I ran across an old article I did for the Kyoto Journal on the social psychology of bloodtype in Japan. You can download it here: Transfusions of Modernity
The piece starts off like this… “MY OWN FIRST ENCOUNTER with a popularized “blood-type knowledge” was in 1983, at a Roppongi oldies livehouse (a Tokyo bar with a live band playing ’ 5 0 s rock and roll) called “Lollipop.” The matchbooks they gave away were printed on the inside cover with blank spaces to be filled in so that you could hand this to a prospective new lover. The spaces were labeled something like: “name,” “age,” “occupation,” “telephone,” “turn-ons,” and…“blood type.”
This last line was a curious, if somewhat morbid, non sequitur to the others. Blood, I figured, was not very high up on the list of bodily fluids one might hope to exchange after an evening of dancing “At the Hop.” Besides, I wasn’t even sure what blood type I had.
Blood-type knowledge began as one of those seriously lame-brained scientific ideas (seen as such from the lofty vantage point of hind-sight) at the beginning of our century: the marriage of the—even then increasingly irrelevant—notion of “race” to the idea of a “national” character type. This discourse led to speculation on the different emotional natures of various tribes and nations, ideas which persist as national stereotypes in jokes that begin like this: “A German, an Englishman, an Italian and a Frenchman were riding in an airplane… ” Then, through the efforts of a few dedicated European theorists in the 1920s, this race-nation/emotion-notion became linked to indexes of (ABO) blood types calculated for individuals who lived within the boundaries of various nation-states. Of course, these national boundaries were often no more than a decade or two old, but already, state institutions were cementing themselves a gene pool that supposedly stretched back into prehistory. Finally the prescriptive role of blood type was sharpened to fit the individual personality (see Takeiji Furukawa, 1927).”
Note: blood-type/personality-type knowledge is still taught as science in many parts of Asia.