The existence of a human blood type i.e. to fend off infectious disease. However, the incompatibility of some actual blood type is just an accident of evolution on the man himself.
There are four four main types of blood type. Blood type A is the most ancient blood group. The reason, this blood type has been around since before the human species evolved from ancestor hominidnya.
Blood type B allegedly strong comes from 3.5 million years ago from a genetic mutation that modifies one of sugar on the surface of red blood cells. Starting at 2.5 million years ago, gene mutation occurs and make it a slow sugar.
Alhasi, created an O blood type has a version of sugar from the blood type A or b. Then, there is a blood type AB blood sugar has A and B Sugar this is what makes some kind of blood type did not match.
If blood from blood donors were given an A in people with blood type B, the recipient's immune system will recognize it as sugar and foreign invaders attack cues.
Immune reaction that occurs can be very deadly. Blood type O negative is known as the ' universal ' because no donor has molecules that would provoke such reactions, the ' negative ' in this case the lack of other types of molecules known as surface antigen Rh.
However, incompatibility is not part of the reason of man has a blood type, said the head of the transfusion medicine Harvey Klein at the National Institutes of Health Clinical Center.
"Blood transfusion is a recent phenomenon (hundreds of years, not millions of years ago), and therefore it has little to do with the evolution of the blood," he explained.
The causes of evolution or at least one of whom is a disease. For example, according to experts on Hematology Christine Cserti-Gazdewich of Toronto General Hospital, malaria seems to be the main force behind the high selectivity blood type o.
Blood group O is more common in Africa and other parts of the world that has a high burden of malaria. This shows, the blood carries some sort of evolutionary advantage.
"In this case, the upside is, the cells were infected with malaria are sticking with good blood cells on blood type O or B," said Cserti-Gazdewich. Malaria-infected blood cells tend to stick to cells with sugar blood type a.
Afterwards, the BLOB is known as ' rose ' will be formed and this can be very deadly lumps when it formed in vital organs, such as the brain.
As a result, according to a 2007 study results published in the Proceedings of the National Academy of Sciences, the blood will not be an O feel pain too severe when infected with malaria.
On the other hand, an O blood is more susceptible to other diseases. For example, an O blood more prone on Helicobacter Pylori, the bacterium that causes ulcers, says Klein.
But unfortunately, the results of the research has not shown whether this or some other diseases explains why humans still have blood type.
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