type AB have both, and people with type O have neither A nor B antigens.
Blood is also commonly classified according to the Rh system, which is why blood types are often written as A positive, O negative, AB positive, and so on.
These characteristics matter greatly when blood transfusions are required because incompatible blood can trigger a dangerous immune reaction.
They do not, however, provide a simple measure of how quickly someone will physically age.
Where Did the Blood Type and Aging Idea Come From?
Researchers have investigated relationships
