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  • [♪ 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,

  • you 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 bloodit'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-calledtreatmentwill 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 justpee 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]

[♪ INTRO]

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