RESUMO
Around 88 large vertebrate taxa disappeared from Sahul sometime during the Pleistocene, with the majority of losses (54 taxa) clearly taking place within the last 400,000 years. The largest was the 2.8-ton browsing Diprotodon optatum, whereas the â¼100- to 130-kg marsupial lion, Thylacoleo carnifex, the world's most specialized mammalian carnivore, and Varanus priscus, the largest lizard known, were formidable predators. Explanations for these extinctions have centered on climatic change or human activities. Here, we review the evidence and arguments for both. Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50-45 ka) and a significant role for climate change in the disappearance of the continent's megafauna.
Assuntos
Mudança Climática , Extinção Biológica , Vertebrados , Animais , Arqueologia , Austrália , História Antiga , Atividades Humanas/história , Humanos , Nova Guiné , Paleontologia/métodos , Especificidade da EspécieAssuntos
Antropologia Física , Biologia , Antropologia Forense , Antropologia Física/educação , Antropologia Física/história , Biologia/educação , Biologia/história , Antropologia Forense/educação , Antropologia Forense/história , História do Século XX , História do Século XXI , Humanos , Masculino , Mentores , Universidades , WisconsinRESUMO
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.
Assuntos
Genoma Humano , Migração Humana , Indígenas Norte-Americanos/genética , Conjuntos de Dados como Assunto , Ásia Oriental/etnologia , Genômica , Humanos , América do Norte , Polimorfismo de Nucleotídeo Único , Dinâmica Populacional , Sibéria/etnologia , América do SulRESUMO
Waters and Stafford (Reports, 23 February 2007, p. 1122) provided useful information about the age of some Clovis sites but have not definitively established the temporal span of this cultural complex in the Americas. Only a continuing program of radiometric dating and careful stratigraphic correlations can address the lingering ambiguity about the emergence and spread of Clovis culture.