Why is nail polish red?

Why is red the traditional color for nail polish? (In the sense that the overwhelming majority of them are some shade or red or similar colors, and blues/greens/whites/blacks are a lot less common and more or less recent.)

I mean, most traditional makeup colors (except maybe eyeshadow, which either has no traditional color or the tradition has already disintergrated so totally that I am unable to identify it) are either close to natural (at least, somebody's natural, if not necessarily the wearer's) or an exaggerated version of it. Lipsticks are red because lips are red; powders come more or less in human skin colors; blushes are pink; mascaras are black. What is the deal with red nail polish, though? Human nails are not red, or even redder than the surrounding skin.