Biologists have noticed a positive correlation between the protein sirtuin and cellular longevity. Moreover, as we age, the levels of NAD go down steadily. Turritopsis dohrnii is also known as the "immortal jellyfish." The process of cellular trans-differentiation means that one type of cell in the body can transform itself into another type of missing cell in the body.
Adult stem cells induced to become embryonic stem cells are known as induced pluripotent stem cells (iPS cells). CRISPR can be used to repair DNA. Cas9 is an example of CRISPR that functions like a police officer to protect the cell's DNA. Some bowhead whales live past 200 years!
Terror management theory is used by people facing death.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season8
#episode2
#cosmology
#astonomy
#spacetime
#spacescience
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Adult stem cells induced to become embryonic stem cells are known as induced pluripotent stem cells (iPS cells). CRISPR can be used to repair DNA. Cas9 is an example of CRISPR that functions like a police officer to protect the cell's DNA. Some bowhead whales live past 200 years!
Terror management theory is used by people facing death.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season8
#episode2
#cosmology
#astonomy
#spacetime
#spacescience
#space
#nasa
#spacedocumentary
#morganfreeman
#death
Category
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LearningTranscript
00:00are we born to die for millennia we've tried to outsmart our own mortality only to find that
00:12death is the greatest certainty but for the first time in history that may be about to change
00:20science is unraveling the mysteries of aging discovering an animal that comes back from the
00:33dead and turning our quest for eternal life on its head are we about to enter the age of immortality
00:41or is death necessary for the survival of our species can we cheat death
00:53space time life itself
01:00the secrets of the cosmos lie through the wormhole
01:11when will i die it's a question i've asked myself i'm sure you've thought about it too
01:27from the day we are born the clock of our lives marks our inevitable decline
01:35ticking inexorably toward our final hour
01:38medical science has made incredible advances in prolonging life
01:44for most of human history people were lucky to survive into their 40s now people often break a
01:50hundred the oldest person we know of lived to celebrate her 122nd birthday and as we probe
01:59deeper into the fundamental biology of life we are now questioning whether death really has to come at
02:05all whether we can stop the clock
02:14david sinclair likes to live in the fast lane
02:18but he knows our bodies like cars can't push the needle forever well i've been interested in studying
02:26aging since i can remember i think it was around the age of four when i realized that my parents
02:31would one day die and and i would too and that seemed extremely tragic and i also thought that
02:37we could figure out why we age and what we could do about it that would have a really big beneficial
02:41impact on the world david spends a lot of time thinking about old age but he's interested in more
02:49than the wrinkles on our skin as a professor of genetics at harvard he asks what role our genes play
02:57in aging an aging body is a lot like a rusty old car rust or oxidation is what causes everything
03:07including our dna to break down
03:13david believes we may soon be able to repair our failing bodies as easily as a mechanic can spruce up
03:19a rusty body panel david research focuses on our body's own set of repair mechanics a group of genes
03:28called sirtuins as our bodies age they accumulate old or senescent cells and longevity genes prevent
03:36those cells from accumulating this would be similar in an old car to the mechanics removing rusty old
03:42parts and replacing them with new ones but these repair genes begin to fall silent as we pass our 30s and
03:4940s so if we could find a way of getting these longevity genes working harder this would be a
03:54way to keep our bodies healthier and working for longer if ourselves have the tools to restore and
04:00rebuild themselves why can't they do that forever in other words stop aging sinclair has dedicated his
04:09career to finding ways to help our repair mechanisms keep going well past middle age it's driven him deep
04:17into the inner mechanics of the cell in order for a human cell to function it requires close collaboration
04:27between two distinct parts the nucleus the cells control center and its tiny power engines called
04:36mitochondria every task the cell performs relies on precise communication between these two
04:44imagine this kitchen is a young cell inside it are the nucleus and mitochondria two chefs working in
04:52concert our genes are just like a recipe book in a young cell the nucleus and the mitochondria
04:59they're reading the recipe perfectly and they're really working well together
05:04a delicious meal is taking shape but over time the communication and coordination between the chefs gets worse
05:14in an old cell the nucleus and the mitochondria they're throwing in things that don't belong they're
05:19leaving things out they don't communicate well one chef might be trying to pass a spoon to the other and
05:23the other one's not paying attention it's as if the chefs are spilling on the recipe book and losing that
05:29ability to read it dna is the recipe of life but over time wear and tear makes the recipe hard to read
05:38and our cells lose the ability to prepare the meal whether it's damage or changes in the environment
05:46the cell eventually loses the memory of which genes should be on and which genes should be off and that
05:51we think causes aging david has been combing through aging cells trying to see if he can identify
06:00which vital ingredient they lack and now he thinks he's found the molecule that will get our cellular
06:07kitchen back on track it's called n a d it's a molecule that's essential for life without it
06:14you'd be dead in about 20 seconds and as we age the levels of this molecule go down steadily to the
06:20point where you have about half the levels of what you once had david wondered if there was a way to
06:26restore n a d to more youthful levels he injected mice with a special compound that boosts production of
06:34n a d the effects were dramatic this mouse is very youthful and energetic and you can see the ears are
06:43still nice and young looking and the fur isn't turning gray so you can see here this mouse is going gray
06:51she's losing hair her ears are getting wrinkled her spine is starting to bend
06:58well what's amazing about these mice is that they were born on the same day
07:04what we saw was a rapid aging reversal in their muscles from a mouse that's equivalent to a 60
07:09year old human back to a 20 year old if we can apply this to humans imagine what a city street
07:15might look like 50 years from now almost everyone would appear youthful free of the illness and
07:22frailties of age david's research may one day slow down and even reverse aging in people we're not
07:32talking here about being older for longer it's quite the opposite it's about being younger for longer
07:38but david's work only treats the symptoms of aging it doesn't attack the root of the problem
07:44the gradual decay of our dna
07:52japanese scientist shin kubota thinks we can turn that tide
07:58my dream is to live with my families of different generations so that we can enjoy our great great
08:10grand children the sea is where all life began and with every empty shell that leaves behind
08:19it seems to prove that all lives must end but shin knows otherwise shin studies a tiny marine animal called
08:28turatopsis dornea or the immortal jellyfish this creature has figured out how to cheat death
08:40at shin's lab in the town of shirahama is the world's only captive population of immortal animals
08:49first discovered in the mediterranean in 1988 this jellyfish is no bigger than your fingernail
08:58the immortal jellyfish is very cute small jellyfish diameter is about several millimeters
09:05but after showing these creatures such tender loving care shin does the unthinkable
09:13he chops them into pieces
09:17try to kill this jellyfish you will be surprised
09:21a remarkable thing happens the jellyfish does not die beneath shin's hand instead it seems to be
09:32reborn the bell reabsorbs the tentacles and becomes a gelatinous blob i call this dish the meatball
09:42the meatball the meatball becomes a polyp and soon it matures into an adult jellyfish
09:52the jellyfish shows very remarkable transformation the jellyfish's secret is a process called cellular
10:01transdifferentiation the cells and any fragment of the animal can figure out what body parts are missing
10:08then retrofit themselves to grow back the entire body if we could determine how to the jellyfish rejuvenate
10:18we could borrow its techniques imagine shin were attacked by a mutant sea monster
10:28it's japan after all so it's not such a crazy idea if the only thing left of shin were the tip of one
10:36little finger transdifferentiation could turn those finger cells into brain cells heart cells
10:44muscle cells shin would come back from the dead
10:51it seems like science fiction but jellyfish and humans have surprisingly similar genes
10:59if a jellyfish can learn this trick perhaps we can as well
11:02from the ruins of a single animal hundreds of identical jellyfish have sprouted it's a feat unequaled
11:11in nature but perhaps not for long if we could unlock the genetic secrets of this jellyfish
11:19we could regenerate aging organs perhaps even entire bodies
11:24i mean one day the humans can become immortal using the same process as the jellyfish
11:36the promise of immortality always seemed a fantasy but the infinite regeneration of the jellyfish is
11:43biological reality so can we get there with our biology some people believe we will and sooner than you think
11:54we'll see you next time
11:58death has always been a fact of life
12:01why because our bodies wear down our hearts won't beat forever our muscles gradually weaken
12:11our brains lose their edge but it doesn't have to be that way
12:17our bodies have built-in technology to repair themselves stem cells
12:25these cells have the potential to replenish any organ in the body if we can coax them into doing it
12:37cell biologist larry goldstein thinks that if we want to extend our lifespans we'll have to leap past a
12:44major obstacle the slow decline of our minds i had the unfortunate experience of helping to care for
12:53my mother when she developed alzheimer's disease in her late 60s it was a terrible experience and i hate
13:01the idea of anybody else having to go through that with their family members and their loved ones
13:05and their loved ones 50 percent of us will develop alzheimer's disease by the time we're 85 years old
13:12it does no good to age to 85 and be physically healthy if your brain doesn't function at the sanford
13:19consortium of regenerative medicine larry keeps an hourglass on his desk it reminds him of all the
13:27people who are running out of time but larry thinks he's found the key to fighting debilitating
13:33diseases of aging like alzheimer's stem cells the problem is that we don't
13:41really understand what goes wrong in brain cells that have the disease and
13:46we're using stem cells to try to tackle that problem in a unique way stem cells
13:51are the body's original building blocks they have the potential to become any
13:57type of cell in the primordial furnace of the room our bodies use these raw
14:06materials much like a master glass blower sculpting beautifully intricate finished
14:12organs from shapeless raw ingredients you can think about stem cells as being
14:18like biological raw material just like these glass pellets are the raw
14:23material that you can throw into a really hot oven and use to make anything
14:28at all that you'd like to make so let's see how this works in you go oh as we
14:36grow from an embryo our bodies prepare and shape stem cells for the adult roles they
14:43will need to fill each stem cell decides what adult cell type to become based on
14:50cues from the cells around it stem cells respond to biochemical signals from other
14:56cells and so a heart cell started out as a stem cell and it got instructions to
15:01become a heart cell you can imagine putting a heart together with different
15:05vessel cells or different muscle cells great glass blower can put all these
15:09different shapes together to make something beautiful at the end cool enough
15:14to touch amazing it's incredible really when you think about it millions and
15:19millions of stem cells get together respond to the right sorts of biochemical signals and
15:24make this heart the power of stem cells to create organs from scratch has drawn the
15:32interest of scientists for decades the goal is to harness this resource to rebuild and replace
15:40failing tissue but there's a problem by the time we're fully grown we've exhausted our supply of
15:48embryonic stem cells and the few stem cells we have left are not nearly as flexible there are so-called
15:56adult stem cells which are partially formed they're committed to make one of the types of adult tissues
16:03skin stem cells make skin brain stem cells make brain tissues but the important point is that it's
16:11partially committed it has part of a shape that commits it to do some things and not others only
16:18embryonic stem cells have the flexibility to become any cell in the body but harvesting them from embryonic
16:26tissue has proved politically controversial then in 2006 scientists made a stunning discovery adult stem
16:36cells can be recycled back to embryonic form by modifying just four of their genes they become what are called
16:46induced pluripotent stem cells or IPS cells so the discovery of IPS cell was like the shocker
16:56around the world it was a true revolution in our understanding of what cells could do and how simply
17:04it could be done by throwing glass back into the furnace we can now restore cells to their embryonic
17:11state and create raw materials we could use to stay eternally young you could make this into brain cells or
17:19heart cells or skin cells or what have you we've used genetic trickery to take for example a skin
17:26cell for my arm trick it using genetic elements into becoming a cell like an embryonic stem cell in its
17:34abilities Larry is now using these rebooted cells to uncover what goes wrong in Alzheimer's he starts
17:44with skin cells of people with the disease and changes them into brain cells then he can study exactly
17:52what's going wrong in those cells and develop new drugs to treat them right now we have zero drugs that
18:00alter the course of Alzheimer's disease I do know that if we want to make it past 85 or 90 on a regular
18:08basis we're going to have to solve the problem Larry hopes his work on Alzheimer's is the beginning of
18:14something bigger he thinks if we stored our stem cells while we're young and healthy we could use
18:20them later to replace our aging organs it's incredible really when you think about it the ability to someday
18:27build an organ from stem cells like this will be a huge breakthrough in the future we may be able to
18:33extend our lives by recreating our failing hearts lungs and kidneys but what happens to our society when
18:41people live longer are we turning nature's plan upside down one scientist has simulated a world where
18:49no one dies of old age and he's reached a startling conclusion if our organs have the power to regenerate
19:00why do they allow us to age and die plants bugs animals happens to us all
19:09perhaps it's because death is programmed into us by evolution
19:15old animals must die to free up space for the young
19:20so if we cheat death if we regenerate the sweetness of youth
19:31will evolution end
19:32it's taken humans more than a thousand years and many lifetimes to master the game of chess
19:41that's a puzzle for brazilian evolutionary biologist andre martins wouldn't it be better if one person
19:48could live long enough to acquire that mastery all by him or herself for quite a while scientists
19:55thought that evolution could not explain aging when does someone die in average they will leave less
20:02children and that's a clear disadvantage from an evolutionary point of view evolution is supposed to
20:10favor the individuals best adapted for survival so why doesn't it let us survive forever why are we
20:18denied the ultimate adaptation andre created a computer simulation to find out i have always find
20:26the evolution problem fascinating i thought it could explain not how but why we age andre's simulation
20:34uses game theory the math of competitive situations he thought he could find out whether dying actually
20:41serves the purpose by staging a competition so what the computer model does is simulate the competition
20:49between mortals and immortals but when you see blue it means that that region of space there is
20:56a mortal living there and if it's red there is an immortal living there they fill out every space and
21:02then they start competing for the limited resources there to picture andre's simulation
21:11imagine a head-to-head contest between two very different soccer teams the immortal players in red do not wear
21:19out with time but the mortals in blue will eventually become too tired to play by pitting the two against
21:29each other in a game lasting many generations andre thought he could find out just how much advantage
21:36immortality conveys every time i run the simulation the same thing happens the advantage of not dying
21:43makes a huge difference and the immortals start winning like soccer life is a competitive struggle
21:52if you compete more effectively you control the game but andre's simulation contains another lifelike factor
22:00environmental change just like in the real world andre's virtual players face constantly shifting
22:08conditions like new diseases predators and climate change while immortals can struggle through them
22:22not all mortals make it however when they die they are replaced with younger stronger players
22:30in any evolutionary process if you are mutating and adapting the new generations will be a slightly
22:36better than the older ones because they are the ones that survive
22:41since the mortal can't evolve this gives them an advantage that allows them to get back in the field
22:50in evolution each new generation has some tricks the last one didn't
22:55and the faster you get them on the field the faster the species improves
22:59the impact after many generations is huge first there is no advantage for any site and then slowly the blue
23:11mortal starts winning and after a while they can actually drive the red team the mortals to extinction
23:21in the end the mortal population wins because the immortals can't adapt they're doomed
23:29this suggests that aging has a biological goal
23:36andre believes to keep pace with a changing world we need new generations with new adaptations and we must
23:44make room for them which makes mortality necessary the mortal can drive the immortals to extinction
23:53it was much easier than what i was expecting from an evolutionary point of view for the species
23:58it is a good thing to die for a personal point of view it's not a good thing at all
24:05we owe our very existence to the wonders of evolution even though it has designed us to get out of the way
24:14but what if we could sidestep natural evolution manipulate the genes that make us die
24:20could we evolve ourselves to live forever
24:29at the core of every living cell is a single fabulously complex molecule
24:36dna its genetic code is the source of life
24:42but dna is also the reason we die as we age our dna code gets slowly jumbled until it can no longer keep
24:51us alive if we can undo those mistakes we can stop death's shadow from creeping up on us
24:59professor jennifer doudna thinks we're on the brink of being able to fix all the errors in our dna
25:12and make ourselves immune to disease and decay it's been an amazing uh decade or more in science when it's
25:20been possible to sequence not only the entire human genome but now many human genomes and what's really
25:28on the horizon is the opportunity to rewrite that information over the past few years jennifer has
25:36developed a revolutionary dna editing technique which has turned the dream of modifying our genes
25:43into practical reality what's exciting right now is that we have a chance to make changes to the dna
25:52at the level of a single letter in the more than three billion letters in the human cell so this is a
25:59wonderful moment when the technology has become available for that kind of precision genome engineering
26:06in the past dna editing has been a crude hit and miss affair imagine trying to fix a pair of eyeglasses
26:17without being able to see them and with tools that are far too big for the job we didn't dare to edit
26:24human genes that way but jennifer and her collaborator emmanuel charpentier have developed a new far more
26:32precise tool that makes dna surgery not only possible but easy it's called crispr and it places almost godlike
26:43powers in the hands of humanity like many scientific wonders crispr was pioneered by nature herself inside
26:52bacteria we began our project with the goal of understanding how bacteria fight viral infection
27:00but if we recognized that molecules involved in those processes in bacteria could be harnessed
27:09as a technology for rewriting the dna in cells
27:17you could think about the dna of a bacterium as a house and the invading viral dna as a burglar
27:24jennifer and emmanuel discovered that bacteria have a built-in surveillance system they can't prevent
27:32the first attack but a system called crispr takes a precise snapshot of the viral dna the same way a
27:40security camera captures the picture of a burglar in a real bacterial cell the crispr sequence is the way
27:48that the cell records images in the form of dna that represent foreign invaders and keep it for future
27:57reference to protect the cell from those same invaders when the intruder shows up a second time
28:06the bacterial cell recognizes the invader from stored surveillance images and calls the cops in the
28:13bacterial cell those cops are the enzyme cas9 so when the house pulls out a picture from the surveillance
28:22camera and identifies a potential invader that's the crispr system using the enzyme cas9 to find and destroy
28:34foreign dna the cas9 molecule acts like a pair of scissors precisely guided by crispr to a matching
28:42site on the virus of dna it then cuts the dna in that spot destroying the virus's ability to reproduce
28:51the threat to the bacterium is eliminated but jennifer realized she could adapt this natural mechanism
28:59into a pinpoint method for gene editing accurate down to a single letter of dna this genome engineering
29:08technology provides the opportunity both to identify genetic mutations that cause disease but also to
29:17actually correct those mutations the ability to precisely fix errors in our dna brings the promise of
29:25extending our lives lifting the shadow that death casts over us we could use crispr to stamp out hereditary
29:33diseases like cystic fibrosis and sickle cell anemia or simply make better humans ones with extra strong
29:41bones low risk of alzheimer's or built-in resistance to cancer but a dark side looms could this technology
29:50be used to create genetically engineered embryos for a super race an elite population of designer babies with
29:58enhanced intelligence beauty or strength i myself came to this realization over time and one of the things
30:07that really influenced me was a dream that i had in which i was being asked to explain the crispr
30:13technology to someone in a dark room and when that person turned around it was the profile of hitler
30:21i still feel chills when i think about that moment in my dream when i really felt strongly that this
30:30technology needs to be handled with caution humans genetically engineered to live longer are no longer
30:37the stuff of science fiction the more we study our genome the more opportunities we will see to improve
30:43it in fact scientists are already hunting for the genetic secret to living for 200 years
30:51in the dna of another animal
30:59in 2007 fishermen caught a bowhead whale off the coast of alaska embedded in its flesh they found a
31:09harpoon tip dating to the 1890s no mammal on earth lives longer than the bowhead some of them live past 200
31:20if we're looking for the genetic tools to cheat death all that we need is probably already out there
31:27in nature's vast pool of dna we just have to find it
31:32the secret of longer life one of the mysteries of aging why it is that some animals like mice
31:48live for two and a half years because of their genetic program while other animals like bowhead whales
31:54live for 200 years because of a different program there's a wide range of lifespans across all organisms
32:01in nature but there is a consistent trend large animals tend to live longer you could think of this in
32:08terms of a swimming race between long distance swimmers and sprinters in this analogy the bowhead whale
32:19long live they're like the marathon white cap swimmers and the mice are like the red cap sprinters
32:26big animals move slowly but last for the long haul small guys race along and burn out quickly
32:37but george doesn't think size explains the bowhead whale's long lifespan he thinks the secret lies in how
32:43it takes care of its dna researchers recently found evidence that the bowhead excels at repairing damage
32:50to its genes in humans dna damage is a major cause of aging george thinks we could repair that damage
32:59using the powerful new crisp gene editing technique we're harnessing vast amounts of information gathered
33:07on long-lived animals and converting it into a gene therapy that can test whether we can do aging reversal
33:15in large animals than humans most of us die because our organs fail our hearts our lungs livers our brains
33:26but george thinks we can build better organs by going back and removing genetic defects from the cells
33:32they are made from to test this idea george looked at the genomes of pigs we are using editing methods
33:42to engineer cells that are capable of producing pig embryos scientists have discovered that over the
33:49millennia pig dna has been contaminated by 62 different viruses george decided to use it as a test case
33:59to see if gene editing could delete these tiny contaminants what we did was unprecedented which was
34:07we had to use it as a test case we had to use it as a test case we had to use it as a test case
34:11so that now the pigs are for the first time virus free with sperm and egg cleansed of ancient
34:18contaminants george made his own big embryos using in vitro fertilization but once the pig embryos are
34:26implanted uh we no longer have to keep going back to the embryo stage and then the pigs breed just like
34:32regular pigs would it's just that they no longer produce viruses it also gives the opportunity to
34:38make more healthy organs which are resistant to viruses cancer and aging ultimately george wants
34:47to apply this technique to humans and to a much broader range of genetic defects deleting harmful genes
34:54and adding in beneficial ones we find in long-lived animals like the bowhead whale
34:59today we can test for genetic defects in unborn children but we lack the means to cure them
35:08so when you go to a modern obstetrics clinic like this and you're concerned about genetic disease
35:13the mother and the father can get a readout of their genome and make decisions that might involve
35:19termination george believes that in the near future parents won't have to face these difficult
35:25choices the gene editing techniques he's pioneering in animals will soon be applied to the genes of
35:32human parents before they ever conceive a child in the near future you'll be able to edit either the
35:38mother father's body dna so that the sperm egg does not contain the very serious disease and never even
35:45makes it into an embryo further into the future we'll even add dna modifications so that children are born not
35:53only healthy but with long-lived super organs today living for 200 years is beyond our reach but with
36:02precision editing in the sperm and egg our genes may soon have the staying power of the genes of the
36:09bowhead whale just as our ancestors had a life expectancy of 45 years today it's more like 90 mothers
36:16today can expect their children to live into their hundreds imagine the future where people over
36:22100 years old continue contributing to society as if they were in their 30s again where their vast
36:29experience is valued and ageism is a thing of the past but this man thinks our quest to cheat death
36:37threatens the fabric of civilization itself he says it's time for us to embrace death
36:47a century ago the average life expectancy of an american was around 52. with genetic engineering
36:58living to 150 will fairly soon be the new norm
37:02that sounds great who doesn't want more time to grow to love to create but what happens if we keep
37:15pushing the limit 300 500 maybe forever you'd think a world where death is a rarity would be a utopia
37:26but would it
37:34stephen cave is a professional philosopher he thinks a lot about death
37:43you might say it's what gets him out of bed in the morning
37:47most people most of the time are running away from death we're terrified of death even though it's one of
37:53the most people are in denial of it but stephen is a little different he's actually running towards
38:04death as he sees it our civilization depends on it i think it's important that we actually face up to
38:11mortality that actually life is richer and better and more valuable when we recognize that it is limited
38:19but that awareness of our own mortality causes an intense anxiety to deal with it we repress and deny it
38:28and even lie to ourselves social psychologists call it terror management theory well what do we do
38:36how do we cope with that terror well we tell ourselves stories that deny the reality of death that
38:43tell us that somehow we can keep going forever in other words confront someone with the fact that
38:50they are going to die and they will believe any story claiming we can live forever so every civilization
38:59has some story about why we don't need to fear death now this might be a religion for example the
39:04promises that if we believe we can live forever in heaven or it might be patriotism or nationalism
39:10the promises we can live on as part of this greater whole room
39:18imagine these identically dressed runners represent one subgroup of human society
39:25and now suppose that the group splits in two with each half taking different paths through the city
39:31the two groups remain indistinguishable from one another until one passes through a graveyard
39:40the group who have been running past the cemetery will unconsciously have been reminded about death
39:46and because of that they will be in a different state of mind when they finish their run
39:50when the members of the group join back together they meet a pair of individuals who belong to a new group
39:58the members of the group who saw the tombstones aren't interested in the outsiders
40:03those who never saw reminders of the dead are more open-minded
40:08over 400 studies have shown merely thinking about death causes us to pull tighter into our social groups
40:15this may sound like a bad thing but stephen argues that on balance over the course of history it has not
40:22been fear of death is the engine that drives us to create tight-knit societies and from that culture
40:30and civilization itself are born so much of what we've built is about helping us to live longer
40:38and if we can't stay alive physically you know if buildings and medicine and science doesn't do it
40:44for us then we've got art and culture and religion that helps to carry us forward even after bodily death
40:52stephen believes all civilizations exist to defend us against the fear of death without the fear of death
41:00humanity as we know it would cease to exist
41:03if we all woke up tomorrow and found ourselves immortal then there would be profound changes in
41:08our society religion would lose its unique selling point we wouldn't need to sign up in
41:14order to get eternity in heaven if we already had eternity here on earth the inevitability that our
41:21lives will one day end has spurred us to leave a legacy to create literature art technology everything
41:28that makes us who we are rather than paralyzing us with fear stephen believes knowledge of our demise
41:36can help us live you can see life is like a book just as a book is bounded by its covers
41:44so our lives are bounded by beginning and end and even though a book is limited by its covers still
41:51it can encompass fantastic adventures and distant landscapes and exotic figures the characters in
41:57a book they're not afraid of you reaching the last page and so we shouldn't worry about whether our story
42:06is long or short whether it's a comic story or an epic we should just focus on making it a good story
42:13we've been so busy striving to cheat death we forgot to ask ourselves if we really want to live in a world
42:23filled with immortals as science allows life to last longer it may also grow sweeter free from disease
42:33physical infirmity and the slow decay of the mind but nothing needs to last forever
42:40to the young death's shadow brings fear but to a man of my age it brings vigor the desire to do what
42:51i love while i still have time oh i'm happy to cheat death but only as long as my passion for life remains
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