miércoles, 16 de septiembre de 2015

Data analysis yields striking maps of human expansion in North American Holocene


Añadir leyendaLocations of the archaeological sites in the CARD and the sampling intensity base map. Credit: PNAS 2015 ; published ahead of print September 8, 2015, doi:10.1073/pnas.1505657112

The Holocene began approximately 11,700 years ago, and encompasses the entire history of human civilization, all known written records, the epochs of human migrations, and the development of modern urban civilization. In the absence of written records from deep human history, paleohistorians have only the archaeological record to establish the spread of humanity across time and space, and there are known gaps in our knowledge of human expansion. Some of those gaps in the historical record occurred around the time that the Cordilleran and Laurentide ice sheets retreated and allowed human colonization of North America.

Recently, a group of paleoclimatologists and anthropologists analyzed data recorded in the Canadian Archaeological Radiocarbon Database (CARD), which aggregates 35,905 radiocarbon samples from archaeological sites across the North American continent, and was created by Dr. Richard Morlan of the Canadian Museum of History. By applying a kernel density estimation method to the data, the researchers produced the first maps of temporally distinct paleo-demographic trends that correspond well to existing evidence of human expansion across North America in the Holocene. They've published their results in the Proceedings of the National Academy of Sciences, which include paleo-demographic insights across a 13,000-year span. [...] phys.org/ (Vía B&W3)

Movie S1. Sequential animation of RFPEs based on 14C dates from the CARD between 13 and 0.5 ka (shown as still images in Fig. S1).