CLOSE
istock
istock

How is Blood Type Determined?

istock
istock

Last week’s season finale of The Knick saw the cocaine-addicted Dr. John Thackery try to solve the mystery of blood types before another doctor could do it. I won’t spoil what happened for you here, but the episode did make me wonder: How are blood types determined these days?

First, some basics about your blood. There are 4 to 6 liters of it in the average adult body, and all blood is made of the same essential elements: Red blood cells, which, using a protein called hemoglobin, transport oxygen and remove carbon dioxide; white blood cells, which fight infection; platelets, which help blood clot; and plasma, which contains salts and proteins and is the fluid that transports the other components.

But though all blood is made of essentially the same stuff, there are some differences—which caused problems for patients receiving blood transfusions before 1901, when Austrian Karl Landsteiner discovered human blood groups (this earned him the Nobel Prize in 1930). According to the Nobel Prize website, mixing two different blood types “can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions.” The problem is the immune system. Most blood contains antigens, which are substances that make the body produce antibodies. Usually antibodies are for things like viruses and bacteria, but in a wrong transfusion the immune system sees the new blood as an intruder that must be destroyed. Which can prove fatal.

Two blood group systems are important for transfusions, and Landsteiner was involved in the discovery of both. In the ABO Grouping System, there are four types of blood: Type A, Type B, Type AB, and Type O, which are determined by the presence or absence of certain antigens on the surface of red blood cells. According to the American Red Cross,

Group A – has only the A antigen on red cells (and B antibody in the plasma)
Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma)

Immune systems are adapted to individual blood types. If someone from Group B donated blood to someone from Group A, the B antibodies would recognize the B antigen as a threat and blood clumping would occur. But if someone from Group B donated to someone in Group AB there are no B antibodies, so the immune system doesn’t recognize the intruder.

Additionally, there’s the Rh factor blood grouping system. The Rh antigen is either present (+) or absent (-) in the blood. Typically, Rh negative blood goes to patients without the antigen, and Rh positive blood goes to patients who have the antigen—but an Rh positive patient can receive Rh negative blood without any problems.

So there are eight blood groups you can belong to: A Rh+, A Rh-, B Rh+, B Rh-, AB Rh+, AB Rh-, O Rh+, and O Rh -, although doctors usually leave out the Rh and just say + or -. What blood type a person ends up with is determined by genetics.

To figure out a person’s blood type, doctors can use two methods: ABO Typing or back typing. In ABO typing, doctors take blood and mix it with serums containing the antibodies in Type A and B blood. According to the National Institutes of Health,

If your blood cells stick together when mixed with:

Anti-A serum, you have type A blood
Anti-B serum, you have type B blood
Both anti-A and anti-B serums, you have type AB blood
If your blood cells do not stick together when anti-A and anti-B are added, you have type O blood.

In back testing, known A and B cells are added to samples. If the blood clumps together only when B cells are added, the donor has type A blood. If the blood clumps together when A cells are added, the donor is Type B. And if the blood clumps when either type of cell is added, the donor has Type O blood. No clumping indicates Type AB.

Rh is determined by mixing in anti-Rh serum. If the blood cells stick together when the serum is added, the person is Rh positive; if not, the person is Rh negative.

Fun fact: Everyone knows that people with O Rh- blood are universal donors, but there are also universal receivers—they have the AB Rh+ blood type. The opposite is true for plasma donors. O plasma contains antibodies for both A and B, so it would cause an immune reaction in any other blood type. AB plasma doesn’t have either antibody, so it’s universal.

nextArticle.image_alt|e
iStock
arrow
Big Questions
Why Does Santa Claus Give Coal to Bad Kids?
iStock
iStock

The tradition of giving misbehaving children lumps of fossil fuel predates the Santa we know, and is also associated with St. Nicholas, Sinterklaas, and Italy’s La Befana. Though there doesn't seem to be one specific legend or history about any of these figures that gives a concrete reason for doling out coal specifically, the common thread between all of them seems to be convenience.

Santa and La Befana both get into people’s homes via the fireplace chimney and leave gifts in stockings hung from the mantel. Sinterklaas’s controversial assistant, Black Pete, also comes down the chimney and places gifts in shoes left out near the fireplace. St. Nick used to come in the window, and then switched to the chimney when they became common in Europe. Like Sinterklaas, his presents are traditionally slipped into shoes sitting by the fire.

So, let’s step into the speculation zone: All of these characters are tied to the fireplace. When filling the stockings or the shoes, the holiday gift givers sometimes run into a kid who doesn’t deserve a present. So to send a message and encourage better behavior next year, they leave something less desirable than the usual toys, money, or candy—and the fireplace would seem to make an easy and obvious source of non-presents. All the individual would need to do is reach down into the fireplace and grab a lump of coal. (While many people think of fireplaces burning wood logs, coal-fired ones were very common during the 19th and early 20th centuries, which is when the American Santa mythos was being established.)

That said, with the exception of Santa, none of these characters limits himself to coal when it comes to bad kids. They’ve also been said to leave bundles of twigs, bags of salt, garlic, and onions, which suggests that they’re less reluctant than Santa to haul their bad kid gifts around all night in addition to the good presents.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

nextArticle.image_alt|e
Brett Deering/Getty Images
arrow
Big Questions
Who Was Heisman and Why Does He Have a Trophy?
Brett Deering/Getty Images
Brett Deering/Getty Images

On Saturday night, one of three finalists will be named this year's Heisman Trophy winner. But before anyone brings home the hardware, let’s answer a few questions about John Heisman and his famous award.

Who Exactly Was John Heisman?

© Bettmann/CORBIS

His name is mostly associated with the trophy now, but Heisman (right) was a player, coach, and hugely successful innovator in the early days of football. After playing for Brown and then Penn as a collegian from 1887 to 1891, Heisman became a coach at a series of schools that included Oberlin, Buchtel, Auburn, Clemson, Penn, Washington & Jefferson, Rice, and, most notably, Georgia Tech.

For What Football Innovations Does Heisman Get Credit?

Just some little trivial stuff like snapping the ball. Centers originally placed the ball on the ground and rolled it back to their quarterbacks, who would scoop it up and make plays. When Heisman was coaching at Buchtel (which later became the University of Akron), though, he had a 6’4” QB named Harry Clark. Clark was so tall that picking the ball up off the ground was wildly inefficient, so Heisman invented the center snap as an easy way to get the ball in Clark’s hands. Heisman also innovated the use of pulling guards for running plays and the infamous hidden-ball trick.

Any Other Shenanigans on Heisman’s Resume?

You bet. When Heisman found a way to gain an edge, he jumped on it no matter how ridiculous it seemed. When Heisman was coaching at Clemson in 1902, his team traveled to Atlanta for a game against Georgia Tech. Although Heisman was known for being a rather gruff disciplinarian, the Clemson team immediately started partying upon their arrival.

When Georgia Tech’s players and fans heard that the entire Clemson squad had spent the night before the game carousing, they prepared to coast to an easy win. When the game started, though, Clemson roared out of the gate en route to a 44-5 stomping.

How did Clemson crush Tech when by all rights they should have been ridiculously hungover? The “team” that everyone had seen partying the night before wasn’t really Heisman’s Clemson squad at all. He had sent his junior varsity players to Atlanta the night before to serve as drunken decoys, then quietly slipped his varsity team in on a morning train right before the game.

What Kind of Coach Was He?

Heisman worked as an actor in community stock theater during the summer – he consistently received rotten reviews – and allegedly spoke in a brusque, yet bizarrely ostentatious manner. Georgia Tech’s website relates a story of one of Heisman’s speeches he would break out on the first day of practice while describing a football: "What is this? It is a prolate spheroid, an elongated sphere - in which the outer leather casing is drawn tightly over a somewhat smaller rubber tubing. Better to have died as a small boy than to fumble this football."

How Did His Name Get on the Trophy?

After leaving his head-coaching job at Rice in 1927, Heisman became the athletic director at New York’s Downtown Athletic Club. In 1935 the club began awarding the Downtown Athletic Club Trophy to the nation’s top college football star. (Chicago’s Jay Berwanger won the first trophy.) Heisman died of pneumonia the following fall before the second trophy could be awarded, and the club voted to rename the prize the Heisman Memorial Trophy Award.

Did He Ever Really Throw that Iconic Stiff Arm?

© Bettmann/CORBIS

Possibly, but Heisman didn’t have the ball in his hands all that much. Even though he was a fairly small guy at just 5’8” and 158 pounds, he played as a lineman throughout his college career.

The famous “Heisman pose” is actually based on Ed Smith, a former NYU running back who modeled for the trophy’s sculptor in 1934. Interestingly, Smith went years without knowing that he’d modeled for the famous trophy. His sculptor buddy Frank Eliscu had just needed a football player to model for a project, and Smith volunteered.

Smith figured Eliscu was just doing some little personal sculpture and remained totally oblivious to his spot in football history for the next 48 years until a documentary filmmaker called Smith to interview him about the Heisman in 1982. Smith initially had no idea what the guy was talking about, but he eventually remembered his modeling days. In 1985, the Downtown Athletic Club gave Smith his own copy of the Heisman, and in 1986 he even received recognition on the televised ceremony. He looked at the four finalists – Vinny Testaverde won that year – and quipped, "Whoever wins the award, I feel sorry for you, because you're going to be looking at my ugly face for a long time." [Pictured Above: Auburn's Bo Jackson in 1985.]

What’s a Heisman Trophy Worth on the Open Market?

Quite a bit. A number of Heisman winners have eventually sold their hardware, and the trophies fetch quite a bit of loot. O.J. Simpson got $230,000 for his, and several others have gone for six-figure prices. The most expensive trophy that’s changed hands was Minnesota back Bruce Smith’s 1941 award; it fetched $395,240.

How Did Steve Spurrier Change the Process?

SEC fans are going to be floored by this one, but the Ol’ Ball Coach did something really classy when he won the Heisman in 1966. Instead of taking the trophy for himself, Spurrier gave it to the University of Florida so the school could display it and let the student body enjoy it. Florida’s student government thought Spurrier’s generosity was so classy that they paid for a replica for Spurrier so he’d get to have his own trophy, too. Since then both the school and the player have received copies of the trophy.

So Heisman Must Have Been the World’s Greatest Sportsman, Right?

Well, not really. Heisman was on the victorious side of possibly the most gratuitously run-up score in sports history. In 1916 tiny Cumberland College canceled its football program and disbanded its squad, but it had previously signed a contract to travel to Atlanta to play Heisman’s Georgia Tech team. If Cumberland didn’t show up, they had to pay Georgia Tech a $3,000 penalty, which was quite a bit of cash in 1916.

Rather than forfeiting the money, Cumberland scraped together a team of 16 scrubs and went to take their walloping from Heisman’s boys. For reasons that still aren’t totally clear – some say it was to avenge an earlier baseball loss to Cumberland, while others claim Heisman wanted to make a statement about the absurdity of the old system of using total points scored to determine the national champion – the legendary coach showed Cumberland’s ragtag band no mercy. Tech went up 63-0 in the first quarter, but Heisman kept attacking until the final score was 222-0. There are tons of hilarious stats from the game, but the funniest is Georgia Tech rushing for 1,620 yards while Cumberland only squeaked out negative-96 yards on 27 carries.

This article originally appeared in 2010.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios