Forbes42%
Why Some Women Might More Colors Than Everyone Else? A Biologist Explains 27%
By Scott Travers8%
7/20/2026, 12:30:59 PM
BS Summary: This article contains 28 faulty reasoning types, including Appeal to Authority, Hasty Generalization, and Burden of Proof, with Overconfidence Bias as the most egregious example at 25.5% saturation with 310 hits. Analysis detected 2,285 faulty-reasoning hits from 1,217 analyzed words, generating a BS Score of 38.9% and a BS Rank of 27% (13,788 of 18,786 articles). This article is better (less manipulative) than 73.40% of the article peer group.
Ask two people to describe the color of a rose and they’ll agree without hesitation: red.
That easy consensus hides an assumption — that everyone occupies the same visual world and is simply attaching the same label to it.
There’s no way to test that directly, since subjective experience doesn’t show up under a microscope.
But a small, genetically distinct group of people, almost exclusively women, may be breaking that assumption altogether, not by disagreeing about labels, but by working from more raw material than everyone else: an entire extra channel of color information running in parallel with the three the rest of us rely on.
The trait is called tetrachromacy, and it turns out to be less a biological fluke than a logical consequence of how the human visual system is already built — the same genetic quirk that causes a common vision deficiency in men produces something like its opposite in their mothers, sisters and daughters.
Why Most Humans Can’t Perceive An Extra Set Of Colors
Ordinary human color vision runs on three types of cone cells in the retina, each carrying a light-sensitive pigment tuned to a different band of wavelengths — roughly short (perceived as blue), medium (green) and long (red).
The brain compares the relative signal strength across these three channels and reconstructs something on the order of a million distinguishable colors.
Biologists call this arrangement trichromacy, and it is the standard equipment across humans and most primates.
It is worth noting this is not the ceiling for vertebrate vision generally.
Many birds carry four cone types as a baseline — the standard reference on avian vision is a 2001 study published in Progress in Retinal and Eye Research — including a channel sensitive to ultraviolet light invisible to humans entirely.
It’s a reminder that “normal” color vision is a matter of species-specific hardware, not some universal maximum.
Human tetrachromacy would be a rare instance of a mammal briefly touching the visual range birds inhabit by default.
The genes that build the medium- and long-wavelength pigments both sit on the X chromosome, which turns out to be the entire reason this trait clusters so heavily in women.
Why Only Women Get The Extra Channel Of Colors
Men carry a single X chromosome; women carry two.
In most women, both X chromosomes carry the same version of the color-vision genes, producing the same three cone types found in men.
But a woman who inherits two X chromosomes carrying slightly different versions of the long- or medium-wavelength gene — variation common enough that it is the identical underlying mutation responsible for red-green color blindness in men — sets up a different outcome entirely.
Early in development, every cell in a woman’s body randomly deactivates one of its two X chromosomes, a process geneticists call X-inactivation, detailed in a 2018 study published in Human Molecular Genetics.
The effect is a patchwork: roughly half of a given tissue’s cells run on one X chromosome, half on the other.
In the retina, this mosaicism means some cone cells end up expressing one version of the pigment gene and neighboring cones express the other.
The theoretical result is four distinct cone types operating side by side, rather than three.
Extrapolating from how sharply three cone types expand color discrimination beyond two, some researchers have estimated that a fully functioning fourth channel could unlock somewhere on the order of 100 million distinguishable colors, against roughly a million for a standard trichromat.
That figure is frequently cited, but a 2019 study published in Current Opinion in Behavioral Sciences — a review by the researchers most closely associated with the modern tetrachromacy literature — found the claim rests on extrapolated math rather than anyone’s actually measured experience, and it deserves more scrutiny than the number usually gets.
Why Having The Lens Doesn’t Always Mean Capturing The Color
The genetic setup for a fourth cone type is not especially rare.
Because the color-blindness variants responsible for it are common on the X chromosome, a meaningful share of women likely qualify as carriers in the strict genetic sense.
What is rare is behavioral confirmation — clear, testable evidence that a person’s visual system actually draws on that fourth channel to make finer distinctions than a trichromat can.
A 2010 study published in the Journal of Vision that screened a small group of women for exactly this found just one who met the full criteria for behavioral tetrachromacy.
The test behind that finding was elegantly simple in design.
For anyone with ordinary three-cone vision, a carefully tuned mix of red and green light can be made to look completely identical to a pure orange light — the brain simply has no fourth channel available to tell the two apart.
Researchers presented women carrying the genetic setup for a fourth cone with exactly this kind of match.
A true tetrachromat, with a genuinely independent fourth signal running alongside the other three, should be able to detect that the mixed light and the pure orange light are not actually the same — a distinction a three-cone visual system cannot make no matter how the mixture is adjusted.
Only one participant consistently rejected these matches and reliably told the two apart across repeated trials, which is what set her apart as a confirmed functional tetrachromat rather than simply a genetic carrier of the trait.
Vision researchers generally treat the retina as only half of the equation.
The visual cortex has to learn to interpret an additional dimension of incoming signal that human brains did not evolve expecting, and only a small number of documented cases show unambiguous evidence of superior color discrimination under testing.
Many carriers of the genetic variant likely experience color exactly as trichromats do.
Whether the difference comes down to variation in how the cortex is wired, or to how much a person’s life happens to demand fine perceptual judgment about color, remains an open question in the field.
What The Trait Of Superior Color Perception Actually Reveals
The lasting value of tetrachromacy has little to do with the eye-catching hundred-million-color estimate.
Its real contribution is as a natural experiment bearing on one of the oldest problems in the philosophy of mind, sometimes called the problem of qualia: whether any two people can be shown to experience the same color the same way.
Among ordinary trichromats, the answer has always been unverifiable in principle — two people can agree to call the same wavelength “red” without any way of confirming their internal sensations match.
Tetrachromacy sharpens that gap rather than closing it.
Here is a population that may be receiving genuinely more information from the visual world, and yet neuroscience still cannot say with confidence what, if anything, that additional information feels like from the inside.
That is the deeper takeaway.
Color, for all its apparent objectivity, is a construction of the nervous system rather than a fixed property of light itself, and the machinery producing that construction is demonstrably not identical from one brain to the next.
*Think tetrachromacy sounds like something only a superhero could have?
Find out how much you really know about the machinery behind human sight and color perception with this science-backed test: Human Anatomy IQ Test*
Analysis
Hover over highlighted words in the article to view the associated bias or fallacy analysis.