Men and women see things differently

Men and women see things differently.

You do not have to be a married person to get my point, but if you are a married person, you can appreciate this fact more readily. To explain this, I have to start from the beginning.

In the beginning, as we were told by the Abrahamists, God created the light. The light, as James Maxwell would like us to believe, is an electromagnetic wave.

To be able to see the world in colors, you need to use a special type of protein called opsin to convert the wave signal to electrochemical signals and feed them to the brain.
And in the beginning, God created several opsins, some of them are good at processing long wave (yellow and red), some of them are good at handling medium wave (green), and some of them are only short wave sensitive (blue and ultraviolet).

After the creation exercise, the instruction for building the blue opsin block was carefully saved in Chromosome No. 7 (the program size is about 3 kilobase) and those of the red/green opsin (the program size is about 14 kilobase) were stored in the X chromosome. And copies of these programs were given to the dinosaurs 辰 and our ancestors 子.

But our poor ancestors were not able to compete with the dinosaurs during daytime 晨 and were therefore forced to live nocturnally 子夜. Since full color vision was not of much use in the dark and our ancestor eventually decided to delete the medium-wave-sensitive opsin instruction in their DNA, and in doing so, they lost the ability to be able to differentiate red and green and therefore became red/green color blind.

Birds see more colors than humans. Not only birds perceive familiar colors and parts of the ultraviolet spectrum that are invisible to human eyes, but they also have better visual acuity to determine subtle differences between similar shades of color https://t.co/qZr9MXYgQi pic.twitter.com/vGWr5kH1bs

— Massimo (@Rainmaker1973) May 24, 2023

Then, approximately 66 million years ago, the K-T extinction event completely wiped out the dinosaurs, but fortunately our ancestors were able to survive the impact winter. Many years after the megasized dinosaurs were gone, the small-sized descendants of the dinosaurs and our ancestors flourished and went on to conquer both the diurnal and the nocturnal world (for example, see the species enumerated in the Chinese Zodiac).

Color vision of the animals enumerated in the Chinese Zodiac

Although we have returned to live in the daylight, we didn't regain the full color vision because most of us do not really need the full color vision to do our work.

Simulated dichromatic color vision of a dog

And this is also the reason why your mammalian pets (hamster, dog, cat, rabbit, etc) are all red/green color blind. But there is one exception: the Hanuman tribe.



The Hanuman group in the New World decided that the ability to differentiate red from green/yellow is a very important trait for them to survive, and must be restored. Now, one way to achieve this is simply to take the original code and tweak it a little to make it more sensitive to the medium wavelength. The result is that they have a green X chromosome or a red X chromosome. Since only women can have two copies of X chromosomes, we must have the following possibilities.

• Trichromatic ♀: Green gene (X) + Red gene (X)
• Dichromatic ♀: Green gene (X) + Green gene (X)
• Dichromatic ♀: Red gene (X) + Red gene (X)
• Dichromatic ♂: Green gene (X) + No opsin-coding gene in Y
• Dichromatic ♂: Red gene (X) + No opsin-coding gene in Y

Thus, only one group of women in the New World is able to experience the world in full color.

The group in the Old World, however, approached the problem differently. They solved the problem by simply taking the original program on the X chromosome and pasting it several loci away from the original code. The newly pasted program was then trained to be more sensitive to the medium wavelength. The result is that they have the green code and the red code on the same X chromosome.

• Trichromatic ♀: Green+Red gene (X) + Green+Red gene (X)
• Trichromatic ♀: Green+Red gene (X) + Green+Red gene (X)
• Trichromatic ♂: Green+Red gene (X) + No opsin-coding gene in Y

And this means that both men and women in the Old World can enjoy the world in full color. However, the probability of finding a red/green colourblind man in the Old World is significantly (16 times) higher than women since men do not have a second copy of the green/red opsin-coding gene. Statistically, about 8 percent of the male population will be deprived of the happiness of seeing the world in its full spectrum when this group of men inherits a corrupt copy of the gene from their parents.

1. The cone opsins are named based on the wavelength they are sensitive to. Blue/violet color region (short wavelength region = S-opsin), green color region (medium wavelength region = M-opsin), red/yellow (long wavelength region = L-opsin).
   
   
2. The instructions for building S-opsin are stored in 7q31.3-q32, while the instructions to build M-opsin and L-opsin are stored next to each other in Xq28. The instructions to build the M-opsin and L-opsin are nearly identical (about 96%).
   
   
   Behind the beautiful eye lies the mythical polychromatic opsin
   
   
3. The light-sensitive rhodopsin are mainly for black and white. Its building instruction can be found in 3q22.1.