NGAYÈNE, Sénégal - The worn-out cassette in the tape deck is apparently a favorite, a garbled, tinny, seemingly endless loop of African reggae, a perfect soundtrack to the scene outside the window: palm trees, savannah grasses, and glimpses of the Gambia River, all blanched by a blazing sun.
It's 110 degrees outside and I'm in a crowded van, but there's a breeze. I'm seeing water after days in a dry, remote village in southern Sénégal, and I'm following a trail of prehistoric, megalithic burial sites scattered across 13,000 square miles of Sénégal and The Gambia.
Sénégambian stone circles come in several forms. The most common consists of a dozen or so monolithic, laterite pillars, arranged in a circle around a grave, with one "frontal stone" on the eastern side. These circles, along with smaller stone ones and simple stone-covered mounds, or tumuli, were secondary burial sites. Bones were placed here after the rest of the body decomposed at a primary site. The bones, usually from several bodies, were arranged according to an elaborate plan that no one today understands.
The circles were also grouped in precise arrangements that are equally mysterious. And it was all done by a people that no historian or anthropologist has been able to identify, even though the circles were made continuously for about 2,800 years starting in 1300 BC. The circles are so absent from any conventional history, in fact, that although there are about 17,000 stone circles in 2,000 groupings across the region, most of my Sénégalese friends had never heard of them.
The harder it was to learn about these formations, the more I wanted to know. My obsession led me to the Sénégalese village of Ngayène, whose surrounding prairies are peppered with stone-circle groups, and to Augustin Holl, a professor of anthropology at the University of Michigan, Ann Arbor, and curator of West African archeology at the university's Museum of Anthropology. Holl and his collaborator, Hamady Bocoum of Sénégal's Université Cheikh Anta Diop, are experts on Sénégambia's stone circles.
I arrived at the end of the dry season. The earth was parched; the golden grasses crackled underfoot; and cherry-red grasshoppers the size of hummingbirds made 10-foot-high leaps around me as we walked to the Ngayène II circle group. The stones here are low, 2 to 3 feet above ground, but stunning. The deep-red, rough-hewn pillars look weighty and majestic, but so organic they seem to have grown out of the earth. Holl told me about his excavations in the area: One turned up five full bodies, with all 10 legs bent to form a pattern. In another circle, he and his team found 20 skulls on one side, and on the other, iron spearheads, and hundreds of thigh and arm bones (one still wearing a copper bracelet). Several of the circles have an upper layer of jawbones covered with upside-down clay pots.
Clearly, these people had elaborate "mortuary codes," prescribed rituals for handling the deceased, Holl explained. "There may have been some kind of selection criteria based on the person," said Holl. "It may be, that for older people, the skull was taken, for a hunter, the humerus, the chest for a child. But," Holl said, as he often did when talking of his theories, "we really don't know." I suggested contacting a mathematician; maybe there's an algorithm. He nodded and laughed. "We're trying to crack the code."
The next day we went to Holl's dig at Santhiou Ngayène, where one circle grave was found to contain long bones lined up vertically in a circle, like a white picket fence. Inside the fence were more skulls, and closer to the surface, more pots and teeth. I was pondering this when Holl handed me a dental tool normally used for removing tartar, and told me to start picking. A stone circle had been emptied to about a yard down, revealing a lump of dirt and bones in the middle. We began carefully removing the dirt, trying not to break any bones, which were surprisingly fragile. I kept finding columns of earth that appeared to be bone. "That's just clay," Holl said, but that wasn't the whole story: It turns out that bones actually become clay before dissolving into soil. After several hours, we had uncovered a group of skulls and long bones.
We moved on to nearby Sine Ngayène, which once comprised 52 monolith circles surrounded by hundreds of tumuli across 750 acres. Most of the tumuli have since been flattened for farmland, but the monoliths remain - hundreds of waist-high stones spread out in an asterisk-like burst. Because each circle has a frontal stone facing due east, one theory is that they may have been used to monitor the season as the sun's position changed throughout the year. But then, competition for land was fierce at times. Maybe, Holl hypothesized, putting an ostentatious cemetery on your land prevented anyone from taking it. Advances in DNA testing may help Holl's quest: He hopes that someday the tests will support or disprove another theory - that the cemeteries were related to ancestor worship.
While Holl is working to apply science to the mystery of the stones, the people in The Gambia, where few excavations have been carried out, seem content to bask in the unknown. I continued on to Wassu, a small town near the Gambia River, with two circle groups nearby, Wassu and Kerr Batch. Unlike the circles in Sénégal, these are easy to find and have on-site museums. But here, instead of theories, they have legends.
I wandered around the Wassu circles with its museum attendants, Morro Komma and Pa Sanyang. Like all Gambian megaliths, these are topped with a pyramid of smaller stones. The practice of putting a small rock on a megalith and making a wish has existed for longer than anyone can remember. But it makes the megaliths living, functional monuments: "People stop by to make a wish on their way to the market," Komma said.
The monoliths here are also taller and thicker than those of Ngayène; at one Gambian site, the stone pillars each weigh seven tons. The imposing Wassu stones have a regal quality, and as the sun set on them, I had the uncanny feeling that I was in another time.
But the circles at Wassu ultimately exist very much in the present. They're surrounded by rows of tilled soil, for one. "Oh, those," Sanyang said. "They're sweet potatoes." (Keeping the land cultivated wards off brush fires.) The museum has a display on local stories about the stone circles: "The dead were thrown into a communal pit," "The individuals were buried alive as sacrificial victims," and so on.
But the most intriguing story was one that, according to Komma and Sanyang, was not myth but fact: At night, lights can be seen shining from the Wassu megaliths, but they fade when anyone approaches. "I was here one morning at 6 a.m.," Sanyang said, "and a light flashed on me." I asked what the light was like, thinking it would be soft like an apparition, or radiating warmth. "It was like a car headlight. It came towards me, but when I moved closer, it disappeared," Sanyang said.
By the end of my trip, I had seen dozens of stone circles, but it seemed that I left knowing even less than when I started. Maybe it's only through mystery that we can understand a past that has been lost to us.
Amy Karafin can be reached at firstname.lastname@example.org.