Exploring ancestral population dynamics in northeastern Peru: DNA uniparental markers in the modern Chachapoya

Abstract

This study aimed to provide a better understanding of the population history of the Chachapoyas by assessing 1) the amount and nature of genetic diversity in the modern Chachapoya and their immediate neighbors (Huancas, Jívaro, and Cajamarca), 2) the genetic affinities of the Chachapoya and populations from Andean and Amazonian pools, and 3) whether a severe reduction of the genetic diversity in the Chachapoya occurred since ethnohistorical documents report a drastic population decline in the region. We studied mitochondrial (HVRI and HVRII sequences) and Y-chromosomal (23 STR loci) diversity in four populations (Chachapoya=276, Jívaro=47, Huancas=21, and Cajamarca=34) from the Amazonas region. Our findings show asymmetrical European gene flow in the region (Chachapoya: mtDNA=11%; Y-Chromosome=43%). When examining the Native American component only, the Chachapoya population displayed relatively high levels of genetic diversity and large Tajima’s D and Fu’s Fs values. This suggests that no drastic reduction in the effective population size has taken place in the past. In the context of cultural transformations in the region, the basal position of the Chachapoya amidst the South American populations may suggest that civilizations which developed along the Andes-Amazon divide played a more important role among the societies in the Northeast Andes.