Why do we have different blood types, with some being compatible and others incompatible?

• If you have neither antibody, you have type AB blood, as your immune system leaves both A and B alone.
• If you have anti-A but not anti-B, you'll have type B blood.
• If you have anti-B but not anti-A, you'll be type A.
• If you have both anti-A and anti-B, then you're type O.

This may sound like a cop-out, or perhaps as a lack of curiosity on my part. It doesn’t feel like that to me.

I don’t know why the different blood groups exist, and finding out why is no interest to me.

Here’s why:

There is a great deal to know about blood banking, but the origin of the differences tells you nothing about how to work with them today.

The real origin of the differences is very likely to be very boring. We think of evolution occurring because a change somehow benefits the organism. While that is often the case, “genetic drift,” where a change just happens over time in the absence of any particular benefit, is also a factor in evolution. The presence of different blood types with no apparent benefit to any of them, is a perfect candidate for a genetic drift explanation. There is a current debate over the importance of genetic drift in evolution. The answer might be that genetic drift if more important than previously thought.

Blood type doesn’t show up in most fossils, and figuring out when these appeared is unlikely.

The details of the origins of blood type are unimportant now, and the likelihood of finding an an answer is very small. The chances of finding an important reason is even less. Why don’t you find a different question?

Blood grouping is a test that determines the type of blood of a person. The test is crucial if you need a blood transfusion or you are thinking of donating the blood. Not all blood types are compatible, so it is important to know the bloodstream. Getting blood that is incompatible with the type of blood can cause a dangerous immune response.

Types of blood groups

Your blood group is determined by the type of antigen that your red blood cells have on the surface. Antigens are substances that help your body differentiate between its own cells and foreign, potentially dangerous cells. If your body thinks a cell is alienated, it will destroy it. The ABO blood typing system groups the blood into one of the four categories:

Type A has antigen A.

Type B has the B antigen.

Type AB has antigens A and B.

Type O has neither antigens A nor B.

If your antigenic blood does not enter your system, your body will create antibodies against it. However, some people still can get blood that is not their type of blood. As long as the blood they receive does not have any antigen that marks it as foreign, their bodies will not attack him.

To help you understand it in a more easy way, blood donation work as follows:

O type: Type O individuals can donate blood to anyone because their blood does not have antigens. However, they can only receive blood from other types of individuals O (because blood with all antigens is seen as foreign).

A type: Type A individuals can donate to other types of people A and type AB individuals. Type A individuals can only receive blood from other types of type A and type O individuals.

B type: Type B individuals can donate blood to other individuals B and AB individuals. Type B individuals can only receive blood from type B individuals and type O-type individuals.

AB type: AB type individuals can only give blood to other AB individuals, but they can receive blood of any type.

I hope this help you out with your questions!

Everything Lela stated is true, but also is the fact that human blood types are composed of antigens, or proteins on the red blood cells. Type A, for example, has A antigen. The other blood types form antibodies to the types that do not have. A has antibodies to B antigen or B blood type, O has neither A or B antigen but antibodies to both A & B, and AB has both antigens and no antibodies to A or B (because it possesses both A & B antigens). There are some lesser antibodies involved and Rh factor (- or +). If the incorrect blood type is given, a patient’s serum antibodies react with those antigens causing sometimes severe transfusions reactions that can lead to kidney, liver, heart damage or death.

I read somewhere that certain antigens on our blood cells actually helped our ancestors( could be early mammals as well) be less susceptible to certain viral strains in that they couldnot bind to some types.. so that is how i guess many blood groups sprang up from a single type of antigen long ago.

Also i tink many other factors may be involved like for example.. some of us may have moved to a different place with different antigens(maybe food when we became farmers from hunter gatherers etc) causing allergies and as a defense mechanism our body started producing cells with antigens like those so that allergic reactions wouldnt be there(this sounds a little ridiculous but heyy its not quite impossible either right).

Edit: sorry i just assumed that you(perhaps you do but just in case)would know what different blood groups mean. Our red blood cells have many different antigens on them.. and the a,b and the rh antigens are just the more pronounced ones. So a person with a antigen has a group and vice versa while a o grp person has both the antigens.. and you can either have the rh antigen or not.

Some humans have red hair, and some have black hair. Some humans have blue eyes, and some humans have brown eyes. These differences are due to the genetic code of our cells. We are born with a set of genes from each parent that combine to make up our appearance.

The same is true for blood types. Our blood type is the combination of our parent's blood types. Some humans are group O, and some humans are group A, B, or AB. These groups are the genetic expression of our gene code.

Some of our genes are compatible with others and some are not. This is the science of genetics and blood transfusions.