Washington: Rapid climate change during the Middle Stone Age, between 80,000 and 40,000 years ago, sparked surges in cultural innovation in early modern human populations, a new study has revealed.
The scientists from Cardiff University`s School of Earth and Ocean Sciences, the Natural History Museum in London and the University of Barcelona, studied a marine sediment core off the coast of South Africa and reconstructed terrestrial climate variability over the last 100,000 years.
"We found that South Africa experienced rapid climate transitions toward wetter conditions at times when the Northern Hemisphere experienced extremely cold conditions," Dr Martin Ziegler, Cardiff University School of Earth and Ocean Sciences, said.
These large Northern Hemisphere cooling events have previously been linked to a change in the Atlantic Ocean circulation that led to a reduced transport of warm water to the high latitudes in the North.
In response to this Northern Hemisphere cooling, large parts of the sub-Saharan Africa experienced very dry conditions.
"Our new data however, contrasts with sub-Saharan Africa and demonstrates that the South African climate responded in the opposite direction, with increasing rainfall, that can be associated with a globally occurring southward shift of the tropical monsoon belt," he said.
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," he said.
The South African archaeological record is so important because it shows some of the oldest evidence for modern behaviour 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.
The new study presents the most convincing evidence so far that abrupt climate change was instrumental in this development.
The study is published in the journal Nature Communications.