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What is the Japanese blood type theory of personality?
In some Asian countries, what's in your blood determines who you are.

- In Japan and South Korea, there is a common belief that blood types determine character much in the same way Western countries believe in the zodiac.
- While there's little scientific evidence to back up the claim, the blood type theory of personality remains wildly popular.
- However, how this theory came to be has its roots in a dark history.
If you were to ask a stranger at a bar what their blood type was, the best-case scenario in most of the world would be that you'd receive some very strange looks. But if you were in Japan or South Korea, you might actually get a response. In these cultures, blood type is believed to influence personality much in the same way that zodiac signs work in Western cultures. The reason why this came to be a cultural phenomenon in these places, though, has something of a dark history.
How the blood types break down
For the curious, here's how the system works. People with type A blood are warm, friendly, compassionate, and kind. They get along well with people and make good friends. However, they can be a little obsessive, fastidious, and shy. Sometimes their affection can be overbearing, and they tend to neglect their own happiness. Since the blood type personality theory parallels the zodiac sign system, there's also romance a component: Type A people should try to date other type A people or type AB people.
Type Bs are creative, outgoing, spontaneous, and extroverted. On the negative side, they can be self-centered, impatient, and overly independent. Their dating life looks like type As': they should date other type Bs or type Abs.
Type ABs are, naturally, a mix of type A and type B qualities. They somewhat contradictory—they can be shy at times and outgoing at others. They are considered to be very rational and adaptable, but they can be critical, indecisive, and aloof. Since they're so flexible, they can date pretty much anybody.
Type Os are confident, strong-willed, and competitive. On the negative side, they can be very selfish, arrogant, and aggressive. Again, their best bet is to date other type Os or type ABs.
While there are other blood types out there—like the so-called "golden" blood type, Rh-null—the personality theory really only accounts for the major types listed above.
It's certainly fun to compare and contrast the purported traits with yours and others' blood types, but like zodiac signs, there's little scientific evidence to back up the claims. However, the history of the blood type personality theory does have its roots in academia.
From eugenics to pop psychology
Tim Boyle/Getty Images
Blood types were first discovered in 1901 by the Austrian physician Karl Landsteiner. The discovery was monumental. If an unfortunate individual were to receive a blood transfusion from an incompatible donor, they could expect a host of undesirable symptoms: fever, burning sensations, chills, the formation of lethal blood clots in the veins, and an inexplicable sense of impending doom.
While it ultimately became one of mankind's greatest medical achievements, this research was also turned to dark ends. In the early 20th century racially charged thinking and eugenics were growing in popularity across the world. The Nazis would become obsessed with the idea of blood purity. The different blood types were believed to correspond to the different races, and although the ratio of blood types do vary by ethnicity, researchers at this time also ascribed different racial characteristics according to blood type. In particular, type B blood was seen as degenerate. As reported by Der Spiegel, one bacteriologist claimed that carriers of type B blood had more "individuals identified as inferior," and that the blood type often found in "psychopaths, hysterics and alcoholics" as well as—weirdly—"brunette individuals."
By the mid-1920s, this strand of research had made its way to Japan. One study by the social psychologist Takeji Furukawa titled "The Study of Temperament through Blood Type" put forth the first iteration of the blood type personality theory. His study was significantly flawed, as it used an excessively small sample size and unsound statistical methods to reach its conclusions. Furukawa, however, enthusiastically promoted the research, and it took hold in Japan. Some employers began including a box in their job applications to see if potential hires had compatible blood types for the work, and the increasingly nationalistic and expansionistic Japanese government even began to apply the concept in their military, going so far as to group soldiers by their blood types.
Furukawa himself argued that the blood type personality theory could be useful in the field of eugenics, which had become the subject of a great deal of interest in Japan during the first half of the 20th century. Some pundits believed that it was essential for the Japanese to remain junketsu or pure bred, while others argued that konketsu or mixed-bred Japanese could acquire desirable qualities believed to be found in other races. Furukawa would later engage in a study of Taiwanese blood types to try and clarify why they so passionately resisted being conquered by Japan in 1895. Since the majority of Taiwanese were type O, he concluded that it was due to the alleged type O tendency towards aggression and stubbornness.
How did this disturbing history translate to the comparatively banal (though sometimes still discriminatory) practice of using blood type that we see in modern Japan and South Korea? As the 20th century moved on, the idea of blood types having an influence on personality dropped from the public consciousness until the 1970s, when it was revitalized by a journalist named Masahiko Nomi. Nomi's work removed much of the racist and eugenic aspects of the theory's earlier incarnation. Once again, the subject proved to be wildly popular. Nomi published 65 bestselling books, and, after his death, his son Toshitaka Nomi continued the work until his own death in 2006. The modern incarnation of the blood type personality theory largely originates from these two writers, and, although it is significantly less prejudiced than it was in the early 20th century, people are still sometimes bullied or denied employment because of their blood types. There's even a term for harassment based on blood type: bura hara.
The scientific community
Although the theory has clearly captured the attention of many Japanese and South Koreans, its scientific evidence remains scant. A study by Kengo Nawata, for instance, studied the blood types and personalities of over 10,000 people and found that blood type explained just 0.3% of the variation in personalities, a number that could easily result from statistical error. Other researchers have found that blood type does have a relationship with personality in countries where belief in the blood type personality theory is strong. This study concluded that people changed their personalities to fit their blood type instead in a self-fulfilling prophecy.
The theory certainly holds more water than the idea that zodiac signs influence personality. It's difficult to see how the position of the stars could have an effect on an individual, but its conceivable that some genetic factors might contribute to both blood types and personality to some extent. Still, the bulk of the scientific research on the topic has failed to find any significant correlation between personality and blood type, with only a few controversial outliers. While the idea might be a pleasing diversion, it's probably for the best that human beings aren't so easily placed into boxes based on whether they're a Taurus or a type B. If one had to choose between a world where one's personality was determined by circumstance or molded throughout the course of one's life, most would probably prefer the latter.
No, the Yellowstone supervolcano is not ‘overdue’
Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
Ash deposits of some of North America's largest volcanic eruptions.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
Huckleberry Ridge
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
Mesa Falls
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
Lava Creek
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
Long Valley
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at strangemaps@gmail.com.
Do you worry too much? Stoicism can help
How imagining the worst case scenario can help calm anxiety.
Stoicism can help overcome anxiety
- Stoicism is the philosophy that nothing about the world is good or bad in itself, and that we have control over both our judgments and our reactions to things.
- It is hardest to control our reactions to the things that come unexpectedly.
- By meditating every day on the "worst case scenario," we can take the sting out of the worst that life can throw our way.
Are you a worrier? Do you imagine nightmare scenarios and then get worked up and anxious about them? Does your mind get caught in a horrible spiral of catastrophizing over even the smallest of things? Worrying, particularly imagining the worst case scenario, seems to be a natural part of being human and comes easily to a lot of us. It's awful, perhaps even dangerous, when we do it.
But, there might just be an ancient wisdom that can help. It involves reframing this attitude for the better, and it comes from Stoicism. It's called "premeditation," and it could be the most useful trick we can learn.
Practical Stoicism
Broadly speaking, Stoicism is the philosophy of choosing your judgments. Stoics believe that there is nothing about the universe that can be called good or bad, valuable or valueless, in itself. It's we who add these values to things. As Shakespeare's Hamlet says, "There is nothing either good or bad, but thinking makes it so." Our minds color the things we encounter as being "good" or "bad," and given that we control our minds, we therefore have control over all of our negative feelings.
Put another way, Stoicism maintains that there's a gap between our experience of an event and our judgment of it. For instance, if someone calls you a smelly goat, you have an opportunity, however small and hard it might be, to pause and ask yourself, "How will I judge this?" What's more, you can even ask, "How will I respond?" We have power over which thoughts we entertain and the final say on our actions. Today, Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
Helping you practice StoicismCredit: Robyn Beck via Getty Images
One of the principal fathers of ancient Stoicism was the Roman statesmen, Seneca, who argued that the unexpected and unforeseen blows of life are the hardest to take control over. The shock of a misfortune can strip away the power we have to choose our reaction. For instance, being burglarized feels so horrible because we had felt so safe at home. A stomach ache, out of the blue, is harder than a stitch thirty minutes into a run. A sudden bang makes us jump, but a firework makes us smile. Fell swoops hurt more than known hardships.
What could possibly go wrong?
So, how can we resolve this? Seneca suggests a Stoic technique called "premeditatio malorum" or "premeditation." At the start of every day, we ought to take time to indulge our anxious and catastrophizing mind. We should "rehearse in the mind: exile, torture, war, shipwreck." We should meditate on the worst things that could happen: your partner will leave you, your boss will fire you, your house will burn down. Maybe, even, you'll die.
This might sound depressing, but the important thing is that we do not stop there.
Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
The Stoic also rehearses how they will react to these things as they come up. For instance, another Stoic (and Roman Emperor) Marcus Aurelius asks us to imagine all the mean, rude, selfish, and boorish people we'll come across today. Then, in our heads, we script how we'll respond when we meet them. We can shrug off their meanness, smile at their rudeness, and refuse to be "implicated in what is degrading." Thus prepared, we take control again of our reactions and behavior.
The Stoics cast themselves into the darkest and most desperate of conditions but then realize that they can and will endure. With premeditation, the Stoic is prepared and has the mental vigor necessary to take the blow on the chin and say, "Yep, l can deal with this."
Catastrophizing as a method of mental inoculation
Seneca wrote: "In times of peace, the soldier carries out maneuvers." This is also true of premeditation, which acts as the war room or training ground. The agonizing cut of the unexpected is blunted by preparedness. We can prepare the mind for whatever trials may come, in just the same way we can prepare the body for some endurance activity. The world can throw nothing as bad as that which our minds have already imagined.
Stoicism teaches us to embrace our worrying mind but to embrace it as a kind of inoculation. With a frown over breakfast, try to spend five minutes of your day deliberately catastrophizing. Get your anti-anxiety battle plan ready and then face the world.
Jonny Thomson teaches philosophy in Oxford. He runs a popular Instagram account called Mini Philosophy (@philosophyminis). His first book is Mini Philosophy: A Small Book of Big Ideas.
Study: People will donate more to charity if they think something’s in it for them
A study on charity finds that reminding people how nice it feels to give yields better results than appealing to altruism.
How to get people to want to give you money, literal balls of cash not gaurenteed.
- A study finds asking for donations by appealing to the donor's self-interest may result in more money than appealing to their better nature.
- Those who received an appeal to self-interest were both more likely to give and gave more than those in the control group.
- The effect was most pronounced for those who hadn't given before.
Even the best charities with the longest records of doing great fundraising work have to spend some time making sure that the next donation checks will keep coming in. One way to do this is by showing potential donors all the good things the charity did over the previous year. But there may be a better way.
A new study by researchers in the United States and Australia suggests that appealing to the benefits people will receive themselves after a donation nudges them to donate more money than appealing to the greater good.
How to get people to give away free money
The postcards that were sent to different study subjects. The one on the left highlighted benefits to the self, while the one on the right highlighted benefits to others.List et al. / Nature Human Behaviour
The study, published in Nature Human Behaviour, utilized the Pick.Click.Give program in Alaska. This program allows Alaska residents who qualify for dividends from the Alaska Permanent Fund, a yearly payment ranging from $800 to $2000 in recent years, to donate a portion of it to various in-state non-profit organizations.
The researchers randomly assigned households to either a control group or to receive a postcard in the mail encouraging them to donate a portion of their dividend to charity. That postcard could come in one of two forms, either highlighting the benefits to others or the benefits to themselves.
Those who got the postcard touting self-benefits were 6.6 percent more likely to give than those in the control group and gave 23 percent more on average. Those getting the benefits-to-others postcard were slightly more likely to give than those receiving no postcard, but their donations were no larger.
Additionally, the researchers were able to break the subject list down into a "warm list" of those who had given at least once before in the last two years and a "cold list" of those who had not. Those on the warm list, who were already giving, saw only minor increases in their likelihood to donate after getting a postcard in the mail compared to those on the cold list.
Additionally, the researchers found that warm-list subjects who received the self-interest postcard gave 11 percent more than warm-list subjects in the control group. Amazingly, among cold-list subjects, those who received a self-interest postcard gave 39 percent more.
These are substantial improvements. At the end of the study, the authors point out, "If we had sent the benefits to self message to all households in the state, aggregate contributions would have increased by nearly US$600,000."
To put this into perspective, in 2017 the total donations to the program were roughly $2,700,000.
Is altruism dead?
Are all actions inherently self-interested? Thankfully, no. The study focuses entirely on effective ways to increase charitable donations above levels that currently exist. It doesn't deny that some people are giving out of pure altruism, but rather that an appeal based on self-interest is effective. Plenty of people were giving before this study took place who didn't need a postcard as encouragement. It is also possible that some people donated part of their dividend check to a charity that does not work with Pick.Click.Give and were uncounted here.
It is also important to note that Pick.Click.Give does not provide services but instead gives money to a wide variety of organizations that do. Those organizations operate in fields from animal rescue to job training to public broadcasting. The authors note that it is possible that a more specific appeal to the benefits others will receive from a donation might prove more effective than the generic and all-inclusive "Make Alaska Better For Everyone" appeal that they used.
In an ideal world, charity is its own reward. In ours, it might help to remind somebody how warm and fuzzy they'll feel after donating to your cause.
160-million-year-old ‘Monkeydactyl’ was the first animal to develop opposable thumbs
The 'Monkeydactyl' was a flying reptile that evolved highly specialized adaptations in the Mesozoic Era.
