Evidence of water-rich periods in the Kalahari attracted early humans, according to a new study published in the journal PLOS ONE.
The Kalahari is a large semi-arid sandy savanna in Southern Africa, named from a Setswana word kgala or “great thirst”. Until recently, most evidence for early human development in southern Africa has stemmed from the country’s southern coast.
A research project by the University of Cape Town has been studying tufa rock formations on Ga-Mohana Hill, 12km from Kuruman in the Northern Cape, revealing that the southern Kalahari once had waterfalls, flowing streams and pools of water that supported early humans.
Tufa deposits are porous sedimentary rocks composed of calcium carbonate which are formed by evaporation of water that emerges in springs. Dating sequences of samples from the tufa formations at Ga-Mohana Hill dates the rock to five distinct episodes over the last 110,000 years, three of which coincide with evidence of human occupation.
The study shows that that there are links between human occupation and water availability in the southern Kalahari before 71,000 years ago. Around 20,000 years ago during the Last Glacial Maximum, a break-down in tufa formations suggest that the climate was much drier, although human occupation persisted, challenging the previously held theory that humans occupied these arid regions only during wetter periods, and it may suggest arid-adapted behaviours.
“Tufas are not actively forming today. So that’s really a clue that the environment was different in the past,” said Von der Meden of the Department of Geological Sciences and UCT’s Human Evolution Research Institute (HERI).
“We’ve shown a record of water in the tufas that not only matches the archaeological record but also provides evidence of a crucial resource for the people living at Ga-Mohana. These findings shed light on climate change and the impact of this on human evolution,” added Meden.
https://doi.org/10.1371/journal.pone.0270104
Header Image Credit : Jessica von der Meden
