Craniometric Relationships among Plains Indians: Culture-Historical and Evolutionary Implications

This study presents a broad picture of Plains Indian biological relationships on the basis of craniometric data. It employs a sample of 860 individuals distributed temporally from the Paleo-Indian Period into historic times and distributed geographically among the states of North Dakota, South Dakota, Nebraska, Kansas, Iowa and Missouri.

The sample was analyzed within a culture-historical framework utilizing a variety of statistical methodologies: some conventional, some implemented here in the face of small samples and unbalanced designs.

The results show strong evidence of biological continuity on the Plains stretching from the Paleo-Indian Period, through the Plains Archaic Period and into the Plains Woodland. The Middle Missouri-Mandan sequence appears to be strongly rooted in the Plains Woodland, suggesting an in situ development for the Middle Missouri Tradition. However, most of the phases of the Initial Middle Missouri Variant show greater affinities to Great Oasis and later Chiwere-Siouan groups than the Middle Missouri Tradition proper. It is possible that the Initial Middle Missouri Variant is not a Mandan-Siouan manifestation.

In contrast to the Middle Missouri Tradition, the Central Plains Tradition is fundamentally distinct from the earlier Plains Woodland complexes. It appears to be an intrusion onto the Plains, perhaps from a Woodland or Mississippian base in the south.

There is also a remarkable temporal trend evident in the Caddoan lineage stretching from the Central Plains Tradition into the Coalescent Arikara and Pawnee sequence. It is characterized by a complex of morphological features generally associated with a lowering of the cranial vault, and appears to coincide with the movement of the Caddoan speakers up the Missouri River. In the absence of a more all-encompassing explanation, the Caddoan trend seems to be the result of gene flow between the Caddoans and the indigenous low-headed Mandan groups. The effect of this gene flow on the Mandan is as yet unknown.