Just because our Stone Age predecessors lived in caves doesn’t mean they couldn’t appreciate soft, comfortable bedding. Humans in South Africa used layers of leaves and stems for dozing and lounging as early as 77,000 years ago, according to research appearing in the December 9 issue of Science. And evidence suggests their primitive pallets had advantages over today’s most sophisticated mattresses: Made with plants that naturally repel insects, they protected defenseless sleepers from disease-carrying flies and mosquitoes.

Between 77,000 and 38,000 years ago, hunter-gatherers used the Sibudu rock shelter in South Africa as a home base when they weren’t busy following game herds or seeking out new food sources. Archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg has been excavating the site, which lies above the uThongathi River, since 1998. Last November she and a team of researchers made an intriguing discovery nearly 10 meters below the surface, where they unearthed fossilized layers of grass-like plants known as sedges topped by a thin sprinkling of leaves.

“The fossilized leaves were uncovered as a ‘sheet’ of white plant matter overlying layers of sedge leaves and stems,” recalled Wadley, who described the find in Science along with several co-authors. “I suspected whilst excavating them that the leaves were deliberately collected as part of bedding because all the leaves were clearly the same taxon. If leaves had simply blown into the site from the forest, there would have been several different tree species represented.”

The team determined that Sibudu’s sporadic inhabitants were bunking down on these natural sleeping bags as far back as 77,000 years ago, making the site’s ancient bedding 50,000 years older than other known examples. People probably collected sedges and grasses from the nearby river valley to blanket the shelter’s hard rock floor, Wadley said. Tools and charred boned found among the plant layers imply that the mats also served as comfortable surfaces for sitting, eating and working during the waking hours, Wadley explained.

Further analysis showed that these makeshift cave carpets probably served another important purpose. Botanists identified the leaves covering each layer as belonging to the Cryptocarya woodii tree, which gives off a pleasant smell and contains insecticidal chemicals. “The bedding was topped with aromatic leaves that not only smelt good, but had chemicals to repel insects and possibly other pests,” Wadley said. “The leaves were probably used to repel mosquitoes from this site, which is near a river. People constructed their bedding with this protection in mind. They clearly understood medicinal plants and probably used herbal medicines for a variety of purposes in other contexts, though we presently have no further evidence for this.”

Since insects that carry fatal illnesses are endemic to Africa, the bedding at Sibudu might have improved health conditions at the camp and even saved lives. “Even when mosquitoes are not malaria vectors, their bites can cause infection and disease,” Wadley noted. “The protection of small children from biting insects would have been especially important for preventing child mortality. The leaves may have repelled flies, too, and flies are another cause of disease.”

Around 73,000 years ago, the people of Sibudu began burning their bedding before packing up to leave, archaeological evidence shows. An important clue to the nomadic population’s habits, this suggests that they frequently returned to the same shelter, Wadley sad. “Burning fusty bedding was a way to clean up the site for instant re-use,” she explained. It also sheds light on how the people of Sibudu harnessed fire for more than just cooking, warmth, protection and manufacturing adhesives for tools, she added. “Our research adds that fire was used as a sanitizing agent that enabled a camp site to be occupied repeatedly,” she said. “The bedding was burnt primarily to rid it of pests—insects and perhaps rodents—and to clean up decaying organic material.”

Previous research by Wadley and her colleagues has painted a detailed picture of the lifestyle and culture of Sibudu’s population during the Middle Stone Age. Moving frequently between shelters and open-air campsites, they used spears and other weapons to hunt large animals such as zebras and buffalo. Along with stone and bone tools, they crafted ornaments from seashells. But the bedding discovery in particular rounds out our understanding of their daily lives, Wadley said. “Archaeologists tend to focus on rare finds such as early ornaments and engravings,” she said. “However, domestic activities, like preparing and destroying plant bedding, can also provide important information about changing settlement patterns and even demography.”