Placeholder Image

字幕列表 影片播放

  • Hey, Vsauce. Michael here. And I'm home for the holidays.

  • I'm in my parents' basement, using a different camera than usual.

  • But you know what is always different? Fingerprints.

  • The palms of our hands and the soles of our feet are weird.

  • They are covered with friction ridges, which act like the design of a stamp that stamps

  • everything you touch. Plastic or patent prints are visible to the

  • naked eye. But even with seemingly clean hands on a seemingly

  • clean surface, a fingerprint can be left. A latent fingerprint.

  • But what are those made of? Well, by the square millimetre, they're made

  • out of this. All of this stuff is natural.

  • In fact, a lot of it is produced to keep your skin healthy, waterproof, pliable.

  • But touch a surface enough and the gunk can build up.

  • It's what causes smudges on computer screens and mobile devices.

  • Now, given that protein contains 4 calories per gram, fat contains 9 calories per gram

  • and the surface area of the iPhone 5 is 4,400 square millimetres, completely licking clean

  • a smudgy iPhone 5 screen is gonna give you about 2 calories.

  • If you were to lick clean 245 smudgy iPhones 5, well, that would be the same as eating

  • a Big Mac. But before you run off and get all of your

  • nutrition from smudgy phones, you should know that us humans need a bit more variety than that.

  • I've always found it interesting that cats and dogs can grow up and live great lives

  • eating the exact same food everyday. Well, what about us humans?

  • What can we eat everyday without ever changing it up and be fine?

  • It turns out that there is one type of food that you could eat everyday for the rest of

  • your life and be fine, without ever having something different.

  • If you follow @tweetsauce, you already know what it is.

  • The answer is human breast milk. Whether your ridges loop or arch or whorl

  • is largely genetic. But the tiny minutiae of your prints formed

  • while you were developing inside your mother. It tells a story about the very specific conditions

  • around the dividing cells that became your skin.

  • And for that reason, even identical twins, who pretty much share the exact same DNA,

  • wind up with different fingerprints. I could clone you 100 times and every one

  • of those clones would have a unique set of fingerprints.

  • Your skin has two major layers. The epidermis on the outside and the dermis,

  • which is below. The basal layer of your epidermis creates

  • new skin cells, which migrate up towards the outside world, where they die and flatten

  • out, forming the protective outermost part of your skin - the 'horny layer' - which means

  • that all day, everyday, you are covered with and showing off to the entire world your horny

  • layer. These outer cells are constantly shed away,

  • but their arrangement stays the same, because their shape is determined by the shape of

  • the basal layer down below. This is why you can superficially and temporarily

  • sandpaper or cut off your fingerprints, but they'll still grow back the way they were

  • before. But why do we have fingerprints in the first

  • place? I mean, not all mammals have friction ridges.

  • Is this some sort of cruel joke the universe made to make it more difficult for us humans

  • to get away with crimes? Probably not.

  • The most likely answer is two-fold. First of all, it has been show that friction

  • ridges allow us to sense subtle textures 100 times better than if we didn't have them.

  • And because fingerprints loop and arch and swirl in different directions, all it takes

  • is one simple touch for us to detect a subtle texture moving in any direction.

  • It's also been shown that having friction ridges allows mammals, like us, primates,

  • koalas, the North American fisher, to better climb and grasp wet stuff.

  • Even though no two fingerprints are exactly the same, the methods we have for matching

  • fingerprints aren't always perfect. There are plenty of different ways to model

  • fingerprints and each one is calculated at different probability of a false match.

  • But if you wanna commit a crime, it's best to just avoid fingerprints altogether.

  • How about hiring someone with adermatoglyphia? A few skin conditions can cause the disappearance

  • of fingerprints. But adermatoglyphia is a genetic one that

  • has no other side effects. But it's rare.

  • Only four extended families on Earth are known to have the condition.

  • But if you wanna avoid leaving fingerprints and can't find somebody with adermatoglyphia,

  • don't worry, just find someone who hasn't gone through puberty yet.

  • Sure, kids might snot and slob all over stuff, but they carry far less heavy waxy oil on

  • their skin. And for this reason, the fingerprints of a

  • child will disappear, evaporate, much more quickly than those of an adult.

  • A child's fingerprints can evaporate in only a few hours.

  • So, use kids to commit your crimes.

  • And as always,

  • thanks for watching.

Hey, Vsauce. Michael here. And I'm home for the holidays.

字幕與單字

單字即點即查 點擊單字可以查詢單字解釋

B2 中高級

汙濁的螢幕上有多少卡路里? (How Many Calories are on a Smudgy Screen?)

  • 2 0
    林宜悉 發佈於 2021 年 01 月 14 日
影片單字