I often hear that Japanese people have predominantly A blood group, because their ancestors where supposedly farmers, while Europeans are predominantly O, because they were hunters (except Baltic people who are more B - were they fishermen ?).

What I don't understand is that farming came to Japan from China only in the 1st century, while Greek, Romans and other knew it long before that. Agriculture developed first at about the same time, around 5000BC, in Mesopotamia, Egypt and China. From the Middle East, it spread quickly Westwards to Greece, Europe and whole Mediteranean, and Eastward to Persia and India. That happened of course before the rise of the first civilisations (circa 3000BC).

So why do all Japanese believe that blood group difference are based on different ancient life styles ?

It seems that genetical/physiological differences between East Asians and Europeans date back from a separation of two ethnic groups 500.000 years ago. Furthermore, modern human skulls are said not to have evolved much only for the last 50.000 years.
That probably explains the physiological differences between continents, including the blood group repartition.

I need to do more research on this.

What's your opinion ?