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Comment by zahlman | Hacker News Reader

I assumed that the blue colour would be from internal bleeding (venous blood being apparent at the skin level), but:

> Diphenadione is a vitamin K antagonist that has anticoagulant effects and is used as a rodenticide against rats, mice, voles, ground squirrels and other rodents. The chemical compound is an anti-coagulant with active half-life longer than warfarin and other synthetic 1,3-indandione anticoagulants.[3][4] ... Rat poisons with diphacinone are often dyed bright blue to signal toxicity.[8]

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Blood isn't actually blue. It can appear blue under the skin, but that's only because of refraction[0]. I'm pretty pale[1] and I can tell you that the blue looks NOTHING like that blue. It's much darker and much fainter. Not close to neon at all. Which, btw, as soon as it touches the air it's not going to look blue anymore.

While I don't think the average person is going to notice or care about these "nuances" I would be pretty surprised if anyone that huts would not immediately notice. The "well I look at my veins and they are blue" argument only holds up if you don't look at the pictures in the link. Like they just look very different. Easy to sound right while being very wrong (and often hard to explain why it is wrong without sounding like nitpicking). It's not like they're hunting horseshoe crabs...

[0] https://askabiologist.asu.edu/questions/is-blood-blue

[1] Pale enough that a phlebotomist once told me I was the easiest person to draw blood from because it is so easy to see my veins.

If something “appears” as a color then that’s the color it IS.

The reason anything is the color it is is because that’s how it appears.

Am I missing something?

It’s like saying, “oh the sky is only blue because it scatters blue light”. Well then the sky is blue. Full stop.

“Red paint is only red because it happens to absorb certain other color spectrums leaving mostly red light”. Ok then it’s red.

Look at that blue sky through sun glasses. It may longer be blue to you but I assure you the sky is still blue to everyone else.

  > Am I missing something?

Go grab a thin colored sheet of plastic (or anything transparent will do). Hold it up to the sky and look through it. What color is the sky?

Now yes, the sky will be yellow or whatever color the plastic is but if you go around and start telling everyone that they'll call you crazy.

If you really want to get into it, colors are also determined by what everyone else sees. You could be colorblind and what color something is to you is not what color that thing is to everybody else. Or you could take the sun itself, which everyone agrees is yellow except some armchair expert redditor who once heard in science class that "the sun is green" and is willing to discount his eyes rather than hear the rest of the discussion where it is white because it emits in a broad spectrum and appears yellow on Earth because the blue sky removes some colors before we can see it. So you can imagine a future civilization where most people don't live on Earth might call the sun "white" but for now everyone will call it that because it is yellow. This is a bit in your favor but you might notice the main point of my previous comment isn't about blood looking blue so much as the pigs being fucking neon blue and that blue looks nothing like blood and could not be mistaken for the same thing. Look at the pictures.

Venous blood isn't blue.

> Veins close to the surface of the skin appear blue for a variety of reasons. The factors that contribute to this alteration of color perception are related to the light-scattering properties of the skin and the processing of visual input by the visual cortex, rather than the actual colour of the venous blood which is dark red.[6]

Huh, thanks.

As another commenter mentions, there is no blue food. (Though technically plants can be blue.)

Eyes can't be blue either.

Human eyes aren't pigmented blue, but they are still blue.

Only in the sense that venous blood "is" blue.

We don't see the blood in veins, and it wouldn't be blue if we could, but I would agree that veins are blue.

Human blood can turn blue when consuming enough (collodial) silver?

Like when rich people consumed food and beverages from pure silver plates (100's of years ago) their blood supposedly turned purple/blueish. Hence the term (at least in Dutch) that "he is of blue blood" = he rich af.

Or that's all a myth. Not sure.

> Hence the term (at least in Dutch) that "he is of blue blood" = he rich af.

This is usually said to refer to the fact that someone's skin is so pale you can see the veins through it.

(Also, it refers to pedigree rather than wealth, in English...)

I would expect silver to turn things black, not blue.

(Although see https://en.wikipedia.org/wiki/Argyria )

They would hide from the sun to get extra veiny, because they could

Like the programmers in our time

Perhaps, but according to etymonline the term comes from Spain, where certain families described themselves as having "blue blood" to emphasize that they had no Moorish ancestry. The contrast being drawn isn't one between nobles and laborers. It's between indigenous nobles and intrusive nobles.

see also blue people - https://www.thecollector.com/blue-fugates-kentucky/

elevated methemoglobin in human blood causes brown blood causes blue skin

Why not?

  > Eyes can't be blue either.

I get what you mean, but this is also like saying a butterfly doesn't have color.

The blue in blue eyes (and green) is a structural property, not a pigment property. This is also why eye color changes for these people much more dramatically than people with darker colored eyes (see Hazel eyes).

It's color caused by structure, but that doesn't make it not a color. A lot of things aren't going to "have color" if you use that definition. Including the sky...

> there is no blue food

Have you eveer seen a blueberry? Or a Concord grape? Or a damson plum?

Haemorrhages can take on a purple colour (like a black eye), but nothing like the sky blue colour those pigs were.

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