My fascination with blood group anthropology owes a lot to the maps of A.E.Mourant. These show the distribution of O blood type, the A allele, and the B allele, amongst indigenous populations by region, i.e., before any migrations, visitation or crossbreeding. Therefore the figures are valid for populations a couple of thousand years back, but not since the hordes and invasions of the early Christian era.
The following link displays maps based upon those found in Mourant’s work but can be off by as much as 10%: http://anthro.palomar.edu/vary/vary_3.htm
You might enjoy cross-referring between this column and that map as you read.
Everywhere on the globe (with the tiniest exception, found on the Barents Sea in the Russian Arctic) more than 50% of all populations are type O. There was, originally, no race or people for whom this was not true. This is an important starting point for those who might otherwise tend to succumb to the race-religion-stereotyped misinformation which often rears its head in this field.
The only region of the world that showed the ubiquitous O-majority to be actually exclusive was: The Western Hemisphere, from the Rio Grande south to Tierra del Fuego, where O prevailed at 95 to 100 per cent.
There is no area of the world (with the tiny Arctic exception cited above) where less than 50% of the population was originally Type O, or where more than 45% had the A allele, or more than 30% had the B-allele.
North America, in some areas, shows the same 100% O-incidence as the lower Americas (about ½ the continent shows 65-70% O, the other half 70-75%), but the remainder is usually evenly divided between A and B. In about ¼ of Africa, B-incidence was a high as 20%, i.e., surpassing A-incidence, a finding that explains the much higher incidence (approximately double!) of the B allele amongst blacks that amongst whites worldwide, even today.
The highest A-incidence, in the ancient (indigenous) world would be found in: Australia and New Zealand, Japan, Europe east and west, Ukraine and Western Russia, Asia Minor and the Levant (Lebanon/Palestine). In these areas, A is found in more than 25% of the population, up to as much as 45-50% (in that tiny Barents Sea region, A goes as high as 55%).
Usually the allele of least representation, the highest B-incidence would have been found in Eastern Asia (China, Mongolia, Korea, Siberia), the Southeast Asian peninsula, Central/Himalayan Asia (N. India, Pakistan, Kashmir, Afghanistan), and eastern Russia, i.e., east of the Caspian Sea.
Mourant also conducted some very specific research with regard to races, including the Jews, the Gypsies, and Polynesian peoples. His research on the Jews was with the aim of revealing Jewish-specific patterns in population. But his groundbreaking results instead showed the similarity of Jewish blood type prevalences to their surrounding cultures! Always O-dominant (like the rest of the world), their proportions of A and B varied only slightly, consonant with those of their surrounding populations (e.g., in areas of Russia where B showed a 16% incidence amongst the general population, B showed the same prevalence amongst the regions’ Jews, plus perhaps 1 or 2 % in a few areas). Amongst the Gypsies, Mourant found the incidence of AB type to be very high (over 10%), and he attributed the rise of the blood type to Gypsy and Gypsy-related migrations westward from North India.
I’m greatly indebted to Mourant’ maps and his overview of this subject. Though I have referred to other sources for modern regional numbers, these are always seen in light of anthropologic origins as described by Mourant. For example, in the early 1980’s, US figures looked something like this: O-44%, A-42%, B-10%, AB-4%. If we start to see B rise here at the expense of A, we can refer to Mourant and infer a strong Asian influx.
For those of you with a hankering after the anthropology, Mourant’s fascinating work is worth examining.