Gingers, or people with natural red hair, are relatively rare in the global population. Red hair is caused by a genetic mutation that results in higher levels of the pigment pheomelanin and lower levels of eumelanin in hair follicles. This genetic quirk affects only 1-2% of the world’s population.
The distribution of natural red hair varies globally, with the highest percentages found in northern and western European countries. Thislocalized pattern is likely due to the fact that the genetic mutation for ginger hair first arose thousands of years ago in the areas that are now Scotland, Ireland, and Scandinavia.
What is the genetic basis for red hair?
Red hair is the result of mutations in a gene called MC1R that codes for a protein called the melanocortin 1 receptor. This receptor controls which type of melanin pigment is produced by hair follicles.
There are two types of melanin:
- Eumelanin: A brown/black pigment that produces brown or black hair.
- Pheomelanin: A red/yellow pigment that produces ginger hair.
Everyone inherits one copy of the MC1R gene from each parent. In most individuals, the MC1R gene instructs hair follicles to produce eumelanin. But in people with red hair, mutations in both copies of the MC1R gene impair the receptor and cause more pheomelanin to be produced instead.
Where are redheads most common?
Natural red hair is most frequently seen in populations from northern and western Europe. This includes:
- Scotland – Approximately 13% of the population has red hair, the highest percentage in the world
- Ireland – Approximately 10% of the population has red hair
- Wales – Approximately 10% of the population has red hair
- England – Approximately 4% of the population has red hair
- Germany – Approximately 3% of the population has red hair
- Netherlands – Approximately 4% of the population has red hair
- Denmark – Approximately 4% of the population has red hair
- Sweden – Approximately 4% of the population has red hair
- Norway – Approximately 4% of the population has red hair
- Iceland – Approximately 5% of the population has red hair
Outside of Europe, red hair is rarest among populations from Asia, Africa, and the Americas due to lower rates of MC1R genetic mutations. The estimated percentages of natural redheads from other global regions are:
- North America – 2-3%
- Oceania (Australia, New Zealand) – 2-6%
- South America – 2-3%
- Asia – Less than 1%
- Africa – Less than 1%
Is red hair becoming more or less common?
Contrary to popular belief, the percentage of people with natural red hair is not decreasing but has remained relatively stable over time. However, redheads still represent a small minority in the global population today.
In the late 19th and early 20th centuries, some scientists hypothesized that red hair would disappear entirely within a few generations. It was believed at the time that red hair could only arise in places where both parents carried MC1R mutations, and that over successive generations these mutated genes would be diluted out in populations where redheads married non-redheads.
However, modern genetic studies have disproven this disappearance hypothesis. It turns out that MC1R mutations can remain hidden for many generations before reappearing in later progeny who inherit a copy of the mutation from each parent. Therefore, the MC1R red hair alleles have persisted in European and other populations at relatively steady rates over time.
Could redheads become more common in the future?
Although natural selection has maintained red hair mutations at steady equilibrium frequencies so far, it’s possible their prevalence could increase in the future due to a few factors:
- Relaxed negative selection – In past eras, redheads may have faced discrimination or health disadvantages that selected against the MC1R mutations. But with more inclusive modern societies, these inhibitory forces have lessened.
- Founder events – If subgroups that have higher proportions of redheads splinter off to form new isolated populations, this can increase MC1R allele frequencies. For example, this may have occurred when ancient peoples migrated to Scotland and Ireland.
- Positive selection – There are hypotheses that red hair could become more advantageous in the future due to climate change favoring lighter skin, or even sexual selection if redheads are seen as more attractive.
However, such evolutionary processes tend to occur slowly over many generations. So while shifts in red hair prevalence are possible, dramatic changes are unlikely over our lifetimes. The rarity of natural redheads looks set to continue for the foreseeable future.
What determines different shades of red hair?
Not all red hair is the same shade. The specific MC1R mutations carried determine whether a redhead has deeply saturated auburn hair versus pale ginger locks. There are 4 key red hair color genotypes:
| Genotype | Shade of Red |
|---|---|
| Homogenous M295R alleles | Deep copper red |
| Homogeneous D294H alleles | Auburn red |
| Heterogeneous M295R/D294H alleles | Strawberry blonde |
| Heterozygous MC1R mutations | Light ginger |
The M295R and D294H alleles produce more pheomelanin than other MC1R mutations and result in richly pigmented red hair when two copies are present. Heterozygous mutations produce less pheomelanin and thus lighter ginger shades.
What are some statistics on redheads?
Here are some interesting statistics about people with natural red hair:
- Redheads require about 20-30% more general anesthesia than people with other hair colors
- On average, redheads have 90,000 hairs on their head compared with 100,000 for blonds and brunettes
- Red hair grays later in life than other shades, often not until the 40s or 50s
- Redheads are more sensitive to hot and cold temperatures
- People with red hair sunburn more easily than those with dark hair
- Redheads have a higher risk of developing melanoma skin cancer
- Women with red hair have higher fertility rates than women with other hair colors
These quirks arise from the genetic and biochemical factors underlying red hair. The MC1R receptor not only controls hair pigment but other biological processes as well.
Redheads need more anesthesia
Doctors have observed that people with red hair seem to be more resistant to anesthetic agents used for general anesthesia before surgery. Research suggests that MC1R mutations may interfere with pathways used by anesthetic drugs, so higher doses are needed to achieve sedation.
Red hair grays later
The reduced eumelanin production in redheads also slows down their rate of hair graying. Gray hair results from a decline in melanin levels with age. Since redheads start with less eumelanin, it takes longer for their hair color to fade to white.
Sun sensitivity
Melanin offers natural protection against sun damage. With less eumelanin in their skin, redheads are more prone to burning rather than tanning when exposed to UV rays. They are also at higher risk for melanoma.
Temperature sensitivity
Interestingly, redheads are more sensitive to hot and cold temperatures. Researchers think subtle differences in cellular thermogenesis may make it harder for redheads to adapt to temperature swings.
Redhead fertility
According to some studies, redheaded women have slightly higher ovulation rates compared to women with other hair colors. However, the cause of this phenomenon is unclear since MC1R is not thought to directly affect fertility.
Do both parents need to be ginger to have redheaded children?
Two red-haired parents will always pass on MC1R mutations and have redheaded kids. However, red hair can also appear randomly in families where only one parent is a ginger:
- If one parent carries heterozygous red hair mutations, their children have a 50% chance of inheriting ginger genes.
- Even if neither parent is a redhead, a hidden MC1R mutation inherited from a grandparent or earlier ancestor can be passed down and combine with a mutation from the other side of the family.
- MC1R mutations can also arise spontaneously as new mutations.
So while having two red-haired parents makes red locks a certainty, unusual inheritance patterns mean redheads can turn up in any family line.
Conclusion
With only 1-2% of people worldwide having natural red hair, gingers are definitively a rare breed. However, the genetic mutations that cause red locks have persisted for millennia and remain most concentrated in northern and western European ancestral groups. While we may see shifts in MC1R allele frequencies in the future, dramatic changes are unlikely because evolution acts slowly over many generations. For now, that iconic ginger hair will remain a distinctive and exotic sight across most of the globe.