An international team of researchers has completed the first large-scale study of DNA belonging to ancient humans of the central Andes in South America and found early genetic differences between groups of nearby regions, and surprising genetic continuity over thousands of years.
Archaeological research has showed that the central Andes region is extremely rich in cultural heritage, however up until now the genomic makeup of the region before arrival of Europeans has never been studied.
The findings reveal early genetic distinctions between groups in nearby regions, population mixing within and beyond the Andes, surprising genetic continuity amid cultural upheaval, and ancestral cosmopolitanism among some of the region's most well-known ancient civilizations.
The analysis included representatives of iconic civilizations in the Andes from whom no genome-wide data had been reported before, including the Moche, Nasca, Wari, Tiwanaku and Inca.
Geneticists previously studied the deep genetic history of South America as a whole, including analysis of several individuals from the Andean highlands from many thousands of years ago.
There have also been analyses of present-day residents of the Andes and a limited number of mitochondrial or Y-chromosome DNA analyses from individual ancient Andean sites.
In the study, researchers found that genetic differences between the people of the central Andean Highlands and Coastal regions were in place as early as 9,000 years ago; with a north-south substructure of the Highlands developing by 5,800 before present (BP). These differences are still apparent in people living in those areas today.
After 5,800 BP there was evidence of genetic mingling, indicating movement of the Highlands people between north and south, central and coastal regions. However, the migrations appear to slow down by 2,000 BP, with minimal changes to the genetic structure of the central Andean region between 2,000 and 500 BP.
There were two exceptions to the slowing of migration, and these were within the Tiwanaku and Inca populations, whose administrative centres were largely cosmopolitan - people of diverse ancestries living side-by-side.
Archaeology shows Incans occupied thousands of kilometres from Ecuador through to northern Chile - which is why when Europeans arrived they discovered a massive Incan empire, but researchers found close genetic relationships between individuals at the extreme edges of the empire.
The study has expanded previous research, which provided an overall picture of the whole continent and how people arrived in migration waves.
More detailed genetic picture of populations of the central Andean Highlands will allow archaeologists to ask new questions about the history of the region and will lead to further cultural learnings and strengthen collaboration with local communities.