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Genetic studies on pre-Hispanic populations of the Southern Andes have been increasing steadily in the last decade. Nevertheless, ancient DNA characterization of Formative Period archaeological human remains is particularly scant, especially for Northwest Argentina. To expand current information on genetic characterization of the first agricultural communities of the southern Calchaquí Valleys, we present and discuss the first mitochondrial ancient DNA information obtained on samples dated to ca. 3,600–1,900 years before present from the Cajón Valley, Catamarca Province. Reproducible mtDNA hypervariable region 1 (HVR-1) sequences were obtained in seven individuals. Mitochondrial HVR-1 haplotypes were assigned to three of the four founding haplogroups, D1 (57.1%), C1 (28.5%), and B2 (14.2%), with absence of A2. Our results show that the Cajón Valley sample, with predominance of D1 and C1, differs from that commonly observed in ancient and modern Andean populations, which usually show a high prevalence of haplogroup B2. The fact that the Cajón Valley and Pampa Grande (Salta Province, Argentina) share a prevalence of haplogroup D1 could provide additional evidence to support possible genetic affinities between the valleys and the eastern sub-Andean region during the Formative Period in Northwest Argentina, expanding the archaeological evidence of contact between both populations. Future complete mitogenomic analysis will provide substantial information to formulate new hypotheses about the origins and phylogenetic relationships between the individuals of the Cajón Valley and other groups from the Andes, Gran Chaco, and the Amazon.

Figure A1.tif (851 kB)
Suppl. Mat Fig. A1. Phylogenetic tree of Southern Cajón Valley HVR-1 haplotypes and others ancient CA and SA populations. CA: Central Andes, SA: South Andes, NWA: Northwestern Argentina, ARC: Archaic, FP: Formative Period, RDP: Regional Developments Period. INC: Inca, EH: Early Horizon, EIP: Early Intermediate Period, MH: Middle Horizon, LIP: Late Intermediate Period, LH: Late Horizon, RGDN: Rio Grande de Nasca drainage.

Figure A2.tif (884 kB)
Suppl. Mat. Fig. A2. Phylogenetic tree of Southern Cajón Valley HVR-1 haplotypes and contemporary CA and SA populations. CA: Central Andes, SA: South Andes, Southern Andes, NWA: Northwestern Argentina.

Table A1. HVR-1 primers.docx (24 kB)
Suppl. Mat. Table A1 . Primers

Table A2. FST matrix.xlsx (21 kB)
Suppl. Mat. Table A2. FST matrix

Table 1. Population comparisons.xlsx (175 kB)
Table 1

Table 2. Analyzed samples.xlsx (10 kB)
Table 2

Table 3. HVR-1 Haplotypes.xlsx (10 kB)
Table 3

Figure 1.tif (5724 kB)
Figure 1

Figure 2.tif (4990 kB)
Figure 2

Figure 3.tif (561 kB)
Figure 3

Figure 4.tif (498 kB)
Figure 4

Figure 5.tif (443 kB)
Figure 5