A change in style, cosmetic habit, or the ideal figure, though superficial and arbitrary on the surface, may be deeply tangled in the zeitgeist and tied even more deeply in our biological values about appearances. Skin colors can change rapidly by varying the amount of blood in the skin. There seem to be three themes in the evolution of human communication through flushing the skin with blood. The anger flush is an old tradition used today by many non-human primates. It is far from vestigial in humans, but there is considerable variation in its expression among human subgroups and within them.
Physicians often refer to flushers and blushers as vascularly unstable.
In groups without very dark pigmentation it is common enough to be generally recognized as a signal of internal mood. The more swarthy human subgroups are not as prone to skin flushing with mood changes. The third type of reddening is the sexual flush which was emphasized by Masters and Johnson. One might think that these three social signals all employing skin reddening but having quite different meanings and evolutionary histories might become confusing. However, they seldom do.