congresos y reuniones científicas
Povoamento das Américas: haveria espaço para uma nova síntese? Aproximação à Morfologia Craniofacial dos Americanos
Aguas de Lindoia
Congreso; 51 Congresso da Sociedade Brasileira de Genética; 2005
Twenty years ago, Greenberg and colleagues (1) suggested a multidisciplinary model for the Americas human settlement. Here we review recent findings and current competing interpretations supported by different disciplines and present a new model for the human dispersal into the New World, integrating genetics, morphology, archaeology and linguistics. The model takes into account a founder population occupying Beringia during the last Glaciation, characterized by a high craniofacial diversity as well as founder mtDNA and Y-chromosome lineages. After population expansion of Beringians, which is concomitant with their entry into America, circum-arctic gene flow enabled the dispersion of extreme mongoloid characters and some particular genetic lineages from East Asia to America. Research on the Americas settlement is usually grounded on evidences from several knowledge areas. Greenberg et al. (1), based on linguistic, dental and genetic data proposed that ancestors of Native Americans came from Siberia in three separate migrations. Since the publication of this seminal work, several evidences were listed against it. Two examples can be cited: i) the Single Wave or Out of Beringia model (2-5), which parsimoniously explains the molecular coalescence of most modern Native Americans back to a unique ancestral population, and ii) the Two-Components model (6-8) which considers the presence of two differentiated craniofacial morphologies in America as a result of two distinct and allochronic source populations in Asia coming to the New World. Even though these models are solid to explain molecular and morphological variability, they do not provide an integrative view. This is crucial because, instead of providing an adequate explanation, this situation leads to a (secondary) discussion about limitations of a given type of data. In this context, and taking into account that considerable new data is now available, we make here a review of the state of the art in the fields of physical anthropology, archaeology, linguistics, and genetics, and attempt to explain through a consensus and integrative model the human dispersal from Asia to the New World.