A hairy business

Let your hair down: 10 amazing facts about human hair

Credit: Ali Pazani

The human body is incredible, from its mechanics to its ability to heal and adapt to multiple environments and situations. Hair, as part of our body, is no exception to this complexity and wonder. Let’s take a look at 10 amazing facts about our hair that you may not know!

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The word hair is used to describe two separate and distinct components: the follicle and the shaft. The follicle—what we commonly refer to as the root—is a living organ located in the dermis of the scalp. It’s responsible not only for growing hair but also for helping regenerate skin after a wound.

On the other hand, the shaft—often referred to as the strand—is a filament composed of layers of keratin, the same protein that makes up our nails. Unlike the follicle, the hair shaft is technically dead because it consists of dead cells.

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Each hair strand is composed of three layers. The innermost layer is the medulla, and even scientists are still uncertain about its exact function. Surrounding the medulla is the cortex, which absorbs water and provides strength to the strand. The cortex also contains melanin, the pigment that determines hair color, and its shape plays a major role in whether hair is straight or curly. The outermost layer is the cuticle, which serves primarily to protect the hair shaft.

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Hair color is primarily influenced by several genes, including MC1R, which plays a key role in melanin production. However, not everyone produces the same type or amount of melanin. Higher amounts of melanin result in black hair, while varying levels and types of melanin—along with genetic variations—produce brown, blond, and other shades.

Red hair, the rarest natural color, is caused by a mutation in the MC1R gene and is inherited in a recessive pattern. This means a person must inherit two copies of the mutated gene (one from each parent) to have red hair, though many people carry the gene without expressing the trait.

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Growing at a rate of about 0.2 to 0.5 inches per month, hair is the second-fastest growing tissue in the human body—surpassed only by bone marrow. This rate is influenced by factors such as genetics and ethnic background. Other variables, such as age, lifestyle, or health, can also have an impact on our hair growth and density.

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We usually think of cats or dogs when it comes to shedding, but humans also shed hair regularly. After all, hair is a trait shared by all mammals. The average person sheds between 50 and 100 strands of hair per day, though this number can increase in response to stressors such as illness, hormonal changes, or emotional stress. Once the stress subsides and the body readjusts, the excess shedding typically stops.

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Commonly associated with aging, grey hair isn’t a color in itself but rather the result of a loss of pigment. As part of the natural aging process, melanin production in the hair follicle gradually decreases and eventually stops, causing strands to appear grey or white.

Genetics and ethnic background play a major role in determining when and how the greying process begins. Some people are even genetically predisposed to start greying at a very young age.

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Hair texture is commonly associated with ethnic background, but that’s not the only factor involved. Texture is primarily determined by genetics, and while genetics are closely tied to ancestry, all hair textures can be found across different populations.

Scientists believe that hair texture—specifically curl pattern and volume—is a result of the shape of the shaft. A round shaft typically produces straight hair, while flatter or more oval-shaped shafts tend to create curls and waves.

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Depending on the structure of your hair cuticle, your hair may be more or less water-repellent. Hair shafts with a more porous cuticle absorb water easily but also lose moisture quickly. In contrast, shafts with a tighter-packed cuticle struggle to get wet and are slow to dry.

Credit: Sonja Langford

Hair doesn’t grow continuously or all at once—each strand follows a cycle with distinct phases. First comes the growing phase, which varies depending on the type of hair (for example, facial hair grows faster and for a shorter period than scalp hair). Eventually, growth slows down, and the strand detaches from the root.

After this, the hair enters a resting phase, during which it remains in place until it is naturally shed. At any given time, we have hairs in all stages of this cycle, which is why we regularly shed hair without going bald.

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Like any other part of the body, hair contains DNA and genetic material, which means a person can be genetically identified from a single strand, provided it includes the root. But hair holds even more information. The analysis of a hair strand can reveal substances that were present in a person’s bloodstream over time, including vitamins, minerals, medications, alcohol, and other substances.

Strength in numbers

Words that can’t resist loneliness: 11 plural-only terms explained

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Some words just can’t be left alone. You can have a pair of glasses, climb the stairs, or dip into your savings, but try talking about just one "glass," (for your eyes) "stair," or "saving," and it suddenly feels a bit off. These traits go unnoticed most of the time, but they do exist. These 11 common words exist only in the plural form.

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It probably has to do with a pair of glasses having two separate pieces of glass, one for each eye. A similar element, but with a single glass, would be called a monocle.

Therefore, glasses only exist in their plural form, as only two make a complete set.

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The word "clothes" is always plural because it refers to multiple garments, not just one. Also, it differs from "cloth," which means the material.

Historically, "clothes" evolved from "cloths," once the plural of "cloth," which also meant a garment. As "cloth" shifted to mean just fabric, "clothes" kept their meaning as a collection of items like shirts, pants, or socks.

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A pair of scissors is composed of two blades, each with a handle attached to it, held together by a screw in the center. That is why it is called a pair of scissors and not just one scissors.

Theoretically, one could have a single scissor, meaning one blade, but it would not serve its natural purpose of cutting things by sliding the two blades together.

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The word "stairs_"_ is plural because it refers to a set or flight of steps, not just one. The structure involves multiple steps, making the plural form more natural in everyday use.

Yes, "stair" can appear in older texts or compound words like "staircase," but it’s less common and often refers to a single step or the entire flight. Still, most people use "stairs" to describe the full set.

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Not unlike the previously mentioned glasses, "pants" are always plural because they come from pantaloons, which were originally two separate pieces: one for each leg. Even though modern pants are a single garment, the plural form stuck.

"Pants" is just a shortened form of "pantaloons," and the idea of two leg coverings helped keep the plural usage alive through habit and tradition.

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This one can seem tricky at first, since a person could, theoretically, own a single thing, but there is a logical explanation as to why it is a plural-only word. "Belongings" is plural because it refers to a collection of personal items someone owns, like clothes, books, or furniture. It implies more than one object, making the plural form natural.

The singular "belonging" has a different meaning altogether: it describes the feeling of being accepted or fitting in, not physical possessions.

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The word "headphones" is usually plural because it refers to a device with two earpieces worn on both ears. While "earphones" can describe the individual parts, the full set is commonly called "headphones."

Modern headphones are typically stereo and designed as a pair, which, in turn, reinforces the use of the plural form.

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The word "species" is used for both singular and plural forms, especially in biology. It comes from Latin, where the form was the same in both cases, which explains the modern usage.

In the world of taxonomy, "species" acts as a collective noun for organisms with shared traits.

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Similar to scissors, the word "tongs" is always plural because it describes a tool made of two connected parts that work together, just like scissors or pliers. This dual structure leads to the use of a plural noun, even for a single tool.

In English, tools with two joined parts are often plural nouns used only in the plural. It’s a common use born out of how these items are constructed and used.

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A word with grim connotations, indeed, "remains" is usually plural because it refers to leftover parts or pieces of something, like uneaten food or human remains. Even when it’s one item, it’s seen as part of a whole that’s no longer intact.

It works as a collective noun, emphasizing the idea of multiple fragments. Though not strictly plural-only, it’s almost always used in the plural to reflect this meaning.

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No one talks about "saving," meaning a collected amount of money. And that is because the word "savings" looks plural but can act as either a plural or a mass noun. For example, "significant savings" treats it as plural, while "the savings are substantial" treats it as a total amount.

As a mass noun, "savings" refers to the money saved overall, much like "money" itself. As it was seen in the previous examples, context determines whether it's treated as singular or plural.