Metric Variation on the Arikara Pelvis

Metric variation in the innominates, sacra and articulated pelves of the South Dakota Plains Indian group, the Arikara, are analyzed in an attempt to delineate biological relationships. The specimens examined represent 10 archaeological sites ranging in date from A.D. 1600 to 1832. The following sample sizes for innominate, sacrum and articulated pelvis data sets are employed: 292, 305, and 151, respectively. The data are analyzed utilizing univariate as well as multivariate statistical procedures. The results indicate that consistent within-group patterning exists. Common elements of pelvic structure can therefore be identified. Group analysis results indicate that temporal patterning can be identified on the innominate and articulated pelvis. In general, these results are consistent with those of several Arikara craniometric studies. Several explanations, namely obstetrical significance, demographic age structure differences, and gene flow, for the observed patterning are explored. Neither alone, however, appears to completely explain the patterning noted. An analysis of the patterns of sexual dimorphism expressed in the Arikara groups examined indicates that nutritional factors alone are not responsible for the noted patterning. The results tend to more strongly support a greater genetic component to ranging patterns of Arikara sexual dimorphism and are also consistent with the resent results obtained for the Arikara postcranial skeleton. Future studies employing data from other Plains Indians groups are designed to delineate the environmental and genetic components of variation of the boney pelvis as necessary in order to disprove or substantiate the present results. Data collection for this work was supported by NSF Grant BNS 8102650