text: an explanation for the blood group ab? i know the usual stuff about the abo groups but many years ago i read that ab is an enigma because there is no real reason for it and that in fact it's only been around for about 900-1000 years, also most of the abs can trace their origins to genghis khan and the mongolians. is this poppycock or is there something in it? have a look at this link with frequencies of blood types in different racial groups  highest for type 'o' are aboriginal peoples across the globe (e.g. australia, n. and s. america, inuits). these would have the "original" human blood type, and being isolated from populations in which later mutations ('a' 'b' and 'ab') arose, they remain sometimes pure 'o'  lowest incidence of type 'b' (other than those mentioned above) is in europe, and the site says "early european races are characterized by a very low type b frequency". this suggests to me that type 'b' must have arisen and spread into europe much more recently. interesting that type 'a' is so high among pacific rim races, but also high in lapps and norwegians. maybe it has arisen independently on two separate occasions, or perhaps it confers an evolutionary (survival) advantage on people under certain environmental conditions? the worldwide distribution (except for peoples isolated for tens of thousands of years) suggests type 'a' arose a long time ago  highest for 'b'  are kalmuks (41%) and buryats (38%), who are of mongolian descent. other high scores are among the chuvash (urals) and ainu (japan) whose languages are thought by some to be part of the altaic group originating from the mongol language. romany gypsies also have 35% type 'b'. tartars, peking chinese, koreans, indians, vietnamese and thais also have ~30%+. this seems to me to be entirely consistent with type 'b' originating in mongolia fairly recently and spreading east, south and west with the mongol empire.  'ab' is common in all races with high frequencies of 'b', as 'ab' comes from having parents that are type 'a' and 'b'