Green Sahara
Gobero and the Green Sahara

About 12,000 years ago slight changes in Earth's orbit spurred complex environmental changes that caused the African summer monsoons to shift some five degrees north, bringing wetter conditions to a previously arid swath of the Sahara. In the heart of what is now the Ténéré desert, in northern Niger—one of the Sahara’s most desolate regions—new lakes and rivers fed lush vegetation that drew animal life and eventually people. The Ténéré remained verdant for most of the early- to mid-Holocene (10,000 to 5,000 years ago). Thousands of engravings in the desert rock depict a time when elephants, giraffes, and ostriches roamed the land, and archaeologists have found stone tools and ceramics that have enabled them to get a sense of what life was like for the people drawn to this remote region. Now this part of the Sahara is dry and barren once more, home only to Tuareg nomads and their camels.

In 2000 Paul Sereno, a paleontologist at the University of Chicago, was wrapping up a long dinosaur-hunting expedition in the Ténéré, when team photographer Mike Hettwer happened upon a dune field filled with human bones. His surprising discovery turned out to be the largest known cemetery in the Sahara. Because of an ongoing conflict between the Niger government and the Tuareg who rule the region, expeditions to the Ténéré are difficult—and sometimes forbidden. Sereno wasn't able to return until 2003, when a three-day inventory of the site convinced him that it was time to bring in archaeology and biology experts to properly excavate the cemetery. The team that arrived at the site in 2005 dubbed it Gobero, after the Tuareg name for the region.

With the help of archaeologist Elena Garcea of the University of Cassino in Italy, the group discovered that two populations of Neolithic settlers, the Kiffian and the Tenerian, had once occupied Gobero. One startling finding was that the two groups had lived more than a thousand years apart—the Kiffian from about 10,000 to 8,000 years ago and the Tenerian from about 6,500 to 4,500 years ago—but they'd buried their dead in the same cemetery. As potsherds, debris from middens, former lake-bed sediments, and the skeletons themselves were freed from the sand dunes in 2005 and during a second trip in 2006, the story of these ancient people began to emerge. Subsequent political conflict caused the Niger government to ban foreigners from the Ténéré, and Sereno's team had to cancel plans to return in 2007 and 2008. As relentless desert winds scatter the remains of the Gobero cemetery, the team yearns to go back before the secrets of the ancient Kiffian and Tenerian are lost forever.

De Villiers, Marq and Sheila Hirtle. Sahara, A Natural History. Walker and Co., 2002.

Gwin, Peter. "Lost Tribes of the Green Sahara." National Geographic (September 2008), 126-43.

Kutzback, J., and others. "Vegetation and Soil Feedbacks on the Response of the African Monsoon to Orbital Forcing in the Early to Middle Holocene." Nature. Vol. 384 (1996), 623-26.

UNESCO. "African Pollen Database Report 2001. Records of Past Land Cover Changes: Climate and/or the Human Impact." IGCP 431-EU INCO-DC (DG XII ERB3514PL972473).

Other Resources
Salopek, Paul. "Lost in the Sahel." National Geographic (April 2008), 34-67.

Handwerk, Brian. "Stone Age Cemetery, Artifacts Unearthed in Sahara." National Geographic News, October 26, 2005.

Project Exploration.

Kiffian and Tenerian: What We Know

Little is known about the cultures that occupied the southern Sahara at a time when the desert was wetter and more hospitable to life than it is today. But with the discovery of some 200 burials at Gobero, striking evidence is coming to light about two cultures that lived in the now hyperarid Ténéré desert in Niger. The Kiffian, who began living there about 10,000 years ago, were a fishing-based culture that inhabited a lush setting abundant with water-adapted animals until about 8,000 years ago. More than a thousand years passed before the next inhabitants, the Tenerian, settled in the same region; they seem to have adopted both herding and hunting practices, pursuing animals drawn to the region's diminishing lakes. We can distinguish between the cultures by their pottery, stone tools, and burial practices.

While Paul Sereno's team discovered few ornamental artifacts from this early culture, the Kiffian ceramic vessels they found are decorated with wavy lines and zigzags. The Kiffian also fashioned harpoons and fishing instruments from bone—the size of some of the tools indicates that they sought Nile perch weighing hundreds of pounds and perhaps hunted hippos and crocodiles.

The Kiffian were tightly bundled before burial, perhaps squeezed into a basket or pouch that has long since disintegrated. There's evidence that they stood up to six feet eight inches tall and had a robust musculature. The skeletons the archaeologists found are dark in color, likely because the lakes that flooded around 8,000 years ago inundated the cemetery and stained the bones.

The Tenerian, who occupied the site during the late-mid Holocene, some 6,500 to 4,500 years ago, were shorter and more gracile, with thinner skullcaps and higher foreheads than their predecessors. Their bones weren't darkened from inundation, indicating that the lakes were drying up, which eventually must have forced the Tenerian to leave. The dead were often buried on their sides in casual positions. Double burials and one especially poignant triple one—perhaps a mother and her two small children eternally locked in an embrace—distinguish these people from the Kiffian.

Most of the cultural artifacts found at Gobero are Tenerian. Their ceramics are decorated with dotted patterns created by pivoting a stamp, perhaps made from a clamshell, rather than with the wavy lines seen in the Kiffian ceramics. Many of the stone tools—scrapers, knives, ax heads, arrowheads—are made from a green stone called felsite that's found in a volcanic region about a hundred miles to the northwest; others are made of local rock or bone. Some ornaments are striking: a bracelet made of hippo bone and another of ostrich and warthog-tusk beads. There's also a hippo ivory pendant and other stone and bone pendants and beads.

No one knows whether these people came from the Mediterranean coast or the central African tropical forests or from Egypt. Nor do we know whether they were nomads or colonizers who traded or waged war with neighboring communities. What we do know is that by about 3,500 years ago seasonal monsoons that had brought life-sustaining rain to the previously arid desert had shifted south. The lakes dried up, the vegetation disappeared, and the people vanished.

Gwin, Peter. "Lost Tribes of the Green Sahara." National Geographic, September 2008, 126-143.

Sereno, Paul, and others. "Lakeside Cemeteries in the Sahara: 5,000 Years of Holocene Population and Environmental Change." PloS ONE, August 14, 2008.

The Value of Middens

A midden is essentially a trash heap. In an archaeological context, and especially when there is scant knowledge of a prehistoric culture, such a garbage pile is invaluable. At the Gobero site in northern Niger, zooarchaeologist Hèléne Jousee of the Natural History Museum in Vienna, Austria, has studied remains from five middens dug into the sand dunes by the region's prehistoric inhabitants. Four of the middens date from the time of Tenerian occupation, some 6,500 to 4,500 years ago. Only one reveals details of the Kiffian culture: It dates from a little over 8,000 years ago, when lake levels rose for a short period and forced the Kiffian to leave the site.

Middens can show how people lived (were they hunters, fishers, or gatherers?); what their ceramics looked like; what they ate (was their diet primarily one of fish, clams, or rodents?); and what their environment was like (deeper lakes with bigger fish or lower lake levels with smaller fish?). The middens at Gobero had accumulated rapidly. They hadn't been trampled or otherwise disturbed, and they'd preserved even small bones, which reveal a diversity of life in this now uninhabitable region. There are striking differences between the contents of the Kiffian and Tenerian middens.

The Kiffian midden was only about a meter in diameter and was preserved down to 15 centimeters. It contained a remarkable number of fish bones—more than 30,000. Almost 90 percent of them were tilapia (Tilapia) and less than 10 percent catfish (Clarias). No mollusk shells were found in the Kiffian midden.

By contrast, the later Tenerian midden was bigger and deeper and contained several species of thin-shelled clams. The most abundant fish in the Tenerian middens was catfish; tilapia, so abundant thousands of years earlier, represented less than 20 percent of the fish remains. From the size of the bones, Jousse determined that the fish were fairly small.

The size of the fish and the presence or lack of mollusks can indicate what the environment was like when people lived there—small fish may indicate that the lakes were shallow and that larger fish had escaped before levels dropped. Higher waters may have prevented mollusks from colonizing the lakes, explaining why they aren't found in the Kiffian midden. Evidence from the middens also raises questions: Was fishing done year-round or only seasonally? Why are there so few mammalian bones and so many turtle bones? Why are only small Nile perch bones found in the middens, when large ones can be found in nearby lake-bed sediments? The pursuit of ancient trash should yield a trove of answers.

Sereno, Paul, and others. "Lakeside Cemeteries in the Sahara: 5,000 Years of Holocene Population and Environmental Change." PloS ONE, August 14, 2008.

Jousse, Hèléne. "Animal Remains From Gobero, 2006." Unpublished excavation report.