How Science Discovered Different Types Of Blood

By Debra Kelly on Monday, October 6, 2014
Ampoules

In A Nutshell

It’s fairly common knowledge that we have different blood types and that those blood types dictate what we need when it comes to a blood transfusion. The idea of different blood types was only confirmed in 1900 by Austrian Karl Landsteiner, although earlier doctors had their suspicions when human-to-human transfusions failed. Until then, the idea of giving blood transfusions was a complicated one, and it was even tried with animal blood, although it ended badly.

The Whole Bushel

It’s generally accepted that there are four different blood types—A, B, O, and AB, with positive and negative of each thrown in for good measure.

It turns out that those are just the basics, and there are new blood types that are still being discovered. In 2012, scientists discovered two new blood types—Junior and Langereis. And those aren’t isolated. The International Blood Transfusion Society lists 28 different blood types, and they all have names like Diego and Kidd.

Finding out exactly what blood type you are can help with making cancer treatments and tissue donations more effective, and in some cases, it can also be crucial in determining the success of a pregnancy. A woman with Junior blood type can have major problems when she’s carrying a baby of a different blood type.

While we now know about all these different blood types and the different antigens that make them up, we still don’t know just why people have them. There are plenty of theories—like the idea that O blood, which is the most common type in Africa, evolved to help people resist certain kinds of diseases most prevalent in the area, like malaria. They’re all just guesses, though, and ones like this can be questioned by asking why, if blood types were created as an evolutionary advance, do some make people more susceptible to other types of diseases?

The idea of blood transfusions and the knowledge that there is some fundamental difference between types of blood isn’t anything knew. As far back as Renaissance Europe, people knew that there was something about the blood already in your body that made it special to you. When they saw people bleeding to death, there was the idea that replacing blood with someone else’s might save that person. It was even tried with animal blood, and in case you’re wondering, it absolutely doesn’t work. A recorded case of a doctor trying to inject his patient with blood drawn from a cow states that the man suffered from severe vomiting and ultimately died after a second transfusion.

The confirmation that even humans have different types of blood came from British doctor James Blundell, after he watched as one of his patients died from blood loss after giving birth in 1817. He knew different types of animals had different types of blood, and when attempts at human-to-human transfusions failed, he knew that there had to be some other reason for it. It was only in 1900 that Karl Landsteiner was able to find the difference in the proteins of blood that made transfusions succeed or fail.

So we learned that blood needs to be of the same type in order to be transfused from one person to another, but what about drinking it?

Vampires aren’t anything new, but they’ve only recently gone from feared to revered—and now, some people are aspiring to be one instead of locking their doors against them. For even those that take safety precautions by making sure they’re not drinking blood from someone with any disease, it’s still a very, very risky thing.

Regardless of blood type, the problem with drinking it comes from its high iron content. The human body doesn’t have an efficient way to deal with getting rid of extra iron, especially the amount that gets dumped into your system if you’re drinking more than a few teaspoons of blood at one time. And ill effects might not happen right away. Prolonged drinking of blood can cause chronic dehydration, liver damage, low blood pressure, and the development of nervous disorders. The condition is called haemochromatosis, and it shows up in humans because, simply put, we’re not like other animals that rely on a blood-heavy diet to survive.

Show Me The Proof

LiveScience: Is it safe to drink blood?
BBC Future: Why do we have blood types?
LiveScience: Why Do We Have Different Blood Types?
Science Daily: Blood mystery solved: Two new blood types identified