Human Hair Color and its Genetics

Ever looked in the mirror and wondered at the amazing color of your hair? Or do you wish your hair color to change overnight and have a completely different look the next day?

Though you can customize your hair and looks with varieties of hair dyes and hair straightening/ curling irons, you might want to know the reason beside your natural hair color.

Human hair color might be different than of your sibling and parents. You might have noticed your hair color changing according to seasons. With the change in altitude and climate, you can see corresponding change in human hair color, style and texture.

You might have felt your own hair color changing with age.

So, did you ever wondered how it happens?

Let’s know the reason behind it.

What are the pigments providing color for hair?

Human hair color is determined by the degree of pigment called melanin produced by melanocytes in our hair. They are derived from amino acid named tyrosine. There are three types of pigments namely, eumelanin, pheomelanin and neuromelanin.

An abundance of eumelanin would give your hair a brown or black color and pheomelanin would give your hair a red or yellow color. Every Human hair color is the combination of these two pigments. Neuromelanin colors some areas of the brain and doesn’t have a direct connection to the color of hair.

Types of Human hair color

Predominantly, human hair can be of five colors:

Black, Brown, Blonde, White/grey (auburn) and red. They have different shades depending on the presence of different pigments.

Factors determining hair color

Along with the pigments, several other factors induce the color of your hair. The environment you live in also determines the color, volume and type hair. Stress, smoking habit, poor diet and extreme sunlight cause hair color fade faster. Let’s get to know each of them in brief:

Hormones

Hormones are the chemical signals produced by endocrine gland and released to the bloodstream that our body uses to transmit messages to all other parts. The type and amount of hormone our body makes depend on our age, temperature, nutrition and many other factors. They are responsible for controlling and coordinating activities of our body. So, changes in hormone level can turn the pigment status ‘on’ or ‘off’. That’s what causes the color of our hair change along with hormonal change.

For instance, even if the Human hair color is determined by the presence of pigments, two people can have the same gene and have different hair color. How? It is because hormones can change the way genes work. They have influence over many physiological activities like growth, metabolism, appetite and fertility so that Human hair color also keeps on changing accordingly during these stages. As children get older, blonde hair may grow darker and if melanocytes start dying, black hair may become white. During pregnancy, women experience significant change in Human hair color, strength and texture due to increased production of estrogen and progesterone hormone.

Chemicals

The color of your hair might change if it comes in contact with some chemicals.

For instance, if you spend more time in pool water, then the chlorine or salt might affect the keratin in your hair making it look lighter and tangled. L-Taurine, one of the four amino acids is the building block for proteins like keratin.

The deficiency of such acids may cause hair color to fade faster resulting in weaker and broken hair.

And of course, you can use hair dye to color your hair to your favorite one which mostly uses hydrogen peroxide and ammonia. The ammonia works by breaking down the outer cuticle (cuticle is the outer layer of hair that protects your hair from harmful rays and strengthen it) around the hair shaft so that other chemicals can enter the hair where color development takes place.

Hydrogen peroxide works in the hair cortex, the innermost part of the hair that holds melanocyte responsible for giving color to your hair. It is commonly used to lighten hair color.

Even the citric acid in lemon and apple cider vinegar makes your hair lighter.

If you are allergic or afraid to use hydrogen peroxide, you can try cinnamon or honey to naturally lighten and make your hair shiner.  

Geography

Along with the change in landscapes, climate, culture and altitude, you can see variation in people; physically and culturally. Body metabolism functions correspondingly to make them adaptable to the environment they live in. So, geographic variation stimulates the chemical formation process in our body causing difference in hair color as well.

You might have noticed people in the Himalayas or in colder regions with straight black hair and Europeans with a blonde.

Auburn hair is common among individuals of Northern and Western Europe while red hair is prominently found in the British Isles. Scotland has the highest proportion of people with red hair.

Despite being the rarest hair color in the world, around 13% population of Scotland has red hair and 40% carry recessive red hair genes. Chestnut hair (brown hair with red shade), which is darker in contrast to auburn hair is commonly found in natives of Western, Central, Northern and Eastern Europe.

Almost 80% of the world’s population have black or dark brown hair. Brown hair stands in second position covering 11% of total population while blonde hair is fortuned to only 3%.

Where there is poor sunlight, melanin production is reduced resulting in blond or red hair.

To some extent, climatic variation also has influence over the hormones and hence the color of our hair.

Body Metabolism

Metabolism is the biochemical process by which your body converts the food or drink you take into energy. Two types of metabolism take place in our body, anabolism and catabolism. While anabolic reactions use up energy, catabolic reactions give out energy.

Your hair also needs healthy foods and nutrients to maintain a shining and bright color. Protein deficiency may result into weak and brittle hair and eventually lose the hair color.

Our hair is too sensitive to the changes in our body. As written in the hair shaft, record of past events up to three years can be extracted. No other tissue of our body provides as much information as hair about the ongoing changes in our body.

As hair is the most actively growing tissues of human body, metabolic effects are observed both on hair shaft morphology and color.

So, taking on enough calories and living a healthy lifestyle would have significant impact on the strength and color of your hair. Try workouts, drink enough water, reduce stress levels and watch how your hair starts shining and gives you a great look you had always wished for!

Stress

Stress refers to the way our body responds to physical or emotional tension arising from any event or thought that you feel frustrated about. Stress can have a positive impact if it helps you avoid possible danger or submit your work before the deadline.

Temporary stress, also known as acute stress arises while you are doing something exciting or managing some dangerous situations.

But if you have chronic stress that lasts longer and badly affect your mental health even without making you feel realized you have one, then that will have a severe impact on your health.

The level of stress we have is subjective somehow and every individual responds stressful situations in their own way. So, although direct relationship hasn’t been established between stress and hair color, researchers have proved that stress could trigger hair color fading process.

Hormones regulation changes as a response to chronic stress. Hormones produced as a result of stressful situation cause depletion of melanocyte stem cells responsible for determining hair color.

As the stem cells leave our hair follicles, the color of our hair changes to gray or white.

Inflammation produced by stress hormones drive the production of free radicals (unstable molecules that damage cells) and these free radicals induce bleaching or in any way could influence the production of melanin so the resultant effect being our hairs turning gray or white.

Medical Condition

Your hair derives nutrients from the blood along with other pigments.

So, if you have malnutrition, heart problem, neuromuscular disease, chronic illness, malignancy, thyroid or any other health problem, then your hair would start being weak, prone to breaking and losing color.

If you have drinking habit or you have been aged, even with the outstanding food habits and nutrition, genetic blueprint will eventually take control and you can have no control over the fading color of your hair.

The genetic abnormality termed as ‘Albinism’ cause absence of pigments in human body so that our hair becomes white along with the change in color of our skin and eyes.

Werner syndrome characterized by premature ageing and pernicious ammonia cause a deficiency of red blood cells. Due to lack of vitamin B12, this type of medical condition arises and may trigger bleaching of hair.

Likewise, Vitiligo is the long-term skin condition that occurs as a result of auto-immune disease and leaves patches in the skin with a sharp margin between them.

The hair in such areas also changes the color.

Similarly, the medical condition termed as ‘alopecia areata’ cause the colored (non-gray) hair to be lost suddenly which might lead to overnight graying. If you are recovering, the new hairs might be of the same color as before.

What is the genetic of our hair color? Is it genetically transferred from mother or father or both?

Of course, Human hair color or any hair color is influenced by the gene you receive from your parents. You’ll get four hair color genes from each. Eumelanin gene is either on ‘on’ (active) or ‘off’ (passive) state.

Taking ‘E’ as ‘on’ eumelanin gene you inherit from your parents and ‘e’ as an ‘off’, for instance, if your mom contributes EEEe gene and your dad contributes EEEE gene, then you are likely to have black hair, the end result being EEEEEEEe. So the more ‘on’ eumelanin you receive, the darker your hair will be.

Pheomelanin is passed down to the children via a different gene named allele. Melanocytes will produce pheomelanin when Melanocortin 1 Receptor (MC1R) is in an inactive condition.

It is the same pigment that makes your lips pink. And, the color of your skin and hair is party dependent as the pigments have somehow influence over the color of your skin too. Have you ever seen people with dark skin with blonde hair? I don’t think so.

Which hair color is dominant?

Could it be that the two brunette parents can have a blonde child? Of course, they can. Genetic inheritance necessarily doesn’t mean having the same hair color in every case. Because of the recessive and dominant characteristic of genes, one of the hair types gets hidden in their DNA. DNA is organized into small pieces called genes which determines how our body grow and develop.

If you get all brown allele from your father and all blonde from your mother, then you will have brown hair as the brown is always dominant.

Think of it this way to be precise, if you wear a white t-shirt and black jacket, then obviously the t-shirt gets hidden though it’s there. And it’s hidden doesn’t mean it isn’t there.

So, it’s like passing either the t-shirt or the jacket to the children that determine their dominant hair color. And the jacket representing brown hair is dominating which of course makes the hair brown though you got t-shirt or the blonde hair too.

Which is the rarest Human hair color in the world?

Red hair color is very rare. It is the result of series of mutation in MC1R gene which transmits higher amount of pheomelanin to the hair. Only one 1% of the total population have red hair.

What happens to hair with age and health?

As melanocytes start wearing out as we get older, they are not good at passing melanin to the hair. So, hairs that receive little melanin gets grey and that gets none turns out to be white.

When we are young, even if the melanocytes die, they will get replaced with new one. However, as we get older, the ability of our cells at dividing and forming new cells decreases. So, pulling out your white hair doesn’t make the new one be black or the color you had. As the hair gets pigment from the cells and there is no melanocyte in the cell, your new hair end up being white.

Likewise, your body metabolism and medical conditions have some influence over the color of your hair. For instance, people with thyroid deficiency might develop blonde hair over time. And to the reverse, people with different hair color are susceptible to different types of diseases.

Does your hair color get affected during pregnancy?

Most of the women feel their hair color changing during pregnancy. The degree of melanocyte, along with oestrogen and progesterone hormone increase during pregnancy which cause hair to grow faster and fall less making it seem healthier and stronger than before.

Or you might be among the few to lose hair and watch your hair becoming thinner. Either way, there will be a noticeable change in your hair but these are just temporary.

The color and texture of hair could also change during pregnancy. If you have light hair, it may turn darker and your curly hair may fall flat or your pencil straight hair may start curling.

Does it affect your child health in the womb too?

Melanin is produced only after 6 to 36 of birth of the baby. In the womb, genes that make the pigment aren’t read by melanocyte cell as they are activated by sunlight and the baby at womb doesn’t have direct contact to sunlight. So, how much hair your infant will born with and what color it will be all depends on genetics they receive from their parents.

In the third trimester, the baby develops a fine and colorless hair named as ‘vellus’ and the color and thickness of hair would continue changing even after the birth, similar to skin pigmentation.

Melanocyte cells are below every strand of our hair and the level of melanin they produce would keep changing the color of our hair.

Does long exposure in sun damage your hair color?

Melanin is what protects our hair and skin filtering the harmful ultra-violet rays of the sun. The UV rays oxidize melanin into colorless compound, i.e. bleaches and destroys melanin and break down hair protein so that the hair gets lighter. Your hair will be of the same color until the new hair comes in.

Spending too much time in the sun cause tanned skin and bleached hair. Do you know why this contrast effect happens?

It is because the hair is dead and the skin is alive. So, as more melanin is produced to protect our skin from the harmful rays of the sun, the skin gets darker being alive and the hair gets lighter being dead.

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