If you're here for links, try us as an email.

If you came here for the links, TMN is better as an email. Try our Headlines newsletter!

The Non-Expert

Hair Growth

Experts answer what they know. The Non-Expert answers anything. This week we explain how different hairs on the body grow at different speeds, i.e., get ahead of one another, all puns intended.

Have a question? Need some advice? Ignored by everyone else? Send us your questions via email. The Non-Expert handles all subjects and is updated on Fridays, and is written by a member of The Morning News staff.


* * *

Question: I understand that hair is dead and thus can’t relay any messages back to the body about when it’s been cut or not. How, then, is it that arm hair remains the same length, rather than continuing to grow? And when some is cut, it catches up to the non-cut regions?

It seems like all body hair (including head hair) has some ‘memory’ of how long it should be, and grows to that length and then stops growing. I know that hair falls out from time to time, but can it really be falling out just as it gets longer than the same specific length, every time?

Every once in awhile you get one of those longer hairs, that, for some reason, seems to forget its programming and continue to grow. The existence of these ‘rogue’ hairs would seem to prove my point that there is some information otherwise that normally relays the message to hair to stop growing once it reaches a certain length.

I refuse to end this with a hair-pun closing,

Answer: Well, Dave, because I can tell you’re a head above the rest, I’ll just cut right to the chase. I don’t mean to blow your mind or anything, but the reason the hair knows what length at which to grow back is absolute, shear science. Nevertheless, we’re glad you came to us for the answer, because you could have asked any of the other so-called experts out there—they’re all over, too: you can look hair, thair, everywhair, really. But, fur heaven’s sake don’t wig out, we’ll get to your answer soon enough. We just want to thank you upfront and show our appreciation by letting you know this one’s on the house. Yep, others might want you toupee for answering these kinds of questions, but not The Non-Expert.

Nope, we wouldn’t shaft you. So, yes, waxing us your question was a good move indeed.

But honestly Dave, your query is a real head-scratcher. Yes, you can tress it up anyway you want, but there’s nairy a way out of it: I simply don’t know the real answer to your question. Now, if we follicle this line of reasoning, you might think, ‘Well, what good’s this Non-Expert, anyway? Eh?’

Whoa! I didn’t know you pelt that way!

Calm down, just calm down—you’re getting this for free, remember? Now, the mane thing to keep in mind here is that we try to give our readers quality answers, but we’re not afraid—as you probably know—to weave around the real answer and possibly comb-over a few details to make an entertaining article (a fringe benefit of being a Non-Expert). Oh, you think our logic is fuzzy? Well next time you can shave yourself a lot of pain and heartache and go to a real answer-guy, okay?


No, please don’t leave. To barber a phrase from Robert Burns, ‘The best laid schemes o’ mousse and men…’ You know what I’m saying? No, I don’t mean to brush aside your hopes for a coherent answer, I just want everything to reperm to normal between us, you know? I locks my way somewhere back there and lost my temper. An extension of that is that I kind of freaked out. I’m sorry. So let’s just move right salong…

I know: too little, too blade, right? My apologies. Nevertheless, now I’m at a split end. I don’t know what to do. Should I search out the real answer for you? Or just bleach up over my head and pluck something out of thin air? A quick brows through Google shows promise to the matter at hand. A single clip and I’m whiskered away to the ‘How Stuff Works’ site.

(You can goatee it yourself at www.howstuffworks.com/question100.htm. You’ll need to scroll crown the page to find the answer.)

Each hair on your body grows from its own individual hair follicle. Inside the follicle, new hair cells form at the root of the hair shaft. As the cells form, they push older cells out of the follicle. As they are pushed out, the cells die and become the hair we see.

A follicle will produce new cells for a certain period of time depending on where it is located on your body. This period is called the growth phase. Then it will stop for a period of time (the rest phase), and then restart the growth phase again. When the hair follicle enters the rest phase, the hair shaft breaks, so the existing hair falls out and a new hair takes its place. Therefore, the length of time that the hair is able to spend growing during the growth phase controls the maximum length of the hair.

The cells that make the hairs on your arms are programmed to stop growing every couple of months, so the hair on your arms stays short. The hair follicles on your head, on the other hand, are programmed to let hair grow for years at a time, so the hair can grow very long.

Animals that shed have hair follicles that synchronize their rest phase so that all of the follicles enter the rest phase at once. This way, all of the hair falls out at one time. A dog that sheds will lose its hair in large clumps. Many animals can also switch the coloring agent in the hair follicle on and off—so in the summer, the hair is pigmented brown with melanin, but in the winter it is not pigmented, leaving the hair white.

Now, that wasn’t wooly so difficult, was it?


Andrew Womack is a founding editor of The Morning News. He is always working on the next installment of the Albums of the Year series at TMN. More by Andrew Womack