Laguna Chica Foragers, c. 6800 BP

The Laguna Chica horizon sits in the coastal and lowland Pampas of central Argentina, a landscape reshaped by post‑glacial climates in the Early to Middle Holocene (roughly 7000–4500 BCE). Archaeological data indicates episodic camp occupations and resource use along lacustrine margins and grassland ecotones. Limited radiocarbon and stratigraphic evidence links the site to broader Pampas settlement trends that include mobile forager groups exploiting wetland and terrestrial resources.

Genetically, the tiny ancient dataset from Laguna Chica preserves elements typical of early South American populations: maternal lineages A2, B2b and C1b and a single paternal lineage in haplogroup Q. These haplogroups are broadly distributed across ancient and modern Indigenous populations of the Americas, consistent with deep shared ancestry across the continent. However, with only three genomes recovered, any reconstruction of population movements, local continuity, or demographic change must remain provisional. Limited evidence suggests continuity with other Holocene Pampean sites, but more samples are needed to resolve whether Laguna Chica represents a long‑term local population or repeated seasonal use by diverse groups.

Three ancient genomes from Laguna Chica provide a rare, if limited, genetic window into Early Holocene Pampas populations. Observed mitochondrial haplogroups—A2, B2b and C1b—are among the principal founding maternal lineages recorded across the Americas, and their presence here supports broad maternal continuity with other ancient and modern Indigenous groups. The single observed Y‑chromosome lineage belongs to haplogroup Q, the dominant paternal lineage in many Indigenous American populations.

Genetic signals from Laguna Chica are consistent with ancestral ties across South America, but the tiny sample count (<10) severely constrains population‑level inference. With three samples, population structure, sex‑biased processes, and admixture events cannot be robustly tested. Nevertheless, the data do contribute to continental datasets showing that early Holocene Pampas inhabitants carried the same major founding lineages seen elsewhere, aligning archaeological patterns of mobility and regional interaction with genetic continuity. Future sampling—more individuals and direct AMS dates—will be required to test hypotheses about local continuity, gene flow along the Pampas corridor, or links to Andean and Patagonian groups.