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Thread: Hair length

  1. #1 Hair length 
    Forum Freshman jmd_dk's Avatar
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    How come that the various body hairs scattered around the body stops growing longer, when it has a specific length? The hair on our heads seems to grow on forever (I know the ends split and decay). The hair in our armpits, for instance, isnít very long. If you shave it, it grows right out again to the same length.
    How does your hair know how long it is?


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  3. #2  
    WYSIWYG Moderator marnixR's Avatar
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    my impression was that hair length depends on 2 factors : (1) the speed at which it grows, and (2) the time after which it falls out and gets replaced


    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  4. #3  
    Forum Senior Booms's Avatar
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    it's dictated simply by the physical properties of your hair and the rate at which it's produced
    hair that's produced faster will be longer
    hair thats more brittle and heavier will be shorter

    in general armpit/facial/genital hair grows at a much slower rate than your head, it's also corser and heavier meaning it falls out sooner

    the tiny hairs on your skin however are grown to a specific length, they exist to keep heat trapped when it's cold, so when they do their job at maximum efficiency the pores stop growing the hair





    a better question is, "why does our head hair grow so abnormally long in the first place?"
    It's not how many questions you ask, but the answers you get - Booms

    This is the Acadamy of Science! we don't need to 'prove' anything!
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  5. #4  
    Forum Freshman jmd_dk's Avatar
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    Quote Originally Posted by Booms
    the tiny hairs on your skin however are grown to a specific length
    And how does the hair know when they got the right length? If you take a pair of scissors and cut them in half, they will regrow to their proper size. How do they know about their length?

    a better question is, "why does our head hair grow so abnormally long in the first place?"
    - Because we need lots of hair on the top of our head, to keep the heat from the sun away. That's a reason, but remember that not all the genetically things has a specific purpose. The question "why" doesn't necessary have an answer, when it comes to genetics.
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  6. #5  
    Time Lord
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    That's a good question jmd_dk. You'd think that such a fine balance would be impossible to maintain without some kind of feedback or metering.

    Compare hairs on the backs of fingers vs. those hairs on the toes. Both seem to be the same stuff. Yet obviously toe hairs throughout winter have few excuses to fall out, while the finger hairs get chaffed pretty good from normal activity. I find my toe hairs are slightly longer... but not much.
    A pong by any other name is still a pong. -williampinn
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