To find supporting evidence in the archaeological record, Larbey turned to cooking hearths at sites in South Africa dating back 120,000 years, picking out chunks of charred plant material — some the size of a peanut. Under the scanning electron microscope, she identified cellular tissue from starchy plants6 — the earliest evidence of ancient people cooking starch. “Right through from 120,000 to 65,000 years ago, they’re cooking roots and tubers,” Larbey says. The evidence is remarkably consistent, she adds, particularly compared with animal remains from the same site. “Over time they change hunting techniques and strategies, but still continue to cook and eat plants.”
Early humans probably ate a balanced diet, leaning on starchy plants for calories when game was scarce or hard to hunt. “And being able to find carbohydrates as they moved into new ecologies would have provided important staple foods,” Larbey adds.
Evidence suggests that plants were popular among Neanderthals, too. In 2011, Amanda Henry, a palaeoanthropologist now at Leiden University in the Netherlands, published her findings from dental plaque picked from the teeth of Neanderthals who were buried in Iran and Belgium between 46,000 and 40,000 years ago. Plant microfossils trapped and preserved in the hardened plaque showed that they were cooking and eating starchy foods including tubers, grains and dates7. “Plants are ubiquitous in our environment,” Henry says, “and it’s no surprise we put them to use.”
In May, Christina Warinner, a palaeogeneticist at Harvard University in Cambridge, Massachusetts, and her colleagues reported the extraction of bacterial DNA from the dental plaque of Neanderthals, including a 100,000-year-old individual from what is now Serbia. The species they found included some that specialized in breaking down starch into sugars, supporting the idea that Neanderthals had already adapted to a plant-rich diet8. Plaque on the teeth of early modern humans shared a similar bacterial profile, providing more evidence to suggest that they were eating starchy plants.
The finds push back against the idea that our ancestors spent their time sitting around campfires mostly chewing on mammoth steaks. It’s an idea that has penetrated popular culture, with proponents of the palaeo diet arguing that grains, potatoes and other starchy foods have no place on our plates because our hunter-gatherer ancestors didn’t evolve to eat them.
But it has become clear that early humans were cooking and eating carbs almost as soon as they could light fires. “The old-fashioned idea that hunter-gatherers didn’t eat starch is nonsense,” says Fuller.
The push to better understand how people were cooking in the past also means paying more attention to the cooks themselves. It’s part of a larger trend in archaeology to look at household activities and daily lives. “Essentially, we’re trying to figure out what kind of information you can find out about people who have never had histories written about them,” says Sarah Graff, an archaeologist at Arizona State University in Tempe.
In the past, when researchers found plant remains at archaeological sites, they often considered them as accidental ‘ecofacts’ — natural objects, such as seeds, pollen and burnt wood, that offer evidence for what kind of plants grew in a region. But there has been a shift towards treating food remains as evidence of an activity that required craft, intent and skill. “Prepared food needs to be looked at as an artefact first and a species second,” Fuller says. “Heated, fermented, soaked — making food is akin to making a ceramic vessel.”
Archaeologist Laura Dietrich at work at Göbekli Tepe, where she has documented extensive operations for grinding grain.Credit: Hassan Yıldız
And, as researchers increasingly collaborate to compare ancient remains, they’re finding remarkable similarities across time and cultures. At Neolithic sites in Austria dating back more than 5,000 years, for example, archaeologists found unusually shaped charred crusts. It was as though the contents of a large jar or pot had been heated until the liquid burned off, and the dried crust inside began to burn. The team’s first guess was that the crusts were from grain storage jars destroyed in a fire. But under the scanning electron microscope, the cell walls of individual grains looked unusually thin — a sign, Heiss says, that something else was going on.
After comparing the Austrian finds to similar crusts found in Egyptian breweries from around the same time, Heiss and Valamoti concluded that the thin cell walls were the result of germination, or malting, a crucial step in the brewing process. These early Austrian farmers were brewing beer9. “We ended up with something completely different” from the earlier hypotheses, Heiss says. “Several lines of evidence really interlocked and fell into place.”
Bread, it seems, goes even further back. Arranz-Otaegui was working at a 14,500-year-old site in Jordan when she found charred bits of ‘probable food’ in the hearths of long-ago hunter-gatherers. When she showed scanning electron microscope images of the stuff to Lara González Carretero, an archaeobotanist at the Museum of London Archaeology who works on evidence of bread baking at a Neolithic site in Turkey called Çatalhöyük, both researchers were shocked. The charred crusts from Jordan had tell-tale bubbles, showing they were burnt pieces of bread10.
Most archaeologists have assumed that bread didn’t appear on the menu until after grain had been domesticated — 5,000 years after the cooking accident in question. So it seems that the early bakers in Jordan used wild wheat.
The evidence provides crucial clues to the origins of the Neolithic revolution, when people began to settle down and domesticate grain and animals, which happened at different times in various parts of the world. Before farming began, a loaf of bread would have been a luxury product that required time-consuming and tedious work gathering the wild grain needed for baking. That hurdle could have helped to spur crucial changes. Arranz-Otaegui’s research suggests that — at least in the Near East — demand for bread might have been a factor in driving people to attempt to domesticate wheat, as they looked for ways to ensure a steady supply of baked goods. “What we are seeing in Jordan has implications for bigger processes. What drove the transition to agriculture is one of the fundamental questions in archaeology,” Arranz-Otaegui says. “This shows hunter-gatherers were using cereals.”
The next frontier for archaeobotanists is prehistoric salad bars. Researchers are working on ways to look for the remains of food that wasn’t cooked, such as leafy greens, another overlooked part of the ancient diet. Because raw greens and vegetables are even harder to find in the archaeological record than cooked seeds and grains, Kubiak-Martens calls them the “missing link” in knowledge about ancient diets. “There’s no way to prove green leaves were eaten from charred remains,” Kubiak-Martens says. “But you would be surprised at how much green vegetables are in human coprolites”, or preserved faeces. Kubiak-Martens got a grant in 2019 to look at 6,300-year-old palaeofaeces preserved at wetland sites in the Netherlands, which she hopes will reveal everything prehistoric farmers there had on their dinner tables.
Recreating ancient meals
The quest to understand ancient diets has led some researchers to take extreme measures. That’s the case with Göbekli Tepe, which has yielded very few organic remains that could provide clues to the prehistoric plant-based meals there. So Dietrich has tried innovative thinking — and a lot of elbow grease. Her approach has been to recreate the tools people used to make food, not the dishes themselves.
In her airy lab on a tree-lined street in Berlin, Dietrich explains her time-consuming and physically demanding process. Starting with a replica grindstone — a block of black basalt the size of a bread roll that fits neatly in the palm of her hand — she photographs it from 144 different angles.
After spending eight hours grinding four kilograms of heirloom einkorn wheat kernels, Dietrich photographs the stone again. A software program then produces 3D models from the two sets of pictures. Her experiments have shown that grinding fine flour for baking bread leaves a different finish on the stones from producing coarsely ground grain that is ideal for boiling as porridge or brewing beer. And after handling thousands of grindstones, she is often able to identify what they were used for by touch. “I touch the stones to feel for flattening,” she says. “Fingers can feel changes at the nano level.” By comparing the wear patterns on her modern replicas to the stones piled in Göbekli Tepe’s rock garden, Dietrich could show that fine-ground bread flour was the exception. In a 2020 study11, she argues people there were mostly grinding grain coarsely, just enough to break up its tough outer layer of bran and make it easy to boil and eat as porridge or ferment into beer.
To test the theory, Dietrich commissioned a stonemason to carve a replica of a 30-litre stone vat from Göbekli Tepe. In 2019, she and her team successfully cooked porridge using heated stones, carefully recording and timing each step of the process. They also brewed a Neolithic beer from hand-ground germinated grain, or malt, in the open vessel. The results were “a bit bitter, but drinkable”, Dietrich says. “If you’re thirsty in the Neolithic.” From the grind stones and other plant-processing tools at Göbekli Tepe, a picture is now emerging for what was going on there 12,000 years ago. Rather than just starting to experiment with wild grains, the monument builders were apparently proto-farmers, already familiar with the cooking possibilities grain offered despite having no domesticated crops. “These are the best grinding tools ever, and I’ve seen a lot of grindstones,” Dietrich says. “People at Göbekli Tepe knew what they were doing, and what could be done with cereals. They’re beyond the experimentation phase.”
Her experiments are shifting the way archaeologists understand the site — and the period when it was built. Their initial interpretations made the site sound a bit like a US college fraternity house: lots of male hunters on a hilltop, washing down barbecued antelope with vats of lukewarm beer at occasional celebrations. “Nobody really thought of the possibility of plant consumption” on a large scale, Dietrich says.
In a study late last year12, Dietrich argues the ‘barbecue and beer’ interpretation is way off. The sheer number of grain-processing tools at Göbekli Tepe suggest that even before farming took hold, cereals were a daily staple, not just part of an occasional fermented treat.
Nature 594, 488-491 (2021)