Postcranial morphological variation between hunter-gatherers and horticulturalists from the lower Paraná River Delta, Argentina

Abstract

Introduction: Although pre-Hispanic hunter-gatherer and horticulturalist (known as Guaraní) societies from the lower Paraná River Delta (Argentina) presented differences in diet, pottery decoration, mortuary practices, and places of origin, differences in skeletal morphology between such groups have never been systematically explored. This work focuses on variations in humeral and femoral external linear measurements and derived structural properties of adult individuals from both societies as well as on variations in body mass and stature. Materials and Methods: Bone length, epiphyseal size, and midshaft breadth were measured in 82 adult humeri and 100 femora from hunter-gatherer and Guaraní archeological sites. Epiphyseal and midshaft robusticity, residual strength, midshaft shape and area, stature, and body mass were then estimated. Mann–Whitney tests were run to compare the hunter-gatherer and Guaraní samples. Results: Male Guaraní individuals presented stronger humeri and more robust femoral and humeral proximal epiphyses than hunter-gatherers. In addition, female Guaraní individuals showed rounder femoral diaphyses in comparison with female hunter-gatherers. Concerning stature, the Guaraní individuals were found to be shorter than hunter-gatherers, regardless of sex. No statistical differences were found in body mass. Discussion: Despite the fact that skeletal variations between Guaraní and hunter-gatherers could be a consequence of differences in mechanical loadings and genetic composition, bone robusticity is also positively correlated with increased age, but as the age composition of the Guaraní sample could not be estimated, skeletal variation between the samples could be a consequence of differences in age distribution.