This text might be interesting concerning the history of type O blood in Homo Sapiens:
How The Neanderthals Became The Basques
That said, type O blood is well-distributed over the world (63% of the World Population share it), particularly among Native Central and Latin
Americans. It is also not sure that all Neanderthals had type O blood, even though research indicate that it was a dominant. Interesting to note is
that Oetzi the Ice Man had type O blood, so did the early Celtic populations. Perhaps we can speculate in an early, wide-spread type O blood presence
in European Homo Sapiens thanks to Neanderthal interbreeding.
Also interesting - but speculative - is the theory of personality traits in relation to blood type.
In an independent study of 45 MBA students, naturopathic physician Peter D'Adamo reported that type O’s most often described themselves in ways
related to the following characteristics; responsible, decisive, organized, objective, rule-conscious, and practical. Both male and female Type O’s
reported a higher percentage of the mesomorphic body type (stocky, strong-built, massive torso) when compared to controls. Interestingly, Type O’s
also scored significantly higher than the rest in “sensing” – using the 5 senses to gather information, and in the sensing-thinking combination,
indicating that they are more detail and fact oriented, logical, precise and orderly. D'Adamo identifies type O's as the earliest human blood
As I already speculated, if some populations have up to 5% Neanderthal genes, could 'Neanderthal' mentality express itself in their behavior, and
could some of that be tied into blood type?