Primitive humans who inhabited the coast of South Africa 165,000 years ago and lived on a diet rich in shellfish could be the original ancestors of everyone alive today, a study suggests.
The people who lived in high caves at Pinnacle Point, overlooking the Indian Ocean near Mossel Bay, harvested and cooked mussels, used red pigment from ground rocks as a form of make-up and made tiny, bladed tools. Experts say they are very likely to be the ancestors of Homo sapiens, the anatomically modern human species which migrated across the world.
It is known that Homo sapiens evolved in Africa between 200,000 and 150,000 years ago but scientists are not sure where on the continent they first arose as a distinct species. The latest evidence points to the southern tip of Africa. Archaeologists working at Pinnacle Point identified stone tools and a red pigment used in ritualistic ceremonies which they believe could only have been used by humans showing "modern behaviour".
The coastal community knew how to exploit the protein-rich food source of the sea and could have used this ability to migrate north by gradually foraging further along the coast, possibly continuing outward migration from Africa with the help of beachcombing.
"It is possible that this population could be the progenitor population for all modern humans," said Professor Curtis Marean, a palaeo-anthropologist at Arizona State University, who led the study published in the journal Nature.
"There was no point in living in a coastal environment unless they were able to eat shellfish and, even in the harshest environment, it is still possible to travel along the coastline and still have access to food."
The dig at Pinnacle Point unearthed the remnants of charred shellfish, intermingled with fine stone tools and ochre pigment, which has been linked with the expression of symbolic behaviour – such as burial ceremonies – in early humans. The tools included small "bladelets" which would have been attached to sticks to form a pointed spear, or lined up like barbs on a dart.
Charred shells suggest the shellfish were put on hot embers to open them for eating. The molluscs could only have been carried into the caves, and their presence alongside tools suggest the cave-dwellers were living off seafood, perhaps in response to the harsh environment, 40,000 years earlier than was thought possible. Human pre-history 165,000 years ago coincided with a long period of climate change, dominated by glacial conditions that caused major droughts. Only a few places on the African continent were habitable and food would have been scarce, the professor said.
Pinnacle Point would have been a perfect refuge in arid periods when life on the plains was difficult. This theory was supported by genetic analysis which showed the Kung San bush people – the original natives of South Africa – were one of the oldest human populations alive today.
Professor Marean added: "Coastal areas were of no use to early humans, unless they knew how to use the sea as a food source. Shellfish was one of the last additions to the human diet before domesticated plants and animals.
"Knowing how to exploit the sea for food meant these early humans could use coastlines as productive home ranges and move long distances."
How we came 'Out of Africa'
The 'Out of Africa' hypothesis suggests Homo sapiens emerged from Africa in a single migration between 200,000 and 150,000 years ago, from there moving to populate the entire globe. Modern man, characterised by a large, highly-connected brain and with a developed language and culture, first arrived in Asia about 100,000 years ago, then migrated to Australia 50,000 years later. Homo sapiens arrived in Europe 30,000 years ago, before populating the New World (America) about 20,000 years ago. Up to that point, the Americas were uninhibited by humans. Other species of humans, such as Homo erectus and Neanderthals, migrated from Africa much earlier but they became extinct after modern humans arrived in their midst.