According to the Red Cross:
“there are eight different common blood types, which are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body… There are four major blood groups determined by the presence or absence of two antigens – A and B – on the surface of red blood cells… In addition to the A and B antigens, there is a third antigen called the Rh factor, which can be either present (+) or absent ( – ).
O positive is the most common blood type. Not all ethnic groups have the same mix of these blood types. Hispanic people, for example, have a relatively high number of O’s, while Asian people have a relatively high number of B’s.”
Why do we have these antigens? What are they for?
From Wikipedia: ” These antigens may be proteins, carbohydrates, glycoproteins, orglycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens can stem from one allele (or very closely linked genes) and collectively form a blood group system.
The associated anti-A and anti-B antibodies are usually Immunoglobulin M, abbreviated IgM, antibodies. ABO IgM antibodies are produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses…
Blood group B has its highest frequency in Northern India and neighboring Central Asia, and its incidence diminishes both towards the west and the east, falling to single digit percentages in Spain. It is believed to have been entirely absent from Native American and Australian Aboriginal populations prior to the arrival of Europeans in those areas.
Blood group A is associated with high frequencies in Europe, especially in Scandinavia and Central Europe, although its highest frequencies occur in some Australian Aborigine populations and the Blackfoot Indians of Montana.
If a unit of incompatible blood is transfused between a donor and recipient, a severe acute hemolytic reaction withhemolysis (RBC destruction), renal failure and shock is likely to occur, and death is a possibility. Antibodies can be highly active and can attack RBCs and bind components of the complement system to cause massive hemolysis of the transfused blood.es occur in some Australian Aborigine populations and the Blackfoot Indians of Montana…
The two most significant blood group systems were discovered by Karl Landsteiner during early experiments with blood transfusion: the ABO group in 1901 and in co-operation with Alexander S. Wienerthe Rhesus group in 1937.
A popular belief in Japan is that a person’s ABO blood type is predictive of their personality, character, and compatibility with others… Deriving from ideas of historical scientific racism, the theory reached Japan in a 1927 psychologist’s report, and the militarist government of the time commissioned a study aimed at breeding better soldiers. The fad faded in the 1930s because of its unscientific basis. The theory has long since been rejected by scientists, but it was revived in the 1970s by Masahiko Nomi, a broadcaster who had no medical background.”
According to this theory, type As are sensitive perfectionists but overanxious; Type Bs are cheerful but eccentric and selfish; Os are curious, generous but stubborn; and ABs are arty but mysterious and unpredictable.