The oldest known grass beds from 200,000 years ago included insect repellents

The ancient bed remnants include fossilized grass, bug-repelling ash and aromatic leaves

South Africa’s Border Cave

South Africa’s Border Cave, shown here at its entrance, contains bits and pieces of the oldest known grass bedding, dating to around 200,000 years ago, researchers say.

A. Kruger

People living in southern Africa around 200,000 years ago not only slept on grass bedding but occasionally burned it, apparently to keep from going buggy.

Remnants of the oldest known grass bedding, discovered in South Africa’s Border Cave, lay on the ashes of previously burned bedding, say archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg and her colleagues. Ash spread beneath bound bunches of grass may have been used to repel crawling, biting insects, which cannot easily move through fine powder, the researchers report in the Aug. 14 Science. Wadley’s team also found bits of burned wood in the bedding containing fragments of camphor leaves, an aromatic plant that can be used as a bug repellent.

Prior to this new find, the oldest plant bedding — mainly consisting of sedge leaves, ash and aromatic plants likely used to keep insects away — dated to around 77,000 years ago at South Africa’s Sibudu rock-shelter.

At Border Cave, chemical and microscopic analyses of excavated sediment showed that a series of beds had been assembled from grasses, such as Guinea grass and red grass. Guinea grass currently grows at Border Cave’s entrance. Bedding past its prime was likely burned in small fire pits, the researchers suspect. Remains of fire pits were found not far from Border Cave’s former grass beds.

Grass fragments uncovered in South African cave
Preserved grass fragments uncovered in a South African cave, left, are by far the oldest known examples of grass bedding, researchers say. Close-up images of those fragments taken by a scanning electron microscope, such as the one shown at right, helped to narrow down what type of grasses were used for bedding.L. Wadley

Humans in southern Africa intentionally lit fires by around 1 million years ago (SN: 4/2/12). But Border Cave provides the first evidence that ancient grass bedding was burned on purpose.

Small, sharpened stones were also found among grass and ash remains, suggesting that people occasionally sat on cave bedding while making stone tools.

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