A stone-age hunter’s wisdom tooth has revealed that he had an unusual mix of racial traits – dark, African skin, curly brown hair and blue eyes.
Preliminary DNA analysis of the exceedingly well-preserved 7,000-year-old skeleton, dubbed Brana-1, has overturned ideas about the descent of modern Europeans.
Although the hunter’s closest modern-day relatives live in Sweden and Finland, the genes for his skin colour are African.
Previously, scientists thought that fair skin evolved as people moved to northern latitudes, allowing them to absorb more sunlight for the production of vitamin D.
But Carles Lalueza-Fox of the Institute of Evolutionary Biology (IBE) in Barcelona thinks it was the later shift to agriculture that was decisive. (Link to research--in Spanish.)
Pre-farming humans would have gotten most of their vitamin D from eating meat, fish and eggs, while early agriculturalists would have relied more on sunlight.
An artist's impression of what Brana-1 may have looked like. Credit: Superior Council for Scientific... [+]
“It seems possible that latitude is not the key factor in skin depigmentation, but diet,” said Dr Lalueza-Fox, the lead author of a paper on the discovery in Nature. “This guy had to be darker than any modern European, but we don't know how dark.”
The mutation for blue eyes, a change in the HERC2 gene, is thought to have first appeared around the Black Sea 10,000 years ago and then gradually moved west. Because the gene is recessive, blue-eyed people must have two copies, one from each parent. Remains of the hunter and another human were discovered by cavers in Brana-Arintero, a deep, complex cavern in the Cantabrian Mountains near Leon, Spain, in 2006. The constant cool temperature in the cave, 1,500 metres above sea level, protected the remains from bacteria.
Excavated by Julio Manuel Vidal Encinas, an archaeologist with the Council of Castilla y Leon, they were carbon dated to the Mesolithic era, which in Northwest Europe lasted from 10,000 to 5,000 years ago. Among artifacts found with them were perforated teeth of red deer that decorated their clothing like beads.
Brana-1, the better preserved of the two sets of remains, was 1.7 metres tall and between 30- and 35-years-old when he died. “Before we started this work, I had some ideas of what we were going to find,” Dr Lalueza-Fox said. “Most of those ideas turned out to be completely wrong.”
Among them was his immune system. Previously, scientists thought that farming led to genetic changes to the immune system that helped people deal with infections caught from livestock, including polio and tuberculosis. But Brana-1 already had these changes, possibly because the diseases, and the genetic defences against them, spread faster than the technology.
“It appears that the first line of defense against pathogens was already there,” says Wolfgang Haak, an ancient DNA researcher at the University of Adelaide in Australia. On the other hand, genes for processing lactose, the main sugar in milk, or starch, both of which are more common in agricultural diets, were in “ancestral forms”.
Earlier results from the find, based on an analysis of mitochondrial DNA, showed that Brana-1 shared a common ancestor with the 24,000-year-old remains of a Mal’ta child who lived at Lake Baikal in Siberia. Both are part of the Paleolithic Venus culture, which is identified by small, rounded female figurines. The researchers hope to extract and analyse DNA from Brana-2 next.
