Why does body hair only grow to a certain length?

The human body is fascinating and mysterious organic machine that has tons of pre-programmed instructions that perform a set of specific tasks. Hair growth is one of these predetermined functions that the body performs. But how does it actually work?

The skin has hundreds of thousands of hair follicles situated in specific areas of the body. These follicles produce new hair cells on a regular basis. Older cells are squeezed out of the follicle as new cells are created to take their place. These older cells then die and form the shaft of a hair.

hair growth stages

Depending on where the follicle is placed on the body, it is programmed to create new cells for a specified period of time only. This is called the growth phase (or anagen phase) and can last anywhere from a couple of months (for hair on your face, arms, legs and the rest of your body) to years (the hair on your head or, in men, facial hair).

Once the growth phase ends, the follicle enters a rest phase (or dormant phase) when it will no longer produce new cells to continue the hair growth. If a hair is pulled out of the follicle or falls out naturally, the follicle will resume the growth phase.

So your follicles are programmed to grow hair to a certain length by a predetermined growth phase and the process is set in motion by the lack of a hair in a hair follicle. Simple!

But what about when you cut your hair? How does the hair follicle know that the hair has been cut and re-enter the growth phase until the hair has grown to its previous length? This is a far more interesting question.

The fact is that the body and the follicle don’t know that it has been cut. It will simply continue in the cycle of growth and dormancy. In the same way the growth phase is programmed to last a specified period of time, so is the dormant phase. Once the dormant period has passed, the hair will continue to grow.

If a hair hasn’t been plucked, fallen out or been cut, the new cells will simply push out the old hair to make room for a new hair to grow. As to why a cut hair will still only grow to a certain length, science still doesn’t have the answer.

However, hair length on the body and head are genetically determined. Some people have a longer growth cycle than others meaning that they can grow longer hair than others. No matter how many vitamins you take, how often you cut your hair or even shave it, your hair will only ever grow as long as your genetics dictate.

It is also a myth that cutting your hair will make it grow faster. The growth is constant and results in about 1/4 to 1/3 of millimeter of hair being exposed every day. However, cutting your hair and taking vitamins can improve the health of your allowing the new cells to grow stronger and thicker. Although even the thickness and strength of your hair is genetically predetermined to a certain degree.

Stimulating the scalp through massage or brushing can result in slightly faster hair growth. The stimulation increases the blood flow to the hair follicles which in turn increases the nutrients, proteins and other elements to speed up cell regeneration.

There is absolutely nothing that you can do to alter the growth and dormant phases of hair growth thereby altering the length of hair on a specific area of the body. However, as you grow older, certain areas of the body will grow longer hair while hair will diminish in other locations.

Image Credits: HairFinder.com

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