Sambaqui Shorelines: Brazil's Ancient Builders

Along Brazil’s southern and southeastern shores a long human story is written in shell, bone and sand. Archaeological data indicates occupation stretching from early hunter-gatherers in the Lagoa Santa region (earliest dated material in this dataset to 8547 BCE) to the specialized shell-midden—sambaqui—builders whose monumental mounds define sites such as Jabuticabeira II (South Coast), Cabeçuda, Cubatão I and Galheta IV. The core era highlighted here, linked to Brazil_JabuticabeiraII_Sambaqui_2400BP, marks an energetic phase of mound construction and dense coastal settlement roughly c.2400 BP (≈450 BCE), though shell-midden formation both precedes and post-dates that horizon.

Fieldwork at named localities (Capelinha, Sambaqui do Limão, Loca do Suin, Palmeiras-Xingu and others) reveals repeated seasonal use, middens built from rich marine faunas, and burial deposits often integrated into the mounds. Limited evidence suggests complex lifeways combining fishing, shellfish gathering, and terrestrial resources, with regional variation across the South and Southeast coasts and into Southeast Amazonia. Cultural labels such as “Sambaqui” and “Jabuticabeira II” help order material variation, but stratigraphic mixing, post-depositional processes and centuries of reuse require cautious periodization.

The 32 ancient DNA samples span this deep chronology and are tied to specific sites, allowing us to start linking material culture horizons with genetic signatures while acknowledging that many questions remain open.

Thirty-two ancient samples provide a first-generation genetic window onto these coastal populations. Y-chromosome data are dominated by haplogroup Q (17 samples), a lineage widespread among Native American populations, suggesting male-line continuity with broader Indigenous ancestries. Mitochondrial DNA is strongly represented by C1c (17 samples), with additional maternal lineages B2 (3), D1 (2), D (2) and A (2). This distribution signals deep-rooted East Asian-derived founding branches that persisted in coastal Brazil.

Archaeogenetic patterns align with archaeological expectations of regional continuity, but the sample size and geographic clustering require careful interpretation. While Q and C1c dominance suggests long-term genetic continuity in these coastal groups, low counts for several haplogroups (for example B2 and D1) mean conclusions about demographic proportions or sex-biased processes must remain tentative. Where multiple temporal layers are available — for example Jabuticabeira II versus later historic-era deposits — genetic data hint at stability through time but also local micro-differentiation that could reflect migration, marriage networks, or differential preservation.

When integrated with material culture, aDNA helps distinguish persistent local lineages from episodic gene flow. However, archaeogenetic inference should be framed as probabilistic: additional sampling across inland and coastal sites is needed to resolve population structure, timing of contacts, and relationships to present-day Indigenous groups.