Knowledge Bank

The biological and morphological diversity of Native American populations has been a topic of intense scrutiny over the past decades, with recent studies demonstrating that the process of human dispersion across the American continents was complex and non-linear. Despite this, the two continents are often combined into one macro-continent in studies about past and present biological diversity, and the differences in human history and occupation between them are largely ignored or oversimplified. In this study, we contribute to the debate about past human dispersion in the Americas by analyzing the cranial morphological variation of 39 population samples from both North and South America. Cranial morphology was represented through 18 linear craniometric variables, and their morphological affinities were explored using multidimensional scaling (MDS) and k-means clusters based on Mahalanobis distances. The MDS results show that North and South American populations overlap considerably in their morphological affinities. However, the k-means results plotted over the geographic location of the series show strong similarities between high-latitude North and South American populations and high affinities among Andean South American populations and most North American series. Eastern South American groups differentiate themselves from other populations, highlighting the biological impacts of different population histories across the southern continent. These results contrast with previous perspectives of grouping the settlement of the two continents into a single large dispersion event. The high degree of cranial diversity seen in the American continents reinforces the need to discuss North and South American human occupation separately by considering their unique histories.