Question: What are blood types,do animals have different ones to us if so why?

Hussain Jaffery answered on 15 Nov 2015:

Blood types simply refer to the different kinds of proteins that red blood cells have displayed on their surfaces – these proteins help the immune system identify friendly cells, as opposed to unrecognisable invading cells form outside the body. The blood types between humans are different, and are certainly different between the blood types of animals. As it happens, many animals do have different blood types. Through evolution, the blood types of animals changed and separated. So the proteins on the red blood cells of dogs and those of humans look similar from afar, but are very different when seen up close. This is why can’t transfer blood between species – if we did, the blood recipient’s immune system wouldn’t recognise the surface proteins as their own and would attack the blood cells.

As to answer why there are so many types of blood, we just have to look at our evolutionary history. The different types adapted in response to the infectious diseases that were prevalent during our evolution. For example, in areas where malaria is common, people are more likely to have Type-O blood.