[HN Gopher] Human hair grows through 'pulling' not pushing, stud...
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Human hair grows through 'pulling' not pushing, study shows
Author : pseudolus
Score : 117 points
Date : 2025-12-04 13:22 UTC (9 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| Barathkanna wrote:
| So hair grows by pulling itself upward? Perfect. I'm just going
| to stand under a ceiling fan and wait for my hair to pull itself
| back onto my bald spots. Science has finally given me a plan.
| HexPhantom wrote:
| Just make sure you set the fan to "regrowth" mode and not
| "recede"
| patrick41638265 wrote:
| Immediately had to think of Baron von Munchausen pulling himself
| out of a swamp by his own hair
| https://en.wikipedia.org/wiki/M%C3%BCnchhausen_trilemma
| nickthegreek wrote:
| I just watched this for the first time last week and found it
| rather delightful.
| paxys wrote:
| Damn so it is possible to pull yourself up by your bootstraps.
| seneca wrote:
| I'm reminded of a girlfriend who patiently explained to me that
| your hair grows more if you brush it regularly because the brush
| "pulls it and encouraged it to grow". She said her mother had
| taught her that.
|
| I thought it was nonsense. Shows what I know. I suppose folk
| wisdom is vindicated again.
| saalweachter wrote:
| You should be able to test this by brushing one side of your
| head more than the other
| taeric wrote:
| Curious if it works on beards, now.
|
| Though, I would also somewhat expect pulling at it increases
| blood flow, which I would think to have some impact on growth?
| DANmode wrote:
| Of course it works.
|
| PS Love the bio!
| DANmode wrote:
| But _why_ did you think it was nonsense?
| sjanes wrote:
| I seem to remember there was a report about pulling on the hair
| of guinea pigs or some other small mammal encouraged hair growth.
| mzs wrote:
| Tissot, N., Genty, G., Santoprete, R. et al. Mapping cell
| dynamics in human ex vivo hair follicles suggests pulling
| mechanism of hair growth. Nat Commun 16, 10267 (2025).
| https://doi.org/10.1038/s41467-025-65143-x
| stronglikedan wrote:
| I wonder if that's why it slows/stops growing when split ends are
| present. I've always wondered how that worked if it was pushing.
| dpark wrote:
| I don't think this is relevant to that at all. This "pulling"
| is inside the skin still.
|
| But I am also pretty confident that hair does not stop growing
| because of split ends. That feels like an "old wives tail".
| maxbond wrote:
| Presumably it's produced at the same rate but destroyed by
| drying out and cracking as it gets longer and has less access
| to oil, so it slows down and may find an equilibrium where it
| stays the same length.
| dpark wrote:
| Sure. If your hair is breaking off at the same rate it's
| growing it'll be a stable length. I have no idea if that
| happens though. It seems farfetched that hair would
| actually be splitting that's aggressively unless it's
| visibly very unhealthy.
| maxbond wrote:
| If you take proper care of it (which includes trimming
| split ends so that the cracks don't propagate) then sure,
| but I've previously neglected my hair to the point where
| my split ends had split ends. I'll absolutely cop to
| "visibly unhealthy" but there does come a point where the
| ends start to fall apart and break off easily.
| maxbond wrote:
| Isn't it the opposite, that when your hair starts to split
| pieces break off, and that opposes the growth?
| SoftTalker wrote:
| Is this different from how hair grows on any other animal?
| hbosch wrote:
| So, the centrifugal force of head-banging is why metalheads grow
| long hair?
| sbankowi wrote:
| Or is that centripetal force? :)
| hydrogen7800 wrote:
| Apologies for the "low effort" response:
|
| https://xkcd.com/123/
| smartplaya2001 wrote:
| Wow very interesting. This explains how goku turns level 3 as a
| super saiyan.
| candiddevmike wrote:
| As someone with thinning hair, it's horrible how little
| study/research is being performed to understand how hair grows
| and treat hair loss. Most of the products on the market today
| were discovered by accident and have serious side effects. This
| condition impacts millions++ of people, yet everyone from
| physicians to pharmaceutical companies is fine with the status
| quo of "here, this may work for you" effectively woo medicine.
| HexPhantom wrote:
| The fact that we're only now uncovering fundamental mechanics
| like "hair is pulled, not pushed" kind of highlights how under-
| invested this area has been
| estebank wrote:
| As someone with a race in my head between white hairs and a
| receding hairline, hair loss does afflict millions of people,
| but it has no medical impact on people's life, beyond
| increasing the need to wear a hat when outside in the Sun for
| long. Is it that surprising that medical professionals would
| spend their time on other afflictions instead?
| creata wrote:
| > it has no medical impact on people's life, beyond
| increasing the need to wear a hat when outside in the Sun for
| long
|
| The impact on mental wellbeing can be pretty severe, though.
| BobaFloutist wrote:
| That sounds like a social concern, not a medical one.
| missedthecue wrote:
| A social concern where the path of least resistance
| toward resolution is probably effective medical
| advancements. For example, studies show bald men face
| greater challenges in both straight and gay dating in
| every country where it's researched (so it's not cultural
| context dependent).
|
| Probably easier to figure out the follicular science than
| change universal attraction preferences.
| SoftTalker wrote:
| As someone who has lost at least 80% of his hair as an adult, I
| don't care about it at all. Get a short haircut and forget
| about it.
| missedthecue wrote:
| You aren't the only person with opinions on it though.
| Reminds me of the infamous HN thread where a (woman) poster
| mentioned offhand she and her husband were saving up for
| transplant for the sake of the survival of their marriage!
| arcticbull wrote:
| > Most of the products on the market today were discovered by
| accident and have serious side effects.
|
| Topical minoxidil / finasteride has roughly zero side effects
| (due to the limited systemic exposure) and has something like a
| 90% efficacy rate. With 90%+ efficacy it's not a case of "this
| might work for you" it's "this will almost certainly work for
| you." It's cheap and it works.
|
| Even oral 1mg finasteride has basically the same side effect
| profile after 1 year as placebo, side effects always* stop
| whether you stop taking it or continue taking it. And as an
| added bonus it significantly reduces your risk of low-grade
| prostate cancer (30% ish) while not increasing your risk of
| high-grade prostate cancer. Many of the side effects reported
| are in people taking 5mg doses for prostate hypertrophy, and
| the incidence of side-effects is dose dependent. Studies show
| that sexual side effects are primarily nocebo, if participants
| were told to expect them the rate was 3X higher than placebo,
| if they weren't told, they were about the same.
|
| * the category of persistent side-effects has been defined
| primarily for data collection purposes, there's very little
| evidence for persistent side effects _at all_ let alone a high
| incidence thereof. Many of the side effects people claim are
| related are things that would otherwise happen to you at the
| age you start to lose your hair regardless. It 's good to
| collect more data though.
|
| > As someone with thinning hair, it's horrible how little
| study/research is being performed to understand how hair grows
| and treat hair loss.
|
| Given the size of the market I'd say there's a ton of research
| being done. It's just a tough nut to crack. There's some good
| data on PP405, for example.
| lossolo wrote:
| > With 90%+ efficacy it's not a case of "this might work for
| you" it's "this will almost certainly work for you." It's
| cheap and it works.
|
| Maybe for thinning hair only. If you're Norwood class 5-7, it
| won't help you unless you're a super responder (an outlier).
| arcticbull wrote:
| Yep, you have to start early; it regrows about 2-3 years of
| losses and prevents further losses.
| deadbabe wrote:
| It's not really a big deal to be worth spending so much effort
| on. Baldness doesn't affect your quality of life.
|
| The only reason men care so much is because long hair was often
| associated with nobility and power. Ancient gods or classical
| royalty were usually depicted with long luscious hair. Society
| has conditioned men to feel like less of a man if they lose
| their hair.
|
| But that's BS, bald is also a good look for men. Just embrace
| it. Isn't it crazy that even if we came up with a "cure" for
| baldness, some men would still choose to be bald anyway?
| philistine wrote:
| Jean-Luc Picard raised a generation of proud bald heads. We
| need to continue dreaming of a future where it doesn't
| matter.
| steve_adams_86 wrote:
| I'd stay bald. I like the way I look. I think, conventionally
| speaking, I look more masculine _without_ hair. It 's all
| subjective.
| lossolo wrote:
| Are you bald, or are you just imagining things? It affects
| your quality of life. Because I know a lot of people who
| struggle with baldness including some in my family, I take it
| seriously. If you think depression is worth spending time on,
| then baldness is worth spending time on too. Some people have
| a head shape that doesn't suit being bald, and they don't
| look good bald at all. In today's Western world, the majority
| of women won't choose a bald person if there's a similar
| alternative with hair, it's simple biology. Only a minority
| of people look attractive bald. Good luck on dating apps
| being bald, seriously. You have no idea what you are talking
| about.
|
| What you're saying is basically "Let them eat cake".
|
| Here are some meta analysis + studies that support this:
|
| https://pubmed.ncbi.nlm.nih.gov/37605428
|
| "2024 mixed methods international survey paper summarizes
| prior experimental and cross sectional work and notes that
| studies often find more negative perceptions linked to
| baldness (e.g., being seen as older, less attractive, less
| successful)"
|
| https://pmc.ncbi.nlm.nih.gov/articles/PMC11977830
| tim333 wrote:
| Bill Gates kind of argued the other side of that in his old
| Malaria talk https://youtu.be/ZLkbWUNQbgk?t=258
| HexPhantom wrote:
| That feels like a pretty big clue that mechanics and motility are
| way more central to tissue dynamics than we give them credit for
| tgbugs wrote:
| This points to a potential answer to a long standing question
| I've had about why some hairs stop growing at certain lengths. If
| the force is being generated by cellular migration then control
| over when to stop growing can be mediated by a signal that tells
| the cells to stop migrating, and that could be based on time or
| vibration amplitude or something else that correlates with hair
| length. For hair that grows continually you just ... never turn
| off cell migration.
| dbbk wrote:
| Oh my god I have always asked why eyebrows stop growing and
| NOBODY ever thinks about it.
| JumpCrisscross wrote:
| > _why eyebrows stop growing and NOBODY ever thinks about it_
|
| If you clip your eyebrows, will they grow back to their
| original length? Or is there a process that generates an
| eyebrow hair and then stops after a pre-determined length of
| time (with periodic shedding)?
| saltcured wrote:
| Wait until you get older, and you either start trimming them
| or considering some kind of Yellowbeard style braids
| firmretention wrote:
| I don't believe any hair on the human body truly grows
| continuously. Even head hair has a lifespan of ~7 years and
| whatever you can grow in that time is the max. I was a big
| metalhead in high school and grew my hair out. Indeed, after
| about 7-8 years it stopped getting longer, right at about waist
| level, and was stuck there until I finally got sick of it and
| cut it off.
| doubled112 wrote:
| I think they call this the "terminal length". As long as it
| will grow before it falls out.
| adrr wrote:
| How did this explain in-grown hairs?
| gorjusborg wrote:
| Pulling doesn't have to happen at the surface?
| rambambram wrote:
| And grass? What about grass?
|
| I want to keep my favorite reply phrase: "Gras groeit niet harder
| als je eraan trekt." (Grass doesn't grow faster if you pull on
| it.)
| JumpCrisscross wrote:
| Grass has a unique cell wall organization [1].
|
| [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC5241289/
| JumpCrisscross wrote:
| Are most industrial polymers drawn or extruded?
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