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Does the body replace itself? · Stuff You Should Know

• 0:01
  Speaker 1: Welcome to Stuff you should know, a production of iHeartRadio. Hey,
• 0:11
  Speaker 1: and welcome to the podcast. I'm Josh Clark with Charles W.
• 0:14
  Speaker 1: Chuck Bryant, and guest producer Noel Noels in the house.
• 0:19
  Speaker 1: It's the It and the New Studio. Yeah, man, this
• 0:22
  Speaker 1: place is comfy, cozy. I like it. I wish um,
• 0:26
  Speaker 1: you know, I wish there was a chair version of
• 0:28
  Speaker 1: a water bed. I know this is a nappish little place. Yeah,
• 0:32
  Speaker 1: especially today, I think I'm I'm dragging all apologies. Yeah,
• 0:36
  Speaker 1: same here. So if we're talking kind of slow or low,
• 0:40
  Speaker 1: or we just stopped talking for a little while, it's
• 0:43
  Speaker 1: where its tired. Yeah. We bumped into you at the
• 0:46
  Speaker 1: Hawks game last night. I know. Hey, how many does
• 0:48
  Speaker 1: that you know? Yeah? Just the bumping. Yep, we were
• 0:52
  Speaker 1: both at the Hawks. Gammy in the Hawks. One didn't
• 0:54
  Speaker 1: even know we were going. No. Look over in the line.
• 0:57
  Speaker 1: There's Josh and Yumi. Yeah that's great. There's Chuck and
• 1:01
  Speaker 1: Eddie yep, each other in an arena of eighteen thousand
• 1:07
  Speaker 1: bumping into someone. Is that it? That's all it holds.
• 1:09
  Speaker 1: I think it's something like that. It's a good a
• 1:12
  Speaker 1: lot of people. It's a good arena. Yeah, but you
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  Speaker 1: had box seats because you're special. They were free o.
• 1:18
  Speaker 1: Mine were free to in. The nosebleeds Yeah, I like
• 1:21
  Speaker 1: just about every seat in that place. Yeah, it's not
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  Speaker 1: too bad. I was. I was laughing about the nosebleeds
• 1:26
  Speaker 1: going in, But then I got up there. I was like,
• 1:28
  Speaker 1: this is great. Yeah you can see everything. Did your
• 1:31
  Speaker 1: nose actually bleed just twice? Yeah, once out of a
• 1:36
  Speaker 1: cheer excitement, and then once from the altitude and that
• 1:39
  Speaker 1: was more of a spray, right yeah, yeah, just covering everyone.
• 1:43
  Speaker 1: Everyone was like hawks, Boy, what a weird intro. It's
• 1:47
  Speaker 1: a little weird, um, But I mean it kind of
• 1:50
  Speaker 1: jibes a little bit because we're talking. Yeah, you're mentioning blood. Sure,
• 1:55
  Speaker 1: I was shedding cells and blood. You were like blood
• 1:59
  Speaker 1: is made up of sell and we shed tons of cells.
• 2:01
  Speaker 1: But before we get to that, right, there's the fact
• 2:04
  Speaker 1: of the podcast. You shed cells. Um. I want to
• 2:08
  Speaker 1: mention this one thing I read. Yeah, it's called I
• 2:11
  Speaker 1: think the title of the article is the Self is Moral.
• 2:14
  Speaker 1: It's about like where we get our identity of self from,
• 2:18
  Speaker 1: like where it's rooted. It was written by a person
• 2:20
  Speaker 1: named Nina Stromeyer, I believe is on aon magazine. Just
• 2:24
  Speaker 1: type in the self is moral aon It'll come up.
• 2:28
  Speaker 1: I'll get you there. Uh and uh. It Towards the beginning,
• 2:33
  Speaker 1: the author says, there's this very famous philosophical exercise, which
• 2:38
  Speaker 1: you know, philosophers love to do, like mental exercises. Yeah,
• 2:41
  Speaker 1: that's what that's all they have. So imagine you have
• 2:44
  Speaker 1: like kind of imagine you have like a ship, right,
• 2:49
  Speaker 1: like a boat, ye, a nice Yankee clipper okay, okay,
• 2:54
  Speaker 1: And this Yankee clipper is slowly, over time kind of
• 2:57
  Speaker 1: salvage for parts, okay, but rather than just being stripped,
• 3:01
  Speaker 1: like every time a part is taken out, it's replaced
• 3:05
  Speaker 1: and then over the course of like fifty one hundred years,
• 3:08
  Speaker 1: as each plank, as each bolt, as each like masked head,
• 3:13
  Speaker 1: even the thing the carved lady in front, yeah, eventually
• 3:17
  Speaker 1: just gets replaced with something else. Yeah, a new carved
• 3:20
  Speaker 1: lady that speaks of the time, right, you know? Is
• 3:23
  Speaker 1: it still though, after every single part has been replaced,
• 3:27
  Speaker 1: the same ship that it was before? Yeah, I see
• 3:30
  Speaker 1: what you mean. I don't think that can be possible.
• 3:35
  Speaker 1: Why not, especially if it has the same name and
• 3:38
  Speaker 1: it's the same ship in the same place as before.
• 3:41
  Speaker 1: It was just slowly, over time moved out. True, where
• 3:46
  Speaker 1: does the self lie? Yeah, that's a good point, man,
• 3:49
  Speaker 1: Like redoing a house, same thing, Yeah, I mean all
• 3:52
  Speaker 1: the floors and the walls and the windows, Like when
• 3:54
  Speaker 1: does it cease to become that same house that was
• 3:57
  Speaker 1: built in nineteen thirty exactly? Isn't that cool? Yeah? It
• 4:01
  Speaker 1: is really cool. And the reason that it applies to
• 4:02
  Speaker 1: this episode is because over the course of your lifetime,
• 4:06
  Speaker 1: a significant portion pretty much all of the cells in
• 4:11
  Speaker 1: your body are going to like be replaced. Yeah, so
• 4:16
  Speaker 1: that the the person even after you reach your adult self. Yeah, physically,
• 4:23
  Speaker 1: by the time you die, assuming you're gonna die much later,
• 4:27
  Speaker 1: you're you are essentially a different person, at least on
• 4:30
  Speaker 1: the cellular level. Yeah. Thirty seven trillion cells ish, that's
• 4:36
  Speaker 1: how many we have. Yeah, that's what they estimate. And
• 4:39
  Speaker 1: I did a little looking into lifespans. Sounds like an
• 4:43
  Speaker 1: estimate thirty seven trillions. Yeah, what do you want, like
• 4:46
  Speaker 1: like give or take? Yeah, I did a little research
• 4:50
  Speaker 1: into lifespans just because this all sort of comes back to,
• 4:54
  Speaker 1: like your death basically, because that's all death is is
• 4:57
  Speaker 1: your your cells, you know, dying little by little. Well, yeah,
• 5:04
  Speaker 1: I mean if you think about it, chuck, one of
• 5:05
  Speaker 1: the things that like why do we die? If our
• 5:09
  Speaker 1: we'll get to all that, but it's intriguing, you know,
• 5:11
  Speaker 1: it started, you know, questions started popping up. So apparently
• 5:16
  Speaker 1: we gain about three months every three months of life
• 5:19
  Speaker 1: humanity every year that we progress, Like the average lifespans
• 5:26
  Speaker 1: spans by three months. Yeah, Like if you were born
• 5:28
  Speaker 1: in twenty twelve, the average lifespan is now and this
• 5:31
  Speaker 1: is the United States, is seventy eight point eight. If
• 5:34
  Speaker 1: you were born in nineteen oh one, it was about
• 5:36
  Speaker 1: forty seven and fifty years for men and women respectively.
• 5:40
  Speaker 1: But if you look at the ratio, it's still about
• 5:43
  Speaker 1: three months. Despite all our technologies, three months a year,
• 5:49
  Speaker 1: every year, every year, just slowly creeping along. Yeah, Because
• 5:52
  Speaker 1: I think the article it was like when we're going
• 5:54
  Speaker 1: to live to be one hundred by average, and they
• 5:56
  Speaker 1: say by the year twenty one hundred, if things hold,
• 5:59
  Speaker 1: then the average human or American will be about one
• 6:02
  Speaker 1: hundred years old. I thought that, so I guess that
• 6:06
  Speaker 1: if things are steadily progressing, I had heard that like
• 6:08
  Speaker 1: our generation would be either the last or the first,
• 6:13
  Speaker 1: the last two to not hit triple digits or the
• 6:16
  Speaker 1: first two on average. Yeah. Yeah, again these are all guesses,
• 6:20
  Speaker 1: you know, so who knows. Plus if you believe in like,
• 6:24
  Speaker 1: uh things, speeding science, speeding up? Yeah, what is that?
• 6:29
  Speaker 1: Moore's law? Yea is at it? Yeah, applied to computer
• 6:33
  Speaker 1: or though in that case right right, but I mean
• 6:35
  Speaker 1: you can send it to other stuff. Yeah, then you
• 6:38
  Speaker 1: might think, you know, it's it's but you know, they
• 6:41
  Speaker 1: say it's not increasing like that. No, at least not
• 6:44
  Speaker 1: so far. Moore's law is exponential growth just adding three
• 6:47
  Speaker 1: months every years, non exponentials geometric. I think we're still
• 6:52
  Speaker 1: at non exponential growth definitely. Yeah, we're just adding three months. Yeah,
• 6:57
  Speaker 1: it's not bad though. That's pretty good average every four years.
• 7:00
  Speaker 1: That's an extra year. Yeah. Well, and it's interesting to
• 7:03
  Speaker 1: think about, you know, people that were born you know
• 7:06
  Speaker 1: a lot of our colleagues like eight years behind us.
• 7:10
  Speaker 1: We're going to live an average of two years longer. Yeah,
• 7:15
  Speaker 1: that seems unfair, sad. Yeah, I know, what did they do?
• 7:18
  Speaker 1: Just observe that we're thinking about our own deaths today. Yeah,
• 7:24
  Speaker 1: and chuck that there's this rumor theory legend maybe okay,
• 7:31
  Speaker 1: that your body regenerates itself, of your body regenerates itself
• 7:36
  Speaker 1: every year. Yeah, that's not true. No, it's not true,
• 7:40
  Speaker 1: but it was a very long standing rumor, and it
• 7:42
  Speaker 1: was actually based on science. Yeah, you know, not just
• 7:45
  Speaker 1: the idea that, oh, yeah, ourselves regenerate. So back of
• 7:48
  Speaker 1: the envelope estimate is that, you know, we regenerate ninety
• 7:52
  Speaker 1: five or ninety eight percent of ourselves every year. It
• 7:55
  Speaker 1: was early experimentation by injecting radio act of isotopes into
• 8:01
  Speaker 1: human beings and then following their course and then making
• 8:04
  Speaker 1: estimates based on that led to this idea. It's called
• 8:08
  Speaker 1: pulse labeling, is it. Yeah. It's like tagging an animal
• 8:11
  Speaker 1: in the wild basically, right, but you're just tagging a cell, yeah,
• 8:14
  Speaker 1: for specific types of cell. Yeah. They don't do that
• 8:16
  Speaker 1: to humans anymore. No, it's very animals anything. It's a
• 8:19
  Speaker 1: very dumb thing to do. Sure, ejecting radiation exactly, Yeah, unless,
• 8:23
  Speaker 1: of course you know it's radiation treatment. That's true, which
• 8:28
  Speaker 1: is still a really weird thing if you think about it.
• 8:29
  Speaker 1: It's Yeah, I have a feeling it's gonna be like
• 8:31
  Speaker 1: one of those things we look back on as like
• 8:33
  Speaker 1: a primitive treatment. Yeah, yeah, yeah, I hope so. Um,
• 8:38
  Speaker 1: but there there was this long standing science for decades
• 8:41
  Speaker 1: or this idea, scientific idea that we regenerated ourselves by finally,
• 8:47
  Speaker 1: and I think two thousand five, Um, there was a
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  Speaker 1: a researcher named doctor Jonas Freezing. He was Swedish. Dude's awesome.
• 9:00
  Speaker 1: He said, this whole urban legend is really bringing me down.
• 9:04
  Speaker 1: I want to figure out a way to really track
• 9:09
  Speaker 1: how often the human body regenerates itself. Yeah, and the
• 9:13
  Speaker 1: biggest question has been the brain, specifically the cerebral cortex
• 9:20
  Speaker 1: and the heart and the heart muscles. I mean, they
• 9:23
  Speaker 1: want to know all this stuff, but those were the
• 9:24
  Speaker 1: two biggest mysteries. I think. Right, there's still the mysteries.
• 9:27
  Speaker 1: But if you went back to prior to two thousand
• 9:30
  Speaker 1: and five, in doctor Freeson's research, it was all a mystery. Yeah,
• 9:33
  Speaker 1: he figured out he basically put a very accurate time
• 9:37
  Speaker 1: stamp on how often human tissue and human cells regenerate themselves. Right,
• 9:43
  Speaker 1: So the way he did this is very clever. For
• 9:47
  Speaker 1: a long time, botanists knew that the trees around the
• 9:52
  Speaker 1: world contained a spike of carbon fourteen radiation, Yes, thanks
• 9:59
  Speaker 1: to humans and nuclear bombs. Exactly from nineteen fifty four
• 10:02
  Speaker 1: to nineteen sixty three, tree rings for tree growth around
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  Speaker 1: the world show a big spike in carbon fourteen. Carbon
• 10:11
  Speaker 1: fourteen is naturally occurring too, So like just cosmic rays
• 10:15
  Speaker 1: from the Sun bombard Earth's atmosphere and create radioactive isotopes
• 10:21
  Speaker 1: by knocking electrons from particles in our atmosphere, right, those
• 10:26
  Speaker 1: radioactive particles become carbon fourteen, which is radioactive, and in
• 10:32
  Speaker 1: the atmosphere, carbon fourteen binds to oxygen and creates carbon dioxide,
• 10:38
  Speaker 1: which comes to Earth. Every living thing breathes this stuff in,
• 10:43
  Speaker 1: whether it's a plant, whether it's a human, Like we
• 10:45
  Speaker 1: just have C fourteen in our bodies. We also eat
• 10:49
  Speaker 1: plants exactly contain the C fourteen bids breathing it in,
• 10:53
  Speaker 1: and we also eat the animals that eat the plants
• 10:55
  Speaker 1: that in just C fourteen. Right, Yeah, so like we
• 10:59
  Speaker 1: got CAR fourteen in our bodies, that's right. But because
• 11:05
  Speaker 1: of the spike in carbon fourteen that was introduced to
• 11:08
  Speaker 1: the atmosphere from nuclear testing there there is a spike
• 11:14
  Speaker 1: in humans as well. So you can roughly age like
• 11:18
  Speaker 1: a human compared to another human if they were born
• 11:22
  Speaker 1: in say nineteen fifty nine, and one who was born
• 11:25
  Speaker 1: in nineteen seventy after there was that spike of carbon
• 11:29
  Speaker 1: fourteen had gone away, right, right, that's pretty cool. But
• 11:32
  Speaker 1: what doctor Freezen did is even cooler. He basically went
• 11:36
  Speaker 1: back to those tree trunks, those tree rings that show
• 11:39
  Speaker 1: a spike in carbon fourteen, and created a calendar of
• 11:46
  Speaker 1: carbon fourteen to Kay and basically said, Okay, on this date,
• 11:52
  Speaker 1: this is how much carbon fourteen was on Earth. And
• 11:56
  Speaker 1: if I take this cell and compare it, knowing that
• 11:59
  Speaker 1: carbon fourteen decays at a constant rate, yeah, I can
• 12:03
  Speaker 1: tell you exactly how old this cell is exactly. And
• 12:07
  Speaker 1: he used it to date cells and tissues and all
• 12:10
  Speaker 1: sorts of cool stuff. Yeah. He he went looking for
• 12:13
  Speaker 1: a marker and he found one due to our atomic
• 12:17
  Speaker 1: testing program. Yeah, which is pretty weird. Just released all
• 12:21
  Speaker 1: that junk in the atmosphere, and now all these years
• 12:24
  Speaker 1: later it has a nice use. Yeah, you know it does.
• 12:28
  Speaker 1: So we now know when we're gonna die, right, And
• 12:31
  Speaker 1: the reason he was able to use this as a marker, Chuckers,
• 12:34
  Speaker 1: is that, um, when you when you take a breath
• 12:37
  Speaker 1: of life, your first breath of life. That's right, and
• 12:41
  Speaker 1: you get some you get some of that C fourteen
• 12:44
  Speaker 1: into your DNA um and a steady amount stays in there,
• 12:48
  Speaker 1: like you don't keep ingesting C fourteen as far as
• 12:51
  Speaker 1: I understand, as far as your DNA goes, Oh okay,
• 12:54
  Speaker 1: once it's in your DNA, as your cells divide, yeah,
• 12:59
  Speaker 1: that original amount becomes divided evenly. Right, So the less
• 13:04
  Speaker 1: C fourteen that's in tissue, the older those that cell line,
• 13:09
  Speaker 1: is right, or the younger the actual cells are, right?
• 13:13
  Speaker 1: Is that right? I think so? Which would mean the
• 13:15
  Speaker 1: new cell the marker would be a fresh batch of
• 13:19
  Speaker 1: the C fourteen. No, it have less C fourteen? Oh really? Yeah,
• 13:23
  Speaker 1: let's say you have because the cell divided, Yes, exactly, Yeah,
• 13:26
  Speaker 1: like you have ten grams of C fourteen, which you don't.
• 13:31
  Speaker 1: I can't imagine that would be Like let's say you're
• 13:33
  Speaker 1: you're one cell that's never divided has ten Yeah, when
• 13:37
  Speaker 1: it divides into two, it's each of those two cells
• 13:39
  Speaker 1: is going to have five grants, and then two and
• 13:42
  Speaker 1: a half and then one point seven five and so
• 13:44
  Speaker 1: on and so on. Um, So, since you know that
• 13:47
  Speaker 1: C fourteen is generated at a constell rate, you know
• 13:50
  Speaker 1: that it decays that a half life of fifty seven
• 13:52
  Speaker 1: hundred and thirty years. You can look at the amount
• 13:57
  Speaker 1: of C fourteen and then also the decay of it
• 14:02
  Speaker 1: as well. Yeah, you can date things that are no
• 14:04
  Speaker 1: longer living too, to see when when they ingested that
• 14:07
  Speaker 1: C fourteen was. Yeah, he's a little like a bingo card.
• 14:10
  Speaker 1: He just from the calendar that he made with the
• 14:13
  Speaker 1: trees and he holds it up in the light and
• 14:15
  Speaker 1: that's how he determines it. It's not true. But what
• 14:18
  Speaker 1: he did determine though, was which is really cool. And
• 14:21
  Speaker 1: this is sort of what we've been building toward, is
• 14:23
  Speaker 1: that most of your cells are about seven to ten
• 14:29
  Speaker 1: years old, yes, in the body, and there are variances,
• 14:32
  Speaker 1: and of course we're going to talk about all that,
• 14:34
  Speaker 1: and right after this break, we're going to give you
• 14:37
  Speaker 1: a little primer on cells. So you know what all
• 14:40
  Speaker 1: this means, right, all right, Josh, we were promised to
• 15:03
  Speaker 1: sell primer and we like to deliver on those promises.
• 15:07
  Speaker 1: Here stuff you should know. So I guess we started
• 15:11
  Speaker 1: off by saying they're thirty seven trillion cells about in
• 15:15
  Speaker 1: the human body, give or take, and water makes up
• 15:20
  Speaker 1: about two thirds the weight of those cells. Oh yeah,
• 15:23
  Speaker 1: that's right. They're tiny. You need a microscope to seum
• 15:27
  Speaker 1: and it's like it's the tiniest thing that can still reproduce. Yeah.
• 15:31
  Speaker 1: And even though we have many different kinds of cells,
• 15:34
  Speaker 1: I think two hundred types, and within those cells there
• 15:38
  Speaker 1: are differences, but there are a lot of similarities with
• 15:41
  Speaker 1: all cells in their structure. Um. Namely, they have a
• 15:45
  Speaker 1: cell membrane, they have a nucleus. They have a nucleus.
• 15:48
  Speaker 1: I have more than one. And these membranes are what
• 15:51
  Speaker 1: allows nutrients to pass in and out, ways to pass
• 15:54
  Speaker 1: out water through osmosis travels in reverse, osmosis travels out. Yeah.
• 16:04
  Speaker 1: And what else you got your mitochondrian as well. That's
• 16:08
  Speaker 1: where this is the important, really important thing, which is
• 16:11
  Speaker 1: basically what keeps your cells alive. That's the power center,
• 16:14
  Speaker 1: right yeah, and that's um. You know, your cells need
• 16:17
  Speaker 1: food to live just like your body does. But you
• 16:20
  Speaker 1: can't pass that that hamburger straight into your cell. It
• 16:24
  Speaker 1: needs to be broken down so your cell can use
• 16:26
  Speaker 1: it exactly into what adnosine triphosphate ATP is like the
• 16:32
  Speaker 1: the universal cell fuel, right. Yeah. So there's a lot
• 16:38
  Speaker 1: of stuff that the body does make I think you
• 16:40
  Speaker 1: need like twenty three. I think you need twenty three
• 16:44
  Speaker 1: amino acids, and like nine of them your body doesn't
• 16:47
  Speaker 1: really manufacture. So those are the nine non essential amino acids. Right,
• 16:51
  Speaker 1: And you use amino acids to build proteins, and use
• 16:54
  Speaker 1: proteins for everything from making muscles to making red blood
• 16:59
  Speaker 1: cells to um, you're mounting an immune response. Proteins are very,
• 17:04
  Speaker 1: very vital, and some of them you have to build
• 17:07
  Speaker 1: by eating stuff from your environment. Right. Yeah, So you
• 17:11
  Speaker 1: go out and you find yourself a nice pig and
• 17:13
  Speaker 1: you cut off its back leg. You say, sorry, pig,
• 17:16
  Speaker 1: here's a peg leg for you. But I need this leg.
• 17:19
  Speaker 1: I'm going to eat this leg. And what I'm really
• 17:21
  Speaker 1: eating is the muscle, and what I'm really really eating
• 17:24
  Speaker 1: is the glutamine. Yeah, and my body is going to
• 17:26
  Speaker 1: take this glutamine. It can make it itself, but it
• 17:29
  Speaker 1: doesn't hurt to have an extra little bit of glutamine. Yeah,
• 17:31
  Speaker 1: it doesn't hurt to have that pig leg. And you're
• 17:33
  Speaker 1: exactly right, So I'm chomping on the pig legs, like right,
• 17:38
  Speaker 1: just use your imagination for a second, sure, um, And yes,
• 17:42
  Speaker 1: I'm sorry too, uh, so you're eating the pig leg
• 17:45
  Speaker 1: and you're gaining this glutamine as a result, and your
• 17:48
  Speaker 1: body's metabolizing the glutamine and then reusing it, right, Yeah,
• 17:52
  Speaker 1: And it can be glutamine, it can be um anything.
• 17:56
  Speaker 1: We if we're ingesting a protein, if we're ingesting amino acids,
• 17:59
  Speaker 1: before eating any kind of food, sugars, whatever, our bodies
• 18:03
  Speaker 1: break it down into its constituent parts, and then a
• 18:07
  Speaker 1: lot of those constituent parts become part of our bodies. Yeah.
• 18:12
  Speaker 1: So if you think about it in this sense, when
• 18:15
  Speaker 1: we eat, when we breathe, we're taking in stuff we
• 18:19
  Speaker 1: need from the environment. Yeah, and that stuff that we
• 18:22
  Speaker 1: take in from the environment becomes a part of us
• 18:24
  Speaker 1: literally physically on the molecular level. It becomes a part
• 18:28
  Speaker 1: of us, for better or worse, depending on what it is.
• 18:30
  Speaker 1: Of course. Yeah, that's a that's a great I think
• 18:32
  Speaker 1: that's ultimately one of the side lessons of this whole
• 18:35
  Speaker 1: thing is we should take care of our environment because
• 18:38
  Speaker 1: that environment becomes us and we either suffer or thrive
• 18:42
  Speaker 1: as a result of it. You ever heard the expression
• 18:44
  Speaker 1: you are what you eat exactly? You know, you literally
• 18:46
  Speaker 1: are what you eat, quite literally, and then also chuck
• 18:49
  Speaker 1: it goes. It goes the other way as well. When
• 18:52
  Speaker 1: we excrete waste, when we exhale CO two that's taken
• 18:57
  Speaker 1: up by other things in the environment, is deposited into
• 18:59
  Speaker 1: the environment and it becomes part of the environment itself. Yeah.
• 19:03
  Speaker 1: So not only do we regenerate our cells, regenerate tissue
• 19:09
  Speaker 1: every on average seven to ten years, become almost wholly
• 19:14
  Speaker 1: a new version of ourselves. Yea, we are also the
• 19:20
  Speaker 1: boundary between us and the surrounding environment is really nonexistent
• 19:26
  Speaker 1: because there's a constant exchange of molecules. Yeah, we lose
• 19:32
  Speaker 1: on average, they say nine average adult male loses ninety
• 19:35
  Speaker 1: six million cells per minute, but we also replace those
• 19:43
  Speaker 1: at the rate of ninety six million per minute, yeah, roughly. Yeah. Yeah,
• 19:48
  Speaker 1: so that's the good news. So we've got all these
• 19:50
  Speaker 1: cells that we're losing, we've got all these new cells
• 19:52
  Speaker 1: that are replacing them. And I think, like you said
• 19:54
  Speaker 1: earlier before the break, that these the different types of
• 19:59
  Speaker 1: cell and then hence different tissues regenerate at a different rate, right, Yeah,
• 20:05
  Speaker 1: And they all have specialized jobs, and the cells are
• 20:08
  Speaker 1: often built in such a way to aid that job physically,
• 20:13
  Speaker 1: you know, different to make that job easier, which is
• 20:15
  Speaker 1: really cool too. Shows how versatile they are. Yes, you know,
• 20:20
  Speaker 1: like stem cells are very versatile. Super. So let's say
• 20:24
  Speaker 1: your skin. Yeah, your skin regenerates every two to four weeks.
• 20:30
  Speaker 1: I think, ye, so exactly, you get a new healthy
• 20:33
  Speaker 1: coating of skin every two to four weeks because your
• 20:36
  Speaker 1: epithelial cells are particularly good at regenerating themselves. That's right,
• 20:42
  Speaker 1: and that is well. I guess that would fall on
• 20:46
  Speaker 1: the low side obviously, if we're talking seven to ten years.
• 20:49
  Speaker 1: On the super low side, you have the cells that
• 20:52
  Speaker 1: line like you're intestine and your gut, and those things
• 20:56
  Speaker 1: don't last long at all because it's such a harsh environment.
• 20:59
  Speaker 1: You know, you would expect him to last like weeks
• 21:01
  Speaker 1: and months and years, but I think, how long is it?
• 21:04
  Speaker 1: Five days? Yeah, that's nothing. But the structure of your guts,
• 21:08
  Speaker 1: they that are beneath that membrane lining that turns over
• 21:12
  Speaker 1: five days, they last about fifteen years. Yeah, it's it's
• 21:18
  Speaker 1: such a like a beautiful, elegant system. Yeah, that we
• 21:22
  Speaker 1: have to keep us alive. Red blood cells last about
• 21:25
  Speaker 1: one hundred and twenty days. But then you have things
• 21:28
  Speaker 1: like cells in your bone which actually regenerate as well,
• 21:33
  Speaker 1: so your bones are over time, over a much longer
• 21:36
  Speaker 1: period of time, actually becoming I mean, I hate to
• 21:39
  Speaker 1: call them new bones, but they kind of are, you know, well, yeah,
• 21:44
  Speaker 1: I mean compared if you took your femur and somehow
• 21:49
  Speaker 1: compared it to your femur when you were fifteen years old, Like,
• 21:53
  Speaker 1: they are two totally different bones, even though they're your bones. Yeah,
• 21:56
  Speaker 1: they were in the same place, growing in the same
• 21:58
  Speaker 1: person with the same DNA. There's still different bones because
• 22:02
  Speaker 1: they're made of different cells. Ten years or so for
• 22:06
  Speaker 1: the bones, yeah, something like that. For the human skeleton,
• 22:09
  Speaker 1: three hundred to five hundred days. For the liver, very
• 22:12
  Speaker 1: important organ it is. And one of the other cool
• 22:14
  Speaker 1: things about the liver is it's just gangbusters that regenerating itself. Yeah.
• 22:19
  Speaker 1: You can apparently cut out ninety five percent of a
• 22:22
  Speaker 1: person's liver and it will grow back, and you won't
• 22:26
  Speaker 1: have full function, but it will function and you'll survive
• 22:29
  Speaker 1: with just five percent of your liver. That's pretty amazing actually, yeah,
• 22:33
  Speaker 1: because it will just grow right back, kind of like
• 22:35
  Speaker 1: a hornet's nest. Uh. Interestingly, the inner lens cells of
• 22:41
  Speaker 1: your eye um form in your embryo and basically don't change. Yeah, Now,
• 22:48
  Speaker 1: is that why you have suffer from degeneration and vision?
• 22:52
  Speaker 1: That's what I would guess. Is that the reason? Yeah,
• 22:53
  Speaker 1: So with the corneo lens Chuck, when you're when you're born,
• 22:57
  Speaker 1: when you're conceived, right, you are a cell that divides. Finally,
• 23:04
  Speaker 1: once that first division takes place, those corneal cells, they're
• 23:08
  Speaker 1: set in stone. Like your corneal cells are as old
• 23:11
  Speaker 1: as you are, the same age as you. Other cells
• 23:15
  Speaker 1: that make up different parts of the eyes they're far newer.
• 23:18
  Speaker 1: But your corneal cells, your cerebral cortex cells, they think, Yeah,
• 23:24
  Speaker 1: that's the one I mentioned. The brain and the heart muscles,
• 23:26
  Speaker 1: those are the two big ones. Because obviously the reason
• 23:30
  Speaker 1: we have diseases like Alzheimer's and dementia are because the
• 23:34
  Speaker 1: cerebral cortex has long thought to not to regenerate cells
• 23:39
  Speaker 1: at all. Now I think they believe that they do
• 23:45
  Speaker 1: in a very small number or different regions, like the
• 23:48
  Speaker 1: olfactory bulb supposedly does. Yeah, in the hippocampus, so we
• 23:52
  Speaker 1: can learn new things. Our sense of smell can be
• 23:55
  Speaker 1: refined over time. Yeah, And I think isn't that also
• 23:57
  Speaker 1: the reason the smell is very much tied to your memory,
• 24:02
  Speaker 1: probably like a smell can conjure up a memory more clearly. Yeah,
• 24:08
  Speaker 1: but the cerebral quartex itself, they don't think. Who was
• 24:12
  Speaker 1: her name? Elizabeth Gould Princeton did a lot of work
• 24:16
  Speaker 1: on this because it was just basically set in stone
• 24:20
  Speaker 1: for years like, no, it doesn't happen. And she did
• 24:22
  Speaker 1: a lot of work over the years trying to prove
• 24:25
  Speaker 1: that it did using tracer studies. And I think that
• 24:29
  Speaker 1: where they are now as they think it does some
• 24:32
  Speaker 1: yeah here there, here there, But obviously we still have
• 24:35
  Speaker 1: to mention Alzheimer, so it's not it doesn't regenerate like
• 24:38
  Speaker 1: the rest of the body. Name close. Yeah, Alzheimer's also
• 24:41
  Speaker 1: maybe produced I guess by plaques rember plaque build up.
• 24:45
  Speaker 1: Oh yeah, in between your neurons that keep them from
• 24:47
  Speaker 1: firing as well. Yeah, that's it seems like we're so
• 24:50
  Speaker 1: close to figuring out the secret, you know. Yeah, to uh,
• 24:55
  Speaker 1: I don't know about not dying ever, I'm not talking immortality,
• 25:00
  Speaker 1: but um, living much longer lives. Well, let's talk about that,
• 25:04
  Speaker 1: because all of this stuff kind of leads to that
• 25:07
  Speaker 1: question if we regenerate, so often why do we die?
• 25:11
  Speaker 1: And we'll address that right after this. All right, So
• 25:34
  Speaker 1: chuck Um, there's this kind of there's this idea that
• 25:38
  Speaker 1: if we are regenerating ourselves every seven to ten years,
• 25:41
  Speaker 1: where like the vast majority of our body cells regenerate,
• 25:46
  Speaker 1: why do we age and why do we die? It
• 25:50
  Speaker 1: doesn't it doesn't really make sense in that respect. Yeah,
• 25:53
  Speaker 1: it's um. What they think is it has to do
• 25:55
  Speaker 1: with your DNA actually in the cell. Our cells as
• 25:59
  Speaker 1: we age, even the new ones to get replaced, which
• 26:01
  Speaker 1: really stinks, become what they call sentisent, which means that
• 26:06
  Speaker 1: they can't divide any longer. We've talked about the Hayflick
• 26:09
  Speaker 1: limit before, or replicative citizens is basically how many times
• 26:15
  Speaker 1: your cells can divide over its lifetime. Yeah, and I
• 26:19
  Speaker 1: think like a fibroblast, which is the cells of the
• 26:22
  Speaker 1: connective tissue in mammals, it's about fifty cell divisions. Yeah,
• 26:27
  Speaker 1: and then it hits that point of senticence and it
• 26:30
  Speaker 1: starts sending out repair signals to your body that aren't
• 26:33
  Speaker 1: necessary and that causes inflammation. And we've talked about inflammation
• 26:38
  Speaker 1: kind of being the source of most most of the
• 26:42
  Speaker 1: original problems that will eventually lead to your debt. Yeah,
• 26:45
  Speaker 1: you know. Yeah, something becomes inflamed and leads to all
• 26:49
  Speaker 1: kinds of problems, so there's no repair needed. So it's
• 26:51
  Speaker 1: a false signal. So they're trying to come up with drugs. Now,
• 26:55
  Speaker 1: there's one called repamycine that pries to stop the cells
• 27:01
  Speaker 1: from sending out those false signals, which is amazing. Yeah,
• 27:05
  Speaker 1: that would be wonderful. You know. There's another explanation for
• 27:09
  Speaker 1: it as well, is that when our cells divide, especially
• 27:13
  Speaker 1: over time as we age, they're basically making photocopies of themselves. Yeah,
• 27:19
  Speaker 1: and you ultimately, years down the road, end up making
• 27:22
  Speaker 1: photocopies of photocopies and those don't tend to pan out
• 27:26
  Speaker 1: very well. So as far as analogies go, that one
• 27:30
  Speaker 1: kind of makes sense that, yes, we have brand new cells,
• 27:34
  Speaker 1: but the DNA copies, the DNA blueprints that they're based on,
• 27:39
  Speaker 1: have seen better days. Yeah, many years back. You know. Yeah,
• 27:42
  Speaker 1: that makes sense. It's a good way to say it.
• 27:44
  Speaker 1: We also talked a little bit about whether or not
• 27:48
  Speaker 1: the heart muscle itself replenishes itself in the cells, and
• 27:55
  Speaker 1: for a long time they had no idea. But um, now,
• 27:58
  Speaker 1: thanks to our buddy doctor Frisson, He uh is pretty much.
• 28:03
  Speaker 1: I don't even think we said what his um who
• 28:05
  Speaker 1: he works with, did we? Uh? No, he works with
• 28:09
  Speaker 1: the with A K. Carolinska team. Yeah, just like incredible
• 28:14
  Speaker 1: scientists that are making like amazing advancements and trying to
• 28:17
  Speaker 1: figure the stuff out. But they did, in fact find
• 28:20
  Speaker 1: that the heart does replace itself the muscle cells. About
• 28:23
  Speaker 1: one percent of the heart muscles replaced every year at
• 28:25
  Speaker 1: age twenty five, and that falls over your lifetime to
• 28:28
  Speaker 1: less than half a percent per year by the age
• 28:31
  Speaker 1: seventy five. I spoke too soon. That does make sense. Yeah,
• 28:34
  Speaker 1: So what they basically said is about half of your
• 28:37
  Speaker 1: heart's muscle cells will be exchanged during a normal lifetime, Okay,
• 28:42
  Speaker 1: which is okay, it is, but it's slowing down over time.
• 28:45
  Speaker 1: I mean, the heart's kind of essential. Yeah, but they're
• 28:48
  Speaker 1: hoping again to develop drugs that can accelerate that process too. Yeah.
• 28:53
  Speaker 1: And I don't know how far along they are on that,
• 28:54
  Speaker 1: but that'd be amazing. So there's this whole thing that
• 28:59
  Speaker 1: kind and it came up to me man like that
• 29:01
  Speaker 1: I don't all of this raises this question to me, right, Yeah,
• 29:06
  Speaker 1: if you look at like you or me or any
• 29:09
  Speaker 1: living thing as as an investment, like a molecular investment
• 29:16
  Speaker 1: in the ability to reproduce. Right, Okay, once you finish
• 29:20
  Speaker 1: your reproductive age, then it does make sense that you
• 29:25
  Speaker 1: would just kind of there would be built in this
• 29:28
  Speaker 1: mechanism of aging and then death and then decay, which
• 29:33
  Speaker 1: is what we do. Yeah, we return back to the earth.
• 29:36
  Speaker 1: To put it in kind of biblical terms, there's like
• 29:38
  Speaker 1: that whole ashes to ashes dust to us thing. It
• 29:41
  Speaker 1: is very very true. And if you look at us
• 29:45
  Speaker 1: and you look at all living things as it is
• 29:50
  Speaker 1: something that exchanges molecules with the external environment, takes them in,
• 29:55
  Speaker 1: puts them out right, and you look at us as
• 29:59
  Speaker 1: all connect acted in that sense. Yeah, like we're just
• 30:02
  Speaker 1: like a plant exactly, or we're just like a rock,
• 30:05
  Speaker 1: Like we're all that stuff and those things are us
• 30:07
  Speaker 1: because we're able to exchange basic ingredients. Then it makes
• 30:14
  Speaker 1: total sense that a person would come together, be conceived,
• 30:17
  Speaker 1: start dividing as cells, you know, make more of itself,
• 30:21
  Speaker 1: and then start to age and then die in decay,
• 30:24
  Speaker 1: and then it would give something else a chance to
• 30:26
  Speaker 1: come up from that again. Right, sure, but then it
• 30:28
  Speaker 1: makes you it makes you wonder what's the point of that?
• 30:33
  Speaker 1: What I mean, like, think about it. If we're just
• 30:35
  Speaker 1: the same as plants, Like why are we all here? Yeah, Like,
• 30:38
  Speaker 1: if we're if the whole point is to just basically
• 30:41
  Speaker 1: recycle materials, because we are just recycling stuff from the environment,
• 30:45
  Speaker 1: and we're recycled as we die in decay, what is
• 30:49
  Speaker 1: the point? Is our point just to be part of
• 30:52
  Speaker 1: the carbon cycle, so we're moving carbon in and out
• 30:55
  Speaker 1: of ourselves and in and out of the environment, moving
• 30:57
  Speaker 1: it around. Or I don't understand what the point is
• 31:01
  Speaker 1: of life, I guess is what I'm saying here nihilists. No,
• 31:04
  Speaker 1: I'm not saying I don't believe that there isn't a point.
• 31:06
  Speaker 1: I'm just curious what it is. Because because if we
• 31:11
  Speaker 1: are the same as any other living thing, and the
• 31:15
  Speaker 1: definition of living is an exchange with an active exchange
• 31:20
  Speaker 1: with the surrounding environment and breathing, true, eating whatever, yes,
• 31:25
  Speaker 1: then and then if you kind of take that a
• 31:29
  Speaker 1: little further and say, well, clearly we're meant to like
• 31:32
  Speaker 1: reproduce or something like that, and then after that we
• 31:35
  Speaker 1: age and die, what's the what's the point? Like why
• 31:39
  Speaker 1: not just have one species? Of living thing and just
• 31:42
  Speaker 1: let that do all of your carbon recycling or whatever. Yeah,
• 31:47
  Speaker 1: I think are you about to quit the show? Um? Yeah,
• 31:52
  Speaker 1: see what you mean? Like, um, if we look at
• 31:55
  Speaker 1: ourselves as a purely mechanical serving a purely mechanical function
• 31:59
  Speaker 1: right on the planet, like we are to the carbon cycle,
• 32:02
  Speaker 1: what say evaporation is to the rain cycle? Yeah, like
• 32:06
  Speaker 1: we're a means of moving something along. Well, I think
• 32:10
  Speaker 1: that's when you, man, this is getting philosophical. I think
• 32:12
  Speaker 1: that's when you start getting into questions of the soul.
• 32:16
  Speaker 1: Well yeah, I mean it kind of makes me wonder, like, well,
• 32:20
  Speaker 1: why would there be more than one species? It will
• 32:22
  Speaker 1: be much more efficient to just have one, maybe two.
• 32:24
  Speaker 1: There's all these different ones, so why. Yeah, the fact
• 32:27
  Speaker 1: that that why is just sitting there and flashing neon
• 32:30
  Speaker 1: lights definitely made me wonder basically the opposite. It's made
• 32:34
  Speaker 1: me think in a different direction than nihilistically, right, you know,
• 32:39
  Speaker 1: like we're only here for so long, and so if
• 32:41
  Speaker 1: there is the point is to make the most of
• 32:45
  Speaker 1: your time, well I think that's a separate that's a
• 32:47
  Speaker 1: separate part of it. Yeah, Because no matter what conclusion
• 32:50
  Speaker 1: you come to, whether nope, we're just a means of
• 32:53
  Speaker 1: recycling carbon and that is it. Yeah, kind of like
• 32:57
  Speaker 1: a Guya theory view of things. Or if you say no,
• 33:01
  Speaker 1: like the fact that we're inefficient and redundant as far
• 33:05
  Speaker 1: as that carbon recycling thing goes, Yeah, suggests that maybe
• 33:09
  Speaker 1: there is a higher purpose to us. Either way, I
• 33:12
  Speaker 1: feel like you come to the conclusion, or you should
• 33:15
  Speaker 1: come to the conclusion that the one thing we do
• 33:18
  Speaker 1: know is that we are here right now, and the
• 33:21
  Speaker 1: best thing we can do is make the absolute best
• 33:24
  Speaker 1: of it for ourselves and for other people as well. Yeah,
• 33:27
  Speaker 1: and there are probably others out there that think the
• 33:28
  Speaker 1: whole point is to make as much cash as you
• 33:30
  Speaker 1: can so you can buy products. Yeah, Edward Burns would
• 33:35
  Speaker 1: probably say that, Yes, he would. Man, he lived that
• 33:37
  Speaker 1: way then, Man, that's interesting. I think we should. I'd
• 33:41
  Speaker 1: love to tackle something philosophical and deep, like the soul,
• 33:44
  Speaker 1: the meaning of life. Yeah, that'd be tough. I mean
• 33:46
  Speaker 1: that'd be cool, though, it would be cool. We don't
• 33:48
  Speaker 1: delve into that very much, No, we should. I'd like
• 33:51
  Speaker 1: to do that. And consciousness that's a really interesting one too,
• 33:55
  Speaker 1: Like it doesn't make any sense a sense, very trippy
• 33:58
  Speaker 1: way forward. For this show. Yeah, we're gonna start getting weird.
• 34:01
  Speaker 1: I took a lot of acid this morning. So that's
• 34:03
  Speaker 1: great if you want to know more about some just
• 34:08
  Speaker 1: weird trippy stuff. How stuff works has a surprising amount
• 34:13
  Speaker 1: of it on there. Um, I don't know. Just try
• 34:15
  Speaker 1: typing the word trippy into the search bar. You can
• 34:18
  Speaker 1: also type does your body really replace itself every seven years?
• 34:21
  Speaker 1: And it'll bring up this cool article. And I think
• 34:24
  Speaker 1: I said search bar at some point in time. So
• 34:27
  Speaker 1: how about some listener mail. I like how you specified
• 34:31
  Speaker 1: you took a lot of acid, not just just a little. Yeah,
• 34:35
  Speaker 1: there's a lot out of it. Um, all right, I'm
• 34:38
  Speaker 1: gonna call this multiple we had. We got like a
• 34:40
  Speaker 1: bunch of emails in one day about people picking at
• 34:44
  Speaker 1: our grammar and things. Oh yeah, so I'm just decorded
• 34:48
  Speaker 1: to read three of them because they're short. Okay, hey, guys,
• 34:50
  Speaker 1: I generally enjoy the episodes, but you do have one
• 34:55
  Speaker 1: issue with your grammar and noun verb agreement. You tend
• 34:58
  Speaker 1: to say they're are many lines of evidence or there's
• 35:01
  Speaker 1: lots of experiment showing, instead of there are not. There
• 35:06
  Speaker 1: is boo when the pronoun refers to a plural subject.
• 35:09
  Speaker 1: Check yourselves next time, guys. You typically make the mistake
• 35:12
  Speaker 1: about ten times every show. Why don't you go recycle
• 35:15
  Speaker 1: some carbon power. That's from Kim Keller in Temple Terrorists, Florida.
• 35:23
  Speaker 1: I always like to pick apart their emails too, about
• 35:26
  Speaker 1: because people usually make a mistake or two in their
• 35:28
  Speaker 1: own emails. Hey, guys, system's from Blair. I love the show.
• 35:31
  Speaker 1: I hate to be nitpicky. They always say that, yeah,
• 35:35
  Speaker 1: right before they knitpick. But I have a grammar correction.
• 35:37
  Speaker 1: It's been bugging me for months, and Stonehenge was a
• 35:40
  Speaker 1: major offender. At least one of you not naming names
• 35:43
  Speaker 1: frequently used the word further when you really mean farther.
• 35:47
  Speaker 1: The latter term is used for literal distances. Further is
• 35:51
  Speaker 1: only supposed to be used figuratively. Huh. I didn't know that, Okay,
• 35:55
  Speaker 1: so thanks Blair. Yeah. And then the last one, Phil,
• 35:58
  Speaker 1: who was an English and grammar pronunciation freak, He says, hey, guys,
• 36:03
  Speaker 1: when there's an Italian word, you take your time to
• 36:05
  Speaker 1: pronounce it properly. The same with Japanese in the Far
• 36:08
  Speaker 1: East in general. So why don't you extend that same
• 36:10
  Speaker 1: courtesy to English words? Because we're masters of the language,
• 36:14
  Speaker 1: and I mean words actually in the UK vernacular, not
• 36:16
  Speaker 1: American English. Salisbury, No, it's Salisbury, the marl Borough Downs, Nope,
• 36:24
  Speaker 1: marl Browdowns. Well, we're using the American vernacular because we're
• 36:29
  Speaker 1: in America and recording as American. That's from Phil I had.
• 36:35
  Speaker 1: I've addressed all those. I think, yeah, I think that's
• 36:37
  Speaker 1: I feel good about it. I think it's good and
• 36:39
  Speaker 1: very big of you two have read those as listener mail.
• 36:42
  Speaker 1: Why not? Nice job man? Yeah, we just we don't
• 36:46
  Speaker 1: profess to talk gooder than other people. We just do
• 36:49
  Speaker 1: our little thing here in the studio, send it out
• 36:51
  Speaker 1: into the world nice for people to pick apart. What
• 36:55
  Speaker 1: we're doing is we're creating grammatical tableaus like that Highlights
• 36:59
  Speaker 1: Magna ze, where it's like pick out the things that
• 37:01
  Speaker 1: don't belong. Yeah, that's what we're doing for you guys. Yeah,
• 37:04
  Speaker 1: keep you entertained. If you didn't have something to complain
• 37:06
  Speaker 1: about it, it'd be so boring. Yep. If you want
• 37:09
  Speaker 1: to nitpick or compliment or suggest something whatever. If you
• 37:14
  Speaker 1: want to get in touch with us for any reason,
• 37:16
  Speaker 1: you can do that by tweeting to SYSK podcasts. You
• 37:20
  Speaker 1: can join us on Facebook, dot com slash Stuff you
• 37:22
  Speaker 1: Should Know. You can send us an email to Stuff
• 37:24
  Speaker 1: Podcast at HowStuffWorks dot com, and as always, join us
• 37:27
  Speaker 1: at our home on the web. Stuff you Should Know
• 37:29
  Speaker 1: dot com. Stuff you Should Know is a production of iHeartRadio.
• 37:35
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