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There’s a lot we just don’t know about death, but even among the things we think we do know, there are a lot of misconceptions. Here are 5 weird things we believe about death!

Hosted by: Hank Green

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https://commons.wikimedia.org/wiki/File:Oxygenated_vs_deoxygenated_RBC.jpg
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[♪ INTRO].

There’s a lot we just don’t know about death. But even among the things we think we do know about death, there are a lot of misconceptions.

Like, we have ideas about things that can and can’t kill us, what the moment of death is actually like, and even how much biology keeps goin’ afterward. A lot of this supposed knowledge has persisted through pop culture, urban legends, or been passed down through families. But as deep-rooted as these ideas are, they’re not necessarily true.

So we’re going to debunk five misconceptions about death, starting with one urban legend that’s persisted for over 100 years! At some point in your life, particularly if you went to summer camp here in the. United States of America, you may have heard someone say that if you swim right after eating, you could get a cramp and drown.

Parents and guardians have been warning kids for decades not to go back into the water until at least 30 minutes after eating, cuz apparently you might die. But this well-meaning advice is definitely a myth. People believed that during digestion, a bunch of blood would rush to your stomach to help digest your food, leaving other parts of your body with less blood flow.

The idea was that this reduced blood flow could cause muscle cramping and make you drown. But, while it is true that a little extra blood does go toward digestion… the change in blood flow is not enough to disable you in the water. When the idea first emerged around the early 1900s, medical experts were super obsessed with digestion.

They believed all kinds of stuff about it that we now know isn’t true, like that you need to chew your food 40 times to digest it properly. According to the wisdom of the time, it was improper to rush an important health process like digestion just by racing off after a meal to jump into a pool. The advice made its way into places like Boy Scout handbooks that were meant to help people cultivate good, proper behavior.

So it was part medical advice, part etiquette advice. Somehow, though, the idea that it’s bad to swim after eating stuck, even after being removed from the Boy Scouts of America’s handbook in the 1960s. In fact, it stuck so much that, in an effort to debunk it, the American Red Cross published a detailed report in 2011 examining all the related literature they could find.

According to that report, no studies have found a link between eating before swimming and drowning. Plus, there have been no reported medical cases of drowning associated with swimming right after eating. Now any kind of physical activity, particularly things like running and swimming, have the potential to cause nausea, cramps, or stitches, especially on a full stomach.

But while that might not be comfortable, it’s not very likely to kill you. On the other hand, sometimes popular culture makes light of things that actually are more serious than they seem. Like cheesy old Westerns where the good guy soldiers on with a wounded limb, or heroically incapacitates the bad guy with a shot to the leg without killing them.

But in reality, a shot to the leg can be extremely dangerous. And that’s because your legs have lots of important blood vessels. The main one is called the femoral artery, which pumps blood through your thigh to your lower leg.

On average, it transports over a liter of blood every two minutes. There’s a lot of variation, but that’s about a fifth of a hypothetical average adult’s entire blood supply. So, if that vessel gets severed, a person can lose a catastrophic amount of blood in just seconds.

And once our perfectly average adult loses about 40% of their blood, their organs may fail, they may go into a coma, or they could even die if they don’t get immediate treatment. But it’s not just this major artery that makes our legs so vulnerable. Our legs also have lots of large veins that can lose blood pretty quickly.

On top of all that, our long leg bones are basically corridors full of blood vessels linking the bone marrow, where blood is made, to the rest of the body. So if the bone gets damaged, these blood vessels will bleed profusely. What all this means is that a bullet to the leg, or any kind of damage to the leg, is not something to shrug off.

And if an injury like this does happen, the number one priority for emergency responders is to act quickly and keep blood inside the body. Now, in movies and on TV, the moment of death often looks quite peaceful, with a person’s eyes fluttering shut as they take their last breath. Whereas open eyes at death are seen as a sign of something frightening.

Now, there’s not a lot of research on this topic. But what we do have suggests it probably just has to do with the way the body shuts down. One of the first things that happens to the body after death is that the muscles relax.

Muscle tone disappears, and everything goes limp. It happens to big body parts like arms and legs, and also to smaller ones like eyelids. And as eyelids go limp, they can fall open.

One researcher in New Zealand actually took notes on the eyes of 100 hospice patients after they died. And they found that a full 37% of them died with their eyes open, or, at least, not completely closed. The researcher also found little connection between the cause of death, or what the circumstances were at the time, and whether their eyes closed.

So, probably nothing to do with whether their death was shocking or sudden. Though, of course, this was a small sample of terminally ill patients. So, while open eyes on a dead body aren’t exactly the picture of eternal rest, it’s actually not rare, and is perfectly natural.

Next up, maybe you have heard the common myth that a person’s nails keep growing after they die. Now, nails can appear longer after death, but that’s because the skin around them tends to dehydrate and tighten, pulling away from the nail. This can give the illusion of growth.

But nails can’t actually grow on a dead body. Fingernails and toenails are all made out of a kind of protein called keratin. And while we’re living, different molecules, vitamins, and hormones in our bloodstream drive cells to produce this keratin.

As a result, our nails grow by about a tenth of a millimeter each day. But all of this obviously comes to a halt after death. In brief, once a body stops pumping oxygenated blood, cells are left with whatever reserves of oxygen and energy they have on hand to make proteins or do other cellular work.

At best, they might extend their lives for a few minutes by switching to anaerobic respiration, the cellular process of energy production that doesn't require oxygen. But as waste products like carbon dioxide and lactic acid accumulate, the cellular environment becomes increasingly acidic, and that’s toxic for cells, so it’s not a long-term strategy. After about ten minutes, max, even the most resourceful cells will die.

So, while not every cell in the body perishes instantaneously when a person dies, no cells can survive long, and they certainly can’t continue protein production long enough to make a difference in your nails. Technically, nails could maybe continue growing for a few minutes, at most, but definitely not beyond that, and definitely not long enough to be noticeable. So, if it looks like the nails on a dead body have grown, it’s just an illusion caused by the tightening skin.

And this brings us to our final misconception. Many cultures around the world have practiced cremation for millennia. But here in the US, it’s seeing a surge in popularity.

These days, more than half of people in the US are choosing cremation over an in-ground burial. Now people have all sorts of reasons for making this choice, and whether or not this factors into their decision, many of them have the impression that it’s more eco-friendly. For example, they may reason that it doesn’t require a large burial plot.

Though, cremated remains may still be buried at times. But unfortunately, cremation takes a toll on the environment too, and that’s because it takes a huge amount of energy to cremate a human body. Like, in order to reduce a human body to just bone fragments and ashes, you need a fire that’s at least 800 degrees Celsius.

And a crematorium using natural gas generates about as much carbon dioxide as a car running through 75 liters of gasoline. That’s comparable to two tanks for an average sedan. And those emissions do start to add up.

But if you are looking for an eco-friendly way to go, you do have some options. One procedure is called alkaline hydrolysis, or water cremation. In this process, the body is dissolved in a solution of water and lye.

Lye is a highly alkaline substance, in other words, it’s the opposite of acidic. And it’s really effective at dissolving objects. This solution quickly decomposes the soft parts of the body.

Then, the leftover bones can be prepared as powdered remains for the loved ones to keep. This process requires far less energy than standard cremation, and it generates fewer byproducts. And the byproducts it does create are non-toxic.

In fact, the so-called waste water makes a pretty good fertilizer. However, there are simpler options, and if you’re Jewish or Muslim, you might be yelling one of them at the screen already. A natural burial is pretty much exactly what it sounds like.

Unlike the most common burials in the US where a body is embalmed, placed in a casket, and buried in a concrete vault, in a natural burial, the body is simply placed in the ground. At most, it may be buried in a shroud or a wicker casket, something that decomposes easily. There are a few more creative ideas out there as well, like having burial grounds double as land set aside for conservation.

So there are options to make your passing gentler for Mother Earth, if that’s what you desire. In the end, when it comes to death, the unknown is still much greater than the known. But by tackling our misconceptions, we can form a clearer picture of the science surrounding the end of life.

Thanks for watching this episode of SciShow, which was brought to you with the help of our patrons. If you wanna to get involved, help make us make this thing, and show your support for what we do, you can get started at patreon.com/scishow. [♪ OUTRO].