viernes, 20 de enero de 2017

Mysterious 5,000-year history of ancient Libyan rock art revealed

1/2. (Heiko Riemer)

Rock art and pottery reflect the rise and fall of cattle grazing in the Gilf Kebir region.

Archaeologists have established an "absolute chronology" of prehistoric rock art in the Gilf Kebir region for the first time, using data from rock art, carbon dating, stratigraphy and other archaeological methods.

The history of rock art in the Gilf Kebir region, which stretches across parts of Libya, Sudan and Egypt, has been the subject of much speculation until now. Archaeologists have now published a new timeline for art in the region according to three distinct phases in a paper published in the journal Antiquity.

The research uses three independent datasets on the history of the region: climate data recorded in the rocks, archaeological data from inside and around the caves analysed by carbon-dating, and analysis of the styles of rock art and their superimposition.

"All three confirmed the same chronology completely independently," study author Stefan Kröpelin of the University of Cologne told IBTimes UK.

Around 8500 BCE, groups of hunter-gatherers occupied the area. The climate of the region was different today: summer monsoons influenced the climate of the region leading to heavy rainfall in Gilf Kebir.

This first occupation of the area lasted for about 2,000 years, archaeologists say, using data from carbon-dating, stratigraphy and other natural environmental records. Humans in this epoch, known as Gilf A, did not dabble much in rock art, and there are few examples of rock paintings from this era.

After 6500 BCE, a new phase of human life in the Gilf Kebir region took hold: Gilf B. This period saw an explosion of art, including ceramics, engravings and a range of painting techniques.

"The start of this period coincided with the first major production of rock art, both engravings and paintings," the authors write in the paper... (Video)

Actualización: Primeras dataciones absolutas para el arte rupestre de Gilf Kebir
Esta región, entre Libia, Sudán y Egipto, atesora representaciones realizadas entre 8.500 y 3.500 años a.C.
En muchas ocasiones, las dataciones absolutas del arte rupestre resultan especialmente complicadas, al ser necesario recurrir a información del entorno de las pinturas, que nos proporcionan datos indirectos. Esto había provocado grandes discusiones cronológicas sobre el arte rupestre de Gilf Kebir, una zona actualmente desértica que se extiende entre Libia, Sudán y Egipto. Ahora por fin se ha podido presentar una periodización de estilos acompañada de una cronología absoluta, gracias a los datos obtenidos sobre los cambios climatológicos de la zona, las dataciones por radiocarbono de elementos arqueológicos localizados en el entorno de los abrigos y cuevas, y las propias superposiciones identificadas en los paneles con representaciones artísticas...

Archaeologists discovered 7 thousand old years old house in Moldova

1/2. View of the excavation site where the house of the Linear Pottery culture was discovered, photo by M. Dębiec

More than twenty meters could be the length of the relics of a wooden house from approx. 7 thousand years ago, discovered by an international team of researchers near the city of Balti, about 100 km from Chisinau in Moldova. This is the first known so-called "long house" discovered in Moldova.

"This is an important discovery, because we finally have proof that representatives of the Linear Pottery culture, who inhabited huge areas in Europe - from Paris Basin in the west to Kiev in the east, built houses typical for this culture on the south-eastern frontiers" - said Dr. Maciej Dębiec from the Institute of Archaeology, University of Rzeszów and the University of Regensburg, who led the excavations in the town of Nicolaevca together with Stanislav Terna of the High Anthropological School University in Chisinau.

Only few similar relics of houses have been discovered in the neighbouring Ukraine, and none in Romania - which is why the discovery is very important for scientists.

From approx. 7 thousand. years BC, knowledge of breeding and cultivation began to spread from the Middle East to the territory of Europe; it was a huge cultural and social change. As a result, people abandoned their mobile lifestyle and settled down. [...] Scholarship in Poland

Caves in central China show history of natural flood patterns

Scanned image of a polished stalagmite showing growth layers... Credit: Becky Strauss (Minnesota Ph.D. 2016)

Researchers use cave structures to identify historical precipitation

Researchers at the University of Minnesota have found that major flooding and large amounts of precipitation occur on 500-year cycles in central China. These findings shed light on the forecasting of future floods and improve understanding of climate change over time and the potential mechanism of strong precipitation in monsoon regions.

The research is published in the published in the Proceedings of the U.S. National Academy of Sciences (PNAS).

"To predict how climate change will impact the future, it's important to know what has happened in the past," said Joshua Feinberg, a University of Minnesota associate professor of Earth Sciences and associate director of the Institute for Rock Magnetism, who supervised the research.

"As the variability and intensity of storms increase in the world, we need to reevaluate what the frequency of these major storms could be," Feinberg said. "We didn't have the potential to develop these kinds of precipitation records for most of the world, until now. These speleothems provide more than 8,000 years of data that led us to identify with strong confidence the presence of a 500-year cycle," he added [...] ScienceDaily

Humans, not climate change, wiped out Australian megafauna

Illustration by Peter Trusler / Monash University

New evidence involving the ancient poop of some of the huge and astonishing creatures that once roamed Australia indicates the primary cause of their extinction around 45,000 years ago was likely a result of humans, not climate change.

Led by Monash University in Victoria, Australia and the University of Colorado Boulder, the team used information from a sediment core drilled in the Indian Ocean off the coast of southwest Australia to help reconstruct past climate and ecosystems on the continent. The core contains chronological layers of material blown and washed into the ocean, including dust, pollen, ash and spores from a fungus called Sporormiella that thrived on the dung of plant-eating mammals, said CU Boulder Professor Gifford Miller.

Miller, who participated in the study led by Sander van der Kaars of Monash University, said the sediment core allowed scientists to look back in time, in this case more than 150,000 years, spanning Earth’s last full glacial cycle. Fungal spores from plant-eating mammal dung were abundant in the sediment core layers from 150,000 years ago to about 45,000 years ago, when they went into a nosedive, said Miller, a professor in the Department of Geological Sciences.

“The abundance of these spores is good evidence for a lot of large mammals on the southwestern Australian landscape up until about 45,000 years ago,” he said. “Then, in a window of time lasting just a few thousand years, the megafauna population collapsed.”

A paper on the subject was published online Jan. 20 in Nature Communications. [...] University of Colorado Boulder

Actulización: Humanos acabaron con megafauna australiana, según estudio / Link 2
Canberra, 20 ene (PL) Nuevas pruebas con excrementos de la megafauna que pobló Australia indican que su extinción hace 45 mil años fue causada por el ser humano y no por el cambio climático, informa hoy la Universidad Colorado Boulder.

Investigadores de las universidades Monash y Colorado Boulder utilizaron información de un núcleo de sedimentos perforado en el Océano Índico frente a la costa del suroeste de Australia para ayudar a reconstruir el clima pasado y los ecosistemas del país.

Dicho núcleo contiene capas cronológicas de material como polvo, polen, cenizas y esporas de un hongo llamado Sporormiella que prosperó en el estiércol de los mamíferos que comen plantas, explicó el profesor de Colorado Boulder, Gifford Miller.

El experto dijo que el núcleo de sedimentos permitió a los científicos mirar hacia atrás en el tiempo, en este caso más de 150 mil años, abarcando el último ciclo glaciar de la Tierra.

Las esporas de hongos producidas por el estiércol de mamíferos de plantas fueron abundantes en las capas centrales de los sedimentos desde hace 150 mil años hasta hace unos 45 mil años, cuando cayeron en picado, señaló Miller, profesor del Departamento de Ciencias Geológicas.