Cranial morphology of early South Americans: Implications for understanding human dispersion into the new world

Abstract

Early South American groups have been described as possessing a different cranial morphology from the one typically observed among recent Native American populations. This peculiar morphology has been recurrently included in discussions about the initial human dispersion into the Americas, with different authors favoring contrasting scenarios to explain the origin of the morphological and biological diversity inside the continent. In this chapter, we summarize our latest results on the morphological affinities of Early Holocene South American groups and their implications for our understanding of the settlement of the Americas. Our analyses focus on early series from Lagoa Santa, East-Central Brazil, and Sabana de Bogotá, Colombia, and are based on multivariate analyses of linear craniometric measurements of these series and reference worldwide populations. Our results indicate strong morphological affinities between early Americans and Late Pleistocene specimens from Europe and East Asia, suggesting that the first American groups shared the same morphological pattern seen in other parts of the planet by the end of the Pleistocene. These analyses suggest that the best scenario to explain the morphological diversity seen in the continent across time is one that assumes an extra influx of morphological diversity into the continent during the Holocene, given that in situ differentiation cannot explain the diversity observed across time. However, it is unclear with the present data the nature of this extra influx, if due to two discrete dispersion waves into the continent or if due to continuous gene-flow from Asia during the Holocene.