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.
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.
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
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.
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.
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.
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.
> 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.
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
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?
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?
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:
"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)"
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.
It's like that three-finger meme from the Tarantino movie, lol.
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.)
https://xkcd.com/123/
But I am also pretty confident that hair does not stop growing because of split ends. That feels like an “old wives tail”.
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.
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).
The impact on mental wellbeing can be pretty severe, though.
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?
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
I thought it was nonsense. Shows what I know. I suppose folk wisdom is vindicated again.
Though, I would also somewhat expect pulling at it increases blood flow, which I would think to have some impact on growth?
PS Love the bio!