Today we’re going to look at what scientists have worked out to be the very limits of our
survival!
How hot or cold can we go, is the ‘Survival rule of 3’ true? What’s the longest we
can live? The list goes on. So, If you think you know your breaking point, think again.
However we do not encourage anyone to attempt to match or beat these limits.
I’m Stu, this is Debunked and we’re here to sort the truths from the myths and facts
from the misconceptions. Let’s start all the way down at the bottom of the scale...
HOW COLD CAN WE GO?
This is all down to our core temperature. Unfortunately, the human race isn’t built
for the cold, having evolved in the hot climates of the African Savannah our bodies are designed
to displace heat rather than retain it.
So, take away our cosy fires and thermal underwear, and what temperatures can we handle at the
lower end of the gauge?
Survival here is about protecting your core temperature, this usually sits at 37ºC (98.6)
but when your body is cold and loses heat faster than it can make it, then your core
temperature can start to reduce. If it drops as little as 2ºC then hypothermia will set
in.
This sequence of events usually follows: At 35ºC you’ll experience shivering and
pale skin as your blood is diverted from your extremities.
At 30ºC you’ll fall unconscious. At 25ºC you’ll go into cardiac arrest.
By 24ºC you’ll most likely be dead.
As with many of the body’s limitations however, there are exceptions to the rule, with some
survivors going far beyond the norm, and this survival story changed medical history.
While skiing Anna Bågenholm fell through a sheet of ice and was dragged underneath
by a mountain stream.B096BC
She became trapped under 8 inches of ice for around 80 minutes, causing her core temperature
to plummet all the way down to 13.7ºC. Inevitably Bågenholm experienced cardiac arrest, but
she didn’t die. Before the freezing temperature stopped her heart, the constant flow of ice
water had already chilled the vital organs and specifically her brain to such a extent
that the oxygen demand was significantly reduced meaning they needed very little O2 to survive.
Although Bågenholm was clinically dead for more than 2 hours, the low temperature preserved
her brain and vital organs before her heart stopped beating and so delayed her cells from
dying. And incredibly this allowed medical staff to revive her.
Not only did Bågenholm go on to recover, but the results of her survival story went
on to change medical practices and introduced the use of therapeutic hypothermia where the
body is cooled down to mild hypothermia (32-34C) as a technique to protect patients during
open heart surgery, as well as victims of strokes, liver failure and epileptic seizures.
13.7 ºC remains the coldest anyone has ever been and survived.
Though not quite to that extent, but a reduced temperature is exactly the condition you need
for our next question…
HOW LONG CAN WE HOLD OUR BREATH?
Most people find it tough to hold their breath for much more than a minute, but as a rule
of thumb the limit for the majority of us will be about 3 minutes, much more than this
and you’re dicing with danger.
However there is a specific technique that trained freedivers employ,
called static apnea, whereby you hold your breath face-down in chilled water without
moving. This method was employed by the current recorded holder Stephane Mifsud, achieving
an impressive 11 minutes 35 seconds, but has since been superseded by a confirmed, but
unofficial, record of 11minutes 54 seconds by Branko Petrović.
So what’s the science behind this technique? Termed the Mammalian Diving Reflex, when you
submerge your face in cold water, outer blood vessels constrict, blood is directed away
from your extremities and towards your heart and brain. This reduces your heart rate and
the rate at which oxygen is pumped around your body.
In addition to this, trained ‘breath-holders’ as they’re called, hyperventilate prior
to holding their breath. This is because your brain monitors the level of carbon dioxide
in your blood. Rapid breathing purges your body of CO2 and delays your reflexive response
to take a big gulp of air.
So is Petrović’s 11 minutes 54 the limit of what the human body can be pushed to?
Physiologist Johan Andersson thinks not. “ELITE BREATH-HOLD DIVERS EXPECT THE LIMIT
TO BE EXTENDED TO ABOUT 15 MINUTES BEFORE RECORD-SETTING WILL LEVEL OFF.”
Interestingly you can nearly double your time by taking a breath of pure oxygen before,
a record held by Aleix Segura when he hit 24 minutes and 3 seconds in 2016!
But going back to temperatures,
HOW MUCH HEAT CAN WE HANDLE?
In comparison to the cold, humans, having evolved in them, are actually pretty well
adapted to surviving hot climates; with insane feats like the Badwater Ultramarathon taking
place every year. This 135 mile (217km) race takes place in California’s Death Valley
in temperatures of 53ºC (127.4F), That’s only just shy of the hottest temperature ever
recorded on Earth at 56.7ºC (134°F) in the same place.
The amount of external heat you can endure very much depends on your individual physiology,
exertion, and hydration, among other factors.
But ultimately the general consensus is that a very humid 60ºC (140 F) is the limit of
our survival. The humidity plays a part as it slows or stops your sweat from evaporating
away and making you even hotter. Within 10 minutes of being in this environment your
core temperature could be raised to 40ºC (104 F) or above resulting in severe hyperthermia.
Your organs will start to shut down and if untreated you’ll be dead.
However, the highest recorded core temperature was that of Willie Jones who was admitted
to hospital during an Atlanta heat wave with a body temperature of 46.5ºC (115.7 F)! He
spent 24 days in hospital and incredibly he survived.
The environmental temperature dictates the answer to our next question...
HOW LONG CAN WE GO WITHOUT WATER?
This varies dramatically depending on the scenario we put ourselves in. If we were doing
some pretty strenuous exercise on a very hot and sunny day, then you could be losing 1.5
liters of water each hour!
If you don’t rehydrate, your blood volume decreases and in turn your blood pressure
drops. Your blood then becomes thicker and stickier and will be harder to pump around
your body. Your heart rate then has to increase to compensate. You’ll actually stop sweating,
making you even hotter while you continue to dehydrate. This scenario would see you
dead within a few hours.
Alternatively, in a cool environment with very little exertion you could last around
a week, but as a general rule of thumb under more normal circumstances a person could survive
3-4 days without water.
"YOU CAN GO 100 HOURS WITHOUT DRINKING AT AN AVERAGE TEMPERATURE OUTDOORS."
"IF IT’S COOLER, YOU CAN GO A LITTLE LONGER. IF YOU ARE EXPOSED TO DIRECT SUNLIGHT, IT’S
LESS."
Andreas Mihavecz however beat this life expectancy by quite a stretch, when he was mistakenly
locked in a police cell and forgotten about for 18 days. Although there is some controversy
around this record as it’s alleged he survived by licking condensation off the cell walls.
Surviving without food on the other hand, is quite a different matter...
HOW LONG CAN WE GO WITHOUT FOOD?
In this scenario it actually helps to be obese in the first place. A study published in 1973
at the University Department of Medicine in Dundee, recounts the case of Angus Barbieri
who weighed 456lb (207 kg / 32.6 stone). Barbieri was monitored as he fasted his way down to
180lb (81.6kg / 12.8 stone) for an incredible 382 days! Under medical supervision, Barbieri
had consumed only zero calorie drinks and vitamins for the duration of the fast.
But being fat only helps you survive for such a long time without eating, if you have access
to enough vital water-soluble B vitamins which help metabolise your fat stores. Without these,
your survival rate would be considerably shorter and it would be perfectly possible for someone
to die of starvation and still be fat.
Gandhi's 21 day fast is often cited as the standard limit for human survival. He survived
only by taking sips of water.
Other cases of food starvation whilst receiving adequate hydration have recorded individuals
surviving between 46 and 73 days. These, among other cases, were taken into account when
the British Medical Journal reviewed human starvation in 1997. They surmised that the
survival time for a well hydrated individual is 30-40 days, with severe, possibly irreversible,
symptoms kicking in between 35 to 40 days, and death occurring from 45 days onward.
Essentially the amount of time someone can survive is affected by factors like body weight
and composition, genetic variation, other health considerations and the presence or
absence of hydration.
But no matter how much we eat or drink, we can’t keep going without rest.
Sleep seems to have lost its value in today's overworked and overstimulated world.
But when the sleep debt becomes too great, it can be dangerous.
“WHEN SLEEP DEPRIVATION BECOMES GREAT ENOUGH, THE EFFECTS MIMIC THOSE OF PSYCHOSIS. THE
FAILURE OF THE SCIENTIFIC WORLD TO RECOGNIZE THIS IS DUE TO SOME EXTENT TO THE FOLKLORE
THAT HAS GROWN UP AROUND THE SLEEPLESS MARATHON OF HIGH SCHOOL STUDENT RANDY GARDNER IN 1964.”
Randy Gardner got himself into the Guinness World Records by staying awake for an incredible
264 hours - that’s 11 days! The reports of the feat mainly surmised that Gardener’s
mental health remained stable throughout the challenge, enough to even beat someone at
a game of pinball on day 10.
However, Lieutenant Commander Ross from the U.S. Navy Medical Neuropsychiatric Research
Unit monitored Gardner throughout the challenge, and his report tells quite a different story.
“...A DELUSIONAL EPISODE… ...INCREASED MEMORY LAPSES...
...FRAGMENTED THINKING... ...MORE HALLUCINATIONS...
...PARANOIA FOCUSED ON A RADIO SHOW HOST WHO GARDNER FELT WAS TRYING TO MAKE HIM APPEAR
FOOLISH.”
By day 11 Gardner was reported to have:
"EXPRESSIONLESS APPEARANCE, SPEECH SLURRED AND WITHOUT INTONATION; HAD TO BE ENCOURAGED
TO TALK TO GET HIM TO RESPOND AT ALL. HIS ATTENTION SPAN WAS VERY SHORT AND HIS MENTAL
ABILITIES WERE DIMINISHED.”
These patterns are similar to those experienced by others who have taken part in sleepless
marathons and studies, concluding that prolonged amounts of sleeplessness will lead to serious
mental symptoms.
In fact, Guinness World Records no longer list voluntary sleep deprivation as a record,
soas to not encourage any further attempts, but there have still been recorded challenges
to this title with the longest stint hitting a whopping 449 hours, that’s nearly 19 days!
Whilst Gardner was observed to have made a full recovery after his time awake, sleep
deprivation will eventually be fatal. While there are no recorded instances of people
being forced to stay awake long enough to kill them,
there is a disease called fatal familial insomnia which completely stops you sleeping and appears
to be the ultimate limit, with victims dying within 3 months.
As we’re investigating survival it only makes sense to find out the maximum human
lifespan...
HOW OLD CAN WE GET?
The limit to how long humans can live is a controversial one with many credible studies
contradicting each other.
Some scientists believe that there is a finite age, one that humans cannot age beyond.
Having trawled through the International Database on Longevity to identify trends, expert on
aging Dr Jan Vijg claims that after decades of significant increases in human longevity,
the maximum age limit slowed in the 1980s and has now stopped, with the upper age limit
being 115 years old. Dr Vijg’s team admit there will be the occasional anomaly but
“YOU’D NEED 10,000 WORLDS LIKE OURS TO HAVE THE CHANCE THAT THERE WOULD BE ONE HUMAN
WHO WOULD BECOME 125 YEARS [OLD],” When this finite age was published it sparked
fierce debate among the scientific community, with many criticising Vijg’s work.
A more recent study found that so long as you reach 105 years of age then the risk of
dying plateaus. What does this mean?
Well let’s rewind the clock to someone who is 50. At this age they are 3 times more likely
to die within the next year than someone who is 30 aging to 31.
By comparison someone who has managed to live all the way to 105 is just as likely to live
to 106, as someone who is 120 living to 121. Their chances of dying no longer go up.
Also, statistically the number of people who are now hitting 105 years old is on the increase.
Co-author of the study, and Professor of Demography and Statistics, Kenneth Wachter believes...
“[THAT’S] STRONG EVIDENCE THAT IF THERE IS A MAXIMUM LIMIT TO HUMAN LIFESPAN, WE ARE
NOT CLOSE TO IT YET.” PROF. KENNETH WACHTER | DEMOGRAPHER AND STATISTICIAN
| UNIVERSITY OF CALIFORNIA, BERKELEY.
But far from a standard human trait, it has been suggested that this plateau may instead
be due to a ‘survival of the fittest’ type consequence,
whereby the frailer people have already died off,
leaving the toughest to live through their hundreds.
And the toughest nut of them all was Jeanne Calment from France who set the record for
human longevity in 1997, when she hit the ripe old age of 122!
Stay tuned for a bonus myth about ‘Survival… After Death!’.
But first thanks to our audience for their human survival limit suggestions,
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Whilst our first topic saw Bågenholm return from the dead after 2 hours, incredibly this
isn’t the longest time recorded between death and resurrection!
WHAT’S THE LONGEST WE CAN SURVIVE, AFTER DEATH?!
In 2008 it was widely reported that when Velma Thomas suffered a heart attack,
doctors tried everything to revive her, even using the techniques learned from Bågenholm’s
experience by inducing hypothermia. But for 17 hours no brain activity was detected. According
to Velma’s son...
“HER SKIN HAD ALREADY STARTED HARDENING, HER HANDS AND TOES WERE CURLING UP, THEY WERE
ALREADY DRAWN. THERE WAS NO LIFE THERE.”
With no pulse, blood pressure or measurable brain activity the decision was made to take
her off life support. But just 10 minutes later as doctors were removing the respiratory
tubes, Velma moved her arm, coughed and then just woke up.
Dr Eggleston, who treated Velma, said…
"THERE ARE THINGS THAT AS PHYSICIANS AND NURSES, WE CAN'T ALWAYS EXPLAIN. AND I THINK THIS
IS ONE OF THOSE CASES."