Why do humans have different blood types?

Question

What is it that makes them different and why please? Just saw a programme on t.v and the man had to have a blood transfusion and of course he had to have the same blood type, why is that?

Answer 1

Only important when having a transfusion, differences only discovered in 1909.

At first all were group O, then a change began ?due to farming in a particular area.  Then type B in Japan and Asia.  As races mixed so did blood groups.

There are 600 known antigens and these antigens differ in the various blood groups.

(antigens produce immune response).

Answer 2

its due to differing genes,

there are in fact 5 different genes determining blood groups A,B,C,D,E - and any of these can be active or not.

A and B determine what you call blood group, neither = group O, one = A or B, both = AB. (The answer above gives a good description of this so there is no need to repeat it for you)

C,D & E are used to determine Rhesus grouping the most common is D so you see Rh(D) positive Which is the normal Rhesus positive.  The D gene is the dominant and stronger one, but some people Have no D but C and or E  instead and are still Rhesus Positive but can only accept Rhesus negative blood as they will react to the D antigen  (These are quite rare including myself).

If a person has an active blood group their body CAN tolerate its antigen but if they Don't they cannot tolerate its antigen.

group O negative has none of the A,B,C,D,E and is the universal Donor but A,B,C,D,E is AB Rh(CDE) Positive and can accept ANY blood. I give example:-

I am B Rh(CE) (or Rh2jr as its termed) and cannot Accept any blood that has group A or Rhesus(D).

My partner is A RH(D) and so cannot accept any group B blood but can accept any Rhesus positive blood.

A person may be O Rh negative and although they can donate to anyone they can only accept group O negative blood.

A Person may be AB Rh positive (irrelevant on CDE) and can only donate to same group but can accept any blood.

Hope this explains!

Answer 3

Why do people have different colour skin? Different colour hair?

Answer 4

For the same reason that they have different skin colours, hair & eye colours etc - mutation has caused genetic variation.

There are many different blood groups, of which the most (?) important are A, B, O.

These are due to antigens on the red blood cells. There are three forms of these antigens - A,B, and O. People either have A, B, O or both A & B - giving the  groups A, B, O and AB.

The different antigens are produced by a gene now called "I" which exists in three forms (alleles).

If you give a patient the wrong blood group, the blood cells will clump together (agglutinate) - and clumps of blood cells in the blood vessels won't do the patient any good at all!

For a planned transfusion, other blood groups will have to be considered, not just A,B,O.  

Answer 5

There are four blood types, A, B, AB, and O. I'm not sure why we have different blood types but I assume its a byproduct of evolution. I believe it has to do with some sort of marker on the blood cell.

You don't always have to have the same blood type during a transfusion. People with AB blood can receive any other type: A, B, AB, and O, but, people with O blood can only receive O. People with A can receive A and O. People with B can receive B and O.

O is the most common blood type in the world with something like 70% of the population having it. It's constantly in demand at blood centers since any blood type can receive it. AB is the rarest blood type with less than 10% of the world population having it.

Answer 6

On the surface of cells, there are antigens, These antigens are either 'a' hence a blood group, b hence b blood group, ab blood group is both antigens are present and o blood group is neither are present.

When and blood transfusions or organ transplants occur, you have to gain a complimentary organ or blood group (they have to have the same antigens).

If not, the body will recognise these as not the same antigens as present on the existing cells in the body, and will treat it as a foreign body, which it classes as harmful, as bacterium and virus' are also recognised as foreign bodies, so it will then activate its immune system, and the white blood cells in the existing blood will attack the blood from the donor.

Blood that can be given to each blood group is as follows.

Blood group a- can accept a,o

                  b- b,o

                  ab-a,b,ab,o

                 o-o

Answer 7

Interesting question! I went to http://en.wikipedia.org/wiki/Blood_type but couldn't find anything about the origin of blood types. Then I found this:

http://www.nutrition4health.org/NOHAnews...

"Type O is the oldest and the most common type. About 40,000 BC our ancestors in southern Africa had weapons and tools and they hunted in packs. They were hunter-gatherers, who thrived on meat, which led to their digestive characteristics. In time, hunting grounds became depleted of big game. To survive, the human race migrated to northern Africa. Eventually good hunting there was eliminated leading to migration out of Africa into Europe and Asia. Thus, the basic population of the planet was type O for "old." In time, depletion of large game in Europe and Asia occurred so different kinds of food were needed. Our ancestors survived on berries, small game, nuts, grubs, and fish. Overpopulation by early man led to increasing competition for the remaining meat, which led to war and further migration.

According to D’Adamo, type A first appeared in Asia or the Middle East between 25,000 and 15,000 BC. Type A mutated from type O because the increased population and major diet changes resulted in many infections. This mutation occurred rapidly. The gene for type A thrived. Characteristics of the culture were agriculture and the raising of domesticated animals. Dietary and environmental changes led to further digestive and immune system mutations. People became better able to absorb and tolerate grains and other agricultural products. They were able to sustain themselves and stable communities arose, which led to networking and cooperation. Eventually the type A gene spread into Western Europe.

Type B (for balance) developed between 15,000 and 10,000 BC in the Himalayas. Changes in climate from hot East Africa to the cold Himalayan highlands may have brought about the mutation to type B. It was characteristic of the Steppe dwellers of the Eurasian plains. Some of these were nomads, who penetrated far into Eastern Europe; while others, agriculturally based, spread through China and Southeast Asia. Movement of type B into North America was prevented by the disappearance of the land mass between it and Asia. Earlier populations in North America were all type O.

Type AB is found in less than 5% of the population and did not exist prior to between 900 and 1,000 years ago. When eastern Mongolian invaders overran the last of European civilization, type AB came into existence. AB’s inherited the tolerances of A and B, which gave them enhanced ability to counteract infections, allergies, and immune diseases. However, they have some increased susceptibility to certain cancers."