The timing and mode(s) of the initial human occupation of the Americas are among the most discussed topics in archaeology and biological anthropology, with hundreds of articles published in the last decades dedicated to the topic (for some comprehensive reviews, see References 1-3). Researchers have contributed to the debates through a vast range of disciplines, methodological and theoretical approaches, ranging from traditional archeological and bioarchaeological methods, to climate simulations and ancient DNA analyses. And yet, despite recent advances in the study of the biological variation and prehistoric expansions of populations into and within the Americas, there is still little consensus about key questions including the time and modes of human dispersion across the continents. This brings up a crucial question: why are we unable to find a consensus about the processes behind the initial settlements of the Americas?

The biological variation of the earliest skeletons of South America has been intensely debated for the last two centuries. One of the major research constraints has been the limited number of available samples dating to the early Holocene. We here present the first direct radiocarbon-date for the early Holocene human skeleton from Toca dos Coqueiros (Serra da Capivara, Brazil), also known as “Zuzu” (8640 ± 30 BP; 9526–9681 cal years BP). We performed craniometric analyses using exclusively samples from Brazil, to revisit the sex of the skeleton, and to discuss the evolutionary processes involved in the occupation of the continent. The sex of the individual was estimated as a female when compared to late and early Holocene individuals, but as a male when compared only to the early Holocene series. We also found that Zuzu presents the strongest differences with the late Holocene Guajajara individuals, located nearby, and the strongest similarities with the early Holocene series from Lagoa Santa, attesting for solid biological affinities among early Holocene individuals from Brazil, as well as a moderate level of morphological variation among them. This suggests that the early individuals were part of the same heterogeneous lineage, possibly a different one from which late Holocene populations diverged.

El objetivo de este trabajo es realizar un análisis comparativo de la morfología craneofacial en una muestra de 120 individuos del Holoceno temprano proveniente de Sudamérica y Norteamérica con el propósito de discutir tanto la diversidad biológica que presentaban las primeras poblaciones que llegaron al continente, como sus dinámicas de expansión. Nuestros resultados muestran una relativa estructuración geográfica entre las muestras de este y oeste de Sudamérica, en la cual los individuos de Norteamérica se encuentran en una posición intermedia entre ambas. Asimismo, estos últimos presentan mayores similitudes con las muestras de Brasil, diferenciándose de las de los Andes y Pampa. Los individuos de las Pampas Argentinas presentan similitudes con los de Lagoa Santa pero también con individuos de Camarones 14 y Tequendama. Concluimos que la diversificación morfológica entre las poblaciones del este y oeste de Sudamérica se habría producido tempranamente, y algunas áreas se caracterizan por el aporte de distintos linajes ancestrales.

The biological variation of the earliest skeletons of South America has been intensely debated for the last two centuries. One of the major research constraints has been the limited number of available samples dating to the early Holocene. We here present the first direct radiocarbon-date for the early Holocene human skeleton from Toca dos Coqueiros (Serra da Capivara, Brazil), also known as “Zuzu” (8,640+30 BP; 9,526-9,681 cal years BP). We performed craniometric analyses using exclusively samples from Brazil, in order to revisit the sex of the skeleton, and to discuss the evolutionary processes involved in the occupation of the continent. The sex of the individual was estimated as a female when compared to late and early Holocene individuals, but as a male when compared only to the early Holocene series. We also found that Zuzu presents the strongest differences with the late Holocene Guajajara individuals, located nearby, and the strongest similarities with the early Holocene series from Lagoa Santa, attesting for solid biological affinities among early Holocene individuals from Brazil, as well as a moderate level of morphological variation among them. This suggests that the early individuals were part of the same heterogeneous lineage, possibly a different one from which late Holocene populations diverged.