Placeholder Image

字幕表 動画を再生する

  • You can tell a lot about a person just from their hair. Like I can look at you and know

  • if youre bald just like that.

  • Hi everyone, Julian for DNews. A person’s hair reveals a lot of secrets about them,

  • and you can uncover them. Not by interpreting clumps of human hair with pilimancy or some

  • other form of heresy, but with science.

  • I’m going to wager youve seen the detective shows where they find a single hair at the

  • crime scene, extract the DNA from it, find the murderer, and then David Caruso puts on

  • his sunglasses and says something like, “He almost got away with it but he was just a…

  • hair short.”

  • It’s true that hair can be used to pull a DNA sample, but it’s a lot harder than

  • those shows make it seem. See, most of your hair is dead cells. When they die they are

  • pressed together to form a protein called keratin and new cells are generated underneath

  • them by the root. In the process though, the nucleus inside the cell gets destroyed and

  • the DNA goes with it, so usually to get a hair sample with any useful DNA, it has to

  • have the root attached. Rarely some DNA will survive cornification, but finding hair at

  • a crime scene is not the smoking gun it’s always made out to be. Incomplete hair may

  • help determine maternal lineage though. Because mitochondrial DNA is passed from mother to

  • offspring and is thousands of times more abundant than nuclear DNA, it’s easier to get a sample

  • to analyze.

  • But even without the root, hair can be full of secrets. Keratin has sulfur atoms that

  • bond to trace elements, which explains why Trace is so hairy. Anyway these elements can

  • give away what youve been putting in your body. I know a lot of you immediately thought

  • about drugs. And it’s true, drug tests can find out if someone’s been using marijuana

  • or opiates or amphetamines or PCP. And since those elements bind to your hair when the

  • hair is forming, the longer your hair, the farther back the test goes. So if youre

  • a hippy with dreads finally applying for that big government job, that’s another reason

  • to get a haircut.

  • Don’t think shaving your head bald will help either, because your hair is everywhere,

  • screaming infidelities. Like your body hair. Drug tests can use that too, and since body

  • hair doesn’t grow like the hair on your head, it could actually represent a longer

  • timeframe, possibly up to a year, though there are no conclusive studies on that. Either

  • way though, it hurts your chances of passing a drug test if youre a hairy pothead. Interestingly

  • it takes about 5 to 7 days for forming hair to start protruding past the scalp, so you

  • could do a bunch of drugs and pass a hair drug test that same day. But, y’know, don’t

  • do a bunch of drugs. Please.

  • Keratin’s tendency to grab trace elements can be used to divine more mundane things

  • too. It can tell us what someone’s diet is. This fact makes it useful for studying

  • animals like bears. Researchers have actually developed a new technique that runs a laser

  • down the length of a single bear hair and vaporizes it. The gas is then analyzed by

  • a mass spectrometer. The old method involved analyzing bunches of hair which gave them

  • a general idea of what they had been eating. Doing it this way lets them easily tell exactly

  • when their diets change and monitor how much mercury theyre getting from fish. Plus

  • I imagine it’s safer running up and plucking one hair off a grizzly than grabbing entire

  • handfuls.

  • So, the eternal question still stands: does she or doesn’t she dye her hair? Only her

  • hairdresser knows for sure. Unless it’s blue, then we can all tell, because blue almost

  • never happens in nature. Trace explains why here.

You can tell a lot about a person just from their hair. Like I can look at you and know


動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B2 中上級

髪の毛が語る健康とは (What Your Hair Says About Your Health)

  • 278 20
    Bary Tseng に公開 2021 年 01 月 14 日