Genomic Study Reveals Genetic Diversity in Ancient Brazilian Coastal Communities
A large-scale genomic study of ancient Brazilian sambaqui communities has revealed significant genetic differences between coastal populations, challenging previous assumptions of homogeneity.
Researchers from the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen and the University of São Paulo have published findings that redraw the understanding of ancient Brazil.
Their study, involving the largest genomic dataset compiled from Brazil to date, analyzed 34 individuals from four different regions, spanning up to 10,000 years of history. The sambaqui, large shell mounds built by indigenous coastal societies between approximately 8,000 and 1,000 years ago, are scattered across over 3,000 kilometers of the South American Atlantic coast. While archaeological evidence indicated shared cultural practices among sambaqui builders, the new genomic data shows that these communities were not genetically uniform.
The research, published in "Nature Ecology and Evolution," suggests that distinct demographic trajectories, potentially influenced by interactions with inland populations, account for the observed genetic variations. Early Holocene hunter-gatherer groups also showed genetic distinctions from each other and from later coastal inhabitants, implying limited direct lineage connections.
The study also noted a correlation between intensified contacts between inland and coastal groups around 2,200 years ago and a decline in shell mound construction. This period also saw significant environmental shifts, which researchers believe may have contributed to the eventual cessation of this unique architectural practice. Further regional studies are planned to explore the nuances of South America's deep genomic past.