The origin of the blood groups that showed all this

Why 40% of Caucasians have type A blood, while among Asians only have 27%? Where do different types of blood come from? 

In 1900, the Austrian doctor Karl Landsteiner discovered for the first time the existence of different blood groups, which earned him the Nobel Prize in Medicine and Physiology in 1930. Since then, scientists have developed tools increasingly powerful to investigate biology of blood types and thus be able to improve the application of new medicines. 

While much has been learned about them, blood groups remain strangely mysterious. In fact, scientists have not yet found a good explanation of their own existence. 

"Is not that amazing?" Said Ajit Varki, a biologist at the University of California, San Diego. "Almost 100 years after the Nobel Prize was awarded for this discovery, we still do not know exactly what they are for." 

Because doctors know about the existence of different types of blood, they can save lives by transfusing blood to their patients. However, for most of the story, the idea of ​​giving blood from one person to another was quite disastrous. 

The Renaissance doctors already reflected on what would happen if they injected blood into the veins of their patients. Some thought it could be a treatment for all kinds of ailments, even madness. Finally, in the 1600s, some doctors carried out their ideas with disastrous results.

On one occasion, a French doctor injected calf blood to a patient who shortly after began to sweat, vomit and produce dark colored urine. After a second transfusion, the poor man died irremediably. 

Such calamities gave transfusions a very bad reputation for 150 years. Even in the 19th century, only a few doctors dared to try the procedure. One of them was a British doctor named James Blundell. Like other doctors of his time, he saw many women bleed to death during childbirth. 

"I could not help thinking that the woman could have been saved with a transfusion," he wrote later. 

. 

Blundell did not think twice and set out to design a system of funnels, syringes and tubes that could channel the blood of a donor to a sick patient. 

After testing the device in dogs, Blundell was in the situation of helping a man who was bleeding. "The transfusion could give you a chance to live," he wrote. 

Several donors gave Blundell 400 ml of blood that he injected into the man's arm. After the procedure, the patient stated that he felt better, but two days later he died. 

Still, the experience convinced Blundell that blood transfusion would be a great benefit for humanity, and continued to inject blood to patients who were desperate. In total, he performed 10 blood transfusions, but only 4 patients survived. 

Other doctors also experimented with blood transfusions with equally disappointing success rates. Numerous tests were made, including 1870 attempts to use milk in transfusions (which, unsurprisingly, were unsuccessful and dangerous). 

Blundell was right in believing that humans should only receive human blood, but he was unaware of another crucial fact about blood: humans should only receive blood from certain humans. 

Interestingly, the discovery of blood types, a few decades later, was the result of a fairly simple procedure. The first clues about why transfusions failed had to do with the appearance of lumps in the blood. 

When in the late 1800s scientists mixed the blood of different people in test tubes, they noticed that sometimes the red blood cells came together. Since the blood came from sick patients, the scientists thought that the lumps were caused by a kind of pathology that was not worth investigating. 

Nobody bothered to see if the blood of healthy people behaved in the same way, until Karl Landsteiner checked it. Immediately he could see that mixtures of healthy blood sometimes also formed clusters.

The same rule applied to plasma and red blood cells of group B. But if Landsteiner mixed plasma of group A with red blood cells of B, the cells were grouped (and vice versa). 

It is these agglomerations that make blood transfusions so potentially dangerous. 

Landsteiner did not know what it was that differentiated one type of blood from another. It was later generations of scientists who discovered that the red blood cells of each group have different molecules on their surface. 

Each person's immune system becomes familiar with their own blood type. If people receive a transfusion of the wrong type of blood, their immune system responds as if the blood were an invader. 

The discovery of Landsteiner opened the way to large-scale and safe blood transfusions, and even today blood banks use their basic method of grouping blood cells as a quick and reliable test to check different types of blood.

Did you know the differences between different blood groups?