Here is another one. Ancient South Americans were ALL blood type O. Nowhere else in the world at the time was type O so pure, prevalent, and dominant except one little pocket on the northern tip of New Zealand half a world away across on ocean.
Makes me wonder who came from where. Seems early and distant migration was more often and varied than what we were taught in school. Probably still taught the same bull.
Precolumbian Americans were apparently entirely type O, based on the prevalence among their usually multiethnic descendants.
Primary bloodtypes (ABO family, MN family) are coded (or not, in the case of O) on chromosome 9. Type A and Type O are identical apart from O missing the first base pair. Type A and B differ by something like 16 base pairs.