Why are people from the wealthy class often said to have blue blood?

Flynn_17

Rumour has it that it was very fashionable for the upper classes to have very pale skin, so they did not go out in the sun. This made their blood vessels appear blue. http://en.wikipedia.org/wiki/Nobility Aug 06 06, 5:15 AM

Flynn_17

Horseshoe Crabs (shudder) also have blue blood thanks to haemocyanin, which has two copper atoms attached to a single oxygen. http://en.wikipedia.org/wiki/Hemocyanin Aug 06 06, 5:16 AM

HairyBear

I don't have a reference link for this, but I understood it to come from the fact that the members of the European nobility frequently suffered from anemia and hemophilia due to their being terribly inbred, so their veins appeared blue under the skin. So while being blue-blooded seemed to be a mark of class, it was really a mark of illness. Aug 06 06, 6:41 AM

zbeckabee

Unlike so many other expressions, this one is well documented. It’s a direct translation of the Spanish 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 the blue-tinted venous blood 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. http://www.worldwidewords.org/qa/qa-blu1.htm Aug 06 06, 8:30 AM