Conclusion: The Legacy of Blood Group Research After 1945

The history of blood group research, genetics, and race studies after the Second World War was complicated and changed rapidly. Two of the new developments were a great interest in testing of populations outside Europe, North America, and Japan, and the summary, cumulative work of Arthur Mourant and his collaborators on the worldwide distribution of blood groups. The most important theoretical change was discovery of many new blood groups and a growing understanding of blood group distribution as a reflection of population genetics. This eventually rejected race altogether as a way of categorizing humans and replaced it with the idea of gradually varying differences called “clines.” Following from this, links to disease became a question of whether differences in blood type frequency were the result of random genetic drift or natural selection from fitness in response to disease. There continued to be periodic and popular views of links to human behavior but without much scientific proof.