Independent age estimates resolve the controversy of ancient human footprints at White Sands

Founder effects identify languages of the earliest Americans

The known languages of the Americas comprise nearly half of the world's language families and a wide range of structural types, a level of diversity that required considerable time to develop. This paper proposes a model of settlement and expansion designed to integrate current linguistic analysis with other prehistoric research on the earliest episodes in the peopling of the Americas. Diagnostic structural features from phonology and morphology are compared across 60 North American languages chosen for coverage of geography and language families and adequacy of description. Frequency comparison and graphic cluster analysis are applied to assess the fit of linguistic types and families with late Pleistocene time windows when entry from Siberia to North America was possible. The linguistic evidence is consistent with two population strata defined by early coastal entries ~24,000 and ~15,000 years ago, then an inland entry stream beginning ~14,000 ff. and mixed coastal/inland ~12,000 ff. The dominant structural properties among the founder languages are still reflected in the modern linguistic populations. The modern linguistic geography is still shaped by the extent of glaciation during the entry windows. Structural profiles imply that two linguistically distinct and internally diverse ancient Siberian linguistic populations provided the founding American populations.

OBJECTIVES

Describe early North American linguistic population structure and chronology; align distribution of structural types with archeological and paleoclimatological evidence on the earliest settlements. Propose an improved model of early settlement and expansion and pose some priority research questions.

MATERIALS AND METHODS

Classification of languages based on a tripartite geolinguistic division based on geographical and linguistic evidence. Survey of phonological and morphological patterns of 60 languages representing the structural, geographical, and genealogical diversity of North America. Survey of 16 morphological and phonological features of known or likely high stability and family-identifying value across those languages. Frequency comparison and cluster analysis to elucidate the tripartite analysis and compare to the chronology and geolinguistics implied by paleoclimatological and archeological work.

RESULTS

There is enough evidence (linguistic, archeological, genetic, and geological) to indicate four glacial-age openings allowing entries to North America: coastal c. 24,000 and 15,000 years ago; inland c. 14,000 years ago and continuing; and coastal c. 12,000 years ago and continuing. Geographical distribution of modern languages reflects the geography and chronology of the openings and the two human and linguistic population strata they formed, and plausibly also the structural types of the founding languages.

DISCUSSION

Improved model of North American settlement (two chronological strata, four entries); comparison to other proposed models. Further questions and research issues for linguistic, genetic, and archeological research.

Thematic Layers of Genomic Susceptibility for Conservation Monitoring

Population genomics has great potential to inform applied conservation management and associated policy. However, the bioinformatic analyses and interpretation of population genomic datasets can be daunting and difficult to convey to nonspecialists, including on-the-ground conservationists that work with many state, federal and international agencies. We think that individual population genomic metrics of interest can be interpolated and ultimately distilled into thematic GIS layers that represent spatiotemporal genomic potential (or conversely, susceptibility) in conservation monitoring. As examples relevant to ongoing conservation efforts, we use introgressive hybridisation and individual heterozygosity to illustrate a conceptual approach for mapping population genomic susceptibility. The general framework of thematic layers could be extended to integrate key genomic metrics (e.g., runs of homozygosity and genomic load) that are relevant to many conservation efforts.

Anthropic cut marks in extinct megafauna bones from the Pampean region (Argentina) at the last glacial maximum

The initial peopling of South America is a topic of intense archaeological debate. Among the most contentious issues remain the nature of the human-megafauna interaction and the possible role of humans, along with climatic change, in the extinction of several megamammal genera at the end of the Pleistocene. In this study, we present the analysis of fossil remains with cutmarks belonging to a specimen of Neosclerocalyptus (Xenarthra, Glyptodontidae), found on the banks of the Reconquista River, northeast of the Pampean region (Argentina), whose AMS 14C dating corresponds to the Last Glacial Maximum (21,090-20,811 cal YBP). Paleoenvironmental reconstructions, stratigraphic descriptions, absolute chronological dating of bone materials, and deposits suggest a relatively rapid burial event of the bone assemblage in a semi-dry climate during a wet season. Quantitative and qualitative analyses of the cut marks, reconstruction of butchering sequences, and assessments of the possible agents involved in the observed bone surface modifications indicate anthropic activities. Our results provide new elements for discussing the earliest peopling of southern South America and specifically for the interaction between humans and local megafauna in the Pampean region during the Last Glacial Maximum.

New age constraints for human entry into the Americas on the north Pacific coast

The timing of the initial peopling of the Americas is unresolved. Because the archaeological record necessitates discussion of human entry from Beringia into southern North America during the last glaciation, addressing this problem routinely involves evaluating environmental parameters then targeting areas suitable for human settlement. Vertebrate remains indicate landscape quality and are a key dataset for assessing coastal migration theories and the viability of coastal routes. Here, radiocarbon dates on vertebrate specimens and archaeological sites are calibrated to document species occurrences and the ages of human settlements across the western expansion and decay of the Cordilleran Ice Sheet (CIS) during the Late Wisconsin Fraser Glaciation in four subregions of the north Pacific coast of North America. The results show archaeological sites occur after glacial maxima and are generally consistent with the age of other securely dated earliest sites in southern North America. They also highlight gaps in the vertebrate chronologies around CIS maxima in each of the subregions that point to species redistributions and extirpations and signal times of low potential for human settlement and subsistence in a key portion of the proposed coastal migration route. This study, therefore, defines new age constraints for human coastal migration theories in the peopling of the Americas debate.

Dating the arrival of humans in the Americas

A debate about the age of ancient footprints continues.