00:00:01.08]
(clock ticking)

[00:00:17.07]
♪ I love, I love, I
love my Calendar Girl ♪

[00:00:21.00]
♪ Yeah, sweet Calendar Girl ♪

[00:00:25.00]
♪ I love, I love, I
love my Calendar Girl ♪

[00:00:28.06]
♪ Each and every day of the year ♪

[00:00:32.05]
♪ January, you start the year off fine ♪

[00:00:36.04]
♪ February, you're my little Valentine ♪

[00:00:40.02]
♪ March, I'm gonna March
you down the aisle ♪

[00:00:44.01]
♪ April, You're the Easter
Bunny when you smile ♪

[00:00:48.02]
♪ Yeah, yeah, my heart's in a whirl ♪

[00:00:52.01]
♪ I love, I love, I love
my little Calendar Girl ♪

[00:00:55.08]
♪ Every day, every day of the year ♪

[00:01:04.01]
♪ May, maybe if I ask your Dad and Mom ♪

[00:01:07.07]
♪ June, they'll let me take
you to the Junior Prom ♪

[00:01:11.05]
♪ July, you're like a
firecracker all aglow ♪

[00:01:15.05]
♪ August, when you're on the
beach you steal the show ♪

[00:01:19.04]
♪ Yeah, yeah, my heart's in a whirl ♪

[00:01:23.04]
♪ I love, I love, I love
my little Calendar Girl ♪

[00:01:27.01]
♪ Every day, every day of the year ♪

[00:01:51.04]
♪ Yeah, yeah, my heart's in a whirl ♪

[00:01:55.00]
♪ I love, I love, I love
my little Calendar Girl ♪

[00:01:58.06]
♪ Every day, every day of the year ♪

[00:02:07.01]
♪ September, I'll light the
candles on your Sweet Sixteen ♪

[00:02:10.07]
♪ October, we'll be Romeo
and Juliet on Halloween ♪

[00:02:15.01]
♪ November, I'll be
thankful you belong to me ♪

[00:02:18.09]
♪ December, you're the present
beneath my Christmas Tree ♪

[00:02:22.04]
♪ Yeah, yeah, my heart's in a whirl ♪

[00:02:26.04]
♪ I love, I love, I love
my little Calendar Girl ♪

[00:02:30.03]
♪ Every day, every day of the year ♪

[00:02:39.02]
♪ I love, I love, I
love my Calendar Girl ♪

[00:02:42.09]
♪ Yeah, sweet Calendar Girl ♪

[00:02:46.07]
♪ I love, I love, I
love my Calendar Girl ♪

[00:02:50.09]
♪ Yeah, sweet Calendar Girl ♪

[00:02:53.04]
(ominous music)

[00:03:11.03]
- Why aging?

[00:03:12.02]
Well, the question of why
we age at the rate we do

[00:03:17.06]
or what causes us to age, I mean,

[00:03:19.03]
what can be more close
to home to every person

[00:03:22.05]
than the aging process?

[00:03:23.07]
Really, I mean, maybe not to teenagers,

[00:03:26.06]
but after you become a young adult,

[00:03:28.08]
and you're very intimately
aware of the aging process,

[00:03:35.05]
and I think more so as time goes on.

[00:03:37.06]
Practically nothing is known about it.

[00:03:39.06]
Compared to what we know

[00:03:40.05]
about almost everything else in biology,

[00:03:42.09]
how you switch a gene on and off,

[00:03:44.08]
how you control the cell cycle,
how you make a muscle cell?

[00:03:48.09]
We know lots about all those things.

[00:03:51.07]
We know a lot about cancer, for example,

[00:03:53.08]
a lot about many diseases,

[00:03:55.09]
but we know just a
little more than nothing,

[00:04:00.04]
but almost nothing, about aging.

[00:04:02.01]
It's one of the few
totally unsolved mysteries

[00:04:05.09]
left in the world.

[00:04:08.00]
That is, the world of biology.

[00:04:10.08]
(ominous music)

[00:05:02.00]
(children talking)

[00:05:27.07]
- Evolution is a process in
which the genetic information

[00:05:32.04]
of populations of animals
and plants gets shaped.

[00:05:38.03]
One of the most important forces

[00:05:39.08]
that shapes this genetic
information, is selection.

[00:05:44.02]
In selection, basically,
nature keeps what it likes,

[00:05:50.03]
and gets rid of what it doesn't like.

[00:05:52.07]
So the stuff that it likes
is genes that make you big

[00:05:57.09]
and strong and reproductive
and resistant to diseases

[00:06:00.06]
and able to survive.

[00:06:02.08]
The stuff that it doesn't
like is all of the stuff

[00:06:05.02]
that makes you weak, infirm,
infertile, unable to function.

[00:06:12.01]
This an interesting lead
into the problem of aging,

[00:06:14.07]
because aging is almost exactly the stuff

[00:06:18.00]
that you would think selection would stop.

[00:06:20.00]
Aging involves us losing our fertility,

[00:06:22.01]
losing our ability to survive,

[00:06:23.06]
losing our ability to resist disease.

[00:06:25.07]
Aging is all kinds of bad
things all rolled into one,

[00:06:28.06]
and delivered to us in a nice package

[00:06:30.02]
toward the end of our lives.

[00:06:32.06]
Why would evolution ever
allow this to occur?

[00:06:35.01]
And the answer is, that
evolution allows this to occur

[00:06:37.04]
because basically, selection
has taken a holiday

[00:06:39.03]
by the time you're middle-aged human.

[00:06:41.09]
(speaking foreign language)

[00:07:11.03]
- Because you no longer
matter reproductively,

[00:07:13.01]
you no longer matter to selection,

[00:07:14.08]
you no longer matter to evolution,

[00:07:16.02]
and all kind of bad things
can happen to at later ages.

[00:07:18.08]
And that's why we age.

[00:07:21.03]
(ominous music)

[00:07:58.00]
People often ask me why do
you work with fruit flies?

[00:08:01.09]
The fact is, you and fruit flies have DNA,

[00:08:05.01]
you and fruit flies have RNA,

[00:08:06.08]
you and fruit flies have protein,

[00:08:08.03]
you and fruit flies have lipid,

[00:08:09.04]
you and fruit flies have neurons,

[00:08:11.04]
you and fruit flies have all
these things that are the same.

[00:08:16.06]
So, we're pretty similar
organisms, fundamentally,

[00:08:22.05]
but also, I know that things
like the declining force

[00:08:25.08]
of natural selection
with age, affects humans

[00:08:28.04]
just as much as it affects fruit flies.

[00:08:30.09]
(ominous music)

[00:08:34.00]
Normally fruit flies just
reproduce very quickly

[00:08:36.07]
and then die not too long after that.

[00:08:41.05]
You start the next generation right away.

[00:08:43.04]
Bang, bang, bang, bang, bang.

[00:08:44.02]
Which then go through the same life cycle.

[00:08:52.09]
Using alterations in natural selection,

[00:08:55.06]
our goal was to produce postponed aging.

[00:09:01.03]
The basic experiment is to
take a culture of fruit flies,

[00:09:06.01]
and discard the eggs they produce

[00:09:09.03]
when they're young and
when they're middle-aged.

[00:09:13.00]
We choose the eggs laid
by the older females,

[00:09:16.08]
and use those eggs to
start the next generation.

[00:09:20.06]
What we're basically doing
is delaying the bang.

[00:09:24.00]
The bang comes later.

[00:09:27.07]
And the result of this,
by changing the force

[00:09:29.05]
of natural selection, is clear.

[00:09:32.05]
There's apparently genetic
variation in the population,

[00:09:35.06]
kinds of population that we
study, which will respond

[00:09:38.07]
to the changed natural
selection pattern, and will say,

[00:09:41.07]
"Oh, the rewards are now
for reproducing later.

[00:09:45.00]
Well, we'll change reproduction.

[00:09:46.04]
We will survive longer
and reproduce later."

[00:09:49.01]
And that's what they do,
after some generations.

[00:09:51.09]
And we have produced, by selection,

[00:09:55.01]
fruit flies that have an adult phase

[00:09:57.04]
that's about twice as long.

[00:09:59.02]
So instead of being about forty
days adult life, on average,

[00:10:02.08]
it's about eighty days.

[00:10:04.07]
(ominous music)
(fruit flies buzzing)

[00:10:15.00]
That's the beautiful thing
about evolution is its power

[00:10:18.05]
is shown both in the really
good things it does for you,

[00:10:21.09]
and in the fact that when it dumps you,

[00:10:24.05]
like a former girlfriend,

[00:10:27.07]
you're nothing, you're
garbage, you're history.

[00:10:31.03]
(gentle brooding music)

[00:10:46.03]
(speaking foreign language)

[00:11:50.09]
- One theory for how we
age is that we wear out

[00:11:54.08]
the way a car wears out.

[00:11:58.04]
We get damaged, so we get old and die.

[00:12:01.07]
That's possible.

[00:12:08.06]
It's also possible that
it's not quite so haphazard.

[00:12:14.06]
It might be that there's
actually a program for aging.

[00:12:19.07]
A mouse gets old and dies
after just two years.

[00:12:24.08]
Very, very rapidly.

[00:12:26.00]
And an old mouse has white hair,

[00:12:28.04]
moves slowly, and looks
old in just the same way

[00:12:31.07]
that an old dog looks old
or an old human looks old.

[00:12:35.02]
That's two years.

[00:12:36.04]
A canary gets old and dies after

[00:12:38.08]
about thirteen years, much longer.

[00:12:41.05]
And for a bat, it can be
thirty five to fifty years.

[00:12:45.00]
It's a very very slow
rate of aging for a bat.

[00:12:49.00]
So, it must have something
to do with the genes

[00:12:52.01]
of these animals,

[00:12:53.00]
because that's what makes them
different from one another.

[00:12:58.02]
We work on a tiny worm. It's
only about a millimeter long.

[00:13:02.00]
You can hardly see it with your naked eye.

[00:13:04.05]
And they have short life spans
also, the whole aging process

[00:13:08.04]
takes place and is completed
in just a couple of weeks,

[00:13:10.07]
they get old and they die.

[00:13:14.02]
That means, that if you're
interested in studying

[00:13:16.06]
how an animal ages, and why
it ages at a certain rate.

[00:13:21.03]
You can you do this very
easily in these worms,

[00:13:23.06]
because it all happens so quickly.

[00:13:27.08]
This is a worm that's old,
it's about 24 days old.

[00:13:33.07]
But very few live more
than, say 25 days or so.

[00:13:37.09]
They slow down and they die.

[00:13:41.05]
Yeah, she's a goner.

[00:13:44.07]
She's a worm on her deathbed.

[00:13:48.04]
24 days old.

[00:13:49.06]
She's had a rich, long, satisfying life.

[00:13:54.04]
Our task is to find the
genes inside the worm

[00:13:58.03]
that cause them to age and die
in two weeks instead of, say,

[00:14:02.08]
a year, or 50 years or whatever.

[00:14:06.07]
So we take our worms,
like a zillion worms,

[00:14:08.07]
and then we treat the worms with X-rays,

[00:14:12.02]
and it can change the
components of the DNA.

[00:14:17.09]
So you have a whole new kind
of strain or race of worms

[00:14:21.03]
that differs from the normal worm,

[00:14:23.09]
because one of its genes is defective.

[00:14:26.08]
We call those mutants.

[00:14:32.03]
So treating these worms
with X-rays is analogous

[00:14:38.02]
to taking a gun and just
randomly spraying bullets

[00:14:42.04]
at something like, let's say, a car.

[00:14:45.03]
This is a good New York
analogy, for example,

[00:14:47.05]
spray bullets at a car.

[00:14:48.07]
Now, in some cars, you
might, then you ask,

[00:14:51.03]
"What's wrong with the car?"

[00:14:52.04]
Some cars now have a flat tires.

[00:14:55.01]
So you can say "Hah,
you need tires to move."

[00:14:57.05]
Other cars will be able to move just fine,

[00:14:59.07]
but the windshield wipers won't work.

[00:15:01.07]
You'll say, "Oh, that's
where the bullet is,

[00:15:03.02]
in the windshield wiper, this must be,

[00:15:05.01]
or in some wire inside the car

[00:15:07.01]
that's used to run the windshield wipers."

[00:15:09.04]
You see? So you can just
see, if you do this to a car.

[00:15:12.07]
Think about it, if you
just have a million cars

[00:15:14.09]
and a million bullets and
you shoot them like this,

[00:15:17.02]
you can come up with a kind of
a map for each part of a car.

[00:15:21.01]
Like you can get a map

[00:15:22.01]
for the whole entire
windshield wiper system.

[00:15:26.00]
You'd have, like you could
hit the windshield wiper,

[00:15:28.00]
and you could hit basically this wire,

[00:15:29.04]
you'd have like bullets
going all along here

[00:15:31.04]
that you would have,

[00:15:32.06]
see, if you drew all the cars,

[00:15:33.08]
and you put a little dot for
where all the bullets was,

[00:15:35.04]
you'd come up with the
windshield wiper system, okay.

[00:15:38.05]
So anyway, that's one analogy,

[00:15:41.08]
now a better analogy really,
is if you think not of the car

[00:15:45.05]
but of the blueprint for the car.

[00:15:47.05]
There must be, these people that make cars

[00:15:49.04]
must have directions
for how to make the car.

[00:15:52.04]
It's almost like you're shooting
the gun at the directions

[00:15:56.00]
for how to make the car.

[00:15:57.00]
And so maybe, what you'll do

[00:15:58.07]
is you'll hit the part of the directions

[00:16:00.04]
that tells you how to
make windshield wipers.

[00:16:02.08]
Okay, now the person that makes the car

[00:16:04.06]
following the directions,

[00:16:06.00]
but the part about the
windshield wipers is screwed up,

[00:16:08.00]
so you get a car with
no windshield wipers.

[00:16:09.09]
And that tells you that
this part of the directions

[00:16:12.03]
has to do with the windshield wipers.

[00:16:14.05]
And that's more analogous,
because the DNA,

[00:16:18.03]
that's the instructions
for how to build an animal.

[00:16:22.04]
So what we're doing is
we're finding little bits

[00:16:24.03]
of the instructions for how
that will then allow the animal

[00:16:29.06]
to eventually to age at a certain rate.

[00:16:36.06]
Now what we need to do is find the worm

[00:16:39.08]
in which we have hit a gene for aging.

[00:16:46.02]
From each little family,
we take some worms

[00:16:47.09]
that are very young, and we
allow them to grow up and age.

[00:16:56.00]
After about twenty five days,

[00:16:58.09]
there won't be any worms
alive, for normal worms.

[00:17:02.06]
But the mutant worms, which
are the same in every way

[00:17:07.04]
as the normal worms, except for one gene,

[00:17:09.02]
just one gene is different,
they're still moving around,

[00:17:12.06]
and they're eating, and they don't know

[00:17:16.00]
that it's time to die, they don't.

[00:17:18.01]
They're on the tennis court, they're fine.

[00:17:21.05]
So when you look at the worms, you think,

[00:17:24.08]
"Oh my god, these worms should
be dead, but they're not."

[00:17:30.03]
So, you see?

[00:17:33.03]
And then here what you see
is a, this a mutant worm.

[00:17:38.00]
So this worm differs from
the normal worm by one gene.

[00:17:41.06]
This worm is eighty days old.

[00:17:45.06]
Oops! Oh-oh, there is, look at that!

[00:17:48.05]
So I just picked the worm up
and then put it down again,

[00:17:50.07]
and that has, you now see
a frenzy of motion here

[00:17:54.09]
for this old fellow.

[00:17:58.09]
Don't you feel a kind
of supernatural feeling

[00:18:03.01]
going through you right now?

[00:18:04.00]
This worm should have
been dead by 20 days,

[00:18:06.09]
it's 80 days and is still
living and moving around

[00:18:10.00]
after changing one gene.

[00:18:13.05]
80 days old, ladies and gentlemen.

[00:18:17.05]
The marvel of science!

[00:18:24.04]
(birds chirping)

[00:18:33.02]
Once you're confronted with
genes that regulate aging,

[00:18:37.06]
the question immediately presents itself,

[00:18:41.03]
could we use this information

[00:18:42.09]
to extend the lifespan of humans?

[00:18:53.03]
I can certainly imagine
changing a mouse in some way,

[00:18:55.08]
so that it could have the
30 year lifespan of the bat.

[00:19:00.07]
So when you get to humans, if you ask me,

[00:19:03.08]
"Could a human possibly live longer?"

[00:19:07.01]
I would have to say,
"I think, probably so."

[00:19:13.01]
Of course we wouldn't wanna do it

[00:19:14.01]
if we just extend the
time in the nursing home,

[00:19:16.02]
but if we could prolong
the good part of life,

[00:19:19.05]
would we want to extend
the lifespan of humans?

[00:19:32.07]
(upbeat music)

[00:19:36.07]
- [Narrator] The little
french mountain town of Bassan

[00:19:38.09]
is barely a pinpoint on the map,

[00:19:41.00]
but this birthday celebration
makes it a very special place.

[00:19:44.09]
For it honors, Madame Mariane
Boniface, 100 years old.

[00:19:49.01]
One of the guests is 102 today.

[00:19:52.00]
And what makes the event
even more newsworthy

[00:19:54.04]
is that there are 36
old people hereabouts-

[00:19:57.05]
(speaking foreign language)

[00:20:08.08]
- [Narrator] Nearing the
100 mark, Monsieur Cheminot.

[00:20:11.06]
Proper diet, hard work,
that's the formula.

[00:20:14.06]
(speaking foreign language)

[00:20:40.07]
(birds chirping)

[00:20:52.01]
(speaking foreign language)

[00:21:55.02]
(upbeat music)

[00:22:03.03]
(speaking foreign language)

[00:22:35.00]
(crowd talking)

[00:22:44.09]
(train horn blowing)

[00:22:57.00]
(music box playing)

[00:22:59.05]
(speaking foreign language)

[00:25:29.01]
- [Narrator] To every man who
lives out his normal lifespan,

[00:25:32.00]
there comes sooner or
later the fateful moment

[00:25:34.02]
when he realizes that
he is no longer young.

[00:25:37.00]
- Did you hear Sally's father
at the party the other night?

[00:25:39.09]
- Yes.

[00:25:41.01]
- He must be older than I thought.

[00:25:43.01]
- And I always thought of Sally's father

[00:25:44.07]
as being sort of, well young.

[00:25:47.00]
He almost floored me

[00:25:48.01]
when he said he could
remember back to the days

[00:25:49.06]
when there were no sound movies!

[00:25:51.07]
- That must have been
about twenty years ago.

[00:25:53.05]
- Well, I mean, I didn't have
any idea he was so ancient.

[00:25:59.04]
- Nobody wants to get old and decrepit.

[00:26:01.05]
I think that's what scares us all.

[00:26:03.01]
It's the loss of ability.

[00:26:07.00]
Your brain doesn't work as well,

[00:26:08.08]
your body doesn't work as well.

[00:26:10.00]
It's terrifying. Nobody
wants to go through that.

[00:26:14.04]
So just as nobody wants
to experience cancer,

[00:26:17.09]
nobody wants to experience aging,

[00:26:19.06]
and I would say at the
heart of the major efforts,

[00:26:22.05]
of course, is a way of
controlling it or ameliorating it

[00:26:26.02]
or at least softening the
debilitating effects of aging.

[00:26:32.09]
But for some scientists, I do believe,

[00:26:36.00]
actually for many scientists,

[00:26:38.00]
also at the heart of studying aging,

[00:26:40.08]
is what drives every scientist,
is an insatiable curiosity

[00:26:44.03]
and a hope of gaining new insights

[00:26:47.07]
into how biological systems work,

[00:26:50.02]
that previously we didn't have.

[00:26:53.01]
That's really what drives
many of us in the laboratory.

[00:26:56.06]
Although it makes us feel good to think

[00:26:59.06]
that maybe something we do
will cure cancer or cure aging,

[00:27:05.00]
at the heart of what drives
most of us is this curiosity

[00:27:08.06]
and this hope of uncovering
new insights into biology.

[00:27:14.00]
This is the age of biology,

[00:27:16.04]
and it's an amazing challenge,

[00:27:18.09]
and it's sort of the driving
force behind many of us

[00:27:22.05]
when we get into the lab.

[00:27:25.00]
My own research is to try to understand

[00:27:29.03]
how individual cells age.

[00:27:33.00]
We think, we don't know
for sure, but we believe,

[00:27:36.08]
that one of the components of aging

[00:27:40.09]
is the sum of individual cells
aging within the organism.

[00:27:48.04]
We discovered a way to
identify old cells in tissue.

[00:27:56.07]
We treat them with a dye,
and the old cells turn blue

[00:28:00.00]
and the young cells don't.

[00:28:04.01]
So we could look at skin from
young people and old people

[00:28:08.04]
and simply ask whether
we accumulate blue cells.

[00:28:11.09]
And we do.

[00:28:14.05]
What happens as a person ages,

[00:28:17.02]
is they accumulate more old cells.

[00:28:22.04]
And so the tissue becomes
clogged with cells

[00:28:27.06]
that are not functioning properly.

[00:28:30.03]
(ominous music)

[00:28:33.08]
When a cell becomes old,

[00:28:41.00]
it becomes in a way a
different type of cell.

[00:28:46.09]
It's no longer doing
its proper job in life.

[00:28:52.08]
It also becomes resistant to dying.

[00:28:58.00]
That's probably part of the
problem is that they don't die.

[00:29:05.03]
The problem with aging is
the accumulation of cells

[00:29:08.05]
that are now no longer
producing the right molecules

[00:29:12.01]
but are producing molecules
that can act outside of the cell

[00:29:17.06]
and can cause the tissue to disintegrate.

[00:29:23.03]
(ominous music)

[00:30:24.00]
The cells become old, as
a consequence of dividing.

[00:30:28.08]
They have a clock, a so
called biological clock,

[00:30:32.02]
which determines how many
times they can divide.

[00:30:35.01]
And at the end of that
magic number of divisions,

[00:30:38.02]
they just can't divide anymore.

[00:30:40.02]
(clock ticking)

[00:31:01.07]
So, what is this clock?

[00:31:05.02]
We really don't know for sure,

[00:31:06.09]
but there is a leading hypothesis,

[00:31:09.03]
based on what we know
about the genetic material

[00:31:13.08]
that is the soul of every single cell.

[00:31:18.07]
(dramatic music)

[00:31:23.08]
The genetic material is organized

[00:31:26.01]
into huge, long, long strings of DNA.

[00:31:29.05]
(dramatic classical music)

[00:31:36.05]
(upbeat music)

[00:31:40.02]
(ominous music)

[00:31:42.00]
(upbeat music)

[00:31:42.09]
And at every end of
this long chunks of DNA,

[00:31:47.01]
are structures called the telomere.

[00:31:50.03]
(ominous music)

[00:31:53.07]
(suspenseful music)

[00:31:59.06]
- The telomere has
little sequence of bases

[00:32:02.02]
that's building blocks of DNA,

[00:32:03.09]
repeated over and over, thousands of times

[00:32:06.09]
at the end of all the chromosomes.

[00:32:09.05]
So this is a very simple piece of DNA.

[00:32:13.00]
It kind of reminds me of
that tune that was in a movie

[00:32:16.02]
called "Close Encounters
of the Third Kind,"

[00:32:18.04]
which would drive you
crazy if you heard it over

[00:32:20.05]
and over again.

[00:32:21.03]
It went something like this,

[00:32:22.03]
♪ Ta ta ta ta taaa ♪

[00:32:23.07]
♪ Ta ta ta ta taaa ♪

[00:32:24.06]
♪ Ta ta ta ta taaa ♪

[00:32:27.08]
So in order for a cell to
divide to make two cells,

[00:32:30.09]
each cell has to get a
complete copy of all the DNA.

[00:32:35.09]
(machine squeaks)

[00:32:40.06]
Now, one reason that the
telomere is important,

[00:32:43.08]
is that the copying process
is not quite perfect.

[00:32:53.09]
The enzyme machinery has a little problem,

[00:32:56.07]
it can't quite copy the very very end.

[00:33:13.09]
Each time that cell divides
and makes two copies

[00:33:16.08]
of its genetic material,

[00:33:19.06]
then each of those chromosomes
will be a little shorter.

[00:33:23.09]
(dramatic classical music)

[00:33:28.09]
(suspenseful music)

[00:33:40.07]
And then it divides again,

[00:33:42.03]
and each chromosome will
be a little shorter again.

[00:33:45.05]
(dramatic classical music)

[00:33:48.05]
(suspenseful music)

[00:33:51.06]
And so on and so forth until
the telomere has shrunk down

[00:33:55.02]
into just a few repeats.

[00:33:59.05]
And after a while, the
cells stop dividing.

[00:34:05.02]
So this is a kind of a clock,

[00:34:07.00]
where you run the telomeres
down and then die of old age.

[00:34:15.03]
Some ideas are very appealing

[00:34:16.08]
because of their very simplicity.

[00:34:19.02]
But, I think this is a kind of clock

[00:34:22.05]
where a little kid can run
up and set the hands back

[00:34:28.00]
to zero very easily.

[00:34:32.00]
Cells have a special
enzyme called telomerase.

[00:34:36.01]
(suspenseful music)

[00:34:43.02]
So when telomerase is around,

[00:34:44.09]
it can add a little extra DNA back

[00:34:48.03]
to the end of the chromosome
and make it a little longer.

[00:34:59.06]
So just a few years ago
there was a lot of interest

[00:35:03.00]
in the idea that telomere shortening

[00:35:05.01]
might be the cause of aging.

[00:35:09.00]
And now we find that here's
telomerase like this naughty kid

[00:35:12.04]
coming along and turning back
the hands of the clock again

[00:35:16.04]
and adding more telomeric DNA.

[00:35:18.07]
And it can do that in very
mature cells in our body.

[00:35:24.06]
I think science advances
in a kind of a way

[00:35:27.01]
where what happens is like a watershed.

[00:35:29.05]
You fill up this watershed
with lots of information

[00:35:32.04]
and you get to a point where
it can take you so far,

[00:35:35.02]
and then it has to overflow

[00:35:36.03]
into a whole new completely
different era of information.

[00:35:41.03]
So I think we're filling
up with information

[00:35:44.02]
about genes and molecules
that talk to other molecules

[00:35:48.06]
that talk to other molecules.

[00:35:50.03]
We're getting a lot of what I
think of as linear information

[00:35:53.07]
right, cause and effect
and cause and effect

[00:35:56.03]
in kind of linear pathways.

[00:35:58.06]
I think the next big
questions in biology will be,

[00:36:01.05]
how do you integrate all this together?

[00:36:03.04]
The organism integrates it together.

[00:36:05.06]
But we haven't really begun to sort out

[00:36:09.00]
how to analyze that complexity very well.

[00:36:13.04]
We're great at picking
out individual components

[00:36:18.05]
of that pathway, so we can
follow little short strands,

[00:36:23.02]
if you think of it as a
great big ball of yarn

[00:36:25.03]
made up of strands stuck together,

[00:36:27.03]
we can follow individual little strands,

[00:36:29.05]
but we're not really good at
seeing how all the strands

[00:36:33.05]
integrate information from
all the other strands.

[00:36:36.07]
And maybe we need big computational tools,

[00:36:39.07]
maybe we need other
algorithms, mindsets, to do it.

[00:36:43.06]
So I think we're in an age of biology

[00:36:46.06]
which will evolve into
another kind of exciting age.

[00:36:51.08]
We've got lots of building blocks,

[00:36:53.08]
and now we have to start
building the castles, right?

[00:36:57.04]
And trying to figure out
how the castles are built.

[00:37:01.01]
(birds chirping)

[00:37:17.09]
(ominous music)

[00:38:39.02]
- There's a popular
myth that redwood trees

[00:38:42.06]
are three or four thousand years old,

[00:38:45.05]
and bristlecone pines perhaps even older.

[00:38:50.00]
The fact of the matter is that those trees

[00:38:52.05]
are not as old as we have been
taught to believe they are.

[00:38:59.00]
Those trees are no older
than 30 or 40 years.

[00:39:09.02]
The bark of course is
dead, and the next layers

[00:39:11.07]
that you penetrate are the
living, cambium layers.

[00:39:15.04]
But as you penetrate
further into the trunk,

[00:39:18.08]
that tissue is dead.

[00:39:24.02]
The oldest living cells in a redwood tree

[00:39:27.07]
or bristlecone pine are
found in the needles,

[00:39:30.06]
and they're no older than about 30 years.

[00:39:33.04]
So all viewers who are
older than 30 years,

[00:39:36.09]
are older than the oldest redwood tree.

[00:39:41.04]
The tree has learned how to
hold on to its dead cells

[00:39:46.01]
for architectural purposes.

[00:39:48.02]
You and I have not learned how to do that,

[00:39:50.05]
and consequently don't end up

[00:39:52.05]
being as big as a redwood tree.

[00:39:58.00]
We have, going on in our bodies,

[00:40:00.08]
what's called cell turnover.

[00:40:02.09]
We have cells dividing, some
classes dividing every day,

[00:40:07.07]
others dividing every week,

[00:40:10.00]
and others dividing every month or two.

[00:40:14.04]
With the exception of your
neurons and your muscle cells,

[00:40:18.03]
the cells that were present
in your body 10 or 15

[00:40:21.03]
or 20 years ago are no longer there.

[00:40:24.03]
So that you are, literally,
not the same person

[00:40:28.08]
you were 10 years ago.

[00:40:32.08]
As a matter of fact, when
you celebrate your birthday,

[00:40:35.01]
you should only be
celebrating the birthday

[00:40:37.07]
of your neurons and muscle cells

[00:40:40.05]
which have been around since
birth, everything else is new.

[00:40:46.05]
(ominous music)

[00:41:00.03]
The question of what is an individual,

[00:41:04.06]
is very difficult to determine.

[00:41:25.03]
In the case of replication
of plants, for example,

[00:41:28.05]
through root systems where
a single tree or bush

[00:41:32.08]
gives rise to more trees or bushes,

[00:41:36.03]
all attached to the original parent.

[00:41:40.07]
From an original, single bush

[00:41:44.04]
that sends out roots underground,

[00:41:47.06]
the creosote bush forms a ring.

[00:41:56.01]
Ultimately, the bush in the center dies,

[00:42:00.02]
and you end up with a very wide ring.

[00:42:15.03]
- King Clone at time was dated,

[00:42:18.08]
was the oldest living plant
complex known at the time.

[00:42:22.09]
It was dated at 11,700 years old.

[00:42:29.07]
The plants that make up that ring,

[00:42:32.02]
they aren't 11,000 years
old, but that ring itself.

[00:42:36.06]
To me, that's where the significance lies,

[00:42:39.00]
that it was able to persist so
long and maintain that form,

[00:42:43.03]
and the integrity of
that ring is still there.

[00:42:46.04]
(somber music)

[00:42:56.06]
- We all understand that
our lives are finite.

[00:43:02.08]
But there is an aspect of our bodies

[00:43:06.03]
that is indeed immortal

[00:43:08.02]
and that is either our sperm or egg cells,

[00:43:11.03]
that go on to provide a new generation.

[00:43:16.01]
So that you and I and our viewers
represent the leading edge

[00:43:20.06]
of an immortal lineage of cells

[00:43:24.06]
that have been in existence

[00:43:26.03]
for many millions or tens
of millions of years.

[00:44:47.06]
(somber classical music)

[00:45:48.05]
(speaking foreign language)

[00:46:39.03]
(upbeat music)

[00:46:50.03]
(speaking foreign language)

[00:47:40.05]
(sinister dramatic music)

[00:47:46.03]
(speaking foreign language)

[00:47:55.09]
(somber music)

[00:48:03.05]
(speaking foreign language)

[00:48:47.08]
(somber music)

[00:49:11.06]
(speaking foreign language)

[00:49:14.09]
(somber music)

[00:49:17.06]
(speaking foreign language)

[00:50:38.02]
(speaking foreign language)

[00:52:54.08]
(water whooshing)

[00:54:07.01]
(speaking foreign language)

[00:54:24.00]
- You can imagine a scenario
in which people say,

[00:54:26.02]
"Well, we must never live
longer, we shouldn't do that!

[00:54:28.07]
That would be immoral, unethical.

[00:54:30.08]
So we should stop this research."

[00:54:32.08]
Now, that could happen.

[00:54:34.02]
But I think that would be a shame,

[00:54:37.01]
because I think that from
this understanding of old age,

[00:54:42.06]
we're going to, we know so little now,

[00:54:44.03]
we'll know so much more in the future,

[00:54:45.07]
will we be able to pick
and choose which aspects

[00:54:48.00]
of that we want to incorporate
into new drugs for people?

[00:54:52.05]
And it really, I mean, I just know

[00:54:55.00]
that things coming out of
it will be useful to us,

[00:54:57.03]
it would be, you would
have to be so pessimistic

[00:55:00.01]
not to believe that you'd be irrational,

[00:55:02.07]
people would laugh at you.

[00:55:04.01]
And it seems very likely

[00:55:05.05]
that we could get the
good parts out of it,

[00:55:07.06]
without necessarily getting things

[00:55:09.02]
that we might think would
be detrimental to society.

[00:55:11.07]
But what we need first is knowledge,

[00:55:13.02]
we have to know how it works,
before we can pick and choose.

[00:55:18.04]
- For the first time, we have
enough fundamental information

[00:55:25.04]
about biological processes
that there is a hope,

[00:55:29.08]
real hope of changing what
we are and how we respond

[00:55:36.04]
to our environment, and what
our genes tell us we must do.

[00:55:40.06]
(dramatic music)

[00:57:25.00]
(clock ticking)

[00:57:48.06]
(gentle music)