Investigating the Border Cave, between Swaziland and South Africa, researchers also found layers of ash, probably used against crawling insects.
Researchers at the University of the Witwatersrand, South Africa, found evidence that our ancestors slept on beds made of grass 200,000 years ago.
The discovery was made at Border Cave, located between Swaziland and South Africa, and the results were published this week in the journal Science.
The beds, made up of sheaves of grass, were found at the back of the cave on top of layers of ash, which were apparently used to keep crawling insects away during sleep.
Currently, the material is fossilized and, therefore, scientists had to use magnification and chemical characterization to identify it.
“We speculate that laying grass bedding on ash was a deliberate strategy, not only to create a dirt-free, insulated base for the bedding, but also to repel crawling insects,” said Lyn Wadley, the study’s lead author.
“Sometimes the ashy foundation of the bedding was a remnant of older grass bedding that had been burned to clean the cave and destroy pests. On other occasions, wood ash from fireplaces was also used as the clean surface for a new bedding layer,” Wadley added.
Several cultures used (and still use) ash as a strategy against insects. At the discovery site, scientists identified remains of Tarchonanthus (camphor bush), a plant still used to repel insects in East Africa.
According to the researchers, insects have difficulty moving through the fine powder because it blocks the breathing and the biting apparatus of these animals, eventually dehydrating them.
“We know that people worked as well as slept on the grass surface because the debris from stone tool manufacture is mixed with the grass remains,” Wadley said. “Also, many tiny, rounded grains of red and orange ochre were found in the bedding where they may have rubbed off human skin or coloured objects.”
For centuries, hunter-gatherers used fire as the camp’s reference point: they slept close to it and performed domestic tasks in social contexts.
Among the several generations that passed through Border Cave, they all lit fires regularly: debris of burned material was found that dates from 200 thousand to 38 thousand years ago.
Although hunter-gatherers of the time rarely stayed in the same place for more than a few weeks, safer and cleaner camps had the potential to extend their stay.
“Our research shows that before 200 000 years ago, close to the origin of our species, people could produce fire at will, and they used fire, ash, and medicinal plants to maintain clean, pest-free camps,” Wadley said. “Such strategies would have had health benefits that advantaged these early communities.”