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, and thanks to Raycon Earbuds, who have actually
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15% off your order too! We use our Everyday E25s when writing scripts,
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nifty little carry case that charges them on the go. As they come with a nifty little
charging case. They really have become a faithful pair of companions.
They really have become a faithful pair of companions. 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."
