And you. What do all these things have in common?

They all have an expiration date.

Ben Franklin said there are only two things  certain in life - death, and taxes. However,  

certain prominent citizens have proven it's a  lot easier to get out of paying taxes than it  

is to live forever. From the moment we're born,  we're all ticking down towards the finish line.  

It seems to be the one immutable rule of  life. From that plant that never seemed  

to flower no matter how much sun you gave  it, to your beloved first goldfish Floaty,  

to the most powerful King or President, every  single living being on Earth will inevitably die.

But why? Why were we all  born to eventually expire?  

What purpose does this serve in evolution to  give us all a limited time on this planet?

It's far from exclusive to humans - we've had  the opportunity to study the life cycles of  

most animals and plants and those that don't die  of other causes will inevitably die of old age.  

Life cycles vary, but all follow a similar pattern  of growth, peak years, and natural decline as  

they get older. What is unique to humans is an  awareness of our own mortality, and the desire  

to understand what comes before, during, and  after death. End-of-life care, the branch of  

medicine dedicated to making people comfortable  in their last year, makes up roughly ten percent  

of overall medical spending, encompassing those  who die from both illnesses and from old age.

But it wasn't always this way.

Hundreds of years ago, old age was a much rarer  way to go out. Life expectancy was dramatically  

shorter, and people were more likely to die  from injury, contagious disease, infection,  

or malnutrition. Many of these causes still  persist in countries and regions around the world,  

but the advance of medical treatment and  the industrialization of food production  

has cut them down and let other causes take  the lead. The leading causes of death now  

include heart disease, stroke, respiratory  infections, dementia, cancer, and diabetes. These  

non-contagious illnesses can affect people of any  age but become more likely the older people get.

And of course, there's one common  cause of death - old age, right? Wrong!

Would it surprise you to know that no one has  ever died of old age? Age isn't a cause of death,  

it's a risk factor that eventually leads people  to succumb to an ailment associated with aging.  

The government mandates that every death  certificate lists the cause of death,  

so when someone dies suddenly or in their sleep  without an obvious cause of death, it used to be  

frequently listed as “natural causes” or “old  age”. This is starting to change. Every one of  

these cases has an underlying cause and as medical  science presses forward, coroners are becoming  

more skilled at pinpointing the cause of death.  The exception may be when someone dies peacefully  

at home after a long life, and their family  doesn't want an autopsy or investigation. Also,  

a very old person who has been beating the odds  for a long time may have a lot of underlying  

ailments and it can be hard to determine  which was the one that led to their death.

So does the human body have  a natural expiration date?

It's rare for a person to live past a hundred  years old, although this group - centenarians - is  

the fastest-growing population demographic in  industrialized nations due to the advances in  

medical care. There's an even rarer group,  super-centenarians, who have lived to  

a hundred and ten and beyond! The verified  oldest person ever to live, Jeanne Calment,  

was a French woman born in 1875 who died in  1997, although questions about her story have  

emerged in recent years - with some claiming her  daughter was impersonating her in her last years.  

Most experts still credit her as being the only  person to ever live past a hundred and twenty,  

outliving runner-up American Sarah Knauss by  over three years. They should both watch out,  

though, because the person in third place  is still kicking. Kane Tanaka of Japan is  

currently about to turn a hundred and  eighteen on the second day of 2021.

So is there a secret to living this long,  

or did Jeanne, Sarah, and Kane  find the fountain of youth?

Those who live to over a hundred tend to have  similar characteristics, such as eating well;  

exercising regularly, avoiding smoking  and stress, being connected to family,  

and having an overall good attitude towards  life. The average centenarian is also shorter  

and lighter than the average. But other factors  like location and environment play a role too.  

Unusual concentrations of centenarians have  been found in places as far apart as Okinawa,  

Bulgaria, and Sardinia. Okinawa has the  highest concentration of centenarians,  

with five hundred per million residents,  and scientists give a lot of the credit to  

their diet and comparably low caloric intake,  which may reduce wear and tear on the body.

Is it possible to learn from this and  extend the human lifespan further?

Research into the nature of death has led to  experiments in areas like cryonics, where beings  

are preserved immediately after death for possible  treatment and resurrection in the future. However,  

this is all theoretical at the moment, as no being  has ever been resurrected after death and cryonic  

freezing in tests. Techniques like reperfusion,  where oxygen is pumped into the blood in a very  

controlled manner to prevent cell death, have  been used to test the theory but may have more  

use in standard medical treatment rather than  in reversing death for now. Other concepts,  

like developing digital uploads of the brain  and transferring them into a clone body, remain  

firmly in the realm of science-fiction for now.  At least at this point in time, everything dies.

But what purpose does this serve in  evolution? Why have millions of years  

of development never managed to outgrow death?

There are many theories for the purpose  death plays in evolution, and several have  

been debunked. A common early theory was that we  die so that younger generations can replace us.  

This doesn't make sense with the primary purpose  of life, though - we're a collection of genes,  

and the death of an older person makes room for  only one more person by their absence. As genes  

only have a fifty-percent chance of being passed  on to the next generation through the parent,  

it doesn't make sense for evolution to develop  death to favor the offspring over the parent.

There's also the theory that we die because  our cells or DNA naturally degrade with age.  

That's true, but it's an effect, not a  cause. Our cells mutate as they divide,  

and the more cells divide the higher the chance  of a mutation. This can cause medical problems,  

but our cells are constantly reproducing and  can usually overwhelm any mutated cells. The  

exception? Cancer cells, which reproduce and  overwhelm the healthy cells. Cells only have  

a certain number of divisions before they  reach the end of their natural lifespan.  

Observations of other species indicate that  lifespan varies dramatically between species  

and species with a higher risk of  death from other means are likely  

to have a shorter life expectancy. We're  toward the higher end of the spectrum.

So why hasn't evolution taken care  of this pesky death thing yet,  

or at least kept stretching it out, if it  can affect life expectancy so dramatically?

The problem is, evolution isn't here to be our  friend. The priority is the long-term health  

and survival of the species, not any individual,  and that means genes are more likely to evolve  

to focus on reproduction than preservation. Any  individual can be cut down by anything at any time  

- a sudden heart attack, a fall down the stairs,  or a piano falling on your head from the tenth  

floor. That randomness of life and the chance  of a sudden death means that over a long process  

of evolution, the gene mutations that are likely  to further the long-term survival of the species  

are the ones that will remain, and those that  don't further this goal will naturally die out.

At least every living being on the planet  is in the same boat, right? Yes and no.

If you want to live forever, your best  bet is to be a tree. When undisturbed,  

these towering plants grow and grow, only to be  felled by human intervention or natural disaster.  

Several trees around the world are confirmed  to be well over a thousand years old,  

with the oldest known tree being a bristlecone  pine from California's White Mountains,  

clocking in at a staggering five thousand and  sixty-seven years old from a sample of its core.  

That means this specific tree was standing  before the Great Pyramid of Egypt was built.

But what about animals? Have any of them  managed to beat the strictures of mortality?

Life expectancy among animals varies dramatically,  with some insects only having a lifespan of days  

or weeks. It's common for small mammals to only  live a few years, as many a kid whose parents  

replaced their beloved hamster Snowball with an  identical one while they were at school found  

out. Even powerful apex predators like the bear or  tiger only live ten to twenty years in the wild.  

Some of our closest relatives, like the gorilla  or chimpanzee, can live closer to a human lifespan  

but top out at around thirty-five to forty years  - barely middle age for a human. So we can feel  

pretty good about our average lifespan of the  seventies and beyond. We're beating the odds!

There are a few animals, though,  

who have managed lifespans that  would make the average human jealous.

The animals that can live well into their  hundreds are diverse, and some are unexpected.  

Everyone remembers flushing their pet goldfish  down the toilet after an unexpectedly short stay,  

but one of their close relatives, the Koi fish,  live up to thirty years on average. However,  

one famous Koi named Hanako was found to be  over two hundred years old based on the growth  

rings on her scales! Koi aren't the only sea  creatures that can live longer than most humans,  

with Longfin Eels living up to 106 years old and  sea urchins living into the two hundred range.  

Bowhead whales have an average  lifespan of two hundred years,  

with one being found with a fragment of a harpoon  in its skin dating back to the 1800s. The likely  

champ of long lives in the ocean, though, is the  Greenland Shark. Located in the arctic circle,  

this shark grows very slowly and doesn't even  reach maturity until they're a hundred years old.  

The oldest living specimen? Four hundred years  old, putting it in a range only trees can reach.

But what about land animals? Can they  compete with the aging kings of the seas?

There are a lot of land animals that  can live close to human lifespans,  

including elephants that live up to seventy years.  That's a lot of time to never forget anyone. And  

if you can't bear saying goodbye to another  pet who will die after two to fifteen years,  

consider getting a parrot. There's a good  chance the colorful bird will outlive you  

with a lifespan of fifty years or more. But the  longest-living land animal is one that proves  

the value of taking it slow. The Galapagos Giant  Tortoise, native to the remote islands, can live  

well past one hundred. Their most famous specimen,  Lonesome George, lived to a hundred and one, but  

specimens have been reported to make it past  the one hundred and fifty-year mark. However,  

the tortoise couldn't outlast extinction, as  sadly Lonesome George was the last of his kind.

This just proves that no matter  how long we or any species live,  

there's a ticking clock. Death comes  for every living thing - right?

It turns out there are a few species that  may have come closer to beating death than  

any other. These are species that avoid the  typical process of senescence, the gradual  

deterioration of cell function. Lobsters  are able to constantly repair their own DNA,  

shedding their own shells through a difficult  process while the inner tissue stays healthy  

thanks to an endless supply of an enzyme that  repairs their telomeres. The problem that keeps  

them from being truly immortal is that they get  too big for their shells, and it eventually takes  

too much effort to shed the old shell,  and the lobster succumbs to diseases.  

Of course, for many lobsters, the end comes much  quicker than that, courtesy of a fisherman's trap.

Meanwhile, a jellyfish species named  Turritopsis Dohrnii stunned scientists  

when it seemingly unlocked the  key to immortality. These tiny,  

translucent animals are found in oceans  around the world and have a unique method  

for preventing death. They literally turn back  the clock by turning back into a tiny blob  

that starts the life cycle anew. Imagine  if instead of dying when we hit old age,  

we just turned back into a baby again. While  these jellyfish can easily die for good when  

they're consumed by a predator, their natural  life cycle doesn't seem to have a traditional end.

This raises the question, though, of what death  truly is. These jellyfish may continue their life  

cycle by restarting it, but this would likely  be impossible for a more complex form of life  

that thinks and learns. Still, scientists  are avidly studying these strange creatures  

to see if they can unlock more of the mystery  surrounding our life cycle. Even as we study  

death across the living kingdom it remains,  for almost everything on Earth, inevitable.

For more on what happens to us when we die,  check out “What Happens When You Die?”,  

and for a very modern part of death, why not watch  “What Happens to Your Online Life When You Die?”