March 31, 2015 • 37 mins
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.
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Episode Transcript
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Speaker 1 (00:01):
Welcome to Stuff you should know, a production of iHeartRadio. Hey,
and welcome to the podcast. I'm Josh Clark with Charles W.
Chuck Bryant, and guest producer Noel Noels in the house.
It's the It and the New Studio. Yeah, man, this
(00:22):
place is comfy, cozy. I like it. I wish um,
you know, 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 I'm dragging all apologies. Yeah,
same here. So if we're talking kind of slow or low,
or we just stopped talking for a little while, it's
(00:43):
where its tired. Yeah. We bumped into you at the
Hawks game last night. I know. Hey, how many does
that you know? Yeah? Just the bumping. Yep, we were
both at the Hawks. Gammy in the Hawks. One didn't
even know we were going. No. Look over in the line.
There's Josh and Yumi. Yeah that's great. There's Chuck and
Eddie yep, each other in an arena of eighteen thousand
(01:07):
bumping into someone. Is that it? That's all it holds.
I think it's something like that. It's a good a
lot of people. It's a good arena. Yeah, but you
had box seats because you're special. They were free o.
Mine were free to in. The nosebleeds Yeah, I like
just about every seat in that place. Yeah, it's not
too bad. I was. I was laughing about the nosebleeds
going in, But then I got up there. I was like,
(01:28):
this is great. Yeah you can see everything. Did your
nose actually bleed just twice? Yeah, once out of a
cheer excitement, and then once from the altitude and that
was more of a spray, right yeah, yeah, just covering everyone.
Everyone was like hawks, Boy, what a weird intro. It's
a little weird, um, But I mean it kind of
(01:50):
jibes a little bit because we're talking. Yeah, you're mentioning blood. Sure,
I was shedding cells and blood. You were like blood
is made up of sell and we shed tons of cells.
But before we get to that, right, there's the fact
of the podcast. You shed cells. Um. I want to
mention this one thing I read. Yeah, it's called I
(02:11):
think the title of the article is the Self is Moral.
It's about like where we get our identity of self from,
like where it's rooted. It was written by a person
named Nina Stromeyer, I believe is on aon magazine. Just
type in the self is moral aon It'll come up.
I'll get you there. Uh and uh. It Towards the beginning,
(02:33):
the author says, there's this very famous philosophical exercise, which
you know, philosophers love to do, like mental exercises. Yeah,
that's what that's all they have. So imagine you have
like kind of imagine you have like a ship, right,
like a boat, ye, a nice Yankee clipper okay, okay,
(02:54):
And this Yankee clipper is slowly, over time kind of
salvage for parts, okay, but rather than just being stripped,
like every time a part is taken out, it's replaced
and then over the course of like fifty one hundred years,
as each plank, as each bolt, as each like masked head,
even the thing the carved lady in front, yeah, eventually
(03:17):
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
(03:38):
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 all
the floors and the walls and the windows, Like when
does it cease to become that same house that was
built in nineteen thirty exactly? Isn't that cool? Yeah? It
(04:01):
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 like be replaced. Yeah, so
that the the person even after you reach your adult self. Yeah, physically,
(04:23):
by the time you die, assuming you're gonna die much later,
you're you are essentially a different person, at least on
the cellular level. Yeah. Thirty seven trillion cells ish, that's
how many we have. Yeah, that's what they estimate. And
I did a little looking into lifespans. Sounds like an
(04:43):
estimate thirty seven trillions. Yeah, what do you want, like
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, because that's all death is is
your your cells, you know, dying little by little. Well, yeah,
(05:04):
I mean if you think about it, chuck, one of
the things that like why do we die? If our
we'll get to all that, but it's intriguing, you know,
it started, you know, questions started popping up. So apparently
we gain about three months every three months of life
humanity every year that we progress, Like the average lifespans
(05:26):
spans by three months. Yeah, Like if you were born
in twenty twelve, the average lifespan is now and this
is the United States, is seventy eight point eight. If
you were born in nineteen oh one, it was about
forty seven and fifty 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,
(05:49):
every year, every year, just slowly creeping along. Yeah, Because
I think the article it was like when we're going
to live to be one hundred by average, and they
say by the year twenty one hundred, if things hold,
then the average human or American will be about one
hundred years old. I thought that, so I guess that
if things are steadily progressing, I had heard that like
our generation would be either the last or the first,
(06:13):
the last two to not hit triple digits or the
first two on average. Yeah. Yeah, again these are all guesses,
you know, so who knows. Plus if you believe in like,
uh things, speeding science, speeding up? Yeah, what is that?
Moore's law? Yea is at it? Yeah, applied to computer
or though in that case right right, but I mean
(06:35):
you can send it to other stuff. Yeah, then you
might think, you know, it's it's but you know, they
say it's not increasing like that. No, at least not
so far. Moore's law is exponential growth just adding three
months every years, non exponentials geometric. I think we're still
at non exponential growth definitely. Yeah, we're just adding three months. Yeah,
(06:57):
it's not bad though. That's pretty good average every four years.
That's an extra year. Yeah. Well, and it's interesting to
think about, you know, people that were born you know
a lot of our colleagues like eight years behind us.
We're going to live an average of two years longer. Yeah,
that seems unfair, sad. Yeah, I know, what did they do?
(07:18):
Just observe that we're thinking about our own deaths today. Yeah,
and chuck that there's this rumor theory legend maybe okay,
that your body regenerates itself, of your body regenerates itself
every year. Yeah, that's not true. No, it's not true,
(07:40):
but it was a very long standing rumor, and it
was actually based on science. Yeah, you know, not just
the idea that, oh, yeah, ourselves regenerate. So back of
the envelope estimate is that, you know, we regenerate ninety
five or ninety eight percent of ourselves every year. It
was early experimentation by injecting radio act of isotopes into
(08:01):
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,
for specific types of cell. Yeah. They don't do that
to humans anymore. No, it's very animals anything. It's a
very dumb thing to do. Sure, ejecting radiation exactly, Yeah, unless,
(08:23):
of course you know it's radiation treatment. That's true, which
is still a really weird thing if you think about it.
It's Yeah, I have a feeling it's gonna be like
one of those things we look back on as like
a primitive treatment. Yeah, yeah, yeah, I hope so. Um,
but there there was this long standing science for decades
or this idea, scientific idea that we regenerated ourselves by finally,
(08:47):
and I think two thousand five, Um, there was a
a researcher named doctor Jonas Freezing. He was Swedish. Dude's awesome.
He said, this whole urban legend is really bringing me down.
I want to figure out a way to really track
(09:09):
how often the human body regenerates itself. Yeah, and 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 two thousand
(09:30):
and five, in doctor Freeson's research, it was all a mystery. Yeah,
he figured out he basically put a very accurate time
stamp on how often human tissue and human cells regenerate themselves. Right,
So the way he did this is very clever. For
a long time, botanists knew that the trees around the
(09:52):
world contained a spike of carbon fourteen radiation, Yes, thanks
to humans and nuclear bombs. Exactly from nineteen fifty four
to nineteen sixty three, tree rings for tree growth around
the world show a big spike in carbon fourteen. Carbon
fourteen is naturally occurring too, So like just cosmic rays
(10:15):
from the Sun bombard Earth's atmosphere and create radioactive isotopes
by knocking electrons from particles in our atmosphere, right, those
radioactive particles become carbon fourteen, which is radioactive, and in
the atmosphere, carbon fourteen binds to oxygen and creates carbon dioxide,
(10:38):
which comes to Earth. Every living thing breathes this stuff in,
whether it's a plant, whether it's a human, Like we
just have C fourteen in our bodies. We also eat
plants exactly contain the C fourteen bids breathing it in,
and we also eat the animals that eat the plants
that in just C fourteen. Right, Yeah, so like we
(10:59):
got CAR fourteen in our bodies, that's right. But because
of the spike in carbon fourteen that was introduced to
the atmosphere from nuclear testing there there is a spike
in humans as well. So you can roughly age like
a human compared to another human if they were born
(11:22):
in say nineteen fifty nine, and one who was born
in nineteen seventy after there was that spike of carbon
fourteen had gone away, right, right, that's pretty cool. But
what doctor Freezen did is even cooler. He basically went
back to those tree trunks, those tree rings that show
a spike in carbon fourteen, and created a calendar of
(11:46):
carbon fourteen to Kay and basically said, Okay, on this date,
this is how much carbon fourteen was on Earth. And
if I take this cell and compare it, knowing that
carbon fourteen decays at a constant rate, yeah, I can
tell you exactly how old this cell is exactly. And
(12:07):
he used it to date cells and tissues and all
sorts of cool stuff. Yeah. He he went looking for
a marker and he found one due to our atomic
testing program. Yeah, which is pretty weird. Just released all
that junk in the atmosphere, and now all these years
later it has a nice use. Yeah, you know it does.
(12:28):
So we now know when we're gonna die, right, And
the reason he was able to use this as a marker, Chuckers,
is that, um, when you when you take a breath
of life, your first breath of life. That's right, and
you get some you get some of that C fourteen
into your DNA um and a steady amount stays in there,
(12:48):
like you don't keep ingesting C fourteen as far as
I understand, as far as your DNA goes, Oh okay,
once it's in your DNA, as your cells divide, yeah,
that original amount becomes divided evenly. Right, So the less
C fourteen that's in tissue, the older those that cell line,
(13:09):
is right, or the younger the actual cells are, right?
Is that right? I think so? Which would mean the
new cell the marker would be a fresh batch of
the C fourteen. No, it have less C fourteen? Oh really? Yeah,
let's say you have because the cell divided, Yes, exactly, Yeah,
like you have ten grams of C fourteen, which you don't.
(13:31):
I can't imagine that would be Like let's say you're
you're one cell that's never divided has ten Yeah, when
it divides into two, it's each of those two cells
is going to have five grants, and then two and
a half and then one point seven five and so
on and so on. Um, So, since you know that
C fourteen is generated at a constell rate, you know
that it decays that a half life of fifty seven
(13:52):
hundred and thirty years. You can look at the amount
of C fourteen and then also the decay of it
as well. Yeah, you can date things that are no
longer living too, to see when when they ingested that
C fourteen was. Yeah, he's a little like a bingo card.
He just from the calendar that he made with the
(14:13):
trees and he holds it up in the light and
that's how he determines it. It'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 seven to ten
years old, yes, in the body, and there are variances,
and of course we're going to talk about all that,
(14:34):
and right after this break, we're going to give you
a little primer on cells. So you know what all
this means, right, all right, Josh, we were promised to
(15:03):
sell primer and we like to deliver on those promises.
Here stuff you should know. So I guess we started
off by saying they're thirty seven trillion cells about in
the human body, give or take, and water makes up
about two thirds the weight of those cells. Oh yeah,
(15:23):
that's right. They're tiny. You need a microscope to seum
and it's like it's the tiniest thing that can still reproduce. Yeah.
And even though we have many different kinds of cells,
I think two hundred types, and within those cells there
are differences, but there are a lot of similarities with
all cells in their structure. Um. Namely, they have a
(15:45):
cell membrane, they have a nucleus. They have a nucleus.
I have more than one. And these membranes are what
allows nutrients to pass in and out, ways to pass
out water through osmosis travels in reverse, osmosis travels out. Yeah.
And what else you got your mitochondrian as well. That's
(16:08):
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 um. You know, your cells need
food to live just like your body does. But you
can't pass that that hamburger straight into your cell. It
needs to be broken down so your cell can use
it exactly into what adnosine triphosphate ATP is like the
(16:32):
the universal cell fuel, right. Yeah. So there's a lot
of stuff that the body does make I think you
need like twenty three. I think you need twenty three
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 use
(16:54):
proteins for everything from making muscles to making red blood
cells to um, you're mounting an immune response. Proteins are very,
very vital, and 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,
(17:16):
here's a peg leg for you. But I need this leg.
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 my body is 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. And you're
exactly right, So I'm chomping on the pig legs, like right,
(17:38):
just use your imagination for a second, sure, um, And yes,
I'm sorry too, uh, 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, Yeah,
And it can be glutamine, it can be um anything.
We if we're ingesting a protein, if we're ingesting amino acids,
(17:59):
before 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. Yeah, and that stuff that we
(18:22):
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 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
(18:44):
you are what you eat exactly? You know, you literally
are what you eat, quite literally, and then also chuck
it goes. It goes the other way as well. When
we excrete waste, when we exhale CO two that's taken
up by other things in the environment, is deposited into
the environment and it becomes part of the environment itself. Yeah.
So not only do we regenerate our cells, regenerate tissue
(19:09):
every on average seven to ten years, become almost wholly
a new version of ourselves. Yea, we are also the
boundary between us and the surrounding environment is really nonexistent
because there's a constant exchange of molecules. Yeah, we lose
(19:32):
on average, they say nine average adult male loses ninety
six million cells per minute, but we also replace those
at the rate of ninety six 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
(19:52):
that are replacing them. And I think, like you said
earlier before the break, that these the different types of
cell 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,
(20:13):
you know, different to make that job easier, which is
really cool too. Shows how versatile they are. Yes, you know,
like stem cells are very versatile. Super. So let's say
your skin. Yeah, your skin regenerates every two to four weeks.
I think, ye, so exactly, you get a new healthy
(20:33):
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
(20:56):
don't last long at all because it's such a harsh environment.
You know, you would expect him to last like weeks
and months and years, but I think, how long is it?
Five days? Yeah, that's nothing. But the structure of your guts,
they that are beneath that membrane lining that turns over
five days, they last about fifteen years. Yeah, it's it's
(21:18):
such a like a beautiful, elegant system. Yeah, that we
have to keep us alive. Red blood cells last about
one hundred and twenty 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
(21:39):
call them new bones, but they kind of are, you know, well, yeah,
I mean compared if you took your femur and somehow
compared it to your femur when you were fifteen years old, Like,
they are two totally different bones, even though they're your bones. Yeah,
they were in the same place, growing in the same
person with the same DNA. There's still different bones because
(22:02):
they're made of different cells. Ten years or so for
the bones, yeah, something like that. For the human skeleton,
three hundred to five hundred 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. Yeah.
You can apparently cut out ninety five percent of a
(22:22):
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 five percent of your liver. That's pretty amazing actually, yeah,
because it will just grow right back, kind of like
a hornet's nest. Uh. Interestingly, the inner lens cells of
your eye um form in your embryo and basically don't change. Yeah, Now,
(22:48):
is that why you have suffer from degeneration and vision?
That's what I would guess. Is that the reason? Yeah,
So with the corneo lens Chuck, when you're 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
(23:08):
set in stone. Like your corneal cells are as old
as you are, the 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
(23:30):
we have diseases like Alzheimer's and dementia are because the
cerebral cortex has long thought to not to 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
(23:52):
can learn new things. Our 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 quartex itself, they don't think. Who was
(24:12):
her name? Elizabeth Gould 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 as they think it does some
yeah here there, here there, But obviously we still have
(24:35):
to mention Alzheimer, so it's not it doesn't regenerate like
the rest of the body. Name close. Yeah, Alzheimer's also
maybe produced I guess by plaques rember plaque build up.
Oh yeah, in between your neurons that keep them from
firing as well. Yeah, that's it seems like we're so
close to figuring out the secret, you know. Yeah, to uh,
I don't know about not dying ever, I'm not talking immortality,
(25:00):
but um, 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. All right, So
(25:34):
chuck Um, there's this kind of there's this idea that
if we are regenerating ourselves every seven to ten years,
where like the vast majority of our body cells regenerate,
why do we age and why do we die? It
doesn't it doesn't really make sense in that respect. Yeah,
it's um. What they think is it has to do
(25:55):
with your DNA actually in the cell. Our cells as
we age, even the new ones to get replaced, which
really stinks, become what they call sentisent, which means that
they can't divide any longer. We've talked about the Hayflick
limit before, or replicative citizens is basically how many times
(26:15):
your cells can divide over its lifetime. Yeah, and I
think like a fibroblast, which is the cells of the
connective tissue in mammals, it's about fifty cell divisions. Yeah,
and then it hits that point of senticence and it
starts sending out repair signals to your body that aren't
necessary and that causes inflammation. And we've talked about inflammation
(26:38):
kind of being the source of most most of the
original problems that will eventually lead to your debt. Yeah,
you know. Yeah, something becomes inflamed and leads to all
kinds of problems, so there's no repair needed. So it's
a false signal. So they're trying to come up with drugs. Now,
there's one called repamycine that pries to stop the cells
(27:01):
from sending out those false signals, which is amazing. Yeah,
that would be wonderful. You know. 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. Yeah,
and you ultimately, years down the road, end up making
(27:22):
photocopies of photocopies and those don't tend to pan out
very well. So as far as analogies go, that one
kind of 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. Yeah, many years back. You know. Yeah,
(27:42):
that makes sense. It'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, and
for a long time they had no idea. But um, now,
thanks to our buddy doctor Frisson, He uh is pretty much.
(28:03):
I don't even think we said what his um who
he works with, did we? Uh? No, he works with
the with A K. Carolinska team. Yeah, just like incredible
scientists that are making like amazing advancements and trying to
figure the stuff out. But they did, in fact find
that the heart does replace itself the muscle cells. About
(28:23):
one percent of the heart muscles replaced every year at
age twenty five, and that falls over your lifetime to
less than half a percent per year by the age
seventy five. I spoke too soon. That does make sense. Yeah,
So what they basically said is about half of your
heart's muscle cells will be exchanged during a normal lifetime, Okay,
which is okay, it is, but it's slowing down over time.
(28:45):
I mean, the heart's kind of essential. Yeah, but they're
hoping again to develop drugs that can accelerate that process too. Yeah.
And I don't know how far along they are on that,
but that'd be amazing. So there's this whole thing that
kind and it came up to me man like that
I don't all of this raises this question to me, right, Yeah,
(29:06):
if you look at like you or me or any
living thing as as an investment, like a molecular investment
in the ability to reproduce. Right, Okay, once you finish
your reproductive age, then it does make sense that you
would just kind of there would be built in this
(29:28):
mechanism of aging and then death and then decay, which
is what we do. Yeah, we return back to the earth.
To put it in kind of biblical terms, there's like
that whole ashes to ashes dust to us thing. It
is very very true. And if you look at us
and you look at all living things as it is
(29:50):
something that exchanges molecules with the external environment, takes them in,
puts them out right, and you look at us as
all connect acted in that sense. Yeah, like we're just
like a plant exactly, or we're just like a rock,
Like we're all that stuff and those things are us
because we're able to exchange basic ingredients. Then it makes
(30:14):
total sense that a person would come together, be conceived,
start dividing as cells, you know, make more of itself,
and then start to age and then die in decay,
and then it would give something else a chance to
come up from that again. Right, sure, but then it
makes you it makes you wonder what's the point of that?
What I mean, like, think about it. If we're just
(30:35):
the same as plants, Like why are we all here? Yeah, Like,
if we're 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 in decay, what is
the point? Is our point just to be part of
the carbon cycle, so we're moving carbon in and out
(30:55):
of ourselves and in and out of the environment, moving
it around. Or I don't understand what the point is
of life, I guess is what I'm saying here nihilists. No,
I'm not saying I don't believe that there isn't a point.
I'm just curious what it is. Because because if we
are the same as any other living thing, and the
definition of living is an exchange with an active exchange
(31:20):
with the surrounding environment and breathing, true, eating whatever, yes,
then and then if you kind of take that a
little further and say, well, clearly we're meant to like
reproduce or something like that, and then after that we
age and die, what's the what's the point? Like why
not just have one species? Of living thing and just
(31:42):
let that do all of your carbon recycling or whatever. Yeah,
I think are you about to quit the show? Um? Yeah,
see what you mean? Like, um, if we look at
ourselves as a purely mechanical serving a purely mechanical function
right on the planet, like we are to the carbon cycle,
(32:02):
what say evaporation is to the 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 me wonder, like, well,
why would there be more than one species? It will
be much more efficient to just have one, maybe two.
(32:24):
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,
like we're only here for so long, and so if
there is the point is to make the most of
(32:45):
your time, well I think that's a separate that's a
separate part of it. Yeah, Because no matter what conclusion
you come to, whether nope, we're just a means of
recycling carbon and that is it. Yeah, kind of like
a Guya theory view of things. Or if you say no,
like the fact that we're inefficient and redundant as far
(33:05):
as that carbon recycling thing goes, Yeah, 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,
(33:27):
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. Yeah, Edward Burns would
probably say that, Yes, he would. Man, he lived that
way then, Man, that's interesting. I think we should. I'd
love to tackle something philosophical and deep, like the soul,
the meaning of life. Yeah, that'd be tough. I mean
that'd be cool, though, it would be cool. We don't
(33:48):
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 a sense, very trippy
way forward. For this show. Yeah, we're gonna start getting weird.
I took a lot of acid this morning. So that's
great if you want to know more about some just
weird trippy stuff. How stuff works has a surprising amount
(34:13):
of it on there. Um, 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, not just just a little. Yeah,
(34:35):
there's a lot out of it. Um, all right, I'm
gonna call this multiple we had. We got like a
bunch of emails in one day about people picking at
our grammar and things. Oh yeah, so I'm just decorded
to read three of them because they're short. Okay, hey, guys,
I generally enjoy the episodes, but you do have one
(34:55):
issue with your grammar and noun verb agreement. You tend
to say they're are many lines of evidence or there's
lots of experiment showing, instead of there are not. There
is boo when the pronoun refers to a plural subject.
Check yourselves next time, guys. You typically make the mistake
about ten times every show. Why don't you go recycle
(35:15):
some carbon power. That's from Kim Keller in Temple Terrorists, Florida.
I always like to pick apart their emails too, about
because people usually make a mistake or two in their
own emails. Hey, guys, system's from Blair. I love the show.
I hate to be nitpicky. They always say that, yeah,
right before they knitpick. But I have a grammar correction.
(35:37):
It's been bugging me for months, and Stonehenge was a
major offender. At least one of you not naming names
frequently used the word further when you really mean farther.
The latter term is used for literal distances. Further is
only supposed to be used figuratively. Huh. I didn't know that, Okay,
so thanks Blair. Yeah. And then the last one, Phil,
(35:58):
who was an 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 in 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 marl Borough Downs, Nope,
(36:24):
marl Browdowns. Well, we're using the American vernacular because we're
in America and recording as American. That's from Phil I had.
I've 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
(36:46):
profess to talk gooder than other people. We just do
our little thing here in the studio, send it out
into the world nice for people to pick apart. What
we're doing is we're creating grammatical tableaus like that Highlights
Magna ze, where it's like pick out the things that
don't belong. Yeah, that's what we're doing for you guys. Yeah,
keep you entertained. If you didn't have something to complain
(37:06):
about it, it'd be so boring. Yep. 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 SYSK podcasts. You
can join us on Facebook, dot com slash Stuff you
Should Know. You can send us an email to Stuff
Podcast at HowStuffWorks dot com, and as always, join us
(37:27):
at our home on the web. Stuff you Should Know
dot com. Stuff you Should Know is a production of iHeartRadio.
For more podcasts my Heart Radio, visit the iHeartRadio app,
Apple Podcasts, or wherever you listen to your favorite shows.
Welcome to Stuff you should know, a production of iHeartRadio. Hey,
and welcome to the podcast. I'm Josh Clark with Charles W.
Chuck Bryant, and guest producer Noel Noels in the house.
It's the It and the New Studio. Yeah, man, this
(00:22):
place is comfy, cozy. I like it. I wish um,
you know, 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 I'm dragging all apologies. Yeah,
same here. So if we're talking kind of slow or low,
or we just stopped talking for a little while, it's
(00:43):
where its tired. Yeah. We bumped into you at the
Hawks game last night. I know. Hey, how many does
that you know? Yeah? Just the bumping. Yep, we were
both at the Hawks. Gammy in the Hawks. One didn't
even know we were going. No. Look over in the line.
There's Josh and Yumi. Yeah that's great. There's Chuck and
Eddie yep, each other in an arena of eighteen thousand
(01:07):
bumping into someone. Is that it? That's all it holds.
I think it's something like that. It's a good a
lot of people. It's a good arena. Yeah, but you
had box seats because you're special. They were free o.
Mine were free to in. The nosebleeds Yeah, I like
just about every seat in that place. Yeah, it's not
too bad. I was. I was laughing about the nosebleeds
going in, But then I got up there. I was like,
(01:28):
this is great. Yeah you can see everything. Did your
nose actually bleed just twice? Yeah, once out of a
cheer excitement, and then once from the altitude and that
was more of a spray, right yeah, yeah, just covering everyone.
Everyone was like hawks, Boy, what a weird intro. It's
a little weird, um, But I mean it kind of
(01:50):
jibes a little bit because we're talking. Yeah, you're mentioning blood. Sure,
I was shedding cells and blood. You were like blood
is made up of sell and we shed tons of cells.
But before we get to that, right, there's the fact
of the podcast. You shed cells. Um. I want to
mention this one thing I read. Yeah, it's called I
(02:11):
think the title of the article is the Self is Moral.
It's about like where we get our identity of self from,
like where it's rooted. It was written by a person
named Nina Stromeyer, I believe is on aon magazine. Just
type in the self is moral aon It'll come up.
I'll get you there. Uh and uh. It Towards the beginning,
(02:33):
the author says, there's this very famous philosophical exercise, which
you know, philosophers love to do, like mental exercises. Yeah,
that's what that's all they have. So imagine you have
like kind of imagine you have like a ship, right,
like a boat, ye, a nice Yankee clipper okay, okay,
(02:54):
And this Yankee clipper is slowly, over time kind of
salvage for parts, okay, but rather than just being stripped,
like every time a part is taken out, it's replaced
and then over the course of like fifty one hundred years,
as each plank, as each bolt, as each like masked head,
even the thing the carved lady in front, yeah, eventually
(03:17):
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
(03:38):
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 all
the floors and the walls and the windows, Like when
does it cease to become that same house that was
built in nineteen thirty exactly? Isn't that cool? Yeah? It
(04:01):
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 like be replaced. Yeah, so
that the the person even after you reach your adult self. Yeah, physically,
(04:23):
by the time you die, assuming you're gonna die much later,
you're you are essentially a different person, at least on
the cellular level. Yeah. Thirty seven trillion cells ish, that's
how many we have. Yeah, that's what they estimate. And
I did a little looking into lifespans. Sounds like an
(04:43):
estimate thirty seven trillions. Yeah, what do you want, like
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, because that's all death is is
your your cells, you know, dying little by little. Well, yeah,
(05:04):
I mean if you think about it, chuck, one of
the things that like why do we die? If our
we'll get to all that, but it's intriguing, you know,
it started, you know, questions started popping up. So apparently
we gain about three months every three months of life
humanity every year that we progress, Like the average lifespans
(05:26):
spans by three months. Yeah, Like if you were born
in twenty twelve, the average lifespan is now and this
is the United States, is seventy eight point eight. If
you were born in nineteen oh one, it was about
forty seven and fifty 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,
(05:49):
every year, every year, just slowly creeping along. Yeah, Because
I think the article it was like when we're going
to live to be one hundred by average, and they
say by the year twenty one hundred, if things hold,
then the average human or American will be about one
hundred years old. I thought that, so I guess that
if things are steadily progressing, I had heard that like
our generation would be either the last or the first,
(06:13):
the last two to not hit triple digits or the
first two on average. Yeah. Yeah, again these are all guesses,
you know, so who knows. Plus if you believe in like,
uh things, speeding science, speeding up? Yeah, what is that?
Moore's law? Yea is at it? Yeah, applied to computer
or though in that case right right, but I mean
(06:35):
you can send it to other stuff. Yeah, then you
might think, you know, it's it's but you know, they
say it's not increasing like that. No, at least not
so far. Moore's law is exponential growth just adding three
months every years, non exponentials geometric. I think we're still
at non exponential growth definitely. Yeah, we're just adding three months. Yeah,
(06:57):
it's not bad though. That's pretty good average every four years.
That's an extra year. Yeah. Well, and it's interesting to
think about, you know, people that were born you know
a lot of our colleagues like eight years behind us.
We're going to live an average of two years longer. Yeah,
that seems unfair, sad. Yeah, I know, what did they do?
(07:18):
Just observe that we're thinking about our own deaths today. Yeah,
and chuck that there's this rumor theory legend maybe okay,
that your body regenerates itself, of your body regenerates itself
every year. Yeah, that's not true. No, it's not true,
(07:40):
but it was a very long standing rumor, and it
was actually based on science. Yeah, you know, not just
the idea that, oh, yeah, ourselves regenerate. So back of
the envelope estimate is that, you know, we regenerate ninety
five or ninety eight percent of ourselves every year. It
was early experimentation by injecting radio act of isotopes into
(08:01):
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,
for specific types of cell. Yeah. They don't do that
to humans anymore. No, it's very animals anything. It's a
very dumb thing to do. Sure, ejecting radiation exactly, Yeah, unless,
(08:23):
of course you know it's radiation treatment. That's true, which
is still a really weird thing if you think about it.
It's Yeah, I have a feeling it's gonna be like
one of those things we look back on as like
a primitive treatment. Yeah, yeah, yeah, I hope so. Um,
but there there was this long standing science for decades
or this idea, scientific idea that we regenerated ourselves by finally,
(08:47):
and I think two thousand five, Um, there was a
a researcher named doctor Jonas Freezing. He was Swedish. Dude's awesome.
He said, this whole urban legend is really bringing me down.
I want to figure out a way to really track
(09:09):
how often the human body regenerates itself. Yeah, and 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 two thousand
(09:30):
and five, in doctor Freeson's research, it was all a mystery. Yeah,
he figured out he basically put a very accurate time
stamp on how often human tissue and human cells regenerate themselves. Right,
So the way he did this is very clever. For
a long time, botanists knew that the trees around the
(09:52):
world contained a spike of carbon fourteen radiation, Yes, thanks
to humans and nuclear bombs. Exactly from nineteen fifty four
to nineteen sixty three, tree rings for tree growth around
the world show a big spike in carbon fourteen. Carbon
fourteen is naturally occurring too, So like just cosmic rays
(10:15):
from the Sun bombard Earth's atmosphere and create radioactive isotopes
by knocking electrons from particles in our atmosphere, right, those
radioactive particles become carbon fourteen, which is radioactive, and in
the atmosphere, carbon fourteen binds to oxygen and creates carbon dioxide,
(10:38):
which comes to Earth. Every living thing breathes this stuff in,
whether it's a plant, whether it's a human, Like we
just have C fourteen in our bodies. We also eat
plants exactly contain the C fourteen bids breathing it in,
and we also eat the animals that eat the plants
that in just C fourteen. Right, Yeah, so like we
(10:59):
got CAR fourteen in our bodies, that's right. But because
of the spike in carbon fourteen that was introduced to
the atmosphere from nuclear testing there there is a spike
in humans as well. So you can roughly age like
a human compared to another human if they were born
(11:22):
in say nineteen fifty nine, and one who was born
in nineteen seventy after there was that spike of carbon
fourteen had gone away, right, right, that's pretty cool. But
what doctor Freezen did is even cooler. He basically went
back to those tree trunks, those tree rings that show
a spike in carbon fourteen, and created a calendar of
(11:46):
carbon fourteen to Kay and basically said, Okay, on this date,
this is how much carbon fourteen was on Earth. And
if I take this cell and compare it, knowing that
carbon fourteen decays at a constant rate, yeah, I can
tell you exactly how old this cell is exactly. And
(12:07):
he used it to date cells and tissues and all
sorts of cool stuff. Yeah. He he went looking for
a marker and he found one due to our atomic
testing program. Yeah, which is pretty weird. Just released all
that junk in the atmosphere, and now all these years
later it has a nice use. Yeah, you know it does.
(12:28):
So we now know when we're gonna die, right, And
the reason he was able to use this as a marker, Chuckers,
is that, um, when you when you take a breath
of life, your first breath of life. That's right, and
you get some you get some of that C fourteen
into your DNA um and a steady amount stays in there,
(12:48):
like you don't keep ingesting C fourteen as far as
I understand, as far as your DNA goes, Oh okay,
once it's in your DNA, as your cells divide, yeah,
that original amount becomes divided evenly. Right, So the less
C fourteen that's in tissue, the older those that cell line,
(13:09):
is right, or the younger the actual cells are, right?
Is that right? I think so? Which would mean the
new cell the marker would be a fresh batch of
the C fourteen. No, it have less C fourteen? Oh really? Yeah,
let's say you have because the cell divided, Yes, exactly, Yeah,
like you have ten grams of C fourteen, which you don't.
(13:31):
I can't imagine that would be Like let's say you're
you're one cell that's never divided has ten Yeah, when
it divides into two, it's each of those two cells
is going to have five grants, and then two and
a half and then one point seven five and so
on and so on. Um, So, since you know that
C fourteen is generated at a constell rate, you know
that it decays that a half life of fifty seven
(13:52):
hundred and thirty years. You can look at the amount
of C fourteen and then also the decay of it
as well. Yeah, you can date things that are no
longer living too, to see when when they ingested that
C fourteen was. Yeah, he's a little like a bingo card.
He just from the calendar that he made with the
(14:13):
trees and he holds it up in the light and
that's how he determines it. It'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 seven to ten
years old, yes, in the body, and there are variances,
and of course we're going to talk about all that,
(14:34):
and right after this break, we're going to give you
a little primer on cells. So you know what all
this means, right, all right, Josh, we were promised to
(15:03):
sell primer and we like to deliver on those promises.
Here stuff you should know. So I guess we started
off by saying they're thirty seven trillion cells about in
the human body, give or take, and water makes up
about two thirds the weight of those cells. Oh yeah,
(15:23):
that's right. They're tiny. You need a microscope to seum
and it's like it's the tiniest thing that can still reproduce. Yeah.
And even though we have many different kinds of cells,
I think two hundred types, and within those cells there
are differences, but there are a lot of similarities with
all cells in their structure. Um. Namely, they have a
(15:45):
cell membrane, they have a nucleus. They have a nucleus.
I have more than one. And these membranes are what
allows nutrients to pass in and out, ways to pass
out water through osmosis travels in reverse, osmosis travels out. Yeah.
And what else you got your mitochondrian as well. That's
(16:08):
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 um. You know, your cells need
food to live just like your body does. But you
can't pass that that hamburger straight into your cell. It
needs to be broken down so your cell can use
it exactly into what adnosine triphosphate ATP is like the
(16:32):
the universal cell fuel, right. Yeah. So there's a lot
of stuff that the body does make I think you
need like twenty three. I think you need twenty three
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 use
(16:54):
proteins for everything from making muscles to making red blood
cells to um, you're mounting an immune response. Proteins are very,
very vital, and 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,
(17:16):
here's a peg leg for you. But I need this leg.
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 my body is 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. And you're
exactly right, So I'm chomping on the pig legs, like right,
(17:38):
just use your imagination for a second, sure, um, And yes,
I'm sorry too, uh, 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, Yeah,
And it can be glutamine, it can be um anything.
We if we're ingesting a protein, if we're ingesting amino acids,
(17:59):
before 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. Yeah, and that stuff that we
(18:22):
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 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
(18:44):
you are what you eat exactly? You know, you literally
are what you eat, quite literally, and then also chuck
it goes. It goes the other way as well. When
we excrete waste, when we exhale CO two that's taken
up by other things in the environment, is deposited into
the environment and it becomes part of the environment itself. Yeah.
So not only do we regenerate our cells, regenerate tissue
(19:09):
every on average seven to ten years, become almost wholly
a new version of ourselves. Yea, we are also the
boundary between us and the surrounding environment is really nonexistent
because there's a constant exchange of molecules. Yeah, we lose
(19:32):
on average, they say nine average adult male loses ninety
six million cells per minute, but we also replace those
at the rate of ninety six 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
(19:52):
that are replacing them. And I think, like you said
earlier before the break, that these the different types of
cell 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,
(20:13):
you know, different to make that job easier, which is
really cool too. Shows how versatile they are. Yes, you know,
like stem cells are very versatile. Super. So let's say
your skin. Yeah, your skin regenerates every two to four weeks.
I think, ye, so exactly, you get a new healthy
(20:33):
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
(20:56):
don't last long at all because it's such a harsh environment.
You know, you would expect him to last like weeks
and months and years, but I think, how long is it?
Five days? Yeah, that's nothing. But the structure of your guts,
they that are beneath that membrane lining that turns over
five days, they last about fifteen years. Yeah, it's it's
(21:18):
such a like a beautiful, elegant system. Yeah, that we
have to keep us alive. Red blood cells last about
one hundred and twenty 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
(21:39):
call them new bones, but they kind of are, you know, well, yeah,
I mean compared if you took your femur and somehow
compared it to your femur when you were fifteen years old, Like,
they are two totally different bones, even though they're your bones. Yeah,
they were in the same place, growing in the same
person with the same DNA. There's still different bones because
(22:02):
they're made of different cells. Ten years or so for
the bones, yeah, something like that. For the human skeleton,
three hundred to five hundred 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. Yeah.
You can apparently cut out ninety five percent of a
(22:22):
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 five percent of your liver. That's pretty amazing actually, yeah,
because it will just grow right back, kind of like
a hornet's nest. Uh. Interestingly, the inner lens cells of
your eye um form in your embryo and basically don't change. Yeah, Now,
(22:48):
is that why you have suffer from degeneration and vision?
That's what I would guess. Is that the reason? Yeah,
So with the corneo lens Chuck, when you're 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
(23:08):
set in stone. Like your corneal cells are as old
as you are, the 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
(23:30):
we have diseases like Alzheimer's and dementia are because the
cerebral cortex has long thought to not to 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
(23:52):
can learn new things. Our 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 quartex itself, they don't think. Who was
(24:12):
her name? Elizabeth Gould 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 as they think it does some
yeah here there, here there, But obviously we still have
(24:35):
to mention Alzheimer, so it's not it doesn't regenerate like
the rest of the body. Name close. Yeah, Alzheimer's also
maybe produced I guess by plaques rember plaque build up.
Oh yeah, in between your neurons that keep them from
firing as well. Yeah, that's it seems like we're so
close to figuring out the secret, you know. Yeah, to uh,
I don't know about not dying ever, I'm not talking immortality,
(25:00):
but um, 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. All right, So
(25:34):
chuck Um, there's this kind of there's this idea that
if we are regenerating ourselves every seven to ten years,
where like the vast majority of our body cells regenerate,
why do we age and why do we die? It
doesn't it doesn't really make sense in that respect. Yeah,
it's um. What they think is it has to do
(25:55):
with your DNA actually in the cell. Our cells as
we age, even the new ones to get replaced, which
really stinks, become what they call sentisent, which means that
they can't divide any longer. We've talked about the Hayflick
limit before, or replicative citizens is basically how many times
(26:15):
your cells can divide over its lifetime. Yeah, and I
think like a fibroblast, which is the cells of the
connective tissue in mammals, it's about fifty cell divisions. Yeah,
and then it hits that point of senticence and it
starts sending out repair signals to your body that aren't
necessary and that causes inflammation. And we've talked about inflammation
(26:38):
kind of being the source of most most of the
original problems that will eventually lead to your debt. Yeah,
you know. Yeah, something becomes inflamed and leads to all
kinds of problems, so there's no repair needed. So it's
a false signal. So they're trying to come up with drugs. Now,
there's one called repamycine that pries to stop the cells
(27:01):
from sending out those false signals, which is amazing. Yeah,
that would be wonderful. You know. 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. Yeah,
and you ultimately, years down the road, end up making
(27:22):
photocopies of photocopies and those don't tend to pan out
very well. So as far as analogies go, that one
kind of 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. Yeah, many years back. You know. Yeah,
(27:42):
that makes sense. It'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, and
for a long time they had no idea. But um, now,
thanks to our buddy doctor Frisson, He uh is pretty much.
(28:03):
I don't even think we said what his um who
he works with, did we? Uh? No, he works with
the with A K. Carolinska team. Yeah, just like incredible
scientists that are making like amazing advancements and trying to
figure the stuff out. But they did, in fact find
that the heart does replace itself the muscle cells. About
(28:23):
one percent of the heart muscles replaced every year at
age twenty five, and that falls over your lifetime to
less than half a percent per year by the age
seventy five. I spoke too soon. That does make sense. Yeah,
So what they basically said is about half of your
heart's muscle cells will be exchanged during a normal lifetime, Okay,
which is okay, it is, but it's slowing down over time.
(28:45):
I mean, the heart's kind of essential. Yeah, but they're
hoping again to develop drugs that can accelerate that process too. Yeah.
And I don't know how far along they are on that,
but that'd be amazing. So there's this whole thing that
kind and it came up to me man like that
I don't all of this raises this question to me, right, Yeah,
(29:06):
if you look at like you or me or any
living thing as as an investment, like a molecular investment
in the ability to reproduce. Right, Okay, once you finish
your reproductive age, then it does make sense that you
would just kind of there would be built in this
(29:28):
mechanism of aging and then death and then decay, which
is what we do. Yeah, we return back to the earth.
To put it in kind of biblical terms, there's like
that whole ashes to ashes dust to us thing. It
is very very true. And if you look at us
and you look at all living things as it is
(29:50):
something that exchanges molecules with the external environment, takes them in,
puts them out right, and you look at us as
all connect acted in that sense. Yeah, like we're just
like a plant exactly, or we're just like a rock,
Like we're all that stuff and those things are us
because we're able to exchange basic ingredients. Then it makes
(30:14):
total sense that a person would come together, be conceived,
start dividing as cells, you know, make more of itself,
and then start to age and then die in decay,
and then it would give something else a chance to
come up from that again. Right, sure, but then it
makes you it makes you wonder what's the point of that?
What I mean, like, think about it. If we're just
(30:35):
the same as plants, Like why are we all here? Yeah, Like,
if we're 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 in decay, what is
the point? Is our point just to be part of
the carbon cycle, so we're moving carbon in and out
(30:55):
of ourselves and in and out of the environment, moving
it around. Or I don't understand what the point is
of life, I guess is what I'm saying here nihilists. No,
I'm not saying I don't believe that there isn't a point.
I'm just curious what it is. Because because if we
are the same as any other living thing, and the
definition of living is an exchange with an active exchange
(31:20):
with the surrounding environment and breathing, true, eating whatever, yes,
then and then if you kind of take that a
little further and say, well, clearly we're meant to like
reproduce or something like that, and then after that we
age and die, what's the what's the point? Like why
not just have one species? Of living thing and just
(31:42):
let that do all of your carbon recycling or whatever. Yeah,
I think are you about to quit the show? Um? Yeah,
see what you mean? Like, um, if we look at
ourselves as a purely mechanical serving a purely mechanical function
right on the planet, like we are to the carbon cycle,
(32:02):
what say evaporation is to the 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 me wonder, like, well,
why would there be more than one species? It will
be much more efficient to just have one, maybe two.
(32:24):
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,
like we're only here for so long, and so if
there is the point is to make the most of
(32:45):
your time, well I think that's a separate that's a
separate part of it. Yeah, Because no matter what conclusion
you come to, whether nope, we're just a means of
recycling carbon and that is it. Yeah, kind of like
a Guya theory view of things. Or if you say no,
like the fact that we're inefficient and redundant as far
(33:05):
as that carbon recycling thing goes, Yeah, 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,
(33:27):
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. Yeah, Edward Burns would
probably say that, Yes, he would. Man, he lived that
way then, Man, that's interesting. I think we should. I'd
love to tackle something philosophical and deep, like the soul,
the meaning of life. Yeah, that'd be tough. I mean
that'd be cool, though, it would be cool. We don't
(33:48):
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 a sense, very trippy
way forward. For this show. Yeah, we're gonna start getting weird.
I took a lot of acid this morning. So that's
great if you want to know more about some just
weird trippy stuff. How stuff works has a surprising amount
(34:13):
of it on there. Um, 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, not just just a little. Yeah,
(34:35):
there's a lot out of it. Um, all right, I'm
gonna call this multiple we had. We got like a
bunch of emails in one day about people picking at
our grammar and things. Oh yeah, so I'm just decorded
to read three of them because they're short. Okay, hey, guys,
I generally enjoy the episodes, but you do have one
(34:55):
issue with your grammar and noun verb agreement. You tend
to say they're are many lines of evidence or there's
lots of experiment showing, instead of there are not. There
is boo when the pronoun refers to a plural subject.
Check yourselves next time, guys. You typically make the mistake
about ten times every show. Why don't you go recycle
(35:15):
some carbon power. That's from Kim Keller in Temple Terrorists, Florida.
I always like to pick apart their emails too, about
because people usually make a mistake or two in their
own emails. Hey, guys, system's from Blair. I love the show.
I hate to be nitpicky. They always say that, yeah,
right before they knitpick. But I have a grammar correction.
(35:37):
It's been bugging me for months, and Stonehenge was a
major offender. At least one of you not naming names
frequently used the word further when you really mean farther.
The latter term is used for literal distances. Further is
only supposed to be used figuratively. Huh. I didn't know that, Okay,
so thanks Blair. Yeah. And then the last one, Phil,
(35:58):
who was an 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 in 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 marl Borough Downs, Nope,
(36:24):
marl Browdowns. Well, we're using the American vernacular because we're
in America and recording as American. That's from Phil I had.
I've 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
(36:46):
profess to talk gooder than other people. We just do
our little thing here in the studio, send it out
into the world nice for people to pick apart. What
we're doing is we're creating grammatical tableaus like that Highlights
Magna ze, where it's like pick out the things that
don't belong. Yeah, that's what we're doing for you guys. Yeah,
keep you entertained. If you didn't have something to complain
(37:06):
about it, it'd be so boring. Yep. 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 SYSK podcasts. You
can join us on Facebook, dot com slash Stuff you
Should Know. You can send us an email to Stuff
Podcast at HowStuffWorks dot com, and as always, join us
(37:27):
at our home on the web. Stuff you Should Know
dot com. Stuff you Should Know is a production of iHeartRadio.
For more podcasts my Heart Radio, visit the iHeartRadio app,
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