Tuesday, May 21, 2013

Development of Middle Stone Age innovation linked to rapid climate change

The development of modernity in early human populations has been linked to pulsed phases of technological and behavioural innovation within the Middle Stone Age of South Africa. However, the trigger for these intermittent pulses of technological innovation is an enigma. Here we show that, contrary to some previous studies, the occurrence of innovation was tightly linked to abrupt climate change. Major innovational pulses occurred at times when South African climate changed rapidly towards more humid conditions, while northern sub-Saharan Africa experienced widespread droughts, as the Northern Hemisphere entered phases of extreme cooling. These millennial-scale teleconnections resulted from the bipolar seesaw behaviour of the Atlantic Ocean related to changes in the ocean circulation. These conditions led to humid pulses in South Africa and potentially to the creation of favourable environmental conditions. This strongly implies that innovational pulses of early modern human behaviour were climatically influenced and linked to the adoption of refugia.


From the Press:

Rapid climate change during the Middle Stone Age, between 80,000 and 40,000 years ago, during the Middle Stone Age, sparked surges in cultural innovation in early modern human populations, according to new research.

Professor Ian Hall, Cardiff University School of Earth and Ocean Sciences, said: "When the timing of these rapidly occurring wet pulses was compared with the archaeological datasets, we found remarkable coincidences.
"The occurrence of several major Middle Stone Age industries fell tightly together with the onset of periods with increased rainfall."
"Similarly, the disappearance of the industries appears to coincide with the transition to drier climatic conditions."
Professor Chris Stringer of London's  commented "The correspondence between climatic ameliorations and cultural innovations supports the view that population growth fuelled cultural changes, through increased human interactions."
The South African archaeological record is so important because it shows some of the oldest evidence for modern behavior in early humans. This includes the use of symbols, which has been linked to the development of complex language, and personal adornments made of seashells.

Read more at: http://phys.org/news/2013-05-human-culture-linked-rapid-climate.html#jCp

The climate of South Africa was once much wetter than it is today, and those lush times may have spurred human populations through especially innovative periods, new research shows.

Evidence from these ancient periods suggests humans produced new tools, and used symbolism in wall engravings. The findings suggest a tight link between abrupt climate changes and the emergence of modern human traits, researchers say.

"We provide for the first time really good evidence that the occurrence and disappearance of these first finds of human innovation are linked to climate change," said study author Martin Ziegler, an earth science researcher at Cardiff University in Wales.

Before these periods of innovation, humans were quite primitive, with the most impressive technology being hand axes, Ziegler said. But during these wet periods, more advanced stone and bone tools appear in the fossil record, as well as painted symbols on cave walls that suggest the development of language.

Archaeologists have also found some of the first evidence of constructed plant beds during these periods, and shells thought to be worn as adornments or jewelry, Ziegler said. Among the most important periods analyzed in the study date to 71,000, and a period between 64,000 and 59,000 years ago.

Read more at: http://www.livescience.com/34546-climate-stone-age-innovation.html

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