Researchers at Arizona State University made the ground-breaking discovery that the ability to see red in all its glory is frequently gender-dependent. There is a gene that allows people to see and interpret red and its related colours such as cardinal, maroon, crimson, and so on, and that gene is linked to the x-chromosome. Because women are born with two x chromosomes, they have a better ability to see the entire red spectrum, whereas men, with a single x chromosome, aren't necessarily equipped to tell the difference between red and, say, cardinal.