What is the rarest blood type?
Golden blood sounds like the latest in medical quackery. As in, get a golden blood transfusion to balance your tantric midichlorians and receive a free charcoal ice cream cleanse. Don't let the New-Agey moniker throw you. Golden blood is actually the nickname for Rh-null, the world's rarest blood type.
As Mosaic reports, the type is so rare that only about 43 people have been reported to have it worldwide, and until 1961, when it was first identified in an Aboriginal Australian woman, doctors assumed embryos with Rh-null blood would simply die in utero.
But what makes Rh-null so rare, and why is it so dangerous to live with? To answer that, we'll first have to explore why hematologists classify blood types the way they do.
A (brief) bloody history
Our ancestors understood little about blood. Even the most basic of blood knowledge — blood inside the body is good, blood outside is not ideal, too much blood outside is cause for concern — escaped humanity's grasp for an embarrassing number of centuries.
Absence this knowledge, our ancestors devised less-than-scientific theories as to what blood was, theories that varied wildly across time and culture. To pick just one, the physicians of Shakespeare's day believed blood to be one of four bodily fluids or "humors" (the others being black bile, yellow bile, and phlegm).
Handed down from ancient Greek physicians, humorism stated that these bodily fluids determined someone's personality. Blood was considered hot and moist, resulting in a sanguine temperament. The more blood people had in their systems, the more passionate, charismatic, and impulsive they would be. Teenagers were considered to have a natural abundance of blood, and men had more than women.
Humorism lead to all sorts of poor medical advice. Most famously, Galen of Pergamum used it as the basis for his prescription of bloodletting. Sporting a "when in doubt, let it out" mentality, Galen declared blood the dominant humor, and bloodletting an excellent way to balance the body. Blood's relation to heat also made it a go-to for fever reduction.
While bloodletting remained common until well into the 19th century, William Harvey's discovery of the circulation of blood in 1628 would put medicine on its path to modern hematology.
Soon after Harvey's discovery, the earliest blood transfusions were attempted, but it wasn't until 1665 that first successful transfusion was performed by British physician Richard Lower. Lower's operation was between dogs, and his success prompted physicians like Jean-Baptiste Denis to try to transfuse blood from animals to humans, a process called xenotransfusion. The death of human patients ultimately led to the practice being outlawed.4
The first successful human-to-human transfusion wouldn't be performed until 1818, when British obstetrician James Blundell managed it to treat postpartum hemorrhage. But even with a proven technique in place, in the following decades many blood-transfusion patients continued to die mysteriously.
Enter Austrian physician Karl Landsteiner. In 1901 he began his work to classify blood groups. Exploring the work of Leonard Landois — the physiologist who showed that when the red blood cells of one animal are introduced to a different animal's, they clump together — Landsteiner thought a similar reaction may occur in intra-human transfusions, which would explain why transfusion success was so spotty. In 1909, he classified the A, B, AB, and O blood groups, and for his work he received the 1930 Nobel Prize for Physiology or Medicine.
What causes blood types?
It took us a while to grasp the intricacies of blood, but today, we know that this life-sustaining substance consists of:
- Red blood cells — cells that carry oxygen and remove carbon dioxide throughout the body;
- White blood cells — immune cells that protect the body against infection and foreign agents;
- Platelets — cells that help blood clot; and
- Plasma — a liquid that carries salts and enzymes.6,7
Each component has a part to play in blood's function, but the red blood cells are responsible for our differing blood types. These cells have proteins* covering their surface called antigens, and the presence or absence of particular antigens determines blood type — type A blood has only A antigens, type B only B, type AB both, and type O neither. Red blood cells sport another antigen called the RhD protein. When it is present, a blood type is said to be positive; when it is absent, it is said to be negative. The typical combinations of A, B, and RhD antigens give us the eight common blood types (A+, A-, B+, B-, AB+, AB-, O+, and O-).
Blood antigen proteins play a variety of cellular roles, but recognizing foreign cells in the blood is the most important for this discussion.
Think of antigens as backstage passes to the bloodstream, while our immune system is the doorman. If the immune system recognizes an antigen, it lets the cell pass. If it does not recognize an antigen, it initiates the body's defense systems and destroys the invader. So, a very aggressive doorman.
While our immune systems are thorough, they are not too bright. If a person with type A blood receives a transfusion of type B blood, the immune system won't recognize the new substance as a life-saving necessity. Instead, it will consider the red blood cells invaders and attack. This is why so many people either grew ill or died during transfusions before Landsteiner's brilliant discovery.
This is also why people with O negative blood are considered "universal donors." Since their red blood cells lack A, B, and RhD antigens, immune systems don't have a way to recognize these cells as foreign and so leaves them well enough alone.
How is Rh-null the rarest blood type?
Let's return to golden blood. In truth, the eight common blood types are an oversimplification of how blood types actually work. As Smithsonian.com points out, "[e]ach of these eight types can be subdivided into many distinct varieties," resulting in millions of different blood types, each classified on a multitude of antigens combinations.
Here is where things get tricky. The RhD protein previously mentioned only refers to one of 61 potential proteins in the Rh system. Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system. This not only makes it rare, but this also means it can be accepted by anyone with a rare blood type within the Rh system.
This is why it is considered "golden blood." It is worth its weight in gold.
As Mosaic reports, golden blood is incredibly important to medicine, but also very dangerous to live with. If a Rh-null carrier needs a blood transfusion, they can find it difficult to locate a donor, and blood is notoriously difficult to transport internationally. Rh-null carriers are encouraged to donate blood as insurance for themselves, but with so few donors spread out over the world and limits on how often they can donate, this can also put an altruistic burden on those select few who agree to donate for others.
Some bloody good questions about blood types
A nurse takes blood samples from a pregnant woman at the North Hospital (Hopital Nord) in Marseille, southern France.
Photo by BERTRAND LANGLOIS / AFP
There remain many mysteries regarding blood types. For example, we still don't know why humans evolved the A and B antigens. Some theories point to these antigens as a byproduct of the diseases various populations contacted throughout history. But we can't say for sure.
In this absence of knowledge, various myths and questions have grown around the concept of blood types in the popular consciousness. Here are some of the most common and their answers.
Do blood types affect personality?
Japan's blood type personality theory is a contemporary resurrection of humorism. The idea states that your blood type directly affects your personality, so type A blood carriers are kind and fastidious, while type B carriers are optimistic and do their own thing. However, a 2003 study sampling 180 men and 180 women found no relationship between blood type and personality.
The theory makes for a fun question on a Cosmopolitan quiz, but that's as accurate as it gets.
Should you alter your diet based on your blood type?
Remember Galen of Pergamon? In addition to bloodletting, he also prescribed his patients to eat certain foods depending on which humors needed to be balanced. Wine, for example, was considered a hot and dry drink, so it would be prescribed to treat a cold. In other words, belief that your diet should complement your blood type is yet another holdover of humorism theory.
Created by Peter J. D'Adamo, the Blood Type Diet argues that one's diet should match one's blood type. Type A carriers should eat a meat-free diet of whole grains, legumes, fruits, and vegetables; type B carriers should eat green vegetables, certain meats, and low-fat dairy; and so on.
However, a study from the University of Toronto analyzed the data from 1,455 participants and found no evidence to support the theory. While people can lose weight and become healthier on the diet, it probably has more to do with eating all those leafy greens than blood type.
Are there links between blood types and certain diseases?
There is evidence to suggest that different blood types may increase the risk of certain diseases. One analysis suggested that type O blood decreases the risk of having a stroke or heart attack, while AB blood appears to increase it. With that said, type O carriers have a greater chance of developing peptic ulcers and skin cancer.
None of this is to say that your blood type will foredoom your medical future. Many factors, such as diet and exercise, hold influence over your health and likely to a greater extent than blood type.
What is the most common blood type?
In the United States, the most common blood type is O+. Roughly one in three people sports this type of blood. Of the eight well-known blood types, the least common is AB-. Only one in 167 people in the U.S. have it.
Do animals have blood types?
They most certainly do, but they are not the same as ours. This difference is why those 17th-century patients who thought, "Animal blood, now that's the ticket!" ultimately had their tickets punched. In fact, blood types are distinct between species. Unhelpfully, scientists sometimes use the same nomenclature to describe these different types. Cats, for example, have A and B antigens, but these are not the same A and B antigens found in humans.
Interestingly, xenotransfusion is making a comeback. Scientists are working to genetically engineer the blood of pigs to potentially produce human compatible blood.
Scientists are also looking into creating synthetic blood. If they succeed, they may be able to ease the current blood shortage, while also devising a way to create blood for rare blood type carriers. While this may make golden blood less golden, it would certainly make it easier to live with.
* While antigens are typically proteins, they can be other molecules as well, such as polysaccharides.Excerpt from a 19th century map of the Paris Catacombs, showing the labyrinthine layout underground (in color) beneath the straight-lined structures on the surface (in grey).
Ancient mining areas below Paris for limestone (red) and gypsum (green).Credit: Émile Gérards (1859–1920) / Public domain
"If you're brave enough to try, you might be able to catch a train from UnLondon to Parisn't, or No York, or Helsunki, or Lost Angeles, or Sans Francisco, or Hong Gone, or Romeless."
China Miéville's fantasy novel Un Lun Dun is set in an eerie mirror version of London. In it, he hints that other cities have similar doubles. On the list that he offhandedly rattles off, Paris stands out. Because the City of Light really does have a twisted sister. Below Paris Overground is Paris Underground, the City of Darkness.
Most people will have heard of the Catacombs of Paris: subterranean charnel houses for the bones of around six million dead Parisians. They are one of the French capital's most famous tourist attractions – and undoubtedly its grisliest.
But they constitute only a small fragment of what the locals themselves call les carrières de Paris ("the mines of Paris"), a collection of tunnels and galleries up to 300 km (185 miles) long, most of which are off-limits to the public, yet eagerly explored by so-called cataphiles.
The Grand Réseau Sud ("Great Southern Network") takes up around 200 km beneath the 5th, 6th, 14th, and 15th arrondissements (administrative districts), all south of the river Seine. Smaller networks run beneath the 12th, 13th, and 16th arrondissements. How did they get there?
Paris stone and plaster of Paris
It all starts with geology. Sediments left behind by ancient seas created large deposits of limestone in the south of the city, mostly south of the Seine; and gypsum in the north, particularly in the hills of Montmartre and Ménilmontant. Highly sought after as building materials, both have been mined since Roman times.
The limestone is also known as Lutetian limestone (Lutetia is the Latin name for ancient Paris) or simply "Paris stone." It has been used for many famous Paris landmarks, including the Louvre and the grand buildings erected during Georges-Eugène Haussmann's large-scale remodelling of the city in the mid-19th century. The stone's warm, yellowish color provides visual unity and a bright elegance to the city.
The fine-powdered gypsum of northern Paris, used for making quick-setting plaster, was so famed for its quality that "plaster of Paris" is still used as a term of distinction. However, as gypsum is very soluble in water, the underground cavities left by its extraction were extremely vulnerable to collapse.
Like living on top of a rotting tooth: subsidence starts far below the surface, but it can destroy your house.Credit : Delavanne Avocats
In previous centuries, a road would occasionally open up to swallow a chariot, or even a whole house would disappear down a sinkhole. In 1778, a catastrophic subsidence in Ménilmontant killed seven. That's why the Montmartre gypsum quarries were dynamited rather than just left as they were. The remaining gypsum caves were to be filled up with concrete.
The official body governing Paris down below is the Inspection Générale des Carrières (IGC), founded in the late 1770s by King Louis XVI. The IGC was tasked with mapping and, where needed, propping up the current and ancient (and sometimes forgotten) mining corridors and galleries hiding beneath Paris.
A delightful hiding place
Also around that time, the dead of Paris were getting in the way of the living. At the end of the 18th century, their final destination consisted of about 200 small cemeteries, scattered throughout the city — all bursting at the seams, so to speak. There was no room to bury the newly dead, and the previously departed were fouling up both the water and air around their respective churchyards.
Something radical had to happen. And it did. From 1785 until 1814, the smaller cemeteries were emptied of their bones, which were transported with full funerary pomp to their final resting place in the ancient limestone quarries at Tombe-Issoire. Three large and modern cemeteries were opened to receive the remains of subsequent generations of Parisians: Montparnasse, Père-Lachaise, and Passy.
Who says stacking skulls and bones can't be fun?Credit: Rijin via Wikimedia and licensed under CC BY-SA 4.0
The six million dead Parisians in the Catacombs, from all corners of the capital and across many centuries, together form the world's largest necropolis — their now anonymized skulls and bones methodically stacked, occasionally into whimsical patterns. The Catacombs are fashioned into a memorial to the brevity of life. The message above the entrance reads: Arrête! C'est ici l'empire de la Mort. ("Halt! This is the empire of Death.")
That has not stopped the Catacombs, accessible via a side door to a classicist building on the Avenue du Colonel Henri Rol-Tanguy, making just about every Top 20 list of things to see in Paris.
An underground economy
However, while the Catacombs certainly are the most famous part of the centuries-old network beneath Paris, and in non-pandemic times draw thousands of tourists each day, they constitute just 1.7 km (1 mile) of the 300-km (185-mile) tunneling total.
Subterranean Paris wasn't just used for mining and storing dead people. In the 17th century, Carthusian monks converted the ancient quarries under their monastery into distilleries for the green or yellow liqueur that still carries their name, chartreuse.
Because the mines generally keep a constant cool temperature of around 15° C (60° F), they were also ideal for brewing beer, as happened on a large scale from the end of the 17th century until well into the 20th century. Several caves were dug especially for establishing breweries, and not just because of the ambient temperature: going underground allowed brewers to remain close to their customers without having to pay a premium for real estate up top.
Overview of the Paris Catacombs.Credit: Inspection Générale des Carrières, 1857 / Public domain.
At the end of the 19th century, the underground breweries of the 14th arrondissement alone produced more than a million hectoliters (22 million gallons) per year. One of the most famous of Paris' underground breweries, Dumesnil, stayed in operation until the late 1960s.
In that decade, the network of corridors and galleries south of the Seine, long since abandoned by miners, became the unofficial playground for the young people of Paris. They explored the fantastical world beneath their feet, in some cases via entry points located in their very schools. Fascinated, these cataphiles ("catacomb lovers") read up on old books, explored the subterranean labyrinth, and drew up schematics that were passed around among fellow initiates as reverently as treasure maps.
As Robert Macfarlane writes in Underland, Paris-beneath-their-feet became "a place where people might slip into different identities, assume new ways of being and relating, become fluid and wild in ways that are constrained on the surface."
Some larger caves turned into notorious party zones: a 7-meter-tall gallery below the Val-de-Grâce hospital is widely known as "Salle Z." Over the last few decades, various other locations in subterranean Paris have hosted jazz and rock concerts and rave parties — like no other city, Paris really has an "underground music scene."
Hokusai's Great Wave as the backdrop to the "beach" under Paris.Credit: Reddit
Cataphiles vs. cataphobes
With popularity came increased reports of nuisance and crime — the tunnels provided easy access to telephone cables, which were stolen for the resale value of their copper.
The general public's "discovery" of the underground network led the city of Paris to officially interdict all access by non-authorized persons. That decree dates back to 1955, but the "underground police" have an understanding with seasoned cataphiles. Their main targets are so-called tourists, who by their lack of knowledge expose themselves to risk of injuries or worse, and degrade their surroundings, often leaving loads of litter in their wake.
The understanding does not extend to the IGC. Unlike in the 19th century, when weak cavities were shored up by purpose-built pillars, the policy now is to inject concrete to fill up endangered spaces — thus progressively blocking off parts of the network. That procedure has also been used to separate the Catacombs to prevent "infiltration" of the site by cataphiles.
Many subterranean streets have their own names, signs and all. This is the Rue des Bourguignons (Street of the Burgundians) below the Champs des Capucins (Capuchin Field), neither of which exists on the surface.Credit: Jean-François Gornet via Wikimedia and licensed under
The cataphiles, however, are fighting back. In a game of cat and mouse with the authorities, they are reopening blocked passages and creating chatières ("cat flaps") through which they can squeeze into chambers no longer accessible via other underground corridors.
Catacomb climate control
Alone against the unstoppable tide of concrete, the amateurs of Underground Paris would be helpless. But the fight against climate change may turn the subterranean labyrinths from a liability into an asset — and the City of Paris into an ally.
The UN's 2015 Climate Plan — concluded in Paris, by the way — requires the world to reduce greenhouse gas emissions by 75 percent by 2050. And Paris itself wants to be Europe's greenest city by 2030. More sustainable climate control of our living spaces would be a great help toward both targets. A lot of energy is spent heating houses in winter and cooling them in summer.
This is where the constant temperature of the Parisian tunnels comes in. It's not just good for brewing beer; it's a source of geothermal energy, says Fieldwork, an architectural firm based in Paris. It can be used to temper temperatures, helping to cool houses in summer and warming them in winter.
One catch for the cataphiles: it also works when the underground cavities are filled up with concrete. So perhaps one day, Paris Underground, fully filled up with concrete, will completely fall off the map, reducing the city's formerly real doppelgänger into an air conditioning unit.
Cool in summer, warm in winter: Paris Underground could become Paris A/C.Credit: Fieldwork
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