Distribution of Blood Groups and Agglutinogen M Among Indian “Blackfeet” and “Blood” Tribes. ∗

The early work on the distribution of blood groups among the various races led to the hope that results would indicate clear-cut racial relationships, but the significance of this line of investigation has been overestimated. 1 This was the conclusion of Grove, 2 who in her studies on various aborigines found branches of the same race showing widely different incidences of the 4 blood groups. Previous reports by Coca and Deibert 3 and Snyder 4 supported the view that American Indians are characterized by a high percentage of group O, but more recently Matson and Schrader 5 described other tribes of Indians (“Blackfeet” of Montana and “Blood” of Canada) with a very high incidence of group A. Shanklin 6 found a high percentage of group O among certain Arabian tribes, others having high values for A and B.

All these studies, however, were limited to one set of factors—the 4 blood groups. Other agglutinable blood properties, the factors M, N, and P and the subgroups A₁ and A₂, and the peculiar taste reaction to para-ethoxy-phenyl-thio-urea, were shown to exhibit characteristic racial differences 7 , 8 , 9 and obviously future racial investigation of all these properties may yield more significant data.

The present report deals with a study of the incidence of the blood groups and the factor M in pure-blooded “Blackfeet” and “Blood” tribes. The results show that while these Indians differ radically from the Kansas Indians in the distribution of the 4 blood groups, they behave alike in having a very low incidence of M negative reactions, in comparison with the incidence among white individuals. The contrasting figures for the M reactions among the “Blackfeet” and “Blood” Indians on the one hand, and among white individuals of Montana on the other, were obtained with the use of the same anti-M serum.