Using pollen to reconstruct the environment during the Middle Stone Age

Many of the Middle Stone Age sites on the southern coast of South Africa have a diverse and unique flora. The relative composition of the vegetation types belonging to this flora largely depends on rainfall seasonality. Hence, past changes in the extent and seasonality of rainfall have significantly altered the vegetation in the region. Reconstructing vegetation shifts on the coastal plains of South Africa will help to unravel one of the main questions in SapienCE: How did climate and environment affect the behavioural evolution and development of early humans during the Middle Stone Age?

SapienCE PhD candidate Evi Naudts used pollen preserved in marine sediments to reconstruct past changes in vegetation in South African. Due to the scarcity of lakes and swamps, terrestrial records in southern Africa are often both discontinuous and have a low temporal resolution. In contrast, pollen preserved in marine sediments often provide continuous records of vegetation changes on land. For this project, she used marine records, with a high temporal resolution, from offshore of the Western and Eastern Capes. This allows an interregional comparison of environmental changes over the past 100 000 years.

Preliminary data derived from a marine core close to the Eastern Cape show significant changes in vegetation between 73 000 to 70 000 years ago when compared to 50 000 to 48 000 years ago. Increased abundance of Southern Afrotemperate Forest pollen during the earlier period indicates that wetter conditions prevailed at this time. Moreover, pollen data also suggest that vegetation changes occurred on much shorter timescales. Brief but substantial climatic changes, known as stadials (colder) and interstadials (warmer) in the Northern Hemisphere, can be linked to sudden shifts in our pollen record from the Southern Hemisphere. Comparison of these pollen data with the archaeological record will help us to understand how past environments affected early humans living on the coastal plains of South Africa during the Middle Stone Age.