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
- 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.