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Humans Were Roasting Root Vegetables 170,000 Years Ago, Study Suggests

The find may challenge modern notions about the starch-starved “paleo diet”

The excavation at Border Cave in the Lebombo Mountains on the Kwazulu-Natal/eSwatini border (Copyright Lucinda Backwell)
smithsonianmag.com

The human hankering for roasted root vegetables may have gotten its start at least 170,000 years ago, new research suggests.

Reporting last week in the journal Science, a team of researchers has uncovered the charred remains of carbohydrate-rich plant matter, wreathed in the ash from an ancient fire that once burned in a South African cave. Their findings are the earliest example of humans deliberately cooking and consuming starchy plants to date, predating all previously known evidence by at least 50,000 years.

Despite modern takes on the “paleo diet,” which tends to shirk starchy foods, our prehistoric ancestors were probably “eating a very balanced diet, [with] a combination of carbohydrates and proteins,” study author Lyn Wadley, an archaeologist at the University of the Witwatersrand in South Africa, tells New Scientist.

Wadley and her team first unearthed the telltale food scraps in 2016 during an excavation at Border Cave in the Lebombo mountains, which border the KwaZulu-Natal Province in South Africa and eSwatini. Preserved as small, charred cylinders, the ancient plants were identified as rhizomes, or underground stems that store proteins and starches, sometimes in the form of tubers like potatoes or yams. Prepared and eaten, rhizomes can pack a big nutritional punch—and it seems that’s exactly what our predecessors did.

Based on their structural makeup, the 170,000-year-old plants probably belong to the genus Hypoxis, members of which are still consumed today, frequently for medicinal purposes, explains study author Christine Sievers, also at the University of the Witwatersrand, in a statement. In their heyday, the roasted vegetables eaten by our ancestors were likely white-fleshed, fairly tasty and widely distributed, potentially sustaining hungry hunter-gatherers year-round, reports Gemma Tarlach reports for Discover magazine.

Of course, Hypoxis cookouts weren’t our lineage’s first foray into starch. Per Discover’s Tarlach, humans likely switched to a more carbohydrate-rich diet more than 300,000 years ago, a transition that accompanied an uptick in the expression of genes that facilitate starch digestion. The roots of cooking, well, roots, is a little harder to pinpoint, in part because plant material doesn’t preserve very well in the fossil record.

But heat-treating food likely marked another huge shift in human history. Even for plants that are edible in their raw form, high temperatures can soften foods, making them easier to chew, digest and extract nutrients from.

Ironically, roasting and the fire pits the process required may have also made the long-gone vegetables easier to find by modern archaeologists. (Plants, unlike animals, don’t leave behind telltale bones.)

That leaves open the possibility that prehistoric humans were eating far more starchy plants than we’re aware of. As Wadley tells New Scientist, “I’m afraid the paleo diet is really a misnomer.”

About Katherine J. Wu
Katherine J. Wu

Katherine J. Wu is a Boston-based science journalist and Story Collider senior producer. She holds a Ph.D. in Microbiology and Immunobiology from Harvard University. Previously, she served as a Digital Editor at NOVA Next and was Smithsonian magazine's 2018 AAAS Mass Media Fellow.

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