NEW YORK – A team based in Poland, the US, Bolivia, and Germany has turned to ancient DNA to untangle the population dynamics at a Central Andes site that became a prominent urban settlement in the time before Europeans arrived in South America, detecting relatively diverse ancestry that stretched from present-day Peru and northern Bolivia to the Amazon.
As they reported in Science Advances on Friday, the researchers focused on the ancient civilization near Lake Titicaca that was known as Tiwanaku, which arose alongside new cultural and archeological markers, including a large monument platform called Akapana that was used for ritual human offerings.
"For almost a millennium (500 to 1000 C.E.), Tiwanaku was one of the most influential centers in the southern Andes," first author Danijela Popovic, a researcher with the University of Warsaw's Center of New Technologies, and her colleagues explained. "More than 100 years of archaeological research has revealed how cultural and demographic changes in the Lake Titicaca basin preceded Tiwanaku's emergence as the primary ritual center around 500 C.E."
After screening samples from more than 90 ancient individuals from pre-Columbian burial sites, the team successfully sequenced DNA from 13 ancient Tiwanaku individuals — along with four individuals from distinct Wari and Inca populations found over time in southern Peru — with 0.15-fold to nearly 2.6-fold average coverage. The set included individuals who appeared to have been the subject of sacrificial offerings linked to the Tiwanaku culture.
By combining archeological, paleogenomic, and present-day population genetic clues, the authors of the new analyses explained, they were able to get a look at the populations that resided or moved through Tiwanaku and their ties to broader ancient and modern-day populations.
Although local ancestry in the region appeared to be quite homogeneous over time, the authors reported, they saw subtle genetic differences that coincided with geography. Based on insights at almost 199,200 informative SNPs in ancient and available modern-day genomes, for example, the team saw genetic links between ancient residents of the Lake Titicaca basin and individuals living in Bolivia today.
Ancient individuals in northern Peru tended to cluster separately from populations in the Titicaca area or in southern Peru. The Tiwanaku representatives, on the other hand, encompassed individuals with ancestry resembling that in ancient Peru or admixed individuals with ancestry from more far-flung sites such as the Amazon. That was particularly true when it came to remains found at the sacrificial Akapana site.
"The new genomic and radiocarbon data reported here demonstrate that, in the mostly static genetic landscape of the Central Andes, in which each region seems to have maintained an inner homogeneity with little exchange with outside populations, people from both neighboring valleys and places much further afield — even outside the direct influence of the polity — found their way to the Tiwanaku site," the authors reported. "Although we may never know the reason why certain individuals took or were taken for such a journey, our data suggest that they, and/or their descendants, left a trace at Tiwanaku."