The inhabitants of the Border Cave in the Lebombo Mountains on the Kwazulu-Natal/eSwatini border were cooking starchy plants 170 thousand years ago
The underground food plants were uncovered during excavations at Border Cave in the Lebombo Mountains (on the border of KwaZulu-Natal Province, South Africa, and eSwatini [formerly Swaziland]), where the team has been digging since 2015. During the excavation, researchers recognised the small, charred cylinders as rhizomes. All appear to belong to the same species, and 55 charred, whole rhizomes were identified as Hypoxis, commonly called the Yellow Star flower.
The Border Cave plant identifications were made on the size and shape of the rhizomes and on the vascular structure examined under a scanning electron microscope. Modern Hypoxis rhizomes and their ancient counterparts have similar cellular structures and the same inclusions of microscopic crystal bundles, called raphides. The features are still recognisable even in the charred specimens.
Hypoxis rhizomes are nutritious and carbohydrate-rich with an energy value of approximately 500 KJ/100g. While they are edible raw, the rhizomes are fibrous and have high fracture toughness until they are cooked. The rhizomes are rich in starch and would have been an ideal staple plant food. Cooking the fibre-rich rhizomes would have made them easier to peel and to digest so more of them could be consumed and the nutritional benefits would be greater.
Wooden digging sticks used to extract the plants from the ground
The discovery also implies the use of wooden digging sticks to extract the rhizomes from the ground. One of these tools was found at Border Cave and is directly dated at circa 40,000 years ago
The plants were cooked and shared
The Hypoxis rhizomes were mostly recovered from fireplaces and ash dumps rather than from surrounding sediment. The Border Cave inhabitants would have dug Hypoxis rhizomes from the hillside near the cave, and carried them back to the cave to cook them in the ashes of fireplaces. The fact that they were brought back to the cave rather than cooked in the field suggests that food was shared at the home base. This suggests that the rhizomes were roasted in ashes and that, in the process, some were lost. While the evidence for cooking is circumstantial, it is nonetheless compelling.
Discoveries at Border Cave
This new discovery adds to the long list of important finds at Border Cave. The site has been repeatedly excavated since Raymond Dart first worked there in 1934. Amongst earlier discoveries were the burial of a baby with a Conus seashell at 74,000 years ago, a variety of bone tools, an ancient counting device, ostrich eggshell beads, resin, and poison that may once have been used on hunting weapons.
The Border Cave Heritage Site
Border Cave is a heritage site with a small site museum. The cave and museum are open to the public, though bookings are essential [Olga Vilane (+27) (0) 72 180 4332]. Wadley and her colleagues hope that the Border Cave discovery will emphasise the importance of the site as an irreplaceable cultural resource for South Africa and the rest of the world.
Lyn Wadley, Christine Sievers, Francesco d’Errico, Lucinda Backwell.
— source University of the Witwatersrand | Jan 2, 2020