Studies of the peopling of the Americas have focused on the timing and number of initial migrations. Less attention has been paid to the subsequent spread of people within the Americas. We sequenced 15 ancient human genomes spanning from Alaska to Patagonia; six are ≥10,000 years old (up to ~18× coverage). All are most closely related to Native Americans, including those from an Ancient Beringian individual and two morphologically distinct “Paleoamericans.” We found evidence of rapid dispersal and early diversification that included previously unknown groups as people moved south. This resulted in multiple independent, geographically uneven migrations, including one that provides clues of a Late Pleistocene Australasian genetic signal, as well as a later Mesoamerican-related expansion. These led to complex and dynamic population histories from North to South America.

The rich fossil record of the family Equidae (Mammalia: Perissodactyla) over the past 55 MY has made it an icon for the patterns and processes of macroevolution. Despite this, many aspects of equid phylogenetic relationships and taxonomy remain unresolved. Recent genetic analyses of extinct equids have revealed unexpected evolutionary patterns and a need for major revisions at the generic, subgeneric, and species levels. To investigate this issue we examine 35 ancient equid specimens from four geographic regions (South America, Europe, Southwest Asia, and South Africa), of which 22 delivered 87-688 bp of reproducible aDNA mitochondrial sequence. Phylogenetic analyses support a major revision of the recent evolutionary history of equids and reveal two new species, a South American hippidion and a descendant of a basal lineage potentially related to Middle Pleistocene equids. Sequences from specimens assigned to the giant extinct Cape zebra, Equus capensis, formed a separate clade within the modern plain zebra species, a phenotypicically plastic group that also included the extinct quagga. In addition, we revise the currently recognized extinction times for two hemione-related equid groups. However, it is apparent that the current dataset cannot solve all of the taxonomic and phylogenetic questions relevant to the evolution of Equus. In light of these findings, we propose a rapid DNA barcoding approach to evaluate the taxonomic status of the many Late Pleistocene fossil Equidae species that have been described from purely morphological analyses.DNA taxonomy ͉ equid evolution ͉ macroevolution ͉ phylogeny ͉ ancient DNA T he original sequence of horse fossils found in the 1870s by paleontologist Othaniel Charles Marsh, and popularized by Thomas Huxley (1), has been enriched by a large fossil record over the years and has now become one of the most widely known examples of macroevolutionary change (2). The original linear model of gradual modification of fox-sized animals (Hyracothere horses) to the modern forms has been replaced by a more complex tree, showing periods of explosive diversification and branch extinctions over 55 MY (3). The end of the Early Miocene (15-20 MYA) marks a particularly important transition, separating an initial phase of small leafy browsers from a second phase of more diverse animals, exhibiting tremendous body-size plasticity and modifications in tooth morphology (4). This explosive diversification has been accompanied by several stages of geographic extension from North America to the rest of the New and Old Worlds, so that by the end of the Miocene (5 MYA) more than a dozen distinct genera are represented in the fossil record (4) (Astrohippus,

Tierra del Fuego represents the southernmost limit of human settlement in the Americas. While people may have started to arrive there around 10 500 BP, when it was still connected to the mainland, the main wave of occupation occurred 5000 years later, by which time it had become an island. The co-existence in the area of maritime hunter-gatherers(in canoes) with previous terrestrial occupants pre-echoes the culturally distinctive groups encountered by the first European visitors in the sixteenth century. The study also provides a striking example of interaction across challenging natural barriers

RESUMENSe presentan los resultados de nuevos trabajos realizados en la cueva del Medio, Ultima Esperanza, Chile. Algunos de los principales procesos de formación de la cueva y de acumulación de sus sedimentos han sido identificados. Nuevas excavaciones mostraron evidencias de fauna extinta utilizando la cueva desde aproximadamente 14,000 años radiocarbónicos AP. Las ocupaciones humanas finipleistocenas han sido confirmadas con nuevos hallazgos y fechados, aunque la importancia de la fauna extinta en la subsistencia humana parece ser inferior a lo sugerido con anterioridad.PALABRAS CLAVE: Cueva del Medio, Última Esperanza, Pleistoceno, geomorfología, tafonomía ABSTRACT New studies at cueva del Medio, Ultima Esperanza, Chile, are presented. Some of the main cave formation and sediment accumulation processes were identified. New excavations indicated that extinct fauna was using the cave at least since 14,000 radiocarbon years BP. Human occupations at the end of the Pleistocene were confirmed with new findings and radiocarbon dates. The importance of extinct fauna in the human subsistence was less important than previously sustained.

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