An online article in Discovery News by Tia Ghose of Livescience reports on the recent discovery of 20 Stone Age skeletons in a rock shelter in Libya’s Sahara Desert. The burials spanned thousands of years, dated between between 8,000 and 4,200 years ago, suggesting the place was a persistent cemetery for the local people. The rock art in the area is both numerous and varied.

“It must have been a place of memory,” suggests study co-author Mary Anne Tafuri, an archaeologist at the University of Cambridge. She believes that people throughout time have used it, burying people generation after generation.

About 15 women and 𝘤𝘩𝘪𝘭𝘥ren were buried in the rock shelter, while five men and juveniles were buried under giant stone heaps called tumuli outside the shelter during a later period, when the region turned to desert.

The findings, which are detailed in the March issue of the Journal of Anthropological Archaeology, suggest the culture changed with the climate.

Tafuri and her colleague Savino di Lernia began excavating the archaeological site between 2003 and 2006. At the same site, archaeologists also uncovered huts, animal bones and pots with traces of the earliest fermented dairy products in Africa.

To date the skeletons, Tafuri measured the remains for concentrations of isotopes. The team concluded that the skeletons were buried over four millennia, with most of the remains in the rock shelter buried between 7,300 and 5,600 years ago. These prehistoric communities also grew up not far from the area where they were buried, based on a comparison of isotopes in tooth enamel, which forms early in 𝘤𝘩𝘪𝘭𝘥hood, with elements in the nearby environment.

The males and juveniles under the stone heaps were buried starting 4,500 years ago, when the region became more arid. Rock art confirms the dry up, as the cave paintings began to depict goats, which need much less water to graze than cows.

The findings may reveal a divided society; the exclusive use of the rock shelter for female and sub-adult burials points to a persistent division based on gender. One possibility is that during the earlier period, women had a more critical role in the society, and families may have even traced their descent through the female line. But once the Sahara began its inexorable expansion into the region about 5,000 years ago, the culture shifted and men’s prominence may have risen as a result.

The new discovery also highlights the need to protect the fragile region, which has been closed to archaeologists since the revolution that ousted dictator Moammar el Gadhafi.