Jabuticabeira II Sambaqui (ca. 2400 BP)

Rising like pale coral against the Atlantic horizon, the sambaquis of southern Brazil are monumental palimpsests of coastal life. Jabuticabeira II — a dense shell-mound complex on Brazil’s south coast — preserves stratified deposits, burials, and midden architecture that archaeologists associate with late-Holocene maritime adaptations. Radiocarbon dates for the individuals and contexts sampled here fall between 742 BCE and 1 BCE, a window conventionally summarized as ~2400 BP.

Archaeological data indicates that Jabuticabeira II formed as part of a broader sambaqui tradition that concentrated shellfish, fish, and other marine resources into long-lived midden mounds. These features served both as refuse accumulations and as social landscapes where repeated ceremonies and burials left durable traces. Limited evidence suggests local population continuity at this locus during the late first millennium BCE, but mobility along the coast and seasonal use of resources likely punctuated settlement patterns.

Genetic sampling of 14 individuals from this site now allows us to test questions about origins: whether these mound builders were descendants of long-established coastal groups or part of later coastal expansions. While the data are promising, interpretations must remain cautious: 14 genomes illuminate patterns, but do not yet capture the full regional diversity of the sambaqui world.

Ancient DNA from 14 individuals at Jabuticabeira II provides a rare genetic window into a sambaqui community. Mitochondrial DNA is strikingly homogeneous: all 14 sampled individuals carry mtDNA haplogroup C1c, a subclade widely distributed among ancient and modern Native American populations. This uniformity suggests strong maternal continuity at the site — possibly a local founder effect, matrilocal residence practices, or demographic bottlenecks — though additional regional sampling is needed to distinguish these scenarios.

On the paternal side, Y-chromosome haplogroup Q appears in 9 of 14 males sampled. Haplogroup Q is a major Native American paternal lineage and its prevalence here aligns Jabuticabeira II with broader Pan-American male ancestries. The disparity between near-uniform mtDNA and more variable Y-DNA could reflect sex-biased mobility: men moving between groups more often than women, or differential founder events affecting one sex.

Genome-wide data (limited to these 14 individuals) indicate affinity with other coastal and inland South American populations, but fine-scale structure remains uncertain. Because the sample size is modest though larger than many early aDNA studies, conclusions about population continuity, migration, and social structure are compelling but provisional.