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Border Cave Excavation site, Lebombo Mountains, South Africa.        Source: Credit Dr Lucinda Backwell/ Wits University

170,000-Year-Old Human Diet Contained Roast Vegetables

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New research focused on the roasted remnants of rootstalks found in a Lebombo Mountain cave in South Africa suggests early humans brought the plants to the cave to feed to their young and old.

A new paper published by archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg and her colleagues in the journal  Science reveals that the remains of roast rootstalks found in Border Cave that lies on the western scarp of the Lebombo Mountains in South Africa were taken there by early Stone Age humans as far back as 170,000 years ago, who cooked the carbohydrate-rich plants.

The Timeworn Fight For Nutrition

The roasted plants were discovered in the ancient rock shelter, which is located on the border with Swaziland, and its archaeological heritage stretched back a mind-blowing 200,000 years. According to the paper this new sample is ‘the earliest direct evidence of early humans cooking up rhizomes or any carbohydrate-packed plant.’ Previous evidence of modern humans roasting and eating plant starches dated back only 120,000 years.

While much is understood about animal-diets of early humans , the plant-aspect of their meals has been under-studied, the team told Science Mag , mainly because plant-based foods are perishable leaving only bone and stone tools for archaeologists to interpret what happened in prehistory. But the researchers said that although it still remains unclear exactly when humans first began eating root vegetables, plant-based carbohydrates 'almost certainly’ contributed substantially to ancient nutrition.

Small but distinctive  traces of the plant Hypoxis angustifolia were found in Border Cave  (CC BY-SA 2.5)

Small but distinctive  traces of the plant Hypoxis angustifolia were found in Border Cave  ( CC BY-SA 2.5 )

Veggies Suggest Social Order And Dietary Planning

The team made their discovery while exploring ashes left behind by ancient cooking fires at the Border Cave site, which Dr Wadley described as 'strange little charcoal pieces that seemed very uniform in size.' Electron microscope scans determined that the ash came from a small flowering plant known as Hypoxis angustifolia which has a distinctive white rhizome, which according to Dr Wadley, indicates that the Stone Age people had balanced their meat diets with plant foods.

The paper says a series of splits found in the rhizomes suggest that the plants were cooked while they were still green and fresh and that they had been split after being burnt, rather than being something that had been scorched accidentally. In conclusion, Dr Wadley thinks the rhizomes were shared in the cave after they were cooked, and that it was most likely they were shared with the very young and the very old, speaking ‘to the kind of social organization of the people at the time.’

Excavation have continued at the cave for many years. (Androstachys / Public domain)

Excavation have continued at the cave for many years. (Androstachys / Public domain )

Ancient Plant And Animal Maps

Why these new findings are really important to anthropology and archaeology is because the researchers believe their findings indicate H. angustifolia may have been a familiar source of food for early humans as they travelled throughout Africa and even beyond. To illustrate this point the scientists say that when you plot the flower’s distribution on a map of Africa it occurs all the way from the south up the east coast, right into the northern part of Sudan and then across into Yemen, and onwards ‘out of Africa,' said Dr Wadley.

This means that wherever hunter gatherers were traveling, even 170,000 years ago, they had a regular source of carbohydrate that they could rely on as a travel food wherever they went, which suggests plant foods sustained hunting patterns as early humans moved outwards from Africa .

Ancient Ancestral Plant Knowledge 

This new research builds on the paper described in a 2016 New Scientist article regarding findings at the  Gesher Benot Ya’ aqov site in northern Israel which provide some of the first direct evidence of what plants early humans ate. Occupied 780,000 years ago, probably by  Homo erectus  or a very closely related species, Dr Yoel Melamed and  Naama Goren-Inbar  from Bar-Ilan University in Ramat Gan, Israel presented evidence that ancient humans had ‘extraordinarily broad tastes’ finding no less than 55 different kinds of plant.

This discovery, according to the archaeologists, is evidence that early humans found ‘palatable food all year round’ giving what would have been a substantial element of security.

Plant Or Animal Based?

Despite the diverse array of plants collected at Gesher Benot Ya’aqov most scientists agree that it’s very unlikely the people who lived there could have remained healthy as strict vegetarians. However, according to  Amanda Henry  at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, early human diets may have tipped towards being plant-rich and that only a ‘very little amount’ of animal protein and fat is needed to supplement a predominantly plant-based diet.

Either way, the site of Gesher Benot Ya’aqov and these new findings in South Africa suggest early hominins processed foods before cooking them and that their knowledge of the plant world potentially allowed them to inhabit the same location year-round.

Top image: Border Cave Excavation site, Lebombo Mountains, South Africa.        Source: Credit Dr Lucinda Backwell/ Wits University

By Ashley Cowie

References

Lyn Wadley, Lucinda Backwell, Francesco d’Errico, Christine Sievers, ‘Cooked starchy rhizomes in Africa 170 thousand years ago’. Sciencemag, AAAS, 2019. DOI: https://doi.org/10.1126/science.aaz5926

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