Blood Type

By Deane Barker

This categorizes the surface of red blood cells present in blood.

Different blood types have red blood cells with different surface receptors. The profile of these receptors cause the body to recognize or reject cells as “belonging.” If it rejects them, the body will fight off the foreign red blood cells like an infection.

There are eight major blood types, representing a combination of three binary states:

  • Presence of the A antigen
  • Presence of the B antigen
  • Presence of the Rh protein

For example:

  • A+ has the A antigen, not the B, and has the Rh protein
  • AB- has both A and B and does not have the Rh protein
  • O+ has neither A nor B, and has the Rh protein

O- is universal – anyone can take this blood. (It has nothing – no A, B, or Rh.)

AB+ is also universal in the other direction – people with this type they can take blood of any other type. (It has everything – A, B, and Rh.)

(Look at it this way: we can’t have “invaders” we don’t know. O- has no invaders, so it’s good for anyone. And someone with AB+ already has all the invaders, so they’re good with anything.)

There’s considerable research on how blood types affect your health. People with a specific blood type can be more susceptible or resistant to certain diseases and conditions. For example, having Type O is known to protect against severe malaria.

Blood types are simply genetic variations. As such, they’re inherited from your parents. Natural selection causes blood types to group around geographic and ethnic lines.

For example, the malaria effect noted above means that genetic lines from areas prone to malaria – Africa and Latin America – are more likely to have Type O blood, since people in those areas are less likely to have died from malaria and were therefore able to pass their genes on to their offspring.

Why I Looked It Up

Our daughter was contacted by the local blood bank and asked to donate because they had a shortage of her specific type (I have no idea what her type is).

I knew that blood types existed, but I got to wondering about why and how specifically they were different.


Added on

Statistica published an infographic and article entitled –

How Blood Type Prevalence Varies Around the World

For instance, those with type O- are universal donors. This means they can give blood to anyone. AB+ on the other hand is a universal acceptor, so they can receive donations from anyone. Only around seven percent of the world are Rh negative.

Click through to see the graphic, but it clearly shows that O+ is the most common blood type in the world. However, Europe and Russia tend toward A+.

And this note corroborates the malaria theory from above:

The countries with the clearest prevalence of a given blood group are Ecuador, Peru and Zimbabwe, with 75 percent, 70 percent and 63 percent of O+ blood respectively.

Those are all countries historically prone to malaria.

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