Were the San the first Europeans?
Scientists query who left their hand impressions in Europe’s caves, writes Shaun Smillie
A sample of African hands might point out the identity of a mysterious group of prehistoric artists who left their art across France and Spain.
The artists crept deep into caves, braving lions and bears. They placed their hands against rock faces and blew pigment over them, creating hand stencils that survived for tens of thousands of years.
Who these people were is a mystery, as is their reason for creating their art.
Many scientists believe they were the first Europeans, a people known as the Gravettians, who lived between 17,000 and 33,000 years ago. But other scientists argue that the hands that made the prints are small compared with the Gravettians, who were believed to have been tall and robust.
But now a group of South African, Australian and US academics are arguing that the artists were African — and the proof is in the hands of their descendants, who live in the Kalahari today.
In the latest issue of the journal Transactions of the Royal Society of SA, they suggest the hand-print stencils were created by descendants of the San. They argue that they arrived in Europe following a catastrophic super volcano eruption that wiped out most of humanity.
The lead author of the paper, Prof Jack Pettigrew of the Queensland Brain Institute based at the University of Queensland, Australia, came up with this idea after studying the work of Dean Snow, who made detailed measurements of the hand stencils in caves in Spain and France.
"Snow showed greater variance, particularly in sexual dimorphism, in hand metrics in cave stencils," Pettigrew explains. "It was well known that modern humans, all 7.6-billion, have the same very low genetic variance, went through a bottleneck after Toba [a super volcanic eruption that occurred 74,000 years ago in what is now Sumatra], leaving behind a small band of high variance in Africa.
"It was natural to connect the two. Snow gave us all his raw data from the cave stencils, which made the study easy."
The scientists needed a living sample to test their theory so Prof Paul Manger of University headed out into the Kalahari Desert.
He and his team visited two !Kung villages in the Nyae Nyae Conservancy in northeast Namibia. The !Kung are a San people. Hunters in one of the villages still use poison arrows to bring down game.
"We got a little Plexiglas and got the people to put their hands on it with their fingers spread. We took a photograph with a scale, and took the measurements," says Manger.
He and his team obtained accurate recordings of 152 !Kung hand prints, and compared them with the hand stencils.
"You cannot tell them apart," says Pettigrew.
The authors of the paper suggest that the ancestors of the San were survivors of the Toba. It is believed that this eruption spewed so much sulphur into the atmosphere that it plunged the planet into a nuclear winter, thereby killing off most the human population. Supporters of this theory point to bottlenecks in human DNA that suggest a massive die-off.
"Toba was the biggest eruption of the past 2-million years. The ash cloud covered everything from North Africa to Malaysia. The ash was 3m deep in India. A sulphate cloud caused complete darkness over the whole planet for seven years," says Pettigrew.
"Only 100 to 10,000 modern humans survived," he says.
The San hand stencil theory is proving quite controversial. Critics point to the lack of any substantial genetic evidence of these early Africans in modern European populations
The theory holds that small bands of humans were able to hang on in Africa and about 40,000 years ago headed out of the continent.
Pettigrew says that there is other evidence that supports his theory. A recent dating of French rock art has suggested that the art was painted at an earlier date. There is also evidence in the archaeological record.
"The Proto-aurignacians [who arrived in Europe around 43,000 years ago] tracked the warm environs of the Mediterranean from the south and used a very fine point stone industry that is perfectly consistent with the San hunting style of dart and track," he says.
The San hand stencil theory is proving quite controversial. Critics point to the lack of any substantial genetic evidence of these early Africans in modern European populations.
But ancient San genetic lineages are common among South Africans today. Pettigrew says he can explain this.
It is possible that the San lineages in Europe were simply wiped out over time.
"It is now known that other Palaeolithic humans, like Oase-1, have haplotypes that never reached modern human genomes," Pettigrew points out.
He adds: "It is an old-fashioned fallacy to drag that out. Whole races of humans have been wiped off the map, so no surprise for a diminutive, gentle race like the San."
Oase-1 was the name given to a modern human mandible that was discovered in Romania and dated to between 37,000 and 42,000 years old.
When DNA was extracted from the bone, it was found that this individual contributed no genetic material to modern European populations.
A recently released academic paper also suggests the Toba volcanic explosion might not have been as catastrophic as originally thought.
Scientists studying the remains of plant life from the eruption period in the vicinity of Lake Malawi said they found no indication of a die-off.
Another critic of the theory is Prof David Pearce of the Rock Art Research Institute at the University of the Witwatersrand.
"To suggest that contemporary San are somehow unchanged for 400,000 years is absurd," he says.
He adds that there are differences between the rock art the San left behind in Southern Africa and the images in the European caves.
Paul Pettitt, professor of Palaeolithic archaeology at Durham University, UK, says the theory is not surprising.
"We know that Europe was ultimately first occupied from an African source, hence some anatomical and genetic similarities are not surprising. It is a long way from this knowledge, however, to the assumption that it was the San who dispersed into western Europe around 40,000 years ago," he says.
Pettitt says he is concerned about Snow’s database. His research recreating the hand stencils shows that photographs of the images often created distortions, particularly of the subjects’ finger lengths.
He was a co-author of a recent study that suggests the hand stencils are even older than the first out-of-Africa migrations. Using isotope analysis he discovered that some cave art in Spain that is older the 64,000 years. This includes hand stencils, and the authors suggest that the artists were Neanderthals.
Proving that it was indeed the San who left those cave hand prints might be possible with the use of the staple of CSI work — DNA evidence.
Pettigrew would like to try a new ground-breaking technique for recovering ancient DNA. In 2017, geneticists were able to "fish out" tiny DNA fragments of human, Neanderthal and Denisovan DNA from the floor dust of seven caves across the European continent.
Pettigrew believes that San DNA might still linger in the dust below those hand stencils, proving that they trekked out of Africa aeons ago.