Hair color is one of the most visible and defining characteristics of human appearance. The natural hair color of most people ranges from blond to black, with all shades of brown in between. But what determines our natural hair color and what colors are genetically possible in human hair? Let’s take a closer look at the fascinating science behind our tresses.
What gives hair its color?
The shade of our natural hair color is determined by two types of pigment:
- Eumelanin – This pigment gives hair brown and black shades.
- Pheomelanin – This pigment produces red and blond hues.
Everyone has some combination of both eumelanin and pheomelanin in their hair. The particular ratio of these two pigments is controlled by genetics and accounts for the spectrum of natural hair colors.
Common natural hair colors
Here are some of the most commonly occurring natural hair colors and their genetic causes:
- Black hair – Hair with the highest levels of eumelanin and minimal pheomelanin.
- Dark brown hair – High eumelanin with some pheomelanin.
- Light brown hair – Moderate levels of both eumelanin and pheomelanin.
- Auburn/red hair – Low eumelanin and high pheomelanin.
- Blond hair – Very low levels of both pigments.
While these colors cover most people’s natural shades, hair color is a spectrum with many subtle variations in between.
Genetics of hair color
Our hair color is inherited through combinations of gene variants or alleles from both parents. There are two main genes involved:
- MC1R – Controls pheomelanin production and red tones.
- OCA2/HERC2 – Controls eumelanin production and brown/black tones.
Different alleles or mutations in these genes alter their protein function, changing the balance of pigments. For example, red hair is caused by MC1R variants leading to high pheomelanin. The inheritance patterns of these alleles result in the range of natural hair colors we see.
Rare natural hair colors
While shades of blonde, brown, and black are by far the most common, other natural hair colors are possible in rare genetic circumstances:
- Plica polonica – Also called “Polish plait,” this is a condition where hair forms a matted lock with a gray or blonde color.
- Progeria – This premature aging disease can cause hair loss and graying in childhood.
- Albinism – Lack of melanin causes white or very pale blond hair.
- Vitiligo – Depigmentation causes white patches in otherwise normally colored hair.
These conditions disrupt the normal pigment formation in hair follicles, leading to unusual colors.
Gray and white hair
Graying or whitening of hair is not an actual hair color itself but rather loss of color. As we age, pigment cell activity decreases, and hair loses its color and turns gray or white.
Additionally, some people are genetically predisposed to premature graying at an earlier than normal age. The main gene identified is IRF4, which helps regulate melanin production. However, several other genes likely contribute as well.
Can hair change color naturally?
After childhood, our natural hair color is pretty stable throughout life. However, some subtle changes can occur:
- Sun exposure can lighten hair over time, gradually bleaching pigments.
- Hair can darken slightly from childhood to adolescence as melanin production increases.
- Pregnancy hormones can cause temporary lightening or darkening.
- Some women notice hair color changes during menopause as hormone levels shift.
- Dulling and loss of shine can happen with dryness or damage.
Additionally, as already discussed, we all start going gray eventually as we age. But in general, major changes to our natural shade do not occur spontaneously.
Can natural red hair turn blond?
True, rich red hair will not transform into true blond later without bleaching or coloring treatments. However, some common misconceptions exist around red hair:
- Red hair contains pheomelanin but also some eumelanin. So it is not devoid of brown/black pigment.
- “Strawberry blond” is a mix of blond and red, not rich red.
- Red hair often lightens and loses some vibrancy with sun exposure over time.
- Children with reddish hair can turn more blond during puberty as pheomelanin production diminishes.
So while true red hair will not turn blond, the subtle lightening that can occur over time may give a blond appearance in some cases.
Can hair get darker with age?
As discussed above, hair can darken slightly from childhood to the late teens as melanin production ramps up. However, hair is not likely to keep getting progressively darker past this point. The natural hair color spectrum is pretty well established by adulthood.
Some factors that can cause modest darkening over time include:
- Increased sun exposure stimulating melanin production
- Changes in hormone levels during puberty, pregnancy, or menopause
- Improved diet and vitamins increasing melanin
- Oxidative hair dyes gradually coating the strands
However, these effects are generally subtle and slow. Hair does not typically undergo dramatic darkening with age once pigment levels stabilize after the teen years.
Is there a true black hair color?
There is no hair color that is actually jet black. What we call “black” hair is really just a very, very dark brown with the highest levels of eumelanin. When examined closely, even hair that appears black has a subtle brownish tinge.
Additionally, pure black hair would only be possible through hair dye. Even people with the darkest natural shades have some underlying warmth from pheomelanin that affects the tone.
So in summary:
- Natural “black” hair is technically just an extremely dark brown.
- Pure black only occurs with artificial coloring.
- Some minimal warmth exists even in the darkest natural hair.
What determines blond shades?
Blond hair ranges from platinum and silver-blond to golden and strawberry shades. The specific hue depends on:
- Ratio of eumelanin (brown) to pheomelanin (red). More pheomelanin creates warmer gold tones.
- Amount of melanin overall. Less pigment results in lighter blonds.
- Natural hair color contrast. Blonds tend to keep their childhood brightness.
- Hair structure. Fine hair appears lighter than coarse hair.
So the balance of brown to red pigments, degree of brightness, and hair structure work together to create the spectrum of blond tones.
Rarest natural hair colors
Only about 2% of the population has natural red hair. This shade is caused by a rare combination of MC1R gene mutations that boost pheomelanin. Additionally, here are some other very uncommon hair colors:
| Hair Color | Prevalence | Cause |
|---|---|---|
| White | Less than 1% | Extreme lack of melanin production as in albinism |
| Silver/Gray | Less than 1% | Premature graying or aging conditions like progeria |
| Blue | Extremely rare | Optical effect from minimal melanin in extremely fair hair |
| Green | Extremely rare | Optical effect in hair with minimal melanin and unique structural properties |
So in summary, white, silver, blue and green hair rarely occur naturally. Red hair also stands out as unusually uncommon.
What affects hair color intensity?
The richness and depth of hair color depends on a few factors:
- Melanin concentration – More pigment equals deeper color.
- Oxidation – Environmental factors like sun can fade color over time.
- Age – Hair color typically peaks in teens/20s then gradually dulls.
- Damage – Dry, damaged hair loses vibrancy and shine.
- Health – Illness, nutrition deficiencies, or medications can diminish intensity.
Maximizing melanin production, limiting UV exposure, staying healthy, and maintaining the structural integrity of hair are key to optimizing color brightness and saturation.
How hair color genetics work
To understand natural hair color genetics, we need to look at how the two pigment genes interact:
- MC1R – Controls pheomelanin. More activity = more red tones.
- OCA2/HERC2 – Controls eumelanin. More activity = more brown/black tones.
The variants or alleles we inherit of these genes from our parents determine our hair color by influencing the pigment balance. Some key examples:
| Gene Variants | Result |
|---|---|
| High pheomelanin MC1R alleles + low eumelanin OCA2/HERC2 alleles | Red hair |
| Low pheomelanin MC1R alleles + high eumelanin OCA2/HERC2 alleles | Black hair |
| Low pheomelanin MC1R alleles + medium eumelanin OCA2/HERC2 alleles | Medium brown hair |
| Low pheomelanin MC1R alleles + low eumelanin OCA2/HERC2 alleles | Blonde hair |
Many other genetic variants influence hair color, but MC1R and OCA2/HERC2 are the major players in determining our natural shade.
How hair color is passed down
Hair color inheritance patterns are quite complex because multiple genes are involved. However, we can make some generalizations:
- Darker shades tend to be more dominant.
- Red hair has the highest inheritance strength.
- Blond hair is easily overpowered by other colors.
- Parents pass down a random assortment of their alleles.
- Modifying genes can interact with MC1R and OCA2/HERC2.
Additionally, some notable patterns exist in certain ethnic groups. For example, blonde hair is common among Northern Europeans. Overall, both parents make substantial contributions to a child’s hair color outcome.
How melanin controls hair color
Melanin pigments are produced inside hair follicle cells called melanocytes. The main steps in melanin synthesis that determine hair color are:
- Amino acid L-tyrosine is converted into L-DOPA.
- L-DOPA is transformed into melanin by the enzymes TYR and TYRP1.
- Melanin granules are distributed into keratinocyte hair cells.
- Higher melanin = darker color, lower = lighter color.
Genes like MC1R and OCA2/HERC2 control these melanin production steps. Alterations to these genes can create different pigment levels and ratios, producing the natural color variation we see.
The future of hair color genetics
Researchers continue making exciting discoveries about the genetics of hair color. Some future applications of this knowledge could include:
- Better paternity tests using hair color as genetic markers.
- Earlier graying prediction from genetic testing.
- Customized hair dyes based on an individual’s genetics.
- Gene therapies to allow changing of natural hair color.
- Treatments targeting mechanisms of graying and hair whitening.
Additionally, studying other ethnicities can provide new insights, as most research so far has focused on European populations. Overall, unlocking the genetics behind hair color offers many intriguing possibilities.
Conclusion
Our natural hair color is one of our most distinctive physical features. This shade is determined mainly by two melanin pigments: brown/black eumelanin and red/blond pheomelanin. Genes like MC1R and OCA2/HERC2 control the production levels of these two pigments to create the spectrum of human hair colors. Blonde, brown, black, and red hair make up most natural shades, while other colors like white and green are extremely rare. Hair color genetics involve complex inheritance patterns and many contributing genes. Understanding the molecular biology of hair pigments continues to provide insights about our appearance and ancestry. While environment and age affect our hair over time, the specific combination of melanins we are born with remains largely stable throughout life, giving us our unique and vibrant hair color identity.
