Following up on the Blue Eye Controversy and Rudolph the Blue-Eyed Reindeer,
The orthodoxy is correct that the color of the iris is irrelevant to vision, and the genetics behind it, and why the eyes are blue is common knowledge.
People with back/dark brown eyes have a lot of black melanin in the Iris, people with brown/green eyes a mix of black and brown melanin, while the blue eyed have the brown type. In addition to this, eye color is dependent on the density of melanin.
What is not common knowledge, because the information is usually not needed, is that the Iris is a part of the Choroid, a layer that contains melanin, and goes behind the retina.
Melanin, a darkly colored pigment, helps the choroid limit uncontrolled reflection within the eye that would potentially result in the perception of confusing images. In humans and most other primates, melanin occurs throughout the choroid. In albino humans, frequently melanin is absent and vision is low.
In many animals, however, the partial absence of melanin contributes to superior night vision. In these animals, melanin is absent from a section of the choroid and within that section a layer of highly reflective tissue, the tapetum lucidum, helps to collect light by reflecting it in a controlled manner.
The uncontrolled reflection of light from dark choroid produces the photographic red-eye effect on photos, whereas the controlled reflection of light from the tapetum lucidum produces eyeshine
If the melanin in the Choroid is mostly of the black type you get dark brown eyes, and little uncontrolled reflection in strong light. The blue eyed have brown melanin, and less of it, so they will have some reflection.
It’s not uncontrolled reflection, because the Albinos lack all melanin and have poor eyesight, because reflections blurs the image on the retina.
To finish up, you have two different adaptations to seeing better in the dark.
1. The tapetum lucidum a reflective layer immediately behind the retina, where it reflects visible light back through the retina, increasing the light available to the photoreceptors, though blurring the initial image of the light on focus.
2. Having less black melanin in the choroid, giving you a more sensitive eye to movement in the shadows, at the cost of blurring. That this makes the Iris as the visible part of the choroid look blue in the extreme, is thus of little importance.
The first adaptation is found all over the world, among many species, but not humans, while the second is also found among many species including humans it’s only found in the polar regions, where it gives better detection to movement the blue winter nights.
The first adaptation give the eyeglow effect, while the second gives us the red-eye.
When the blue light is reflected, light is spread laterally onto the retina and many light receptors are simultaneously stimulated. The downside is that the image is blurred and visual acuity is actually worse. But the advantage is that the animals are considerably more sensitive to movement in the shadows in winter, which means they can detect prey in the dark more easily.
The BIG problem that makes this theory so toxic, is that everybody knows blue eyes are functionally the same as brown eyes, and that blue eyes could not have developed in the Arctic, because it was all covered with Ice.
If I were to show that the the whole of N-Europe wasn’t covered with ice last Ice age, it wouldn’t matter, because the academics would still call it pseudoscience. Only a racist white supremacist is interest in why blue eyes are better than brown, and because the racists peddles wishful thinking as science, all they do is pseudoscience.
A good academic interested in having a career understands that they need to keep their distance from the pseudoscientists, so not to give them credibility. You thus get the silent treatment if you are correct, rather than anybody meeting your arguments or calling you a cook.
What is true here is then irrelevant before we even begin on the human eye, because academics can’t say what is true before others say the same thing, and make it controversial.
This actually makes academics at best useless, and at worse harmful, when it comes to correcting mistakes in science, as the only ones that can take the risk, is the amateur that have a secure income elsewhere.
tunglet 