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Early modern humans from the Middle Stone Age were prompted to innovate during rapid climate shifts, report C3W scientists in Nature Communications.

C3W scientists Dr Martin Ziegler and Prof Ian Hall at Cardiff University, along with the Natural History Museum and the University of Barcelona, have published new evidence of a relationship between the climate and the origins of human culture, in Nature Communications this month.

Image showing bifacial points recovered from Blombos Cave, South Africa.  The tools were manufactured during the Middle Stone Age (Still Bay industry, ca. 75 ka BP) by anatomically modern humans and are made of silcrete and finished by pressure flaking.  Scale bar = 5cm. Courtesy of Christopher Henshilwood, University of the Witwatersrand.

Image showing bifacial points recovered from Blombos Cave, South Africa.  The tools were manufactured during the Middle Stone Age (Still Bay industry, ca. 75 ka BP) by anatomically modern humans and are made of silcrete and finished by pressure flaking.  Scale bar = 5cm. Courtesy of Christopher Henshilwood, University of the Witwatersrand.

Early Homo sapiens from the Middle Stone Age underwent periods of dynamic cultural innovation, most notably the South African Still Bay and Howiesons Port industries, 100,000 – 40,000 years ago. These included developments of stone and bone tools, plant bedding and the use of symbols and ochre engravings. These early developments occurred in intervals, with various inconclusive explanations for the gaps in innovation and disappearance of these settlements.

Ziegler and Hall’s research of marine sediment core from South Africa’s coast reconstructs the past 100,000 years of climate.

New rainfall data reveals a stark correlation between more hospitable warmer and wetter climates in South Africa and the timing of early industrial developments.

“When we compared the timing of these rapidly occurring wet pulses with the archaeological datasets, we found remarkable coincidences,” says Hall.

“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.”

Each climatic event can be linked to extreme cooling events in the Northern Hemisphere, and a southward shift of the tropical monsoon belt. Ocean atmosphere models show that this resulted from circulation changes in the Atlantic Ocean causing opposing weather conditions in the North and South.

Climatic influence on human development

This is the strongest explanation for the disappearance or movement of early human settlements.

While early human development in South Africa coincided with favourable weather, the intermittent nature of human occupation of these sites suggests human dispersal from increasingly arid regions. The climate appears to have been a critical influence on early human behaviour.

by Lydia Beaman

 

Electronic version of the paper – Development of Middle Stone Age innovation linked to rapid climate change.  Martin Ziegler, Margit H. Simon, Ian R. Hall, Stephen Barker, Chris Stringer & Rainer Zahn.

Nature Communications 4, Article number: 1905 doi:10.1038/ncomms2897 Published 21 May 2013