Blood transfusion is a relatively novel medical procedure. The idea that the primordial red liquid might be a positive force when introduced into the human body only saw widespread adoption beginning in the 19th century. Until that point, leeches and bloodletting remained at least somewhat in vogue. The pseudoscience was based on an ancient medicine requiring the body’s "humours" or fluids be in proper balance to achieve optimum health. Basically, when your health was in trouble, deliberately draining blood was considered a medically sound response—a tactic that, perhaps most infamously, may have hastened George Washington's death in 1799.

Even after decades of experimentation, transfusion didn't seem to be going anywhere until the era of modern warfare. World War I, the most spectacular military struggle the planet had ever seen, provided new forums for transfusion—as did the even more brutal and catastrophic conflict that followed two and a half decades later. But as blood transfusion proliferated in modern medicine, it also got more complicated. These days, if you get a blood transfusion, chances are you're going to get something best understood as "component" rather than "whole" blood. When you donate, the red liquid taken out of your arm goes to a processing center, where it is split into parts that can be targeted at specific conditions afflicting individual people.

Of course, the segmentation of blood parts also presents plenty of opportunities for profit.

In her new book, Nine Pints: A Journey Through the Money, Medicine, and Mysteries of Blood, British journalist Rose George explores the history, ethics, and allure of blood transfusion in modern society. I called her up for a chat about how people have conceived of blood over time—and what it means that the most human substance there is has more value than oil.

VICE: Why do you think blood, at least in modern life, makes so many so squeamish and carr**ies such enormous taboos?** If you look throughout history and geography, blood can be so many things to so many people, it sort of crisscrosses all over the place. The ancient Greeks had Homer—he thought blood was magical, [that] it had this amazing power to give life. He actually has one of his characters, Nereid Thetis—his mother—comes briefly back to life just by drinking some sheep's blood.

Before modern medicine, if you saw blood, for most people that probably meant injury or death. The menstrual taboo is because that countered the usual connection. There were these people bleeding and not dying. First, they were thought to have really magical powers—it was seen as positive. And then it turned into witch powers, and how can women bleed and survive? Because of course the powerful woman is a threatening woman, it must be witchery. I think that's why the menstrual taboo has come about.

In the book, you say blood has developed into a commodity that's more costly than oil. Why and how did that happen in the United States specifically?

In the US, it was seen as very normal to pay someone for blood. There were people—particularly men—during the Depression who would go around the country just giving blood, probably giving too much of it for their own health. At one point, I think it was $100 for a pint of blood in New York. It was seen as quite the standard thing to do—to give blood. In fact, that's the reason we have the phrase "blood-banking." Blood and money have always been associated, but really it's been only recently in the US that blood and money have been separated.

It's actually not illegal to pay for blood in the US, but you have to label the blood donation as coming from a paid donor or a volunteer. Hospitals don't use blood from paid donors because the World Health Organization is emphatic that it is much safer to have a blood supply that relies on donations from volunteers—the argument being that if you are paying someone for blood, then they’re probably going to want to do it more often than is good for them, because they’re getting money for it. They may be pushed to lie about their health conditions.

You also talk about the US becoming the sort of OPEC of plasma. Can you explain that analogy?

Plasma, for some reason, is not seen as blood. It's the liquid in blood, the yellow stuff. In the US, you can't sell the red stuff, but you can quite happily sell the yellow stuff and you can sell it up to two times a week—usually for about $30 a pop. That's how the US has become the OPEC of plasma. You can't sell your red blood, whole blood, but you can sell your plasma, and the US has this thriving plasma industry which supplies a lot to the world. About half of the stuff in Europe is from the US, and it's a huge, huge industry. The US exported $19 billion worth of plasma in 2016, which is about the same as they got from exporting medium sized cars and clothing. It’s a big business.

It's being fueled by the products you can make—for example, immunoglobulin and other proteins, which are really useful in certain immune conditions and immunity disorders. It's an industry with a pretty positive future, but there's been persuasive research done that shows a lot of plasma clinics are located in lower-income areas. A lot of plasma sellers are students, but a lot of people, particularly in the current climate, are from lower income backgrounds. There are ethical questions about that.

Is modern humanity capable of keeping up with the need given the contemporary potential for climate or other disasters, terrorist attacks, and the like?

You should always have a buffer and a safety net of blood, but sometimes you don't need as much as you think. In any combat situation, or any wartime situation—obviously blood is always useful in trauma. But it's also used in so many other conditions. I don't know what would happen in a nuclear blast and what survivors, what condition they would be in, but I'm guessing there would be white blood cell issues, maybe anemia.

What a blood supply really wants is a donor who comes back. The proportion of people who give blood is only 4 percent of the population in the UK. That's just about enough, but it means that at certain times of year, for example Christmas, or if the Olympics are on or a big sporting event, people don't give blood. What people do tend to do and always have done, is that when there’s a big catastrophic event, people feel really helpless and think: what can they do? After 9/11, a lot of the blood that was donated wasn't used.

Can you talk about the role blood plays in pop culture, say, with vampire and slasher movies?

Vampires are really interesting—not necessarily in pop culture, but in general culture and history. I mean, they're glamorous, aren't they? That's why they came about. It's slightly rebellious to show lots of blood, but the vampire is a combination of very glamorous and yet there's the nice bodily fluids context. I don't have any profound theory about why they're so popular, but I think humans in general created the vampire as a figure because it was a way of understanding death or a failure to understand death. In the Middle Ages, people didn't understand that a corpse would not necessarily decompose. Some were dug up and hadn't decomposed, [and] so came the theory of the undead.

Why do you think the word blood has remained so strong in our culture with phrases like "blood brothers," "blood feuds," "bloodlines," and 'blood money'? Is it just the primordial or carnal nature of the substance? Something more?

If you open the Oxford English Dictionary, there's two or three pages of them. It's so profoundly important. We cannot live without blood. We all know that, even if we don't see the stuff. If it was spilled, it generally meant injury or death, and there’s nothing more terrifying than that. Something that powerful is obviously going to resonate within language. And it can mean so many things. It has so many meanings and so many levels of metaphor. That's why it's so pervasive. It's still powerful, even though we understand it far more than we ever did.

This interview has been lightly edited and condensed for clarity. Learn more about George's book here.

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