Having naturally purple eyes is an extremely rare occurrence in humans. While eye color is determined primarily by genetics, the specific genetic mutation that can result in purple irises is very uncommon. There are only a few documented cases of true purple eyes throughout history. However, there are also ways to make your eyes appear more purple through intentional modification.
Genetics of Eye Color
Eye color is determined by the amount of melanin pigment in the iris of the eye. Melanin comes in two forms: eumelanin which produces brown/black pigment, and pheomelanin which produces red/yellow pigment. Most commonly, eye color is determined by the amount of brown eumelanin in the iris. Higher amounts result in brown or black eyes, while lower amounts lead to green, blue, or gray eyes.
The specific shade of eye color is determined by the concentration and distribution of melanin within the iris. Increased deposition of melanin towards the front of the iris results in lighter colored eyes. Iris melanin concentration is regulated by at least 8 different genes, though the main regulators are the OCA2 and HERC2 genes. Mutations in these genes can reduce melanin production and result in blue eyes (which have very low melanin levels).
The tyrosinase gene also plays a role by regulating the production of melanin. Complete loss of tyrosinase activity results in oculocutaneous albinism type 1 (OCA1), characterized by milky white skin, white hair, and red/pink irises. Partial loss of tyrosinase causes oculocutaneous albinism type 2 (OCA2) which features hazel or light brown irises. Mutations in OCA2 and HERC2 genes can also lead to blue eyes by reducing overall melanin production in the iris.
True Purple Eyes
So where does purple eye color come from? For an individual to have truly purple eyes, they must have an extremely rare genetic mutation that results in high levels of both eumelanin and pheomelanin pigments within the iris. Having both red and brown melanin together can create an eye color that appears dark purple or violet. However, this specific mutation is not fully characterized and is thought to be extremely rare in humans.
There are only a handful of reports of people with naturally occurring purple eyes throughout history. Famous examples include the notorious Roman Emperor Caligula, Cleopatra’s son Ptolemy XV (nicknamed Caesarion meaning “little Caesar”), and Elizabeth Taylor. However, most historians believe that Caligula and Caesarion likely had dark blue/gray eyes that only appeared purple under certain lighting. Elizabeth Taylor’s eyes were technically a very deep blue with a violet tint.
True purple eyed individuals photographed under standardized conditions are nearly unheard of. Swedish model Alexandra Johansson is perhaps the most widely recognized person with violet-colored eyes. Some researchers believe she may have a rare mutation in a yet-unidentified gene that controls both eumelanic and pheomelanic pigments in the iris.
| Person | Eye Color |
|---|---|
| Caligula | Dark blue/gray, appeared purple |
| Ptolemy XV | Dark blue/gray, appeared purple |
| Elizabeth Taylor | Deep blue with violet tint |
| Alexandra Johansson | True deep purple |
So while possible, true purple colored eyes are exceptionally rare and require very specific genetic mutations. Most reported cases of purple eyes throughout history were likely a trick of lighting or had bluish hues rather than true violet. There are likely only a handful of people in modern times with naturally purple irises.
Ways to Make Your Eyes Appear More Purple
While naturally purple eyes are extremely uncommon, there are some ways individuals can make their eyes take on a more violet appearance:
- Using violet-colored contact lenses – Color contact lenses with a bright violet tint can make eyes look dramatically more purple when worn. The effect is especially noticeable on people with light colored eyes.
- Eye tattooing – Tattooing the whites of the eyes and underside of eyelids with violet ink can provide a background color that brings out purple hues. This is an extreme modification that carries significant risks however.
- Eye jewelry – Placing violet colored jewels or sequins on the skin around the eyes can reflect purple hues onto the irises.
- Eye drops – Using over-the-counter enhancing eye drops containing a violet dye called Red No. 17 can stain the whites of the eyes red/purple for several hours, making the iris appear more violet as well. However this will also discolor sclera.
- Violet eye makeup – Applying violet eyeliner, eye shadow, or mascara that contains light reflecting particles can also make eyes look more purple temporarily.
With the right techniques and makeup, people can take their natural eye color from blue/gray to a dramatic violet relatively easily. However, these effects are temporary and to achieve permanent purple eyes most likely requires specific rare genetic mutations.
Science of Purple Eyes
The science behind purple eye color involves understanding the genetics of melanin pigments within the iris. As previously discussed, two types of melanin are produced within iris cells:
- Eumelanin – Brown/black pigment
- Pheomelanin – Red/yellow pigment
Most commonly, the concentration and distribution of eumelanin is responsible for eye color. Higher levels of eumelanin lead to brown eyes, while lower levels cause blue eyes. However, pheomelanin also plays a role in producing shades of green, hazel, amber, and yellow eyes. Purple eyes likely involve a mutational change that results in high concentrations of both eumelanin and pheomelanin together in the iris.
The genetics of eye color involve the coordinated regulation of melanin production, deposition, and density within iris cells. Known genes involved include:
- OCA2 – Major regulator of melanin production, mutated in albinism
- HERC2 – Regulates OCA2 expression
- TYR – Encodes tyrosinase enzyme for melanin synthesis
- SLC24A4 – Cation exchanger that regulates melanosomal pH and melanin types
- SLC45A2 – Membrane transport protein that controls melanin metabolism
Mutations in these genes can shift the balance between eumelanin and pheomelanin to favor mixed pigmentation. However, the specific genetics enabling high levels of both melanins in the iris remain unclear. Some small studies have tried to characterize iris pigment levels in people with purple eyes using tools like infrared imaging. But much more research is needed to determine the precise genetic mechanisms involved.
Interestingly, melanin type and content in other parts of the body do not always correlate with iris pigmentation. For example, people with albinism tend to have very fair skin and hair despite having blue irises (low melanin overall). Genome-wide association studies have uncovered numerous genes separately controlling pigmentation in the skin, hair, and eyes.
Therefore, someone with purple eyes may not necessarily have unusual pigmentation anywhere else on the body. The mutation specifically enables production of both eumelanin and pheomelanin together only within the melanocytes of the iris, without affecting other cell types. Though extremely rare, this specificity is biologically plausible.
Prevalence and Geographic Distribution
Only 1 in 1000 people worldwide have green eyes or 0.1% of the global population. In contrast, true purple eyes are thought to occur in less than 1 in 10,000 people or 0.01% of humans. Due to their extreme rarity, robust statistics on purple eyed demographics do not really exist. However, some general observations can be made:
- Northern European ancestry – Most reported cases of violet eyes have been in people of Northern European descent. However, this may be skewed by the fact that lighter eye colors are more common in European populations. Asia and Africa have predominantly brown eyes.
- Fair skin – Similar to blue/green eyes, purple eyes tend to be associated with paler skin that has lower melanin content. However, this may be coincidental.
- Female prevalence – Women appear to be more likely to have purple eyes than men. Many of the few known cases are female such as Elizabeth Taylor and Alexandra Johansson.
- Genetic ambiguity – The genetics are still unclear. Purple eyes may arise sporadically due to new mutations and may not necessarily be inherited from parents.
The table below shows a breakdown of estimated purple eyed demographics:
| Category | Statistics |
|---|---|
| Global incidence | 1 in 10,000 people or 0.01% |
| Gender ratio | Up to 75% female |
| Genetic history | Often sporadic/non-inherited |
| Ethnicity | Mostly European descent |
| Skin pigmentation | Often fair or pale skin |
However, these are very rough estimates due to the extreme rarity of natural purple eyes. The limited photographic evidence makes demographic analysis difficult. It is clear though that violet irises are exceptionally uncommon but can arise in people of any ethnic background.
Hazards and Health Risks
There is no evidence that naturally purple eyes pose any health or vision problems. Like blue and green eyes, purple eye coloration is a benign genetic variation. It does not cause medical issues or require special care. The main hazards associated with purple eyes are social rather than health-related.
Having dramatically unusual eye color can unfortunately lead to bullying and social difficulties, especially during childhood. Purple eyed individuals may be perceived as “weird” or “creepy” due to their rarity. However, as awareness and acceptance of diversity improve, social attitudes are becoming more inclusive.
The only health concerns are related to the various methods some people use to make their eyes look more purple, such as:
- Contact lenses – Can cause eye irritation, infection risk if not properly cleaned
- Eye tattoos – Significant infection/injury risk, vision damage
- Eye drops – May be toxic if used improperly at high doses
Avoiding hazardous cosmetic eye modifications and practicing safe contact lens hygiene can mitigate these risks. But for those born with natural violet irises, there are thankfully no direct health concerns beyond potential social challenges.
Conclusion
In summary, true purple eye color is extremely rare but possible in humans. It likely results from a yet unidentified genetic mutation producing high levels of both brown and red melanin pigments within the iris. There are only a handful of documented cases of purple eyes throughout history. While most reported instances of violet eyes were probably dark blue under certain lighting, true purple irises can naturally occur.
Making eyes appear artificially purple through contact lenses or cosmetics is much more achievable than inheriting the exceedingly uncommon genetics required. But for the few who have won this quirky genetic lottery, purple eyes can provide a uniquely beautiful and striking facial feature without posing any health risks beyond potential social scrutiny.
Hopefully greater education and acceptance of diversity will make it easier for these rare individuals to embrace their unusual eye color safely. With better understanding of genetics, we continue to discover the surprising range of human traits that can arise in our population. From plain brown to piercing violet, eye color serves as a reminder of our shared genetic complexity as a species.
