[♪ INTRO] Let’s say your car breaks down in the middle
of the desert, or in a howling blizzard. Your phone battery is dead, and you didn’t stock up on food
and water like you maybe should’ve. How are you gonna get out of this one? If you find yourself in a survival situation,
you’re going to have certain priorities: water, not dying of exposure, not being
mauled by wild animals, and, y’know, getting back to wi-fi as soon
as possible so you can watch SciShow. For most folks, food can
actually be a lower priority. But there’s a lot of bad survival info out there. Some tips seem too good
to be true, and they are. Others are ingrained enough to be
common knowledge, except they’re wrong. So here’s a list of 8 survival tips
you definitely shouldn’t follow, and what to do instead. First up: water. What about all the snow that’s piling up
in the blizzard? That is made of water. Snow can be safe to eat, especially if it’s
freshly fallen. While it can collect contaminants as it falls,
things like soot from wood fires and coal plants, that generally won’t be enough to
hurt you. Snow that’s already on been the ground for
a while is riskier, since it might have accumulated, like, who knows what, pollutants
from the road, maybe, you know, you can insert
your own yellow snow joke here. But eating snow might be a
bad idea for a different reason: It has to melt inside your body,
and that uses your body heat. Water has a high heat capacity, because it has pretty strong bonds holding
the molecules together. So you need a lot of energy to break those
bonds to boil liquid water or melt ice. Energy your body would otherwise
be using to keep you warm. Plus, you’d have to eat a lot of
snow to get enough water, since piles of snow contain a lot of air. So to keep your body temperature from falling
too much, find a way to melt the snow first. But the worst way to do that is to like hold
it against your skin to melt it. Don’t do that, it’s still going to cool
you down. If you’re in the desert, don’t count on cactuses
as, like, secret jugs of fresh spring water. There’s a lot of water in there, yeah. But there’s also a bunch of noxious chemicals. Cactuses use an unusual type
of photosynthesis, called CAM. CAM photosynthesis uses way less water than
other kinds, so it’s handy in the desert. CAM plants gather CO2 through pores at night
and store it in the form of organic acids. Then they can close those pores during
the day to minimize water loss, using the stored carbon to get on with the
light-dependent parts of photosynthesis. For storage, they mainly use malic acid, which
isn’t so bad for you. It’s in various fruits, although too much
can irritate your mouth. But many CAM plants also make oxalic acid. Oxalic acid is toxic, because it binds to
calcium, which can mess up your body. It can also build up in your kidneys
in the form of calcium oxalate, the stuff kidney stones are made of. In addition to the acids, a lot of cactus
flesh contains alkaloids, which are a diverse family of plant chemicals that generally aren’t
nice to eat and can really affect your body. Cactus juice won’t get you high, like it
did to Sokka in Avatar: The Last Airbender. But it can make you sick enough
to cause puking or diarrhea, which will dehydrate you
and make matters worse. Fishhook barrel cactuses and young prickly
pear cactuses contain few enough of the unpleasant chemicals to be kind of edible when raw. They still don’t taste good,
but they’ll do in a bind. But you’d better be pretty confident in
your botany skills. Bodily fluids are also mostly water, so you
might think you can recycle them. Drinking urine might help you
survive ever so slightly longer, but it’s only safe to do for a day or so. That’s because the waste products
in your pee are waste for a reason. If you put them back in your body, they’ll build
up faster than your kidneys can eliminate them. And that can send you into a state similar
to kidney failure, with your body unable to process all of the potassium, nitrogen compounds,
and calcium you’re throwing at it. As for blood… it’s sometimes
safe to eat in small amounts. In certain places, it’s fairly common,
but that’s more for its protein and iron content
than as a source for water. In large amounts, which you’d need to stay
hydrated, blood contains more iron than your body can handle, and it becomes toxic. Your body tries to store it in
places like your heart and liver, but that can lead to organ failure and death. Plus, you’re at risk from bloodborne pathogens. So going full vampire to survive is probably
not the best idea. But let’s say you’ve found some water, and
now you need a way to get home without GPS. And maybe you’ve heard that moss always
grows on the north sides of trees. This is one of those things that’s true in
general, but not 100% reliable all of the time. So it’s not so useful for navigation. Here in the northern hemisphere, the northern
side of a tree will get the least sunlight, thanks to the Earth’s tilt. That means the northern side of the tree is
most likely to be shady, cool, and damp, all things that moss likes. Mosses are non-vascular plants,
which aren’t as good at retaining water as other types of plants. They essentially lack the plumbing
to transport water inside of them, so they need all the moisture they can get. So if some other situation is creating good
conditions on any particular side of a tree, moss can grow there just fine. It’s not necessarily pointing north,
it’s just the nice-for-moss side. You’re going to need some shelter too,
or at least a way to stay warm. And you might have seen people
in old-timey books or shows giving a swig of booze to warm
someone up, especially in a blizzard. This one almost seems intuitive, because alcohol
brings a flush of warmth to your cheeks. But that is the exact opposite of what you
want if you need to stay warm. Alcohol is a vasodilator, meaning it opens
up the blood vessels near the surface of your skin, probably by altering your brain’s
blood vessel controls. That increased blood flow is why you might
feel or look flushed when you’re drunk. But it also transports warmth
towards the surface of your skin, where it can conveniently diffuse away from
your body and into the colder air nearby. Thanks, thermodynamics. When your body is trying to stay warm, it
actually constricts those blood vessels to try and conserve warmth in your
internal organs and your brain, which need to stay at
37 degrees Celcius to keep ticking. Don’t undo that hard work. And if you’re cold, rubbing yourself to
stay warm seems intuitive, the friction generates a bit of warmth. But once frostbite sets in, that is a horrible
idea. On a cellular scale, frostbite means ice crystals
are starting to form in your tissues. And ice crystals are sharp. They can puncture cell membranes
and other cellular structures, not to mention freeze the water
those cells were using to live. Rubbing will jostle those sharp chunks of
ice around, and cause them to rupture nearby cells. That’s going to make things much worse. Also, even though it’s painful, it’s not
good to thaw those frostbitten toes if they’re still at risk of refreezing. More ice forming again will do more damage
and risk more permanent loss of tissue. Frostbite mostly affects the extremities. If hypothermia actually sets in, meaning the
body’s core temperature has dropped below 35 degrees, the key is careful,
slow reintroduction of warmth. Plunging a victim of hypothermia in a hot
tub could cause irregular heart rhythm or even a heart attack. The proper way to treat frostbite
and hypothermia is, like, by a doctor, but when that’s not possible, caution is best. Try to sit tight, and don’t risk doing more harm. Finally, on your way home, it’s best
if you can avoid being mauled, bitten, or stung by anything. But if you are, be careful
what advice you listen to. Like, that one myth that tells you to like,
slice open the snakebite and suck out the toxin. The effects of snakebite vary based on the
kind of snake and the venom it’s packing. Some bites may cause severe
tissue damage and internal bleeding, while others are neurotoxins, there’s a bunch! Snake venoms are fascinating! So in reality, this so-called “treatment” will
increase the risk of the wound getting infected, possibly spread the venom into the
victim’s bloodstream much faster, and not actually remove very much venom. In other words, don’t do it. An article published in the
New England Journal of Medicine in 2002 strongly discourages incision
and suction for snakebites. Instead, they recommend keeping the
wound below the level of the heart, keeping the victim warm, avoiding tourniquets
or any kind of restrictive clothing or jewelry, and getting to the hospital as soon as possible. Hospitals can administer
antivenom to neutralize the bite. Antivenom is made up of antibodies that
are carefully made to bind to the venom and stop it from having effects on your body. Since different snakes make different
kinds of venom, one of the main things is to remember as much as you can
about what the snake looked like. You don’t need to, like, catch the snake
and, like, bring it along with you though, that’s not gonna help; nobody’s gonna
like that. And some kinds of antivenom work for multiple
kinds of snakes. It depends on the exact cocktail of antibodies. So you’re best off leaving the treatment,
hey, to professionals, because I don’t think you have a venom-binding
antibody serum in your back pocket, and if you do, that should be refrigerated! And last but not least, suppose you’re
stranded on the shore instead of in a forest and got a nasty jellyfish sting. Should you just… pee on it? Besides sounding totally gross and weird,
it’s not worth it. Pee doesn’t work, and it might
even make things worse. Jellyfish tentacles contain
stinging cells called cnidocytes, which discharge tiny harpoon-like stingers
when they touch you, plus the venom. And some of that venom can poke holes in cells
or cause all kinds of biological mayhem. But not many of the cnidocytes on a stinging
tentacle fire when you first touch it. So the trick is to get it off you without
triggering the thousands of others. The myth claims that urine
will neutralize those cnidocytes, so they don’t go off and sting you. But certain chemical changes can
fire off cnidocytes as well as touch. Like, alcohol is known to trigger them. And at least one study has shown
that urine can do so as well. A 2017 study published in the journal Toxins
found that many popular sting treatments, including scraping the stung area with a credit
card or shaving cream, don’t work. Seawater can help you rinse them off, but
it won’t chemically prevent them from firing. That’s where jellyfish live, after all. Instead, they found that a good
dousing with vinegar is best, which is just the chemical acetic acid. That will actually neutralize the ones
that haven’t stung you yet, maybe by bringing the pH too low
for them to function. Then the tentacles can be carefully
plucked away by tweezers, and heating pads will help
ease the pain of a sting. Now, you may never need to use any
of these tips, I certainly hope you don’t, but there’s a lot of misinformation out there,
and emergency survival is something you don’t really want to take chances with. So a little bit of scientific rigor is maybe the
best way to know if a tip could save your life or make things much worse. Thanks for watching this episode of SciShow! If you want to keep learning more about
the weirdness of human bodies and the world we live in, you can go to
youtube.com/scishow to subscribe. [♪ OUTRO]
I love how they actually provide good explanations for why things don't work.
Having experienced the jellyfish sting few times (yep jellyfish love me, if I’m in the water you don’t need to worry about them) i confirm vinegar was the best trick!! Great video!
Good post.
This is actually pretty cool.