Climate Change Linked To Human Evolution
May 22, 2013

Rapid Climate Change In South Africa Linked To Cultural Innovation In The Middle Stone Age

April Flowers for - Your Universe Online

Surges in cultural innovation in early modern human populations were sparked by rapid climate changes between 80,000 and 40,000 years ago — during what was the Middle Stone Age.

A new study conducted by a team of scientists from Cardiff University's School of Earth and Ocean Sciences, the Natural History Museum in London and the University of Barcelona examined a marine sediment core off the coast of South Africa to reconstruct terrestrial climate variability over the last 100,000 years.

Dr Martin Ziegler, Cardiff University School of Earth and Ocean Sciences, said, "We found that South Africa experienced rapid climate transitions toward wetter conditions at times when the Northern Hemisphere experienced extremely cold conditions."

Previously, scientists have linked the large Northern Hemisphere cooling events to a change in the Atlantic Ocean circulation that led to a reduced transport of warm water to the high latitudes in the North. Large portions of the sub-Saharan Africa experienced very dry conditions in response to the cooling in the Northern Hemisphere.

"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," adds Ziegler.

Professor Ian Hall, Cardiff University School of Earth and Ocean Sciences, notes, "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."

The archaeological record of South Africa is important to researchers because it shows some of the oldest evidence for modern behavior in early humans, including the use of symbols — linked to the development of complex language — and personal adornments made of seashells.

Professor Chris Stringer of London's Natural History Museum commented, "The correspondence between climatic ameliorations and cultural innovations supports the view that population growth fuelled cultural changes, through increased human interactions."

"The quality of the southern African data allowed us to make these correlations between climate and behavioral change, but it will require comparable data from other areas before we can say whether this region was uniquely important in the development of modern human culture" added Professor Stringer.

The findings of this study, which are published in Nature Communications, present the most compelling evidence to date that abrupt climate change was instrumental in the development of modern human cultural behaviors.