Is it that they don’t know or the “threshold” is so long that we don’t get to see it very often?
In: Biology
Does the amount of time that scalp hairs will grow vary from person to person? Do people actually have a maximum length that their hair can grow to? I wonder about this because ever since puberty, I’ve never been successful at growing my hair past shoulder length. I wonder if this is because of something inherent in my hair.
They don’t stop growing, they simply fall out. Stronger hairs last longer, and therefore can grow longer (like head hair). Eyebrow hairs for example fall out much more regularly, even though you likely don’t notice them.
Source: have some ultra strong eyebrow hairs (specifically 3) that I have to cut. The rest are normies
Ugh wait till 50. They ALL forget to stop growing and also they decide to grow in areas that have no business having hair in the first place =…(
Your eyebrows stop growing? Must be fucking nice. If i dont trim em for like a week or two I have 90 year old man caterpillar eyebrows. Not bushy… booossshie mother fucking monsters
Every cell in your body has (mostly) the same DNA. However, not every cell looks the same.
Only small parts of the DNA are “activated”, and the method by which certain parts are activated and other parts are not is very complex. It happens though. So, muscle cells will have the “muscle” part of the DNA activated, while skin cells will have the “skin” part of the DNA activated.
Similarly, eyebrow hair follicles will have the “eyebrow hair follicle” part of the DNA activated (which keeps it relatively short as detailed in another answer), while head hair will have the “head hair” part of the DNA activated.
Some poor saps will have the “No hair for you on your head you loser” part of the DNA activated. I am one of those poor saps.
Asked and answered in 2015: Actually, all hair stops growing after a certain length! Leg hair, arm hair, eyelashes, eyebrows, head hair, and even the hair on your butt will stop growing after a certain period of time. Exactly how long your hair can grow depends primarily on your genetics, but age, hormones, and general health can all play a part.
Hair growth occurs in three phases. The first phase is called the anagen phase and it is during this time that the hair actually grows. About 85% of the hair on your head is in this phase at any given time. This phase can last between two and six years for head hair and the duration of this phase will determine just how fast and how long your hair can grow.
The second phase is the catagen phase. During this phase, the hair follicle separates from the hair strand itself and does some things to prepare itself for the next phase.
The third phase is called the telogen phase and it’s known as the resting phase. Around 15% of your hairs will be in this phase at any given moment. Once this phase is over, the cycle begins anew with the anagen phase.
[You can read more about Human hair growth at Wikipedia.](http://en.wikipedia.org/wiki/Human_hair_growth) Take a look at the sidebar for information about the different kinds of hair, too!
It has been five years since I’ve had my head hair last cut and it’s stopped growing about mid-way down my back. That’s a pretty typical length for males. Female hair tends to stop somewhere around the buttocks.
My dad’s eyebrow hairs did not stop. They got long and spindly. Kinda all over the place. Was really funny. May he rest in peace after that eyebrow fiasco he always had going. 🤣❤
There is an actual reason that I don’t see here but I’m late to the party!
As people have said previously, hairs grow from follicles, inside your skin. Some do indeed grow forever, like your head hair (if you’re lucky.) They age and fall out due to a lot of different reasons including what you eat and how healthy you are.
Hairs that don’t grow forever get their length determined in the genes of the cells in the follicle. But how do they sense their length?
Longer hairs wiggle! Cells in the follicle can sense mechanical stress as well as grow hairs.
Say we talk about a hair in your leg, just above your ankle. As it grows, moving in life causes it to wiggle a certain amount. Just a little bit at first. Then as it gets longer it’s more likely to catch air currents, rub on things, and get pulled more. The follicle knows how much wiggle is associated with how long the hair is. If it wiggles just a little it’ll hang on to the hair. If it wiggles to much it stops growing the hair and may even let it go after a certain amount of time.
Incidentally you can see this work, especially around the ankle when people wear socks for a long time. The constant movement of the sock on the ankle can sometimes make hair growth finer or even stop it entirely. This happens in athletes. Now on the other side of the spectrum, people that wear socks for to long but don’t move, say when they’re in a coma, usually grow very long ankle hairs because there is no wiggle.
Wait, you guys have hair that grows on your head?
Can somebody tell my eyebrows? They clearly did not get the memo.
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