Human hair grows through 'pulling' not pushing, study shows

https://phys.org/news/2025-12-human-hair.html

by pseudolus • 8 months ago

129 58 8 months ago

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.

HexPhantom3• 8 months ago

Just make sure you set the fan to "regrowth" mode and not "recede"

patrick41638265• 8 months ago

Immediately had to think of Baron von Münchausen pulling himself out of a swamp by his own hair https://en.wikipedia.org/wiki/M%C3%BCnchhausen_trilemma

nickthegreek• 8 months ago

I just watched this for the first time last week and found it rather delightful.

paxys• 8 months ago

Damn so it is possible to pull yourself up by your bootstraps.

seneca• 8 months ago

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• 8 months ago

You should be able to test this by brushing one side of your head more than the other

taeric2• 8 months ago

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?

DANmode2• 8 months ago

Of course it works.

PS Love the bio!

DANmode2• 8 months ago

But why did you think it was nonsense?

sjanes• 8 months ago

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• 8 months ago

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• 8 months ago

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.

dpark2• 8 months ago

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”.

maxbond2• 8 months ago

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.

SoftTalker2• 8 months ago

Is this different from how hair grows on any other animal?

hbosch• 8 months ago

So, the centrifugal force of head-banging is why metalheads grow long hair?

sbankowi• 8 months ago

Or is that centripetal force? :)

hydrogen7800• 8 months ago

Apologies for the "low effort" response:

https://xkcd.com/123/

smartplaya2001• 8 months ago

Wow very interesting. This explains how goku turns level 3 as a super saiyan.

candiddevmike• 8 months ago

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.

HexPhantom3• 8 months ago

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• 8 months ago

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• 8 months ago

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.

SoftTalker2• 8 months ago

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.

missedthecue2• 8 months ago

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!

arcticbull2• 8 months ago

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.

lossolo4• 8 months ago

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).

deadbabe3• 8 months ago

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• 8 months ago

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• 8 months ago

I'd stay bald. I like the way I look. I think, conventionally speaking, I look more masculine without hair. It's all subjective.

lossolo4• 8 months ago

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• 8 months ago

Bill Gates kind of argued the other side of that in his old Malaria talk https://youtu.be/ZLkbWUNQbgk?t=258

HexPhantom3• 8 months ago

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• 8 months ago

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• 8 months ago

Oh my god I have always asked why eyebrows stop growing and NOBODY ever thinks about it.

JumpCrisscross3• 8 months ago

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• 8 months ago

Wait until you get older, and you either start trimming them or considering some kind of Yellowbeard style braids

firmretention• 8 months ago

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• 8 months ago

I think they call this the "terminal length". As long as it will grow before it falls out.

adrr• 8 months ago

How did this explain in-grown hairs?

gorjusborg• 8 months ago

Pulling doesn't have to happen at the surface?

rambambram• 8 months ago

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.)

JumpCrisscross3• 8 months ago

Grass has a unique cell wall organization [1].

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC5241289/

JumpCrisscross3• 8 months ago

Are most industrial polymers drawn or extruded?

aklemm• 8 months ago

As I’ve ALWAYS suspected

randyrand• 8 months ago

So if you shave your head your hair will grow slower?

Human hair grows through 'pulling' not pushing, study shows

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