The human eye's macula is the central part of the retina responsible for sharp, central vision. It is made up of specialized cells called cones, which detect different colors of light and allow for our detailed central vision. The macula contains a small area called the fovea, which is responsible for our sharpest and clearest vision. While we typically think of four types of cones—sensitive to red, green, blue, and yellow light—there have been claims of a fifth type of cone, known as NCL5.

The Myth of NCL5

The existence of NCL5 has been a topic of debate among scientists for several years. However, there is no definitive evidence to support its existence. Here are a few reasons why the concept of NCL5 is not widely accepted:

Lack of Empirical Evidence

Despite numerous studies and research, there is no substantial empirical evidence to prove the existence of NCL5. The alleged NCL5 cone has not been directly observed or isolated in the human eye.

Inconclusive Genetic Findings

Genetic studies aimed at identifying the gene responsible for encoding NCL5 have produced conflicting results. Some studies claim to have found a candidate gene, while others have failed to replicate these findings.

Absence of Functional Data

Even if a gene for NCL5 existed, there is no evidence of its functionality. The protein encoded by this gene has not been shown to contribute to vision or color perception in experimental studies.

Why We Don’t Need NCL5

Even if NCL5 did exist, it's not clear what additional benefit it would provide. Our current four types of cones allow us to perceive a wide range of colors and visual information. Adding another type of cone would likely not significantly improve our vision.

Color Vision Sufficiency

With our four types of cones, we already possess trichromatic color vision, allowing us to distinguish millions of colors. Adding a fifth cone would not enhance our color discrimination abilities to a noticeable extent.

Visual Acuity Limitations

The sharpness of our central vision is ultimately limited by the density of cone cells in the fovea, not by the number of cone types. Adding another cone type would not increase the density of cones in the fovea and, therefore, would not improve visual acuity.


The concept of NCL5, a fifth type of cone in the human eye, lacks substantial evidence to support its existence. The absence of empirical evidence, inconclusive genetic findings, and the lack of functional data all contribute to the skepticism surrounding NCL5. Furthermore, even if NCL5 did exist, it is unlikely to provide significant benefits to our vision, given that our current four types of cones already enable us to perceive a wide range of colors and visual information.


  1. Why is there so much debate about the existence of NCL5?
    Answer: The debate stems from conflicting research findings, with some studies suggesting its presence and others refuting it. The lack of conclusive evidence has fueled ongoing discussions among scientists.

  2. What are the implications of NCL5's non-existence?
    Answer: If NCL5 does not exist, it debunks the notion that humans can perceive colors beyond the visible spectrum. It also aligns with our current understanding of color vision and reinforces the importance of our four types of cones in visual perception.

  3. Could there be other types of cones that we don't know about?
    Answer: Theoretically, it is possible that there are other types of cones or photoreceptor cells in the human eye that have yet to be discovered. However, the existence of these remains speculative and requires substantial scientific evidence.

  4. Why do we have four types of cones instead of five or more?
    Answer: The evolution and development of our visual system have resulted in four types of cones, which provide optimal color vision and visual acuity for our survival and adaptation to our environment. Additional cone types may not offer significant advantages or could even introduce complications in visual processing.

  5. What are the potential benefits of having a fifth type of cone?
    Answer: Hypothetical benefits of a fifth cone type could include enhanced color perception, improved visual acuity, or the ability to see different ranges of light. However, these remain speculative and would require extensive research and evidence to verify.



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