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Border Cave enters the mountains of the South African border with Eswatini.
Border Cave is a deep cliff-deep cut on top of South Africa’s Lebombo Mountains. Protected from the elements, the site has provided preserved bones, equipment and plant curtains that have provided a detailed picture of human life for more than 200,000 years. Now a new comic strip is emerging: the plants continue to show that the occupants of the cave used grass about 200,000 years ago. Investigators said the occupants of the cave placed their disorder on the ashes to repel the insects.
The preserved disorder will be recorded in the ranks of other “incredible discoveries” in the African archaeological archives, says Javier Baena Preysler, archaeologist of the Autonomous University of Madrid who was not interested in research. But other researchers point to uncertainty at the times and point out that, in the absence of a time machine, scientists will have to speculate on how ancient peoples used stacked herbs and ashes.
Lyn Wadley, an archaeologist at the University of The Witwatersrand, made the discovery of border cave excavation with his team. One morning, he saw white spots on the brown soil of the sediment as he dug. “I looked at them with a magnifying glass and found out they were plant lines,” he says.
Wadley thoroughly disposed of small pieces of sediment and stabilized them into small plaster “shirts”. Under a microscope, she recognized that these plant curtains belong to the panicoideae circle of herbal relatives growing in the region.
Archaeologist Lyn Wadley saw small white marks on the sediments of the Border Cave that appear to be compressed and preserved plant matter.
Amounts of grass recommend that other people deliberately take her to the cave, Wadley said. The sediment showed repeated layers of plants and ashes, he said, and recommended that the curtains be used to create a blank, padded floor surface.
Researchers can’t know for sure that other people slept on the lawn. But they describe it as “liter” because humans are most likely to use the padded surface of the floor to sleep. This is “the credible maximum performance,” admits Baena Preysler.
The sediment layer containing the grass is discovered deep in the layers dug into the cave, near the rock bed. Researchers dated two remote teeth discovered in the same layer about 200,000 years ago measuring the amount of radiation the dental teeth had been exposed to. Date levels for either tooth are wide, one greater than 200,000 and the other younger.
Using only those two teeth dates is a little fragile, says Dani Nadel, an archaeologist at the University of Haifa who doesn’t care about the job: “Sometimes those dates aren’t very accurate.”
If the dates are kept, Border Cave beds would be the first evidence that humans are using camp beds. The earliest known plant leaf littory, in The Sibudu Cave in South Africa, dates back 77,000 years, there is provisional evidence of leaf littoral layers from about 185,000 years ago in Israel.
The bedding itself “doesn’t really tell us anything about the complex cognition of humans,” Wadley says. Many other animal species, adding birds, rodents and other primates make nests. But the fabrics discovered along the lawn recommend more elaborate behaviors. The ashes, as well as burnt grass, woods and bones, recommend that the cave population periodically burn the disorder, to rid the site of “disorder and smelly parasites,” Wadley explains. Some of this burnt wood came here from the broad-leaf camphor shrub, a species still used as insect repellent in South Africa.
Repeated layers of ash and plant matter recommend that ancient humans intentionally put disorder on the ashes, Wadley says. People from all over the world, adding to present-day Cameroon, have long used types of ash to repel and kill insects by blocking their respiratory apparatus and bites. Border Cave’s evidence recommends that humans intentionally used ash and medicinal plants to keep their camps blank and parasite-free, Wadley and his colleagues today reported at Science.
However, “it’s very difficult to solve,” says Dan Cabanes, a microarqueologist at Rutgers University in New Brunswick, “you can’t ask those people.”
However, he says, the discovery underscores how botanical archives are probably not found in archaeological sites around the world. Plants are a giant component of the diet of fashionable humans, along with a variety of other uses, from clothing to medicines, so there is a smart explanation for why our ancestors relied heavily on plants in their daily lives, Cabanes says. But sophisticated lines of old plants can be safely overlooked, he says, “How much of this story do we miss?”
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