Why is it said that royals have blue blood?
Blue blood refers to the direct translation of the Spanish term – sangre azul. Many of the oldest and proudest families of Castile used to boast that they were pure bred, having no link with the Moors who had for so long controlled the country, or indeed any other group. As a mark of this, they pointed to their veins, which seemed bluer in colour than those of such foreigners. This was simply because their blue-tinted veins showed up more prominently in their lighter skin, but they took it to be a mark of their pure breeding. So the phrase blue blood came to refer to the blood which flowed in the veins of the oldest and most aristocratic families. The phrase was taken over into English in the 1830s. By the time Anthony Trollope used it in The Duke’s Children in 1880, it had become common.
Blue blood is an English expression recorded since 1834 for noble birth or descent; it is a translation of the Spanish phrase sangre azul, which described the Spanish royal family and other high nobility who claimed to be ‘pure’, free of Moorish or Jewish blood, being of Visigothic descent. There is no connection between the phrase and the actual blood color of nobility; however, in the ancient agricultural societies of Europe the whole upper class had superficial veins that might be more visible and appear bluish by comparison to the rest of the pale-pinkish skin, as the skin itself was not tanned. In contrast with the working class of the time (mainly peasants), nobility and in general upper class people did not have to work outdoors, and mostly lived sheltered from the sun by dwellings and attire. The same contrast could be observed between untanned upper class Europeans – especially of northern stock whose skin tends to be less pigmented – and all social strata of Mediterranean pop
