On: Why Do We Have Blood Types? (2014)

[folli]

Given your hypothesis you also need an explanation why there aren't thousands of blood types.

[ivanhoe → folli]

Actually there's quite a few, if you count all the subtypes and antigens https://en.wikipedia.org/wiki/Human_blood_group_systems

[lightqa → folli]

I always thought that everything happens/happened , all the possibilities were tried by nature and 99% of those possibilities couldnt produce furthur (got killed diseases/stability) .