That milk in the back of your fridge. That
check your bank is no longer willing to cash. 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?”
