Two million years ago South Africa was wet, wet, wetter
Scientists test the teeth of a herbivore excavated from a cave and find the climate was much wetter then than now
A cave in the Northern Cape has revealed what the weather was like two million years ago.
Anthropologists tested the teeth of a herbivore excavated from Wonderwerk Cave — near Kuruman, between Upington and Kimberley — to show the climate was much wetter then than any modern African environment.
Michaela Ecker, from the University of Toronto in Canada, said the team’s findings showed that southern Africa housed a plant community unlike any seen today in the African savanna. This meant human ancestors were living in environments other than open, arid grasslands.Using carbon and oxygen stable isotope analysis on the teeth, Ecker and her team — who have published their findings in the journal Nature Ecology & Evolution — reconstructed the vegetation from the time the animal was alive.“Understanding the environment humans evolved in is key to improving our knowledge of our species and its development,” said Ecker.
“Our work at Wonderwerk Cave demonstrates how humankind existed in multiple environmental contexts in the past — contexts which are substantially different from the environments of today.”In a blog post, Ecker described how her research in South Africa began at the Florisbad Quaternary Research Station — part of the National Museum in Bloemfontein — “where James Brink has assembled an unparalleled collection of fossil and modern specimens of the bovids of southern Africa”.
She said: “Walking into his lab that is housed in a large building made of corrugated metal is like stepping into a great library, only instead of books the shelves are lined with bones.“Even before I drilled a single tooth for stable isotope analysis, the first thing that caught my attention as we examined the fauna from excavations at Wonderwerk Cave was a tooth of an antelope that most people have never heard of — the southern lechwe.“This animal needs permanent standing water as habitat and is nowadays restricted to the extensive wetlands in northern Botswana, Namibia and Angola. It could not survive in the modern environment around Wonderwerk Cave, which is a semi-arid thornbush savanna that receives rainfall only in the summer months.
“This means the environment must have been extremely different in the past that it could support this species, assuming it had the same habitat requirements as today.”Ecker then visited Wonderwerk, in the Kuruman Hills, and said: “The cave itself is a long tube with a low ceiling, running from a single entrance 140m into the hill until the visitor is surrounded by complete darkness.“The samples for this study were excavated near the entrance, where daylight still reaches and Holocene rock art adorns the cave walls.”The anthropologist said her study highlighted the need for local terrestrial records of climate and environment, and the importance of considering every aspect of the local ecology. “You never know where your first clue might come from,” she said.
Fellow author Michael Chazan has previously discovered early evidence of fire used by human ancestors at Wonderwerk, as well as the earliest evidence of cave-dwelling human ancestors, based on excavations carried out by South African archaeologist Peter Beaumont.
This has established a chronology for human occupation of the front of the cave stretching back two million years.