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Excellent archaeological study, and doubly so for the rarity of the subject, on Neolithic peoples of the Air Massif (Niger). Two distinct populations are found, described as Kiffian and Tenerean by cultural adscription. The first show clear correlation with North African Oranian and Capsian types, as well as other types described as "Mechtoid" (African Cro-Magnids).

Burial site offers rare glimpse of daily life in the stone-age Sahara.

Heidi Ledford Side by side, their faces blurred, they lie in sandSide by side, their faces blurred, they lie in sandMike Hettwer © 2008 National Geographic

She was in her twenties when she died; the children were roughly five and eight. No one knows what killed them or what happened after, but it’s easy to speculate. Perhaps she took her children fishing for catfish or perch in a nearby lake and they all drowned; perhaps their loved ones laid them on a bed of flowers. However it happened, they were buried with their arms wound together in a final embrace.

5,000 years later, the sight of the three skeletons still entwined, long after the bones had been stripped and hardened by sand and heat, long after lakes and flowers had vanished from the landscape, moved the archaeologists who found them almost to tears.

In recent years, nearly 200 human burials have been uncovered in a region of Niger that researchers have named ‘Gobero’. An analysis of these remains, published this week in PLoS ONE1, provides unprecedented detail about life in the Sahara at a time when the region was green and hospitable, a place where antelope and cattle grazed on plants while hippos and crocodiles swam in fish-stocked lakes.

The site’s former residents left behind not only cemeteries but also middens and traces of ceramics. The normally unforgiving desert has preserved it all in intricate detail, all the way down to the neatly-stacked left-over shells of a clam dinner.

The remains reveal the patterns of human migration into and out of the area over the past 10,000 years as the local climate fluctuated between wet and dry. “The Sahara is one of the great laboratories in the world for studying human response to climate change,” says Susan Keech McIntosh, an anthropologist at Rice University in Houston, Texas. “The kind of detail they have uncovered there is just exceptional.” An accidental discovery

A group of palaeontologists stumbled into Gobero eight years ago while trawling the desert for dinosaur fossils. The field work was, to all intents and purposes, over - but one of the team, Paul Sereno from the University of Chicago in Illinois, persuaded the rest to keep going. “Can’t we just go to that little spot over there,” he said, pointing to the horizon. “Then I promise we’ll turn back.”

When they arrived, blackened, fossilized bones were visible from the car window. The team briefly looked around, decided there were perhaps fifteen skeletons in the area, and piled back into the car, vowing to return. It would be another three years before they would begin to excavate the site and realize the enormity of the find. Paul Sereno and a resident of the greener worldPaul Sereno and a resident of the greener worldMike Hettwer © 2008 National Geographic

Since then, Sereno has gathered an international team of researchers and funding from the National Geographic Society to study the site in unusual detail. They have analysed pollen - traces of which suggest that burial bed of flowers - ceramics, rocks and bones. And they have treated the site as palaeontologists treat dinosaur discoveries: rather than removing bones individually, as archaeologists often do, they have treated the sand surrounding the skeletons to harden it, then created plaster jackets to lift out entire skeletons and their immediate surroundings for transport to the lab.

The harsh conditions of the Sahara have made some forms of analysis difficult. Because the remains were found in loose sand, they had to be dated directly, rather than relying on the age of the sediment around them. Researchers normally do this by analysing scraps of collagen left clinging to bone, but the heat and sand had polished these bones clean. Instead, they had to carbon date the carbonate found in the bone and tooth enamel - a more destructive and less familiar method.

The efforts have allowed them to piece together a history of the region that involves two occupations by distinct populations of humans. The first were hunter-fisher-gatherers who arrived in the early Holocene, nearly 10,000 years ago. When the nearby lake dried up, they left, leaving behind some of the bone harpoons they used to fish 200-pound perch.

The next occupants arrived about 7,000 years ago. They were more petite and had longer, narrower skulls. Their burials were also more elaborate, with a fifth of the sites studied so far containing ornaments made of bone, ivory, and shells. Evidence of fishing suggests the lake was back, too.

Not everyone is convinced that the two populations are distinct. Joel Irish, an anthropologist at the University of Alaska, Fairbanks, says that the quality of the Gobero analysis is striking, but he wants to analyse the dental features for unique grooves and cusps characteristic of different populations before he rules out the possibility that the original inhabitants simply returned to the area after the lake reappeared.

Meanwhile, the condition of the bones has also complicated the isolation of DNA from the skeletons. Sereno says that he has tried unsuccessfully to extract DNA from the roots of four teeth but he remains optimistic: “It’s going to take more of an effort, but I think it’s possible,” he says.

nature.com

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