Craig: Hi, I'm Craig, welcome to the salon. Did you know that people used to believe that brass instruments caused hair loss? The myth got started in 1896 when American journalists announced that they'd finally discovered what was making people lose their hair. Music! Specifically, they blamed brass instruments for society's hair loss. But, as most defenders of marching bands will tell you - there is zero truth to the rumor that too much sousaphone will make you go bald. And that's the first of many hair myths that the scientists at Head&Shoulders are helping us clear up in today's episode so I can CONDITION you to stop telling hair lies - I won't be conditioning my own hair, that's for sure, not much up there.

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Another common myth is that baldness only gets passed down from your mother's side of the family, that's not really the case. While your mother's side has slightly more impact on the fate of your locks, your hair is just like everything else in your genetic make-up - a mix of your parent's traits.

A lotta' folks think dandruff is a modern problem and that our great, great grandfathers weren't really concerned with flakes and itchy scalps - but they were! In fact, one of the things that makes the Greek physician Galen so famous is that in 200 AD he made a public service announcement letting the world now that drinking bull urine doesn't actually reduce your dandruff. Any excuse to drink bull urine.

Massaging your head with warm oil is often cited as a remedy for dandruff, that's because popes think the flakes are caused by a dry scalp, in fact, the flakes and the itching are just signs of dandruff. The real culprit is a little microbe called Malassezia globosa. When this microbe feasts on scalp oils, it breaks them down into an irritant called oleic acid and because our scalps are sensitive, they get stressed out and start shedding skin cells more rapidly than usual, it's a vicious cycle of oil-releasing, microbe-feasting, and scratching and flaking - which is exactly what I'm like at a job interview.

Over the course of history, people have had some terrible ideas on how to get rid of flake. Back in the 1890s, snake-oil salesmen used to advertise cure-alls that had cocaine in them. Just because an ointment makes your head tingle doesn't mean it's working. If you actually want to combat dandruff, you put down that cocaine-shampoo, junior, and get something that will stop or control the microbe making oleic acid and irritating your scalp.

Lots of people think shampoo is a Western convention, the word 'shampoo' actually comes from the Hindi word 'champi' used to describe a head-massage done with oils. Sake Dean Mahomed is the man who actually brought shampoo to the West in the late 1700s and early 1800s. After working his way into British society, he began billing himself as a 'shampoo surgeon' and would scrub the heads of European monarchs. Once Kings got into the hair-washing habit, commoners were intrigued and soon they were all about the rinse and repeat. 

As we know from cop shows, you can tell a lot about a person from a single strand of hair. One thing you can't tell, however, is a person's sex. There aren't any characteristics that reveal whether you're looking at a man or a woman's hair, though sometimes you can make an educated guess from the type of product in the locks.

You've probably heard that shaving your hair will make it grow back twice as thick, but that's not true. I've tried. Trust me. Often, shaved hairs look thicker when they grow back because of the way the prickly stubble emerges, but shaving your hair won't actually change your hair's general thickness. Look at all that hair. Yeah, even on her body. Looking good, Mitzy, looking good.

There's a grooming rule of thumb that men should schedule a haircut every four weeks to look sharp, but that's not accurate for everyone, because hair grows different for different people, okay? Not everyone can have a full head of hair! According to a French study published in the International Journal of Dermatology, or IJOD, Asian hair grows up to 30% faster than Caucasian hair, while people with origins from Central, West, and South Africa has hair that grows slower.

Just because you see hair in your shower drain, it doesn't mean that you're going bald. There's a different between hair loss--where your follicles stop generating hair, and hair fall, where the hair breaks from all the itching and dryness because you're not giving your scalp and hair enough love.

Marcia Brady popularized the idea that brushing hair with 100 strokes a day led to shinier healthier hair. But the truth is, that sort of aggressive friction against the head actually leads to cuticle damage and less resilient hair, Marcia!

And now for some ancient superstitions we'd like to disprove quickly.

People with thinning hair have bad luck. That's ridiculous. I would never, ever believe that.

Those with thick hair will suffer in life.

If you cut some hair and bury it at the roots of a bamboo tree, your hair will turn black. That's ridiculous. But if you eat from a bamboo tree, you might be a panda bear.

There's a popular notion that if you pluck grey hair, two more will grow in its place. According to dermatologists, what happens to one hair follicle really doesn't affect the neighbor. There's a strong argument for not plucking your hairs, however. If you keep picking at one follicle too much, you can damage it to the point that it will no longer grow hair. As the saying goes, if you prick me, do I not bleed? If you pluck me, I don't grow, too, into two of me.

So what does cause grey hairs? As several presidents have shown in their second term, grey hairs can result from stress. But contrary to popular belief, stress isn't the only factor. Stress does contribute to your hair's graying, but genetics, pollution, and chemical exposure all speed up the process. In fact, smoking can make you grey much faster, just another good reason to quit. Just don't smoke!

And finally, I return to the salon to tell you that hairstylists often claim that washing your hair in cold water is a great trick for making your hair look shinier. The theory is that ice cold water forces your cuticles to close, so that your hair stays flat and light reflective. But according to dermatologists, none of that is true. Because your hair doesn't contain living cells, it won't react to the cold water. Instead, conditioners and styling products are a better bet for smoothing your cuticles and getting the sheen you want. Not Charlie Sheen. Nobody wants that.

Thanks for watching mental_floss on YouTube, which is made with the help of these hairy people, and thanks again to the scientists at Head & Shoulders for helping us make this episode on hair misconceptions possible, so hopefully you can brush off your friends who are constantly lying about hair. Sorry, I have to part, but comb back next week.

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