The eyes have it: Men do see things differently to women
The way that the visual centers of men and women’s brains works is different, finds new research published in BioMed Central’s open access journal Biology of Sex Differences. Men have greater sensitivity to fine detail and rapidly moving stimuli, but women are better at discriminating between colors.
It’s not really a backup X. In any given cell in a woman’s body, one of the X chromosomes has been inactivated into something called a Barr body. The remaining X chromosome is then the active one.
Women carriers of the gene defect for protan (causing protanopia in males) exhibit Schmidt’s Sign, an abnormal insensitivity to long wavelengths (red light). This is due to the highly skewed L:M cone ratio caused by the defective gene.