Detailed, well-dated palaeoclimate and archaeological records are critical for understanding the impact of environmental change on human evolution. In new research, archaeologists from the University of Cape Town and elsewhere identified and described relict tufas — evidence of past flowing streams, waterfalls, and shallow pools — at the site of Ga-Mohana Hill in the southern Kalahari, South Africa.
Top: map of South Africa with the location of Ga-Mohana Hill (GHN); inset map shows the approximate extent of the Kalahari Basin in southern Africa and the location of the region of interest in relation to it. Bottom: representative photographs of each of the tufa morphologies identified on the Ga-Mohana hillside. Image credit: von der Meden et al., doi: 10.1371/journal.pone.0270104.
“The general assumption is that the Kalahari is a harsh environment not suitable for early human survival, however, they did indeed live there and thrive,” said Dr. Jayne Wilkins, an archaeologist with the Australian Research Centre for Human Evolution at Griffith University and the Human Evolution Research Institute at the University of Cape Town.
“Our research shows during some periods in the past the desert was lush and much wetter than today. Humans could thrive in these wet conditions.”
“We also found out that by 20,000 years ago, humans were living in the Kalahari during the dry conditions providing us with an insight into how climate change impacted human evolution.”
Dr. Wilkins and her colleagues studied the tufa deposits, which are springs, waterfalls or ponds that have turned into rock, at Ga-Mohana Hill in the southern Kalahari in South Africa, a site that has spiritual significance for the local communities.
Through U-Th dating, they produced a new, well-dated record of prolonged water availability linked to human occupation in the Kalahari during the Late Pleistocene.
“Water precipitates out and leaves behind calcium carbonate which the team was able to drill into and date the rock,” Dr. Wilkins explained.
“These dates tell us when it was wetter in the past.”
The researchers also discovered some of the world’s earliest evidence of innovative technological behaviors.
“We found a lot of stone tools and the remnants of bones from a meal they would have consumed,” Dr. Wilkins said.
“A significant find though was calcite crystals, clear crystal cubes that don’t have a functional value but were probably collected for sentimental reasons like a stamp collector, or perhaps for ritual reasons.”
“Our research shows it wasn’t just about surviving for the Homo sapiens in the Kalahari Desert, but they thrived with advanced knowledge, systems and technologies to able to access the resources they needed to survive in dry conditions.”
The findings are published in the journal PLoS ONE.
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J. von der Meden et al. 2022. Tufas indicate prolonged periods of water availability linked to human occupation in the southern Kalahari. PLoS ONE 17 (7): e0270104; doi: 10.1371/journal.pone.0270104
