thirds of the weight of those cells.

Oh, yeah. That's right. They're tiny. You need a microscope to see them. And it's like, it's the tiniest thing that can still reproduce. And even though we have many different kinds of cells, I think 200 types. And within those cells, there are differences, but there are a lot of similarities with all cells in their structure, namely they have a cell membrane.

They have a nucleus. They have a nucleus. Some have more than one. And these membranes are what allows nutrients to pass in and out, waste to pass out, water through osmosis travels in, reverse osmosis, travels out. And what else? We got your mitochondrion as well, that's where this is the important, really important thing, which is basically what keeps your cells alive.

That's the power center, right? Yeah. And that's, you know, your cells need food to live just like your body does, but you can't pass that hamburger straight into your cell. It needs to be broken down so your cell can use it. Exactly. And adenosine triphosphate, ATP is like the universal cell fuel, right? Yeah.

So, there's a lot of stuff that the body does make. I think you need like 23, I think you need 23 amino acids and like nine of them, your body doesn't really manufacture, so those are the nine non-essential amino acids, right? And you use amino acids to build proteins and you use proteins for everything from making muscles to making red blood cells to your mounting and immune response. Proteins are very, very vital. In some of them, you have to build by eating stuff from your environment, right? Yeah.

So, you go out and you find yourself a nice pig and you cut off its back leg. You say, sorry, pig, here's a pig leg for you, but I need this leg and I'm going to eat this leg and what I'm really eating is the muscle and what I'm really, really eating is the glutamine. Yeah. And then my body's going to take this glutamine. It can make it itself, but it doesn't hurt to have an extra little bit of glutamine. Yeah.

It doesn't hurt to have that pig leg in your back back leg. Exactly. Right. So, I'm chomping on the pig leg, eating the pig's muscles. Sorry to have heard vegetarian listeners, by the way. Right. Just use your imagination for a second. Sure.

And yes, I'm sorry too. So, you're eating the pig leg and you're gaining this glutamine as a result and your body's metabolizing the glutamine and then reusing it, right? And it can be glutamine, it can be anything. If we're ingesting a protein, if we're ingesting amino acids, if we're eating any kind of food, sugars, whatever, our bodies break it down into its constituent parts and then a lot of those constituent parts become part of our bodies. Yeah.

So, if you think about it, in this sense, when we eat, when we breathe, we're taking in stuff we need from the environment and that stuff that we take in from the environment becomes a part of us, literally, physically on the molecular level, it becomes a part of us. For better or worse, depending on what it is, of course. Yeah. That's a great... I think that's ultimately one of the side lessons of this whole thing is we should take

care of our environment because that environment becomes us and we either suffer or thrive as a result of it. You ever heard the expression, you are what you eat? Exactly. You literally are what you eat. Quite literally. And then also, Chuck, it goes the other way as well. When we excrete waste, when we exhale CO2, that's taken up by other things in the environment,

is deposited into the environment and it becomes part of the environment itself. So not only do we regenerate our cells, regenerate tissue, on average, seven to ten years, become almost wholly a new version of ourselves, we also, the boundary between us and the surrounding environment is really non-existent because there's a constant exchange of molecules. Yeah. We lose, on average, they say average adult male loses 96 million cells per minute, but we also replace those at the rate of 96 million per minute. Yeah, roughly.

Yeah. Yeah. So that's the good news. So we've got all these cells that we're losing. We've got all these new cells that are replacing them. And I think, like you said earlier before the break, that these, the different types of cells, and then hence different tissues, regenerate at a different rate, right? Yeah, and they all have specialized jobs and the cells are often built in such a way to

aid that job, physically different to make that job easier, which is really cool too. Right. Shows how versatile they are. Yes. You know? Those cells are very versatile. Super. So let's say your skin, your skin regenerates every two to four weeks, I think.

Yeah, exactly. You get a new healthy coating of skin every two to four weeks because your epithelial cells are particularly good at regenerating themselves. That's right. And that is, well, I guess that would fall on the low side, obviously, if we're talking seven to ten years, on the super low side, you have the cells that line like you're intestine and your gut. And those things don't last long at all because it's such a harsh environment, you know?

You wouldn't expect them to last like weeks and months and years. Yeah. How long is it? Five days. Yeah, that's nothing. But the structure of your guts, the, that are beneath that membrane lining that turns over every five days, they last about 15 years. Yeah.

So it's such a, like a beautiful, elegant system that we have to keep us alive. Red blood cells last about 120 days, but then you have things like cells in your bone, which actually regenerate as well. So your bones are over time, over a much longer period of time, actually becoming, I mean, I hate to call them new bones, but they kind of are, you know? Well, yeah. So if you compare, if you took your femur and somehow compared it to your femur when you were 15 years old, like they are two totally different bones.

Even though they're your bones, they were in the same place growing in the same person with the same DNA. They're still different bones because they're made of different cells. Ten years or so for the bones? Yeah, something like that. For the human skeleton, 300 to 500 days for the liver, very important organ. It is. And one of the other cool things about the liver is it's just gangbusters that regenerating

itself. You can apparently cut out 95% of a person's liver and it will grow back. And you won't have full function, but it will function and you'll survive with just 5% of your liver. That's pretty amazing actually. Yeah, because it will just grow right back, kind of like a hornet's nest. Only the inner lens cells of your eye form in your embryo and basically don't change. Now is that why you have suffer from degeneration and vision?

That's what I would guess. Is that the reason? Yeah, so with the corneal lens, Chuck, when you're born, when you're conceived, right, you are a cell that divides finally. Once that first division takes place, those corneal cells, they're set in stone. Like your corneal cells are as old as you are, same age as you. Other cells that make up different parts of the eyes, they're far newer. But your corneal cells, your cerebral cortex cells, they think?

Yeah, that's the one. I mentioned the brain and the heart muscles. Those are the two big ones because obviously the reason we have diseases like Alzheimer's and dementia are because the cerebral cortex has long thought to not regenerate cells at all. Now, I think they believe that they do in a very small number. Or different regions, like the olfactory bulb supposedly does? Yeah, in the hippocampus.

So we can learn new things or their sense of smell can be refined over time. Yeah, and I think isn't that also the reason the smell is very much tied to your memory? Probably. Like a smell can conjure up a memory more clearly? Yeah, but the cerebral cortex itself, they don't think, who was her name? Elizabeth Gould of Princeton did a lot of work on this because it was just basically set in stone for years. Like, no, it doesn't happen.

And she did a lot of work over the years trying to prove that it did using tracer studies. And I think that where they are now is they think it does some. Yeah, here or there? Here or there. But obviously, we still have to mention Alzheimer's, so it doesn't regenerate like the rest of the body. Not even close. Yeah, Alzheimer's also may be produced, I guess, by plaques, ever plaque buildup in

between your neurons that keep them from firing as well. It seems like we're so close to figuring out the secret to, I don't know, about not dying ever. I'm not talking immortality, but living much longer lives. Well, let's talk about that because all of this stuff kind of leads to that question. If we regenerate so often, why do we die? And we'll address that right after this. Hey friends, maybe you've stayed in an Airbnb before and thought to yourself, this actually

seems pretty doable. Maybe my place could be an Airbnb. It could be as simple as starting with a spare room you're not using. Instead of just letting it sit empty, you could Airbnb it. Maybe your roommate's going to move out and you're thinking about what to do with that space. That extra room could be that Airbnb. Or maybe that spare bedroom where friends and family stay every few months.

You could Airbnb that too. Whether you could use a little extra money to cover bills or for something a little more fun, your extra room or extra space might be worth more than you think. Find out how much at airbnb.ca. Hey, it's Megan Devine, host of Here After with me, Megan Devine on the Amy Brown Podcast Network. There's a lot going on lately, which is a massive understatement. From personal losses to bigger, collective sweeps of a lot of awful things, everything

is a lot. We have to start telling the truth about how hard it is to be here sometimes. How absolutely sideways life can go. In a culture that's often afraid of big emotions, it's a radical act just to let things hurt. Hereafter with Megan Devine is the show where everyone's allowed to talk about what's real in the service of a more connected and supportive world. It is also the place where I get to have conversations with interesting people about difficult things, with bestselling authors and a collection of artists and actors and activists.

It's how you'd imagine the coolest dinner party ever might be. Listen to new episodes of Here After with Megan Devine every Monday on the Amy Brown Podcast Network, available on the iHeartRadio app, Apple Podcasts, or wherever you listen to podcasts. Hey, it's Alec Baldwin. This past season on my podcast, Here's the Thing. I spoke with more actors, musicians, policy makers, and so many other fascinating people like actress and director Sheryl Hines.

They were looking for an unknown actress to play Larry David's wife. I said, well, how old is that guy? Isn't he old? And author David Sedaris. I feel like when you meet somebody and they'll say, well, I want to be a writer or I want to be an artist. And I say, well, is it all you care about? Because if it's not, it's going to be pretty hard for you if you're not on fire.

It's like opening the door of an oven and it's like, wow, you know, you take a step back. It's all they think about. It's all they talk about. It's all they care about. They don't have relationships. They're not good friends for other people. This is just what they're always focused on. Listen to the new season of Here's the Thing on the iHeart Radio app, Apple Podcasts, or

wherever you get your podcasts. All right, so Chuck, there's this idea that if we are regenerating ourselves every seven to 10 years, we're like the vast majority of our body cells regenerate. Why do we age and why do we die? It doesn't really make sense in that respect. Yeah. What they think is it has to do with your DNA actually in the cell. Our cells as we age, even the new ones that get replaced, which really stinks, become

what they call senescent, which means that they can't divide any longer. We've talked about the Hayflick limit before, or replicative senescence is basically how many times your cells can divide over its lifetime. Yeah. I think a fibroblast, which is cells of the connective tissue and mammals, is about 50 cell divisions. Yeah. Then it hits that point of senescence and it starts sending out repair signals to your

body that aren't necessary and that causes inflammation. We've talked about inflammation being the source of most of the original problems that will eventually lead to your death. Something becomes inflamed and leads to all kinds of problems, so there's no repair needed. It's a false signal. They're trying to come up with drugs now. There's one called Repamycine that tries to stop the cells from sending out those false signals, which is amazing.

Yeah. It's wonderful. There's another explanation for it as well, is that when our cells divide, especially over time as we age, they're basically making photocopies of themselves. You ultimately years down the road end up making photocopies of photocopies, and those don't tend to pan out very well. As far as analogies go, that one makes sense, that yes, we have brand new cells, but the DNA copies, the DNA blueprints that they're based on have seen better days many years

back. Yeah, that makes sense. That's a good way to say it. We also talked a little bit about whether or not the heart muscle itself replenishes itself in the cells. For a long time they had no idea, but now thanks to our buddy, Dr. Frissen, his pretty much, I don't think we said who he works with, did we? He works with a K, Karolinska team, just incredible scientists that are making amazing

advancements and trying to figure this stuff out. They did in fact find that the heart does replace itself, the muscle cells. About 1% of the heart muscles were replaced every year at age 25, and that falls over your lifetime to less than half a percent per year by the age 75. I spoke too soon, that does make sense. What they basically said is about half of your heart's muscle cells will be exchanged during a normal lifetime. Which is okay.

It is, but as it's slowing down over time, the heart's kind of essential. Yeah, but they're hoping again to develop drugs that can accelerate that process too. Yeah. I don't know how far along they are on that, but that'd be amazing. So this whole thing that came up to me, man, all of this raises this question to me. If you look at you or me or any living thing as an investment, like a molecular investment in the ability to reproduce, once you finish your reproductive age, then it does make sense that there would be built in this mechanism of aging and then death and then decay, which

is what we do. We return back to the earth to put it in kind of biblical terms. There's like that whole ashes to ashes, dust to dust thing. It is very, very true. If you look at us and you look at all living things as something that exchanges molecules with the external environment, takes them in, puts them out, and you look at us as all connected in that sense. Yeah, like we're just like a plant.

Exactly. Or we're just like a rock. We're all that stuff and those things are us because we're able to exchange basic ingredients. Then it makes total sense that a person would come together, be conceived, start dividing his cells, make more of itself, and then start to age and then die and decay, and then it would give something else a chance to come up from that again, right? But then it makes you wonder, what's the point of that? Think about it.

If we're just the same as plants, if the whole point is to just basically recycle materials because we are just recycling stuff from the environment and we're recycled as we die and decay, what is the point? Is our point just to be part of the carbon cycle so we're moving carbon in and out of ourselves and in and out of the environment and moving it around, or I don't understand what the point is of life, I guess, is what I'm saying? You're a nihilist. No, I'm not saying I don't believe that there isn't a point.

I'm just curious what it is because if we are the same as any other living thing and the definition of living is an exchange with an active exchange with the surrounding environment through breathing, through eating, whatever. Eating, pooping. Yes. And then if you take that a little further and say, well, clearly we're meant to reproduce or something like that, and then after that we age and die, what's the point? Why not just have one species of living thing and just let that do all of your carbon recycle

cycling or whatever? Yeah. I think, are you about to quit the show? Yeah, see what you mean. If we look at ourselves as a purely mechanical, serving a purely mechanical function on the planet. Like we are to the carbon cycle, what say evaporation is to rain cycle. Yeah.

Like we're a means of moving something along. Well I think that's when you, man this is getting philosophical, I think that's when you start getting into questions of the soul. Well, yeah, I mean it kind of makes you wonder like, well, why would there be more than one species? It would be much more efficient to just have one, maybe two, there's all these different ones. So why?

Yeah. The fact that that why is just sitting there and flashing neon lights definitely made me wonder, basically the opposite, it's made me think in a different direction than nihilistically. Right. You know? It's been going on for so long and so the point is to like make the most of your time on that?

Well I think that's a separate part of it. Because no matter what conclusion you come to, whether, nope, we're just a means of recycling carbon and that is it, kind of like a Gaia theory view of things. Or if you say, no, the fact that we're inefficient and redundant as far as that carbon recycling thing goes suggests that maybe there is a higher purpose to us, either way, I feel like you come to the conclusion or you should come to the conclusion that the one thing we do know is that we are here right now and the best thing we can do is make the absolute best of it for ourselves and for other people as well.

Yeah. And there are probably others out there that think the whole point is to make as much cash as you can so you can buy products. Edward Bernays would probably say that. Yes he would. Man, he lived that way, didn't he? Man, that's interesting. I think we should...

I'd love to tackle something philosophical and deep like the soul. Meaning of life? Yeah, that'd be tough. I mean... That'd be cool though. It would be cool. We don't delve into that very much. No, we should.

I'd like to do that. And consciousness. That's a really interesting one too, like it doesn't make any sense. I sense a very trippy way forward for this show. Yeah. We're going to start getting weird. I took a lot of acid this morning, so... Oh, that's great.

If you want to know more about some just weird trippy stuff, House Stuff Works has a surprising amount of it on there. I don't know, just try typing the word trippy into the search bar. You can also type, does your body really replace itself every seven years and it'll bring up this cool article. And I think I said search bar at some point in time, so how about some listener mail? I like how you specified you took a lot of acid. Just a little.

Yeah. A ton of it. All right, I'm going to call this multiple. We got like a bunch of emails in one day about people picking at our grammar and things. Oh, yeah. I just decided to read three of them because they're short. Okay. Hey guys, I generally enjoy the episodes, but you do have one issue with your grammar

and noun verb agreement. You tend to say there are many lines of evidence or there's lots of experiment showing instead of there are, not there is. When the pronoun refers to a plural subject, check yourselves next time, guys. You typically make the mistake about 10 times every show. Why don't you go recycle some carbon, pal? That's from Ken Keller in Temple Terrace, Florida. I always like to pick apart their emails too, because people usually make a mistake or two

in their own emails. Hey guys, this one's from Blair. I love the show. I hate to be nitpicky. They always say that, don't they? Yeah, right before they nitpick. But I have a grammar correction. It's been bugging me for months and Stonehenge was a major offender, at least one of you,

not naming names. I frequently use the word further when you really mean farther. The latter term is used for literal distances. Further is only supposed to be used figuratively. I didn't know that. Okay. So thanks, Blair. And then the last one, Phil, who was in English and grammar, pronunciation freak.

He says, hey guys, when there's an Italian word, you take your time to pronounce it properly. The same with Japanese and the Far East in general. So why don't you extend that same courtesy to English words? Because we're masters of the language. And I mean words actually in the UK vernacular, not American English. Salisbury? No, it's Salisbury. The Marlboro Downs?

Nope, Marlboro Downs. Well we're using the American vernacular because we're in America and recording as Americans. That's from Phil. I addressed all those, I think. Yeah, I think that's, I feel good about it. I think it's good and very big of you two have read those as listener mail. Why not? Nice job, man.

Yeah, we just, we don't profess to talk gooder than other people. We just do our little thing here in the studio, send it out into the world for people to pick apart. What we're doing is we're creating grammatical tableaus like that highlights magazine where it's like pick out the things that don't belong. That's what we're doing for you guys. Yeah, keep you entertained. If you didn't have something to complain about, it'd be so boring.

If you want to nitpick or compliment or suggest something, whatever, if you want to get in touch with us for any reason, you can do that by tweeting to S-Y-S-K podcast. You can join us on facebook.com slash stuff you should know. You can send us an email to stuffpodcast.howstuffworks.com. As always, join us at our home on the web, stuffyoushouldknow.com. Stuff You Should Know is a production of iHeartRadio. For more podcasts on my heart radio, visit the iHeartRadio app. Apple podcasts are wherever you listen to your favorite shows.

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I am Liv Albert, and let's talk about Mitt's Baby is the Greek and Roman mythology podcast here with all the dirty details and then some. Listen to Let's Talk About Mitt's Baby on the iHeartRadio app, apple podcasts, or wherever you get your podcasts.