> If there is a difference between male/female retinas Is this even an "if"? It's well established that men are more likely to be colorblind, and it's likely

> If there is a difference between male/female retinas Is this even an "if"? It's well established that men are more likely to be colorblind, and it's likely many women are tetrachromats (most people are mere trichromats). The genes for the extra cone pigments are in the X chromosome, and are seemingly expressed more often when somebody has two X chromosomes. Similarly, people with two X chromosomes are less likely to be colorblind because most forms of colorblindness are caused by defects in genes in X chromosomes. https://en.wikipedia.org/wiki/Tetrachromacy#Humans https://en.wikipedia.org/wiki/Tetrachromacy#Humans https://en.wikipedia.org/wiki/Color_blindness#Genetics https://en.wikipedia.org/wiki/Color_blindness#Genetics Perhaps most men and women, men and women with normal trichromatic vision, have identical retinas. But with genes so important to eyeballs residing in the X chromosome, who knows. But I'm left wondering why experts are particularly surprised by this result.