March 23, 2019 • 45 mins
Throughout history, humans have faced the inexorable process of aging and death. We’ve dreamt up countless myths to explain why we age and what comes of seeking immortality, but what does science tell us about the process? Why do we age? What purpose does it serve in natural selection? Indeed, what can science offer us in the way of eternal youth? Robert Lamb and Joe McCormick seek to find out in this two-part Stuff to Blow Your Mind exploration. (Originally published Jan. 4, 2018)
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Episode Transcript
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Speaker 1 (00:05):
Hey, are you welcome to stuff to blow your mind?
My name is Robert Lamb and I'm Joe McCormick, and
it's Saturday. Time to venture into the vault, this time
with an episode about youth and aging. This is Eternal Youth,
Part one, originally published January four. This is one of
the episodes. I think we did a pair here where
we were sort of asking the question why animals age? Why?
(00:29):
Why why not just stay young? Forever? Yeah? Youth like
diamonds in the sun, right, um, forever young Alphaville. Hopefully
I don't remember if I referenced that track uh in
these episodes, but I hope I did. I think you
referenced it more recently when pointing out how creepy the
lyrics are that they they sound like a serial killer. Note, yeah,
they're they're they're super creepy. That track is the reason
(00:50):
I didn't share my You know a lot of people
are sharing, uh, these curated lists of what tracks they
listened to the most in the previous year. That was
your number one? It was, it was, it was, it
was up there way too much, and I have to
I can only share that with people if I can
also explain to them that I have a very creepy
interpretation of the song and therefore me listening to Forever
(01:12):
Young is like most people listening to death metal. I'm
gonna see you and raise you there because the other
Forever Young also has creepy lyrics if you listen to them.
Oh yeah, this is the Bob Dylan r. Yeah yeah yeah,
just go listen, you'll you'll see. All right, Well, let's
jump right into it. Welcome to Stuff to Blow your
Mind from how stuff dot com. Hey you, welcome to
(01:41):
Stuff to Blow your Mind. My name is Robert Lamb
and I'm Joe McCormick and Robert, I want to ask
you about a Greek commit go for it. You know,
the myth of tiffan Us. This is not one that
I am am readily familiar with off stuff of my head. Well,
it's one of those great ones with doomed lovers. Are
doomed lovers? Just fantastic? Yea? Is there? Does a god
show up the act particularly crappy towards mortals? Uh not.
(02:04):
I don't know if it's on purpose. You do get
Zeus being a jerk, but he might be like he's
a jerk by accident. Or maybe he's a jerk on purpose.
It's kind of hard to tell, because being a jerk
is kind of Zeus is default thing in general. Yeah,
Zeus in this myth acts kind of like the Monkeys
Paul and the classic short story, where you get the
wish but not quite in the way you wanted it.
(02:26):
So here's how it goes. And this is the version
that's in the Homeric Hymn to Aphrodite. So the myth
involves the goddess aos Aus is the goddess of Dawn,
and she falls in love with a mortal man from
Troy named tiffan Us. And this is horrible, right, It's
horrible for a goddess to fall in love with a
(02:48):
mortal because while the gods may live eternally, dining on
the ambrosia and just going on into the future, of course,
mortal people, as the name implies, will die. And she
hates this idea. She hates the idea that the man
she's fallen in love with will someday die while she
gets to go on living forever. She can't bear the
thought of it. So she goes to Zeus and she
(03:10):
makes a request, Well, you grant my lover Tiffanus eternal life,
and Zeus does it. Usually, you know, usually Zeus is
a jerk, but here he's like, yes, yes, I will
do that for you. Aos. Well, maybe he was busy
and he's just like, okay, yeah, I'm just go ahead
check this off the list because I've I've got this, uh,
this other torment in mind for another mortal. Right, don't
(03:31):
have time to be a jerk. Just bam, eternal life.
You will not perish and die like the other mortals.
But then it takes a dark turn. So let me
read from the translation of the Home Eric him to Aphrodite,
and this is translated by Hugh Evelyn White. Quote. So
also golden throned Aos wrapped away Tiffanus, who was of
(03:53):
your race and like the deathless gods. And she went
to ask the dark clouded son of ChRI On knows
that he should be deathless and live eternally. And Zeus
bowed his head to her prayer and fulfilled her desire. Okay,
so he's granning the wish. Too simple, was queenly Aos.
She thought not in her heart to ask youth for
(04:16):
him and to strip him of the slough of deadly age.
So while he enjoyed the sweet flower of life, he
lived rapturously with golden throned Aos, the early born by
the streams of ocean at the ends of the earth.
But when the first gray hairs began to ripple from
his comely head and noble chin, queenly Aos kept away
(04:39):
from his bed, though she cherished him in her house,
and nourished him with food and ambrosia, and gave him
rich clothing. But when loathsome old age pressed full upon him,
and he could not move nor lift his limbs. This
seemed to her in her heart the best counsel. She
laid him in a room and put to the shining doors.
(05:00):
There he babbles endlessly, and no more has strength at all,
such as once he had in his supple limbs. M Okay, well,
this makes me think Zeus probably just agreed to her request,
because all the gods know that mortals are going to
ask for immortality at some point or the other, and
they're probably not going to phrase the question properly, and
you should let them have it because it will teach
(05:22):
them a lesson. Well, yeah, he'll learn when he's old
and babbling and decrepit. But cannot die. Yeah, because global
myth cycles are filled with stories of of immortality gone wrong.
You know, it's either a wandering immortal who's doomed or
or lovers who you know, obtain a portion of immortality
(05:43):
and it's mishandled. There's a there's a wonderful example of
this in in Chinese myth with the the Elixir of
Immortality and the and the Woman of the Moon. Oh
does it come back to bite her? Or come back
to bite the person who wants it? Um it gets
There are a few different versions of the tale, but essentially,
you know, one person is immortal and the other is not.
(06:04):
That sort of thing, this this this mismatch that we
see president in the Greek tale as well. Man, why
are there so many myths and folk tales where people
get punished for wanting better than their lot in life? Well,
because you can't have it, I mean, especially when it
comes to things like avoiding death and avoiding aging. You're
(06:25):
not gonna get it. So there's something refreshing about stories
in which people do get it and it backfires because
that way we think, oh, well, this this thing that
I cannot have is actually not that great. So thank goodness,
I'm going to grow old and die. Yeah. I wonder
if it makes you feel like you're not so bad off.
It's like, well, I'm gonna die one day, but I
could be like Tiffanous, and that's even worse. Exactly, So,
(06:47):
I think the myth is sort of an embodiment of
this cruel fact about human nature. It's not just that,
as they say in Bravos, all men must die, but
that all people must decline. I think warrensy On put
it best. He said time treats everybody like a fool.
And I think that's the case. And no amount of lawyers, guns,
(07:07):
or money will get you out of this, that's right.
So on one hand, you've got the idea of death.
And death is a sort of unavoidable fact about biology
because living organisms are these finely tuned factories of chemical reactions,
and if you make substantial changes to the factory, say
by jamming a rock through part of it, or biting
(07:28):
part of it off, or filling it up with parasites
that gum up all the gears, the factory isn't going
to work the same anymore. It might not work at all.
Were physical creatures were subject to physical disruption. So the
potential for death is unavoidable. It's sort of part of
what it means to be alive. But aging not quite
(07:48):
so much. This steady time correlated decline in our biological fitness.
Why does that have to happen? That's not physically inevitable
in same way that death is. Yes, and this is
going to be the question we're gonna be discussing in
this pair of episodes. Now, we do want to drive home.
We're not going to get as much into some of
(08:10):
the mechanics of aging, like we're not going to get
into telomeres and telomerase and all and all of that,
although that's a wonderfully insightful topic onto itself. We're gonna
be talking more about the these this sort of evolutionary
function of aging, if it has one, right, aging is
something that has such a cost for the organisms that
(08:31):
undergo it, like tiffanus. What pays for it biologically? Why
does it exist? Now, to underscore the fact that aging
is not necessarily something that is inevitable, and especially not
aging as early as we do, we should maybe look
at some organisms that do not age in the same
way we do. Yeah, they're there are a number of organisms.
(08:53):
I'm sure a number of them come to to everyone's
mind here. You think of ancient hoary tortoise is stumbling
across the the ground, right, or perhaps your mind turns
with the greenland shark. Will come back to that one
in a second. But really one of the more insightful
examples here is the hydra, or at least individuals in
the Hydra genus. So you're talking about the monster that
(09:15):
gets its head cut off and grows two more. No,
as much as I do love the mythical hydra, now
these are the natural world. Hydra's tiny tentacled creatures that
need to continue to wow scientists because they have a
number of just wonderfully bizarre and monstrous capability. So they
can reproduce through a sexual butting. They have these mouths
(09:37):
that open up kind of like wounds in their body
and then close. There's some fabulous videos of them doing that.
It looks like you're staring into the mouth of hell.
And they have this seemingly natural inability to grow, grow old,
and die of natural causes. They boast low mortality rates
throughout their lives, and apparently this is according to when
(09:58):
Dr Owen Jones from the University of Southern Denmark. He
has claimed that it would take four hundred years for
of a hydro population to die of natural causes in
the lab. Wow, well, well that's a hardy species. Yeah,
So let me let me back some of that up
here with with some more the facts about the life
of the hydra, so their fertility rates remain constant their
(10:22):
entire lives, which, as will discuss is is pretty unique.
And according to Pomono College biology researcher Professor Daniel Martinez,
he has repeatedly found no evidence of sinescence in laboratory
caddled hydra. Yeah, and even goes so far as to
state that an individual hydra can live forever under the
(10:44):
right laboratory circumstances. Now, of course, that's the catch, right.
The hydro's natural environment offers sufficient hostilities to make natural
death by old age and impossibility. You got disease, predators,
water contamination. These are the things that usually all a
hydra off in due time, and likewise, scientists have yet
to create a hydra utopia that can sustain them indefinitely. Now,
(11:07):
this is a good point in the use of the
word immortality, which sometimes comes up when people are covering
organisms like these. There are a couple of different ways
you could look at immortality. One would be the Highlander
version or something like that, where there's just like nothing
that can kill you except maybe one or two little things,
but that you are generally invulnerable to death. And then
(11:30):
there'd be a different version of immortality that says, yeah,
you're vulnerable to death by injury or disease, you just
don't naturally grow old and die. You don't have a
cap on your life span. That would be more like
what are the elves of Middle Earth? Kind of like that,
Like they can be killed in battle, but they don't
grow old and die. Yeah. Well, I mean I would
argue that the immortals of Highlander are much the same,
(11:52):
Like there's a there's a very specific thing you can
do to kill them, uh, and technically anyone can do it.
It's just you've got to get the drop on a right.
We should mention that we're popping in little references to
Highlander to get you ready for the fact that one
day soon we're going to do a Science of Highlander
two episode and I'm not kidding. Yeah, you have advanced
warning so you can all go review at least the
(12:13):
first two films. Well, I would say just the first
two films actually, okay, but back to the hydra and
biological immortality in the real world. Yeah, so this is
a major point really for all organisms. The natural world
is generally sufficient to ensure mortality. It's dangerous, It's filled
with competitors, predators, pathogens, accidents, and all manner of additional hazards. Now,
(12:34):
humans and their captives tend to live in a very
privileged space, largely removed from the threat of predation. At least,
you'll find other creatures with no natural predators as well.
Typically these are apex predators, but that doesn't mean they
don't have to deal with all these other dangers. Well. No,
when you think about an apex predator, just because there's
nothing that tackles it and tears it apart and eats it,
(12:57):
that doesn't mean that it's not subject to attacks from
its environment, right. I mean, it of course is subject
to disease. But one of the other things to think
about with an apex predator is these creatures are very
often constantly at the edge of starvation. And so when
you see the antelope running from the cheetah or something.
Of course, the cheetahs trying to kill the antelope, but
(13:19):
by escaping, the antelope is sort of also trying to
kill the cheetah. It is starving the cheetah to death
by escaping. The cheat is a great example too, because
either cheetah injures itself in the pursuit of a prey,
especially if it tackles prey that is a little beyond
its ability or or is potentially beyond its ability, it
(13:42):
can sustain an injury that results in death, not because
it becomes infected or what have you, but because say,
a wounded limb on a cheetah can mean it cannot
pursue prey and it starves. Right. This is another thing
we often fail to appreciate in the natural world is
how how absolutely damning a small injury can be to
(14:04):
an organism that has to hunt or escape hunters to survive.
You also, of course, have read about large cats that
have turned man killer, and uh in some of these
cases I remember correctly, Sometimes it has to do with
the decline of dental health, like their their inability to
depend on their their teeth for their traditional prey, and
(14:26):
it leads to sort of a desperate switch in their
their selection of prey. So anyway, most most individuals are
going to die or be killed before they can grow old,
so there's already a low probability of being alive and
reproductive at an advanced age. Still, hyders are are really
interesting because it give us a real world of world
example of how how undying creatures would work on a
(14:49):
biological level. They're hardy, their regenerative they have they have
evolved to thrive in harsh environments, and it actually reminds
me of an alien species that shows up in Ian
m banks. The Culture series, of course, go into the
Culture Yeah, I mean he he always managed to work
so many wonderful scientific topics into his his books, and
one of these topics is biological immortality. Alright, So we
(15:12):
meet in the really the very first Culture book, we
meet the Adherens. And here's just a quick quote. The
Adherens themselves had evolved on their planet a deer as
the top monster from a whole planet full of monsters.
The frenetic and savage ecology of a deer in its
early days had long since disappeared, and so had all
(15:33):
the other homeworld monsters. Except those in zoos. But the
Adherens had retained the intelligence that made them winners, as
well as the biological immortality, which, due to the viciousness
of the fight for survival back then, not to mention
a deer's high radiation levels, had been an evolutionary advantage
rather than a recipe for stagnation. Now, I think that
(15:54):
might be something interesting to come back to, maybe in
the second episode, and consider whether it would actually work
that way and what the effect of high mortality at
different stages of life would have on the life span
of an organism. Alright, Well, on that note, let's take
a quick break, and when we come back, we're gonna
roll through just a few other long living organisms, uh
(16:15):
that are not a hydra or an endearing thank alright,
we're back. So I mentioned the greenland shark earlier. This
one is pretty impressive because greenland sharks live where we
understand now about four hundred years uh. And this is
an exclusively wild species as well. This is not something
(16:36):
you're gonna find growing old and fat and an aquarium.
These are sharks generally don't do very well in aquariums. Correct. Yeah,
it's and no one has a greenland shark that I
am aware of as of this recording. At two thousand sixteen,
University of Copenhagen study estimated that one female greenland shark
UH had it was, it was at least four hundred
(16:56):
years old, and that the species doesn't even reach sexual
mature until one fifty. So think of that, not until
they've reached an age that exceeds every human being who
has ever lived, and that's counting unverified but not mythic
individual humans, right, not the Highlanders or you know, like
you know, biblical days. Right. Yeah. Now, of course that's
(17:20):
still not the oldest animal, because there was a clam
named Ming. This is the first line of a children's book.
I know it should be. Well, I would be. I
would actually be surprised if there's not a children's book
about Ming. There was a clam named Ming. Yeah, and
Ming did love to sing. Yeah, it's this here writes itself.
So technically Ming was a qua hog clam. This is
(17:43):
uh an Arctic variety of clam, and it was discovered
off the coast of Iceland in two thousand six Now
at the time they thought it was around four hundred
and five years old, so they named it after the
Ming dynasty that would have ruled China at this time.
Later estimates, and this is supported by urban dating, would
boost that age to five hundred and seven years half
(18:04):
a millennium. So this means that the creature was born
in fourteen and that's still within the Mean dynasty which
went four And to throw another point of context in there,
this was around the time that Leonardo da Vinci completed
the Last Supper. It's the year Portuguese explorer Vasco da
(18:24):
Gama reached India. That's when this this thing was was
born and then it died in two thousand and six,
there was a clam named Ming, and Ming remembered everything.
There you go now the plant where world, of course
has all of this beat uh. There's the great basin
bristle cone Pine or Pinus along Gava and it can
(18:45):
only lived to over five thousand years of age, and
that takes us back to the very end of the
Neolithic period. Work on Stonehenge had begun. This was the
age of the Pharaoh, so it lived through the rise
and the fall of the Roman Empire. Now, of course
this highlights that different kinds of organisms have massively different
potential when it comes to lifespan. Yeah, and of course
(19:06):
plants are very different from animals. This reminds me that
one of the ideas that was brought up recently. I
believe on our discussion module on on Facebook or Facebook group,
that we should do something just on plants, like what
is a plant? To sort of strip it down to
its basics. I kind of like that idea, it's a
really lazy animal. Well, I've got a really lazy one.
(19:26):
Then for you here, Uh, there's at least one step
beyond the great basin bristle Cone pine. And this is
something you'll find in fish Lake National Park in Utah
here in the United States, Uh, the quaking aspen tree,
which is also the state tree by the way, also
known as the trembling Giant or pando, which means I spread.
(19:48):
So what we have here and this is this is
one where not everybody necessarily agrees with that this might
be sort of bending the definition a little bit of
what is a long living organism. But what we have
here is a single clone of quaking asp been connected
by a single extensive roots system that's roughly the size
of Vatican City, a hundred and six acres thirteen million
pounds and it's all eighty thousand years old. So what
(20:12):
you're talking about is a forest that is all sort
of in some way the same organism. Right, you can.
It's it's not as simple as the clam was born
in the century and it died in this one. But
if you if you've been the definition enough and you
accept this as an example, we're talking about a thing
that has lived since humans first left Africa to colonized
(20:34):
the world. Wow. Yeah, Now, Robert, here's something I've always
wondered about. Okay, dinosaurs. You got to wonder how long
they lived, especially because this gets warped by our sense
of history. I think because they lived so long ago,
you just naturally go to this completely illogical place where
they must have lived a long time. Like, Okay, tyrannosaurs
(20:57):
rex lived maybe three hundred years. I mean they they
they've got very big, so you have to imagine it
took them a while to grow as big as they did.
This would take a lot of years of eating and
cell division and all that. So so surely they had
very long lifespans. Well, this used to be the main theory,
and this was in part because of ai their size
(21:17):
or at least the size of many of the specimens
and the fact that we thought, well, they were essentially
giant reptiles, and so based on slow reptile growth rates
and their size, they said, well, big dinos probably lived
several hundred years. But today paleonto just believed they grew
more like birds and mammals, and this cuts back on
their lifespans somewhat. So, for instance, the Field Museum of
(21:39):
Chicago they have this, uh, this these t rex remains
that they named Sue. Sue. Sue is great. Yeah, she's
a wonderful specimen. You get to look right up at
her and get a sense of the true size of
this this amazing species. Can I say something embarrassing, go
for it. I cried a little bit at Sue. Yeah,
I'm not kidding. When we were in Chicago and I'm
(22:00):
just sitting there looking at Sue for a while, I
did something to me a little misty. That's that's beautiful.
I I can understand it because it is like looking
back in time to encounter, you know, a fossil like that.
So Sue is a rather big specimen, or at least
the fossil remains are rather large and speak to a
large specimen. They we think now that she probably achieved
(22:23):
adult size at age twenty and lived to a ripe
old age of twenty nine. So I am now older
than than this Tyrannosaurus rex was when it dies exactly. Yeah,
and uh, and you just underlines that what you had
with the dinosaurs was likely rapid growth but short lives.
Now one sort of side question that we won't fully explore.
(22:46):
But this this may raise the question, well, dinosaurs have
cancer because you're thinking about rapid growth, right of course. Well,
basically this is the question we have to come back to.
But based on the research I was looking at, we
only have evidence of the haddress sores the duck build
dinosaurs developing any form of cancer. Now that's the caveat
that's the only the only ones we have evidence of
(23:08):
that that occurring in. But it is interesting to think
of like the late model dinosaur as being the place
where we see the cancer showing up. We got to
come back and do an episode on dinosaur cancer in
the future. Yeah, by all means, well, I want to
do something that we often end up having to do,
which is that after we've explored a concept for a while,
it becomes more and more complicated, and our lay definition
(23:30):
starts to get a little less useful. So I think
maybe we should ask the question what actually is aging? Now?
We have a pretty uh intuitive, gut level understanding of
what aging is. We know when we see it, But
how would you define it? I mean, it's it is
something different from death, and it is something different from
(23:53):
just like, I don't know, your skin getting wrinkles or
something like that. What what is the actual scientific thing
that all of the stuff we call aging has in common. Well,
this is a great question. I mean, on one hand,
it is closely tied to death, and I think one
of the stumbling blocks is that will will alreadily admit
that aging is something that our body does, but we
(24:15):
tend there's tends to it tends to be a cultural
bearer in place to saying that death is something our
body does. We like to push that off onto some
sort of external force of of fade or anthropomorphized dread,
you know, or some sort of limit imposed on us
by the gods. Well, yeah, yeah, death is something that
we more often characterize as happening to us. Death happens
(24:37):
to you. It's not something you do, though, there you
can kind of see that the division between the death
and the aging death I was talking about at the
beginning of this episode comes into focus, because of course
death can happen to you if you get a rock
jammed through your you know, through your body or something
like that. But the body does seem to naturally progress
(24:58):
toward death of time, and that's kind of a weird question,
like why would it do that. We will definitely explore
the science behind that question in the second episode that
we will look at some archaic ancers to it in
this one, because when especially with the human, with the
human experience of aging and death, it seems completely illogical
that in many cases a human being would spend the
(25:22):
majority of its life progressing towards death, Like the majority
of your life is declined. Uh, that just feels either
gross or cruel or just like a horrible design flaw
or yeah, or nonsensical. Where's my eternal youth? Doesn't make
any sense? Um? So. In his book The Evolutionary Biology
(25:44):
of Aging published by Oxford University Press, the biologist Michael R.
Rose defined aging in the following way quote a persistent
decline in the age specific fitness components of an organism
due to internal physic eological deterioration. Now Rose actually has
offered has said that in some ways we might need
(26:06):
to update that understanding a little bit to accommodate for
some new discoveries. But I think this is a good
place to start. So let's look at the parts of
that definition. Number one, it's persistent decline, which means aging
only goes one way. It's not characterized by say decline
and rebound. And some organisms do have patterns like this
is not quite aging, like you can think about the
(26:28):
jellyfish that have regenerative capabilities where they can revert to
a younger stage of life. But then so it's persistent decline.
And then in the quote age specific fitness components biological
fitness meaning the ability to survive and reproduce. So these
are the things that are persistently in decline. You become
(26:48):
less able to survive and less able to reproduce. And
then it's due to internal physiological deterioration. So it's saying
that this persistent decline in the ability to survive and
reproduce is not due to disease or injury, but to
something deteriorating within the body. Tissues themselves, yeah, this is
(27:11):
this makes me think, of course, of the phrase cradle
to the grave and with the with the hydra. The
cradle to the grave is kind of a straight line
with reproduction taking place at all levels until something happens
to kill it. Whereas most of the models that that
we look at, most of the models we looked at
in researching this episode, it's more of a of a
(27:32):
rise rising and lowering. There's a rise towards like peak
sexual maturity, peak reproductive maturity, and then a decline. Yeah. Yeah,
and then it gets even stickier, right because we we've
just tried to be very careful and how we're defining this.
But then I realized that I said the it's a
decline in the ability to survive and reproduce, not due
(27:53):
to disease or injury. But a lot of the things
that are the characteristic signals of aging are sometimes thought
of as diseases, even though maybe they're not caused by
say a germ or something. Uh. There are all kinds
of things like diabetes melitas, or like rheumatoid arthritis that
(28:15):
are totally characteristic signs of aging and human beings, and
they're thought of as diseases. But they're not so much
something that gets done to the body by external forces.
There are a thing that happens when the body is
around for a long time under certain conditions. It makes
me think back to our episode on Chinese immortality and
about the the idea of the the older body being
(28:38):
kind of an alien body, Like it's a different biology.
We're changing into a different being with different physical characteristics,
generally characteristics that that lean towards towards weakness. Absolutely, But
then again, you can also look at aging through the microscope,
look at it on the cellular level, and this is
(28:59):
where you'll often see people using words like senescence. Defined
by by Nature's scientific glossory quote, senescence is the process
by which cells irreversibly stop dividing and inter a state
of permanent growth arrest without undergoing cell death. Senescence can
be induced by unrepaired DNA damage or other cellular stresses.
(29:23):
So this is looking at it on the microscopic level
and saying senescence, often used as as a synonym for aging,
happens when the cells stop making new rejuvenated cells. This
is kind of the lack of upkeep keep model. It's
the idea that well, the house is falling apart because
nobody's working on it, nobody's maintaining, or at least the
(29:45):
maintenance has really been scaled back or it's all. It's
been my experience thus far with aging that you find
the maintenance requests are are kind of rolled out in
an a logical way where you you may think yourself, well,
why am I still sore from this injury I sustained
last month? But my my, what my body is really
(30:07):
trying to do is like grow a bunch of nose hair.
You know, it's like, why why is that the the
main operative that's been passed down to my body? You know,
everything is beginning to get out of whack. It's as
if it's as if there's nobody in charge anymore. Uh,
and they're just letting the house fall apart. Yeah, if
you were the superintendent of an apartment building, it would
(30:29):
be like, there's a water leak in the basement that
has not been fixed for months, and your repair person
is busy building hundreds of kitchen cabinets on the roof.
Yeah yeah, and you think, well, in the old days,
we we didn't have all these kitchen cabinets on the
roof and things got fixed. Why do things not got
to get fixed anymore? That is a great question, and
I guess we should try to look at some answers
(30:50):
to that when we come back from this next break.
Than alright, we're back, all right, So let's look at
some historical and lay answers to the question, and why
do we age? What's the point? Why does it happen?
One common example that seems to make sense to people
is the idea that our body is over time quote
get worn out. Uh So. In his nine paper Pleotropy,
(31:15):
Natural Selection and the Evolution of Senescence, which we will
definitely come back to in the second episode here, the
American biologist George C. Williams pointed out that one problem
explaining the true biological reason behind aging is that many
people think they already understand what aging is and why
it happens. And they're wrong. They're wrong. But if you
(31:37):
think you've already got the answer, you'll never go asking
the question and writing of these kind of folk explanations
for aging. He says, quote the most injurious of these
is the identification of senescence with the quote wearing out
That is shown by human artifacts, And doesn't this seem
very sensical? Right? Our tools get worn out over time.
(32:00):
If you use a knife a whole lot, eventually it'll
lose the sharpness of its blade. Uh, any tool you
use too much. I'm thinking about a broom that we
used to have for years around our house that eventually
got worn down to nubs. There were just really no
bristles on it anymore. Shouldn't our bodies be the same.
This reminds me I've had to explain this to my
(32:20):
my son recently, where he'll get some sort of cheap toy,
you know, as a prize or something, and uh, and
he'll be really into it, and I'll have to explain
to him that this is not the sort of toy
that lasts very long. You know, toys like this may
last a week or so. And He's like, no, some
some toys last forever. And I'm like, well, they don't.
They don't. Really, you have to try to explain how
(32:42):
pretty much everything that is made by man is going
to fall apart. Okay, after I finished my children's book
about ming the clam, I'm writing a second children's book
called Toys Die. What it reminds me of the short
story that that A I was was based on. Oh yeah,
I forget the exact title, but to believe it was
(33:03):
Super Toys Last All Summer, which I always thought was
a rather fun title. That is great, But knowing knowing that,
we also know that they won't last forever, like you,
like you say so. Going back to what Williams wrote, quote,
A moment of serious consideration should convince a biologist of
the fundamental dissimilarity between these two processes, meaning the body
(33:25):
wearing out and tools wearing out. The breakdown of human
artifacts is strictly mechanical and is readily cured by mechanical repairs.
The system is a static one, since the same material
is continuously present and there is no endogenous change with
the passage of time. An organism, on the other hand,
(33:46):
is an open system in a state of material flux.
Even such structures as bones maintain constant exchanges with the environment. Moreover,
an organism produces itself by a morphogen netic process. It
is indeed remarkable that after a seemingly miraculous feat of
morphogenesis and that means like growing into the adult shape,
(34:10):
a metazoan should be unable to perform the much simpler
task of merely maintaining what is already formed. I think
this is a fantastic point. I mean, it doesn't make
sense to say we get old because over time our
bodies just get worn out. Because our bodies have the
ability to rejuvenate tissues. They built the tissues in the
first place, they could just keep building them as long
(34:30):
as they wanted. Yeah, I mean, I think part of
this is the I mean part of it is just
that we are so close to the aging process. We
experience it and we see it in others. Uh, we're
almost too close to it to have an objective view
of it. And then to your point, we're informed by
what happens to our tools. And then I also they're
tying into the experience as well, and the wearing out
(34:52):
of things. I think dental health has a has a
huge impact on it because we observe this happening with
our very teeth. Teeth of others that you get that
those adult teeth in and those are the ones you're
going to have for the rest of your life as
long as you can keep them. You know they are
going to wear out, and unlike other organisms, there's not
(35:12):
going to be an additional set there that are going
to lock into place. Third children's book for when children
get their baby teeth knocked out, it's called this is
your Last Chance. Yeah, I've actually heard parents, I think
half joking, we talk about not worrying with brushing that
much for young children because now they're gonna go they're
(35:34):
gonna get that second pit. You know they're gonna be
These are not even these are just the baby teeth.
Wait till the adult teeth come in and then start
worrying about Yeah. Now, beyond these simple folk explanations, we
know that there have been lots of thinkers throughout history
who must have tried to explain why aging happens before
we had modern modern genetics to really understand the true mechanisms. Right, Yeah,
(35:56):
this is you know, aging is part of the human experience,
and so some of the great thinkers and human history
have pondered it. We have a few examples here to
run through. For instance, Lucretius B. C. E uh he
wrote about it in his text on the Nature of Things,
and he argued that aging and death are beneficial because
(36:17):
they make room for the next generation. This is probably
another folk explanation. A lot of people would employ. Right,
It totally seems to make sense. You can't just keep
living forever because you've got to make room for the
next generation. Yeah. It especially makes a sort of sense,
I think for human populations when you have, say, individuals
who have over the course of their lifetime, accumulated certain
(36:40):
benefits and powers and possessions. And then the idea as well,
when they fall away, those resources spread to someone else,
you know, I mean we we we have always lived
in a world of of finite resources. And I want
to be clear, it is good that that happens. The
next generations actually do benefit from the fact that older
(37:00):
generations grow old and die. Uh, but there are some
serious problems with thinking about this as the reason biologically
that they grow old and die. Yeah. Though this this
observation persisted well up into the twentieth century. For instance,
nineteenth century German biologist August Weismann also believe that the
death mechanism created room for the next generation of young
(37:22):
to thrive at And you know, I have to men
as well that I always it always, I always kind
of felt this was the case, you know, at a
gut level, without putting a lot of serious thought behind it.
Oh yeah. Before I investigated this, I assumed something along
these lines. But then I started to doubt myself because
I was like, oh, wait a minute, that's group selection
and I always feel iffy about that. The problem here
(37:44):
is pointed out by Daniel Fabian of the Institute of
Population Genetics in in the publication Nature is that quote
the cost of death to individuals likely exceeds the benefit
to the group or species. And because long lived individuals
leave more off ring been short lived individuals given equivalent
reproductive output, selection would not favor such a death mechanism. Yeah.
(38:08):
This is one of the classic arguments against any kind
of group level selection influence. And we can revisit this
in more detail in the second episode. Now, of course,
another great thinker is Aristotle, right yeah, and he of
course wrote about this as well in on Longevity and
Shortness of Life. Aristotle tell us how it is? All right? Well,
(38:32):
before I got going here, I do want to point
out I I am going to be the last person
to to criticize Aristotle. Uh. I feel like he uh
he did did a lot with the wisdom of the day, obviously,
and that's an understatement. Uh, but he was not able
if We're not going to take the opinion that Aristotle
was dumb though I was talking. I was actually talking
(38:55):
about this with my my wife last night when I
was running through the material I'm about to to relate here,
and she said, well, that would actually make a wonderful
like BuzzFeed style article like six things that dummy Aristotle
got wrong. I mean, he got a lot of stuff wrong,
but I mean everybody in the ancient world did. I
mean he people just didn't know what we knew today, right,
and he was attempting and attempting to figure it out.
(39:17):
He threw out a number of hypotheses that were not
that did not shake out. So here are just a
few quotes from the work that will give you an
idea of where he was going. The reasons for some
animals being long lived and other short lived and in
a word, causes of the length and brevity of life
call for investigation. Fair enough, Yeah, same question, we're asking
(39:38):
why does it happen? And then he goes on to
say race is inhabiting warm countries have longer life, those
living in cold climates have a shorter time. Likewise, there
are similar differences among individuals occupying the same locality. I
don't know if that's true. I mean, we already touched
on the greenland shark, and I think we've gone more
in depth in the greenland shark in the past on
(39:58):
this show. But a part of it is its environment,
which is quite cold. Okay uh. He also commented on
the connection between the soul and the body. The soul
must stand in a different case in respect of its
union with the body. And then this at least rings true,
hints to all things are at all times in a
(40:19):
state of transition and are coming into being and passing away. Okay,
So this could be interpreted to mean something kind of
like the fact that we're constantly undergoing cell division and
our bodies maintain them I mean, obviously Aristotle didn't know this,
but that our bodies maintain themselves through cell division and
repair of tissues. Yes. And then there's this quote speaking generally,
(40:40):
the longest lived things occur among the plants, example of
the date palm. Next, in order we find them among
the sanguineous animals rather than among the bloodless, and among
those with feet rather than among the denizens of the water. Hints.
Taking these two characters together, the longest lived animals fall
amongst sanguineous animals which have feet. Uh, men and elephants. Well,
(41:03):
clearly we've learned how to make your aquarium fish live longer.
You transplant some feet onto them. Uh, this at least
as good quote. As a matter of fact, also, it
is a general rule that the larger live longer than
the smaller. For the other long lived animals to happen
to be of a large size are also those I
(41:24):
have mentioned. Now, I'm sure this is not a hard
and fast rule, though I think there are probably some
weak correlations along these lines. So, I mean, we already
touched on the dinosaur thing. But but certainly there are
some examples of rather large animals that have longer lifespans
within typical longevity. Now Aristotle's working theory, though, is that
(41:45):
all of it revolves around moisture in an organism. Yes, quote,
we must remember that an animal is by nature human
and warm, and to live is to be of such
a constitution, while old age is dry and cold, and
so is a corpse. I think Aristotle also tried to
explain earthquakes by way of moisture, maybe misremembering that. And
(42:08):
he also said that aquatic animals don't count here because
they're not humid. Their watery and quote watery moisture is
easily destroyed since it is cold and readily congealed. And finally,
he also throws in four in animals, the males are
in general the longer lived. I don't think that's true either. Yeah,
I believe in in in in many cases it is
the It is the female that lives longer, certainly in humans,
(42:31):
though that may be more pronounced in cases where we
have been removed from the like when we've got modern
medical care, because, for example, there is a lot of
natural mortality during childbearing. Correct. So I don't know, you
can maybe a point for Aristotle. There maybe a point
for modern science. We'll see, um. But anyway, that's that's
(42:55):
that's what Aristotle had to say in the matter. And uh,
and I like, I say, it's it's it's fascinating to
look back on his writings and see how he's working
this all out totally. So in the end, I think
we're still left with this biological paradox of aging. Once
we think about aging in a biological context, it's sort
of fails to make sense. Evolution selects for genes that
(43:19):
increase biological fitness, meaning that increase the chances of survival
and reproduction. Aging is characterized by an organism level decline
in the chances of survival and reproduction. So why would
organisms that have been evolving for billions of years still age, deteriorate,
(43:39):
lose the ability to reproduce, and eventually die. Shouldn't we
have evolved to maximize survival and reproduction as long as possible.
Shouldn't we survive and keep making babies until a leopard
bites our head off? But obviously this is not how
things are. So what's the answer to this mystery? Will
explore that in the next episode. As right, we have
(44:00):
a cliffhanger. Will it be cruel twist of fate? Accident? Uh,
biological mechanism that serves a purpose? I don't know. We'll
find out maybe our genome has been evolving to feed
leopards all right. Well, in the meantime, while you're waiting
for that next episode, head on over to Stuff to
Blow your Mind dot com. That's the mothership. That's where
(44:21):
you'll find all the podcast episodes. You'll find videos, blog
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(44:42):
com for more on this and thousands of other topics.
Does it how stuff works dot com. They visit many
(45:12):
four stars far f
Hey, are you welcome to stuff to blow your mind?
My name is Robert Lamb and I'm Joe McCormick, and
it's Saturday. Time to venture into the vault, this time
with an episode about youth and aging. This is Eternal Youth,
Part one, originally published January four. This is one of
the episodes. I think we did a pair here where
we were sort of asking the question why animals age? Why?
(00:29):
Why why not just stay young? Forever? Yeah? Youth like
diamonds in the sun, right, um, forever young Alphaville. Hopefully
I don't remember if I referenced that track uh in
these episodes, but I hope I did. I think you
referenced it more recently when pointing out how creepy the
lyrics are that they they sound like a serial killer. Note, yeah,
they're they're they're super creepy. That track is the reason
(00:50):
I didn't share my You know a lot of people
are sharing, uh, these curated lists of what tracks they
listened to the most in the previous year. That was
your number one? It was, it was, it was, it
was up there way too much, and I have to
I can only share that with people if I can
also explain to them that I have a very creepy
interpretation of the song and therefore me listening to Forever
(01:12):
Young is like most people listening to death metal. I'm
gonna see you and raise you there because the other
Forever Young also has creepy lyrics if you listen to them.
Oh yeah, this is the Bob Dylan r. Yeah yeah yeah,
just go listen, you'll you'll see. All right, Well, let's
jump right into it. Welcome to Stuff to Blow your
Mind from how stuff dot com. Hey you, welcome to
(01:41):
Stuff to Blow your Mind. My name is Robert Lamb
and I'm Joe McCormick and Robert, I want to ask
you about a Greek commit go for it. You know,
the myth of tiffan Us. This is not one that
I am am readily familiar with off stuff of my head. Well,
it's one of those great ones with doomed lovers. Are
doomed lovers? Just fantastic? Yea? Is there? Does a god
show up the act particularly crappy towards mortals? Uh not.
(02:04):
I don't know if it's on purpose. You do get
Zeus being a jerk, but he might be like he's
a jerk by accident. Or maybe he's a jerk on purpose.
It's kind of hard to tell, because being a jerk
is kind of Zeus is default thing in general. Yeah,
Zeus in this myth acts kind of like the Monkeys
Paul and the classic short story, where you get the
wish but not quite in the way you wanted it.
(02:26):
So here's how it goes. And this is the version
that's in the Homeric Hymn to Aphrodite. So the myth
involves the goddess aos Aus is the goddess of Dawn,
and she falls in love with a mortal man from
Troy named tiffan Us. And this is horrible, right, It's
horrible for a goddess to fall in love with a
(02:48):
mortal because while the gods may live eternally, dining on
the ambrosia and just going on into the future, of course,
mortal people, as the name implies, will die. And she
hates this idea. She hates the idea that the man
she's fallen in love with will someday die while she
gets to go on living forever. She can't bear the
thought of it. So she goes to Zeus and she
(03:10):
makes a request, Well, you grant my lover Tiffanus eternal life,
and Zeus does it. Usually, you know, usually Zeus is
a jerk, but here he's like, yes, yes, I will
do that for you. Aos. Well, maybe he was busy
and he's just like, okay, yeah, I'm just go ahead
check this off the list because I've I've got this, uh,
this other torment in mind for another mortal. Right, don't
(03:31):
have time to be a jerk. Just bam, eternal life.
You will not perish and die like the other mortals.
But then it takes a dark turn. So let me
read from the translation of the Home Eric him to Aphrodite,
and this is translated by Hugh Evelyn White. Quote. So
also golden throned Aos wrapped away Tiffanus, who was of
(03:53):
your race and like the deathless gods. And she went
to ask the dark clouded son of ChRI On knows
that he should be deathless and live eternally. And Zeus
bowed his head to her prayer and fulfilled her desire. Okay,
so he's granning the wish. Too simple, was queenly Aos.
She thought not in her heart to ask youth for
(04:16):
him and to strip him of the slough of deadly age.
So while he enjoyed the sweet flower of life, he
lived rapturously with golden throned Aos, the early born by
the streams of ocean at the ends of the earth.
But when the first gray hairs began to ripple from
his comely head and noble chin, queenly Aos kept away
(04:39):
from his bed, though she cherished him in her house,
and nourished him with food and ambrosia, and gave him
rich clothing. But when loathsome old age pressed full upon him,
and he could not move nor lift his limbs. This
seemed to her in her heart the best counsel. She
laid him in a room and put to the shining doors.
(05:00):
There he babbles endlessly, and no more has strength at all,
such as once he had in his supple limbs. M Okay, well,
this makes me think Zeus probably just agreed to her request,
because all the gods know that mortals are going to
ask for immortality at some point or the other, and
they're probably not going to phrase the question properly, and
you should let them have it because it will teach
(05:22):
them a lesson. Well, yeah, he'll learn when he's old
and babbling and decrepit. But cannot die. Yeah, because global
myth cycles are filled with stories of of immortality gone wrong.
You know, it's either a wandering immortal who's doomed or
or lovers who you know, obtain a portion of immortality
(05:43):
and it's mishandled. There's a there's a wonderful example of
this in in Chinese myth with the the Elixir of
Immortality and the and the Woman of the Moon. Oh
does it come back to bite her? Or come back
to bite the person who wants it? Um it gets
There are a few different versions of the tale, but essentially,
you know, one person is immortal and the other is not.
(06:04):
That sort of thing, this this this mismatch that we
see president in the Greek tale as well. Man, why
are there so many myths and folk tales where people
get punished for wanting better than their lot in life? Well,
because you can't have it, I mean, especially when it
comes to things like avoiding death and avoiding aging. You're
(06:25):
not gonna get it. So there's something refreshing about stories
in which people do get it and it backfires because
that way we think, oh, well, this this thing that
I cannot have is actually not that great. So thank goodness,
I'm going to grow old and die. Yeah. I wonder
if it makes you feel like you're not so bad off.
It's like, well, I'm gonna die one day, but I
could be like Tiffanous, and that's even worse. Exactly, So,
(06:47):
I think the myth is sort of an embodiment of
this cruel fact about human nature. It's not just that,
as they say in Bravos, all men must die, but
that all people must decline. I think warrensy On put
it best. He said time treats everybody like a fool.
And I think that's the case. And no amount of lawyers, guns,
(07:07):
or money will get you out of this, that's right.
So on one hand, you've got the idea of death.
And death is a sort of unavoidable fact about biology
because living organisms are these finely tuned factories of chemical reactions,
and if you make substantial changes to the factory, say
by jamming a rock through part of it, or biting
(07:28):
part of it off, or filling it up with parasites
that gum up all the gears, the factory isn't going
to work the same anymore. It might not work at all.
Were physical creatures were subject to physical disruption. So the
potential for death is unavoidable. It's sort of part of
what it means to be alive. But aging not quite
(07:48):
so much. This steady time correlated decline in our biological fitness.
Why does that have to happen? That's not physically inevitable
in same way that death is. Yes, and this is
going to be the question we're gonna be discussing in
this pair of episodes. Now, we do want to drive home.
We're not going to get as much into some of
(08:10):
the mechanics of aging, like we're not going to get
into telomeres and telomerase and all and all of that,
although that's a wonderfully insightful topic onto itself. We're gonna
be talking more about the these this sort of evolutionary
function of aging, if it has one, right, aging is
something that has such a cost for the organisms that
(08:31):
undergo it, like tiffanus. What pays for it biologically? Why
does it exist? Now, to underscore the fact that aging
is not necessarily something that is inevitable, and especially not
aging as early as we do, we should maybe look
at some organisms that do not age in the same
way we do. Yeah, they're there are a number of organisms.
(08:53):
I'm sure a number of them come to to everyone's
mind here. You think of ancient hoary tortoise is stumbling
across the the ground, right, or perhaps your mind turns
with the greenland shark. Will come back to that one
in a second. But really one of the more insightful
examples here is the hydra, or at least individuals in
the Hydra genus. So you're talking about the monster that
(09:15):
gets its head cut off and grows two more. No,
as much as I do love the mythical hydra, now
these are the natural world. Hydra's tiny tentacled creatures that
need to continue to wow scientists because they have a
number of just wonderfully bizarre and monstrous capability. So they
can reproduce through a sexual butting. They have these mouths
(09:37):
that open up kind of like wounds in their body
and then close. There's some fabulous videos of them doing that.
It looks like you're staring into the mouth of hell.
And they have this seemingly natural inability to grow, grow old,
and die of natural causes. They boast low mortality rates
throughout their lives, and apparently this is according to when
(09:58):
Dr Owen Jones from the University of Southern Denmark. He
has claimed that it would take four hundred years for
of a hydro population to die of natural causes in
the lab. Wow, well, well that's a hardy species. Yeah,
So let me let me back some of that up
here with with some more the facts about the life
of the hydra, so their fertility rates remain constant their
(10:22):
entire lives, which, as will discuss is is pretty unique.
And according to Pomono College biology researcher Professor Daniel Martinez,
he has repeatedly found no evidence of sinescence in laboratory
caddled hydra. Yeah, and even goes so far as to
state that an individual hydra can live forever under the
(10:44):
right laboratory circumstances. Now, of course, that's the catch, right.
The hydro's natural environment offers sufficient hostilities to make natural
death by old age and impossibility. You got disease, predators,
water contamination. These are the things that usually all a
hydra off in due time, and likewise, scientists have yet
to create a hydra utopia that can sustain them indefinitely. Now,
(11:07):
this is a good point in the use of the
word immortality, which sometimes comes up when people are covering
organisms like these. There are a couple of different ways
you could look at immortality. One would be the Highlander
version or something like that, where there's just like nothing
that can kill you except maybe one or two little things,
but that you are generally invulnerable to death. And then
(11:30):
there'd be a different version of immortality that says, yeah,
you're vulnerable to death by injury or disease, you just
don't naturally grow old and die. You don't have a
cap on your life span. That would be more like
what are the elves of Middle Earth? Kind of like that,
Like they can be killed in battle, but they don't
grow old and die. Yeah. Well, I mean I would
argue that the immortals of Highlander are much the same,
(11:52):
Like there's a there's a very specific thing you can
do to kill them, uh, and technically anyone can do it.
It's just you've got to get the drop on a right.
We should mention that we're popping in little references to
Highlander to get you ready for the fact that one
day soon we're going to do a Science of Highlander
two episode and I'm not kidding. Yeah, you have advanced
warning so you can all go review at least the
(12:13):
first two films. Well, I would say just the first
two films actually, okay, but back to the hydra and
biological immortality in the real world. Yeah, so this is
a major point really for all organisms. The natural world
is generally sufficient to ensure mortality. It's dangerous, It's filled
with competitors, predators, pathogens, accidents, and all manner of additional hazards. Now,
(12:34):
humans and their captives tend to live in a very
privileged space, largely removed from the threat of predation. At least,
you'll find other creatures with no natural predators as well.
Typically these are apex predators, but that doesn't mean they
don't have to deal with all these other dangers. Well. No,
when you think about an apex predator, just because there's
nothing that tackles it and tears it apart and eats it,
(12:57):
that doesn't mean that it's not subject to attacks from
its environment, right. I mean, it of course is subject
to disease. But one of the other things to think
about with an apex predator is these creatures are very
often constantly at the edge of starvation. And so when
you see the antelope running from the cheetah or something.
Of course, the cheetahs trying to kill the antelope, but
(13:19):
by escaping, the antelope is sort of also trying to
kill the cheetah. It is starving the cheetah to death
by escaping. The cheat is a great example too, because
either cheetah injures itself in the pursuit of a prey,
especially if it tackles prey that is a little beyond
its ability or or is potentially beyond its ability, it
(13:42):
can sustain an injury that results in death, not because
it becomes infected or what have you, but because say,
a wounded limb on a cheetah can mean it cannot
pursue prey and it starves. Right. This is another thing
we often fail to appreciate in the natural world is
how how absolutely damning a small injury can be to
(14:04):
an organism that has to hunt or escape hunters to survive.
You also, of course, have read about large cats that
have turned man killer, and uh in some of these
cases I remember correctly, Sometimes it has to do with
the decline of dental health, like their their inability to
depend on their their teeth for their traditional prey, and
(14:26):
it leads to sort of a desperate switch in their
their selection of prey. So anyway, most most individuals are
going to die or be killed before they can grow old,
so there's already a low probability of being alive and
reproductive at an advanced age. Still, hyders are are really
interesting because it give us a real world of world
example of how how undying creatures would work on a
(14:49):
biological level. They're hardy, their regenerative they have they have
evolved to thrive in harsh environments, and it actually reminds
me of an alien species that shows up in Ian
m banks. The Culture series, of course, go into the
Culture Yeah, I mean he he always managed to work
so many wonderful scientific topics into his his books, and
one of these topics is biological immortality. Alright, So we
(15:12):
meet in the really the very first Culture book, we
meet the Adherens. And here's just a quick quote. The
Adherens themselves had evolved on their planet a deer as
the top monster from a whole planet full of monsters.
The frenetic and savage ecology of a deer in its
early days had long since disappeared, and so had all
(15:33):
the other homeworld monsters. Except those in zoos. But the
Adherens had retained the intelligence that made them winners, as
well as the biological immortality, which, due to the viciousness
of the fight for survival back then, not to mention
a deer's high radiation levels, had been an evolutionary advantage
rather than a recipe for stagnation. Now, I think that
(15:54):
might be something interesting to come back to, maybe in
the second episode, and consider whether it would actually work
that way and what the effect of high mortality at
different stages of life would have on the life span
of an organism. Alright, Well, on that note, let's take
a quick break, and when we come back, we're gonna
roll through just a few other long living organisms, uh
(16:15):
that are not a hydra or an endearing thank alright,
we're back. So I mentioned the greenland shark earlier. This
one is pretty impressive because greenland sharks live where we
understand now about four hundred years uh. And this is
an exclusively wild species as well. This is not something
(16:36):
you're gonna find growing old and fat and an aquarium.
These are sharks generally don't do very well in aquariums. Correct. Yeah,
it's and no one has a greenland shark that I
am aware of as of this recording. At two thousand sixteen,
University of Copenhagen study estimated that one female greenland shark
UH had it was, it was at least four hundred
(16:56):
years old, and that the species doesn't even reach sexual
mature until one fifty. So think of that, not until
they've reached an age that exceeds every human being who
has ever lived, and that's counting unverified but not mythic
individual humans, right, not the Highlanders or you know, like
you know, biblical days. Right. Yeah. Now, of course that's
(17:20):
still not the oldest animal, because there was a clam
named Ming. This is the first line of a children's book.
I know it should be. Well, I would be. I
would actually be surprised if there's not a children's book
about Ming. There was a clam named Ming. Yeah, and
Ming did love to sing. Yeah, it's this here writes itself.
So technically Ming was a qua hog clam. This is
(17:43):
uh an Arctic variety of clam, and it was discovered
off the coast of Iceland in two thousand six Now
at the time they thought it was around four hundred
and five years old, so they named it after the
Ming dynasty that would have ruled China at this time.
Later estimates, and this is supported by urban dating, would
boost that age to five hundred and seven years half
(18:04):
a millennium. So this means that the creature was born
in fourteen and that's still within the Mean dynasty which
went four And to throw another point of context in there,
this was around the time that Leonardo da Vinci completed
the Last Supper. It's the year Portuguese explorer Vasco da
(18:24):
Gama reached India. That's when this this thing was was
born and then it died in two thousand and six,
there was a clam named Ming, and Ming remembered everything.
There you go now the plant where world, of course
has all of this beat uh. There's the great basin
bristle cone Pine or Pinus along Gava and it can
(18:45):
only lived to over five thousand years of age, and
that takes us back to the very end of the
Neolithic period. Work on Stonehenge had begun. This was the
age of the Pharaoh, so it lived through the rise
and the fall of the Roman Empire. Now, of course
this highlights that different kinds of organisms have massively different
potential when it comes to lifespan. Yeah, and of course
(19:06):
plants are very different from animals. This reminds me that
one of the ideas that was brought up recently. I
believe on our discussion module on on Facebook or Facebook group,
that we should do something just on plants, like what
is a plant? To sort of strip it down to
its basics. I kind of like that idea, it's a
really lazy animal. Well, I've got a really lazy one.
(19:26):
Then for you here, Uh, there's at least one step
beyond the great basin bristle Cone pine. And this is
something you'll find in fish Lake National Park in Utah
here in the United States, Uh, the quaking aspen tree,
which is also the state tree by the way, also
known as the trembling Giant or pando, which means I spread.
(19:48):
So what we have here and this is this is
one where not everybody necessarily agrees with that this might
be sort of bending the definition a little bit of
what is a long living organism. But what we have
here is a single clone of quaking asp been connected
by a single extensive roots system that's roughly the size
of Vatican City, a hundred and six acres thirteen million
pounds and it's all eighty thousand years old. So what
(20:12):
you're talking about is a forest that is all sort
of in some way the same organism. Right, you can.
It's it's not as simple as the clam was born
in the century and it died in this one. But
if you if you've been the definition enough and you
accept this as an example, we're talking about a thing
that has lived since humans first left Africa to colonized
(20:34):
the world. Wow. Yeah, Now, Robert, here's something I've always
wondered about. Okay, dinosaurs. You got to wonder how long
they lived, especially because this gets warped by our sense
of history. I think because they lived so long ago,
you just naturally go to this completely illogical place where
they must have lived a long time. Like, Okay, tyrannosaurs
(20:57):
rex lived maybe three hundred years. I mean they they
they've got very big, so you have to imagine it
took them a while to grow as big as they did.
This would take a lot of years of eating and
cell division and all that. So so surely they had
very long lifespans. Well, this used to be the main theory,
and this was in part because of ai their size
(21:17):
or at least the size of many of the specimens
and the fact that we thought, well, they were essentially
giant reptiles, and so based on slow reptile growth rates
and their size, they said, well, big dinos probably lived
several hundred years. But today paleonto just believed they grew
more like birds and mammals, and this cuts back on
their lifespans somewhat. So, for instance, the Field Museum of
(21:39):
Chicago they have this, uh, this these t rex remains
that they named Sue. Sue. Sue is great. Yeah, she's
a wonderful specimen. You get to look right up at
her and get a sense of the true size of
this this amazing species. Can I say something embarrassing, go
for it. I cried a little bit at Sue. Yeah,
I'm not kidding. When we were in Chicago and I'm
(22:00):
just sitting there looking at Sue for a while, I
did something to me a little misty. That's that's beautiful.
I I can understand it because it is like looking
back in time to encounter, you know, a fossil like that.
So Sue is a rather big specimen, or at least
the fossil remains are rather large and speak to a
large specimen. They we think now that she probably achieved
(22:23):
adult size at age twenty and lived to a ripe
old age of twenty nine. So I am now older
than than this Tyrannosaurus rex was when it dies exactly. Yeah,
and uh, and you just underlines that what you had
with the dinosaurs was likely rapid growth but short lives.
Now one sort of side question that we won't fully explore.
(22:46):
But this this may raise the question, well, dinosaurs have
cancer because you're thinking about rapid growth, right of course. Well,
basically this is the question we have to come back to.
But based on the research I was looking at, we
only have evidence of the haddress sores the duck build
dinosaurs developing any form of cancer. Now that's the caveat
that's the only the only ones we have evidence of
(23:08):
that that occurring in. But it is interesting to think
of like the late model dinosaur as being the place
where we see the cancer showing up. We got to
come back and do an episode on dinosaur cancer in
the future. Yeah, by all means, well, I want to
do something that we often end up having to do,
which is that after we've explored a concept for a while,
it becomes more and more complicated, and our lay definition
(23:30):
starts to get a little less useful. So I think
maybe we should ask the question what actually is aging? Now?
We have a pretty uh intuitive, gut level understanding of
what aging is. We know when we see it, But
how would you define it? I mean, it's it is
something different from death, and it is something different from
(23:53):
just like, I don't know, your skin getting wrinkles or
something like that. What what is the actual scientific thing
that all of the stuff we call aging has in common. Well,
this is a great question. I mean, on one hand,
it is closely tied to death, and I think one
of the stumbling blocks is that will will alreadily admit
that aging is something that our body does, but we
(24:15):
tend there's tends to it tends to be a cultural
bearer in place to saying that death is something our
body does. We like to push that off onto some
sort of external force of of fade or anthropomorphized dread,
you know, or some sort of limit imposed on us
by the gods. Well, yeah, yeah, death is something that
we more often characterize as happening to us. Death happens
(24:37):
to you. It's not something you do, though, there you
can kind of see that the division between the death
and the aging death I was talking about at the
beginning of this episode comes into focus, because of course
death can happen to you if you get a rock
jammed through your you know, through your body or something
like that. But the body does seem to naturally progress
(24:58):
toward death of time, and that's kind of a weird question,
like why would it do that. We will definitely explore
the science behind that question in the second episode that
we will look at some archaic ancers to it in
this one, because when especially with the human, with the
human experience of aging and death, it seems completely illogical
that in many cases a human being would spend the
(25:22):
majority of its life progressing towards death, Like the majority
of your life is declined. Uh, that just feels either
gross or cruel or just like a horrible design flaw
or yeah, or nonsensical. Where's my eternal youth? Doesn't make
any sense? Um? So. In his book The Evolutionary Biology
(25:44):
of Aging published by Oxford University Press, the biologist Michael R.
Rose defined aging in the following way quote a persistent
decline in the age specific fitness components of an organism
due to internal physic eological deterioration. Now Rose actually has
offered has said that in some ways we might need
(26:06):
to update that understanding a little bit to accommodate for
some new discoveries. But I think this is a good
place to start. So let's look at the parts of
that definition. Number one, it's persistent decline, which means aging
only goes one way. It's not characterized by say decline
and rebound. And some organisms do have patterns like this
is not quite aging, like you can think about the
(26:28):
jellyfish that have regenerative capabilities where they can revert to
a younger stage of life. But then so it's persistent decline.
And then in the quote age specific fitness components biological
fitness meaning the ability to survive and reproduce. So these
are the things that are persistently in decline. You become
(26:48):
less able to survive and less able to reproduce. And
then it's due to internal physiological deterioration. So it's saying
that this persistent decline in the ability to survive and
reproduce is not due to disease or injury, but to
something deteriorating within the body. Tissues themselves, yeah, this is
(27:11):
this makes me think, of course, of the phrase cradle
to the grave and with the with the hydra. The
cradle to the grave is kind of a straight line
with reproduction taking place at all levels until something happens
to kill it. Whereas most of the models that that
we look at, most of the models we looked at
in researching this episode, it's more of a of a
(27:32):
rise rising and lowering. There's a rise towards like peak
sexual maturity, peak reproductive maturity, and then a decline. Yeah. Yeah,
and then it gets even stickier, right because we we've
just tried to be very careful and how we're defining this.
But then I realized that I said the it's a
decline in the ability to survive and reproduce, not due
(27:53):
to disease or injury. But a lot of the things
that are the characteristic signals of aging are sometimes thought
of as diseases, even though maybe they're not caused by
say a germ or something. Uh. There are all kinds
of things like diabetes melitas, or like rheumatoid arthritis that
(28:15):
are totally characteristic signs of aging and human beings, and
they're thought of as diseases. But they're not so much
something that gets done to the body by external forces.
There are a thing that happens when the body is
around for a long time under certain conditions. It makes
me think back to our episode on Chinese immortality and
about the the idea of the the older body being
(28:38):
kind of an alien body, Like it's a different biology.
We're changing into a different being with different physical characteristics,
generally characteristics that that lean towards towards weakness. Absolutely, But
then again, you can also look at aging through the microscope,
look at it on the cellular level, and this is
(28:59):
where you'll often see people using words like senescence. Defined
by by Nature's scientific glossory quote, senescence is the process
by which cells irreversibly stop dividing and inter a state
of permanent growth arrest without undergoing cell death. Senescence can
be induced by unrepaired DNA damage or other cellular stresses.
(29:23):
So this is looking at it on the microscopic level
and saying senescence, often used as as a synonym for aging,
happens when the cells stop making new rejuvenated cells. This
is kind of the lack of upkeep keep model. It's
the idea that well, the house is falling apart because
nobody's working on it, nobody's maintaining, or at least the
(29:45):
maintenance has really been scaled back or it's all. It's
been my experience thus far with aging that you find
the maintenance requests are are kind of rolled out in
an a logical way where you you may think yourself, well,
why am I still sore from this injury I sustained
last month? But my my, what my body is really
(30:07):
trying to do is like grow a bunch of nose hair.
You know, it's like, why why is that the the
main operative that's been passed down to my body? You know,
everything is beginning to get out of whack. It's as
if it's as if there's nobody in charge anymore. Uh,
and they're just letting the house fall apart. Yeah, if
you were the superintendent of an apartment building, it would
(30:29):
be like, there's a water leak in the basement that
has not been fixed for months, and your repair person
is busy building hundreds of kitchen cabinets on the roof.
Yeah yeah, and you think, well, in the old days,
we we didn't have all these kitchen cabinets on the
roof and things got fixed. Why do things not got
to get fixed anymore? That is a great question, and
I guess we should try to look at some answers
(30:50):
to that when we come back from this next break.
Than alright, we're back, all right, So let's look at
some historical and lay answers to the question, and why
do we age? What's the point? Why does it happen?
One common example that seems to make sense to people
is the idea that our body is over time quote
get worn out. Uh So. In his nine paper Pleotropy,
(31:15):
Natural Selection and the Evolution of Senescence, which we will
definitely come back to in the second episode here, the
American biologist George C. Williams pointed out that one problem
explaining the true biological reason behind aging is that many
people think they already understand what aging is and why
it happens. And they're wrong. They're wrong. But if you
(31:37):
think you've already got the answer, you'll never go asking
the question and writing of these kind of folk explanations
for aging. He says, quote the most injurious of these
is the identification of senescence with the quote wearing out
That is shown by human artifacts, And doesn't this seem
very sensical? Right? Our tools get worn out over time.
(32:00):
If you use a knife a whole lot, eventually it'll
lose the sharpness of its blade. Uh, any tool you
use too much. I'm thinking about a broom that we
used to have for years around our house that eventually
got worn down to nubs. There were just really no
bristles on it anymore. Shouldn't our bodies be the same.
This reminds me I've had to explain this to my
(32:20):
my son recently, where he'll get some sort of cheap toy,
you know, as a prize or something, and uh, and
he'll be really into it, and I'll have to explain
to him that this is not the sort of toy
that lasts very long. You know, toys like this may
last a week or so. And He's like, no, some
some toys last forever. And I'm like, well, they don't.
They don't. Really, you have to try to explain how
(32:42):
pretty much everything that is made by man is going
to fall apart. Okay, after I finished my children's book
about ming the clam, I'm writing a second children's book
called Toys Die. What it reminds me of the short
story that that A I was was based on. Oh yeah,
I forget the exact title, but to believe it was
(33:03):
Super Toys Last All Summer, which I always thought was
a rather fun title. That is great, But knowing knowing that,
we also know that they won't last forever, like you,
like you say so. Going back to what Williams wrote, quote,
A moment of serious consideration should convince a biologist of
the fundamental dissimilarity between these two processes, meaning the body
(33:25):
wearing out and tools wearing out. The breakdown of human
artifacts is strictly mechanical and is readily cured by mechanical repairs.
The system is a static one, since the same material
is continuously present and there is no endogenous change with
the passage of time. An organism, on the other hand,
(33:46):
is an open system in a state of material flux.
Even such structures as bones maintain constant exchanges with the environment. Moreover,
an organism produces itself by a morphogen netic process. It
is indeed remarkable that after a seemingly miraculous feat of
morphogenesis and that means like growing into the adult shape,
(34:10):
a metazoan should be unable to perform the much simpler
task of merely maintaining what is already formed. I think
this is a fantastic point. I mean, it doesn't make
sense to say we get old because over time our
bodies just get worn out. Because our bodies have the
ability to rejuvenate tissues. They built the tissues in the
first place, they could just keep building them as long
(34:30):
as they wanted. Yeah, I mean, I think part of
this is the I mean part of it is just
that we are so close to the aging process. We
experience it and we see it in others. Uh, we're
almost too close to it to have an objective view
of it. And then to your point, we're informed by
what happens to our tools. And then I also they're
tying into the experience as well, and the wearing out
(34:52):
of things. I think dental health has a has a
huge impact on it because we observe this happening with
our very teeth. Teeth of others that you get that
those adult teeth in and those are the ones you're
going to have for the rest of your life as
long as you can keep them. You know they are
going to wear out, and unlike other organisms, there's not
(35:12):
going to be an additional set there that are going
to lock into place. Third children's book for when children
get their baby teeth knocked out, it's called this is
your Last Chance. Yeah, I've actually heard parents, I think
half joking, we talk about not worrying with brushing that
much for young children because now they're gonna go they're
(35:34):
gonna get that second pit. You know they're gonna be
These are not even these are just the baby teeth.
Wait till the adult teeth come in and then start
worrying about Yeah. Now, beyond these simple folk explanations, we
know that there have been lots of thinkers throughout history
who must have tried to explain why aging happens before
we had modern modern genetics to really understand the true mechanisms. Right, Yeah,
(35:56):
this is you know, aging is part of the human experience,
and so some of the great thinkers and human history
have pondered it. We have a few examples here to
run through. For instance, Lucretius B. C. E uh he
wrote about it in his text on the Nature of Things,
and he argued that aging and death are beneficial because
(36:17):
they make room for the next generation. This is probably
another folk explanation. A lot of people would employ. Right,
It totally seems to make sense. You can't just keep
living forever because you've got to make room for the
next generation. Yeah. It especially makes a sort of sense,
I think for human populations when you have, say, individuals
who have over the course of their lifetime, accumulated certain
(36:40):
benefits and powers and possessions. And then the idea as well,
when they fall away, those resources spread to someone else,
you know, I mean we we we have always lived
in a world of of finite resources. And I want
to be clear, it is good that that happens. The
next generations actually do benefit from the fact that older
(37:00):
generations grow old and die. Uh, but there are some
serious problems with thinking about this as the reason biologically
that they grow old and die. Yeah. Though this this
observation persisted well up into the twentieth century. For instance,
nineteenth century German biologist August Weismann also believe that the
death mechanism created room for the next generation of young
(37:22):
to thrive at And you know, I have to men
as well that I always it always, I always kind
of felt this was the case, you know, at a
gut level, without putting a lot of serious thought behind it.
Oh yeah. Before I investigated this, I assumed something along
these lines. But then I started to doubt myself because
I was like, oh, wait a minute, that's group selection
and I always feel iffy about that. The problem here
(37:44):
is pointed out by Daniel Fabian of the Institute of
Population Genetics in in the publication Nature is that quote
the cost of death to individuals likely exceeds the benefit
to the group or species. And because long lived individuals
leave more off ring been short lived individuals given equivalent
reproductive output, selection would not favor such a death mechanism. Yeah.
(38:08):
This is one of the classic arguments against any kind
of group level selection influence. And we can revisit this
in more detail in the second episode. Now, of course,
another great thinker is Aristotle, right yeah, and he of
course wrote about this as well in on Longevity and
Shortness of Life. Aristotle tell us how it is? All right? Well,
(38:32):
before I got going here, I do want to point
out I I am going to be the last person
to to criticize Aristotle. Uh. I feel like he uh
he did did a lot with the wisdom of the day, obviously,
and that's an understatement. Uh, but he was not able
if We're not going to take the opinion that Aristotle
was dumb though I was talking. I was actually talking
(38:55):
about this with my my wife last night when I
was running through the material I'm about to to relate here,
and she said, well, that would actually make a wonderful
like BuzzFeed style article like six things that dummy Aristotle
got wrong. I mean, he got a lot of stuff wrong,
but I mean everybody in the ancient world did. I
mean he people just didn't know what we knew today, right,
and he was attempting and attempting to figure it out.
(39:17):
He threw out a number of hypotheses that were not
that did not shake out. So here are just a
few quotes from the work that will give you an
idea of where he was going. The reasons for some
animals being long lived and other short lived and in
a word, causes of the length and brevity of life
call for investigation. Fair enough, Yeah, same question, we're asking
(39:38):
why does it happen? And then he goes on to
say race is inhabiting warm countries have longer life, those
living in cold climates have a shorter time. Likewise, there
are similar differences among individuals occupying the same locality. I
don't know if that's true. I mean, we already touched
on the greenland shark, and I think we've gone more
in depth in the greenland shark in the past on
(39:58):
this show. But a part of it is its environment,
which is quite cold. Okay uh. He also commented on
the connection between the soul and the body. The soul
must stand in a different case in respect of its
union with the body. And then this at least rings true,
hints to all things are at all times in a
(40:19):
state of transition and are coming into being and passing away. Okay,
So this could be interpreted to mean something kind of
like the fact that we're constantly undergoing cell division and
our bodies maintain them I mean, obviously Aristotle didn't know this,
but that our bodies maintain themselves through cell division and
repair of tissues. Yes. And then there's this quote speaking generally,
(40:40):
the longest lived things occur among the plants, example of
the date palm. Next, in order we find them among
the sanguineous animals rather than among the bloodless, and among
those with feet rather than among the denizens of the water. Hints.
Taking these two characters together, the longest lived animals fall
amongst sanguineous animals which have feet. Uh, men and elephants. Well,
(41:03):
clearly we've learned how to make your aquarium fish live longer.
You transplant some feet onto them. Uh, this at least
as good quote. As a matter of fact, also, it
is a general rule that the larger live longer than
the smaller. For the other long lived animals to happen
to be of a large size are also those I
(41:24):
have mentioned. Now, I'm sure this is not a hard
and fast rule, though I think there are probably some
weak correlations along these lines. So, I mean, we already
touched on the dinosaur thing. But but certainly there are
some examples of rather large animals that have longer lifespans
within typical longevity. Now Aristotle's working theory, though, is that
(41:45):
all of it revolves around moisture in an organism. Yes, quote,
we must remember that an animal is by nature human
and warm, and to live is to be of such
a constitution, while old age is dry and cold, and
so is a corpse. I think Aristotle also tried to
explain earthquakes by way of moisture, maybe misremembering that. And
(42:08):
he also said that aquatic animals don't count here because
they're not humid. Their watery and quote watery moisture is
easily destroyed since it is cold and readily congealed. And finally,
he also throws in four in animals, the males are
in general the longer lived. I don't think that's true either. Yeah,
I believe in in in in many cases it is
the It is the female that lives longer, certainly in humans,
(42:31):
though that may be more pronounced in cases where we
have been removed from the like when we've got modern
medical care, because, for example, there is a lot of
natural mortality during childbearing. Correct. So I don't know, you
can maybe a point for Aristotle. There maybe a point
for modern science. We'll see, um. But anyway, that's that's
(42:55):
that's what Aristotle had to say in the matter. And uh,
and I like, I say, it's it's it's fascinating to
look back on his writings and see how he's working
this all out totally. So in the end, I think
we're still left with this biological paradox of aging. Once
we think about aging in a biological context, it's sort
of fails to make sense. Evolution selects for genes that
(43:19):
increase biological fitness, meaning that increase the chances of survival
and reproduction. Aging is characterized by an organism level decline
in the chances of survival and reproduction. So why would
organisms that have been evolving for billions of years still age, deteriorate,
(43:39):
lose the ability to reproduce, and eventually die. Shouldn't we
have evolved to maximize survival and reproduction as long as possible.
Shouldn't we survive and keep making babies until a leopard
bites our head off? But obviously this is not how
things are. So what's the answer to this mystery? Will
explore that in the next episode. As right, we have
(44:00):
a cliffhanger. Will it be cruel twist of fate? Accident? Uh,
biological mechanism that serves a purpose? I don't know. We'll
find out maybe our genome has been evolving to feed
leopards all right. Well, in the meantime, while you're waiting
for that next episode, head on over to Stuff to
Blow your Mind dot com. That's the mothership. That's where
(44:21):
you'll find all the podcast episodes. You'll find videos, blog
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