if you’re 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 you’ve 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 you’ve 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 you’re

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 you’re 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 they’re 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.