Saharan surprise

Normal 0 false false false MicrosoftInternetExplorer4 Investigators searching for dinosaur fossils in the Sahara in 2000 suddenly took an unexpected and scientifically exciting leap backward in time. They came upon a stretch of sand littered with the bones of ancient people positioned in ways characteristic of intentional burials.

Investigations of the bones and associated finds made since that fateful discovery show that they come from the largest and oldest Stone Age graveyard in the Sahara, team members report online in the Aug. 14 PLoS ONE. They also described their findings August 14 during a press briefing held at the National Geographic Society in Washington, D.C., which partly funded the excavations.

The Gobero archaeological site, which dates to as early as 10,000 years ago, lies in the western African nation of Niger. The area had already gained fame earlier when excavation director and paleontologist Paul Sereno of the University of Chicago found 110-million-year-old dinosaur fossils nearby.

Work at Gobero indicates that two successive human populations divided by 1,000 years lived by a lake, perhaps seasonally, during a time of regular Saharan rainfall. These hunter-gatherer groups buried their dead in separate gravesites by the lake, leaving an unprecedented biological and material record of their poorly understood cultures.

Although hunter-gatherer groups are typically mobile and small in number, those living in resource-rich areas tend to stay for long periods at seasonal sites, comments anthropologist Henry Harpending of the University of Utah in Salt Lake City. “It’s interesting that at Gobero these ancient populations became dense enough to require large cemeteries,” he says.

Excavation seasons in 2005 and 2006 have revealed 200 graves. Human and animal bones, as well as bone artifacts, have yielded 78 radiocarbon dates, which are based on ratios of different isotopes of carbon in the bones and artifacts.

“I’ve never seen an archaeological site that’s as exceptional as Gobero is,” archaeologist and team member Elena Garcea of the University of Cassino in Italy said at the press briefing.

The older Gobero group, members of the Kiffian culture, hunted large game and speared two-meter-long perch with bone harpoons. They colonized the Sahara from 10,000 to 8,000 years ago, when heavy rains created a deep lake at Gobero. Pottery pieces at the site are decorated with zigzags and wavy lines already linked to the Kiffians, Garcea says.

Kiffians buried dead individuals with their legs pulled up tightly against their body, suggesting that the deceased were bound up with some type of wrapping. Both adult males and females often reached two meters in height.

The later Gobero residents, from the Tenerian culture, hunted small game using tiny stone arrowheads, caught small catfish and tilapia and herded cattle. The Tenerians inhabited the site from 7,200 to 4,200 years ago, when it featured a shallow lake. Parallel lines of impressed dots cover Tenerian pottery. Tenerians were shorter and had slighter builds than Kiffians did.

Tenerians often buried their dead with jewelry and placed them in ritual poses. The 4,800-year-old skeleton of a girl lying on her side, with arms and legs slightly bent, includes an upper-arm bracelet carved from a hippo’s tusk. Based on her bone development, the researchers estimate that the girl was 11 years old when she died.

The most striking find occurred in 2006, when the researchers uncovered what they say is Africa’s first triple burial. A petite, 40-year-old Tenerian woman lay on her side, facing two children, an 8-year-old and a 5-year-old. Their entwined arms reached out and their hands clasped in what Sereno’s team calls the “Stone Age embrace.” These individuals died from undetermined causes 5,300 years ago.