Intersection of economics, history, and human biology: secular trends in stature in nineteenth-century Sioux Indians.

An unusual confluence of historical factors may be responsible for nineteenth-century Sioux being able to sustain high statures despite enduring adverse conditions during the early reservation experience. An exceptionally long span of Dakota Sioux history was examined for secular trends using a cross-sectional design. Two primary sources were used: One anthropometric data set was collected in the late nineteenth century under the direction of Franz Boas, and another set was collected by James R. Walker in the early twentieth century. Collectively, the data represent the birth years between 1820 and 1880 for adult individuals 20 years old or older. Adult heights (n = 1197) were adjusted for aging effects and regressed on age, with each data set and each sex analyzed separately. Tests for differences between the adult means of age cohorts by decade of birth (1820-1880) were also carried out. Only one sample of adults showed any convincing secular trend (p < 0.05): surprisingly, a positive linear trend for Walker's sample of adult males. This sample was also the one sample of adults that showed significant differences between age cohorts. The failure to find any negative secular trend in this population of Amerindians is remarkable, given the drastic socioeconomic changes that occurred with the coming of the reservation period (ca. 1868). Comparisons with contemporary white Americans show that the Sioux remained consistently taller than whites well into the reservation period and that Sioux children (Prince 1989) continued to grow at highly favorable rates during this time of severe conditions. A possible explanation for these findings involves the relatively favorable level of subsistence support received by most of the Sioux from the US government, as stipulated by various treaties. Conservative estimates suggest that the Sioux may have been able to sustain net levels of per capita annual meat consumption that exceeded the US average for several years before 1893.