13 Things Every Woman Doesn't Know About Her Own Body

Your obsession with those caramel-colored leather boots is genetic.

The gene that allows people to perceive the color red is found only on the X chromosome, and men are more likely to have mutations that compromise their ability to distinguish between red and green (making them technically more Christmas-blind than color-blind). But researchers have recently discovered that the combination of a normal gene on one X chromosome and a mutated one on the other, which occurs in about 40 percent of women, enhances the ability to see a broader spectrum of hues in the red-orange range. The scientists, who published their findings in the American Journal of Human Genetics, say that this amount of variation, especially one that benefits only one gender, is unusual in genes (nature usually weeds it out). They speculate that it may have evolved to help our ancestral female gatherers to distinguish among berries, foliage and bugs.