The real ‘paleo’ diet had plenty of fruits and veggies

Discarded dirty dishes are providing new hints about the cuisines of Stone Age hunter-gatherers in northern and eastern Europe. A new analysis of pottery shards from the region reveals that people living from 6,000 to 3,000 B.C. were choosy about which plants—berries, grasses or legumes—that they mixed with fish.

“We believe these culinary traditions are very far back into the past,” says Lara González Carretero, archaeobotanist the University of York in England who led the work published March 4 in PLOS One. Researchers have found that humans developed elements of cuisine, preparing certain foods, once they started planting crops and domesticating animals. The findings suggest “this perhaps is happening far earlier on than what we thought,” she says.

Archaeologists have long known that ancient people who lived in these parts of Europe, often at sites on rivers, ate their fish. They’ve found objects such as harpoons and nets and traces of lipids, fatty molecules, from fish in ancient pots. But far less was known about veggies hunter-gatherers were eating.

Plants don’t have as many oils, waxes and fats, and their signals get swamped by the compounds from fish. Though researchers know that prehistoric people were foraging wild plants, it’s been difficult to discern which they ate and how they prepared them. Using both lipid traces and powerful microscope images, González Carretero and her colleagues not only found plenty of evidence that European hunter-gatherers ate plants, but also tried to recreate some of their ancient meals.

(This 7,000-year-old woman was among Sweden's last hunter-gatherers.)

The crust of the matter

Traditional archaeological methods don’t reveal whether ancient people actually ate plants found at sites or whether the plants served other purposes or simply grew in the environment. Archaeologists typically collect soil, place it in water and recover whatever floats. That can include seeds, charcoal and other materials, González Carretero says.

Linking archaeological material to food is more conclusive if traces show up in the vestiges of meal prep. González Carretero previously developed an approach to search foodcrusts, charred grub remnants that can stick to pottery, for dietary clues. People might cook in pots without washing them, depositing a new charred layer on an old one. To discard pots, they’d throw them in the fire, she says. Even though the crusty bits burned several times, tiny structures from the original materials persist. “What we see is the actual cells and tissues that relate to certain plants and also relate to certain animals,” González Carretero says. Sometimes, seeds or fruits are even visible.

The technique first relies on low-powered microscopes to survey the crusts and digital microscopes to study the crusts’ structure. Then González Carretero uses a high-powered microscope, known as a scanning electron microscope, to zoom in on potential plant or animal matter and identify it. Using these methods, González Carretero has studied doughlike fragments found at the proto-city of Çatalhöyük in Turkey and the earliest known breadmaking, some 14,000 years ago.

In the new work, González Carretero’s team studied 85 foodcrust-laden pottery pieces from 13 sites from Russia to southern Denmark. Compounds from fish and shellfish dominated the lipids analysis, though a few showed markers of deer fat and dairy products.  Using the microscopy approach, they identified plant remains, such as wild grasses, tubers, rhizomes, fruits and roots in 58 of the pieces.

“That really shows the omnipresence, actually, of plant foods in this hunter-gatherer pottery,” says Dimitri Teetaert, an archaeologist at Ghent University in Belgium who wasn’t part of the work. “Plant foods were important for all of these hunter-gatherer-fisher populations.”

The crusts left on pots are thin—remnants of only the last two or three cooking events, González Carretero says. It’s not clear whether they reflect pots’ whole history. Still, the team was able to draw trends about which plants people cooked millennia ago.    

Cuisine and culture

During this period, known as the Mesolithic, people in northern and eastern European formed fairly complex societies likely connected by trade, González Carretero says. But they didn’t cultivate crops or raise animals. All of their ingredients were foraged from the environment. Yet despite many plants’ prevalence, the team found specific combinations that varied from site to site. “Those foods are growing everywhere really, and available to loads of people, but it seems that they’re only selecting certain ones to put into the pots,” says paper coauthor Oliver Craig, an archaeological scientist at the University of York.

For instance, from sites near the Don River, in present-day Russia, pots contained traces of wild legumes and grasses that had been combined with freshwater fish. But at sites along the Volga River, also in Russia, and one site in Poland, the team found that guelder rose berries were cooked with fish. 

To study how foods formed crusts on these pots, the team did a bit of cooking with these berries. In some experiments, they combined equal parts guelder rose berries and carp and boiled them in water in replica pots. A guelder rose berry, which is mildly toxic before cooking, looks like a cranberry, González Carretero says. “It tastes horrible, and it smells like wet socks.”

But cooking helps. Cooked alone, the berries remain bitter, she says. But their taste changes when combined with fish. “It becomes sweeter, and it’s quite pleasant.” People today in parts of Japan and Russia still make something like a fish jelly with cranberries or guelder rose berries, she says. The berries themselves are culturally important in Northeast Europe, including Poland, Ukraine and Russia.

(Could eating like our ancestors make us healthier?)

Pottery’s flavorful origins

The hunter-gatherers, too, had specific culinary traditions, Teetaert says. “They did not just eat because they needed the vitamins, the lipids, the calories.” Their chosen mixtures probably created new flavors and textures that weren’t available before the use of pottery, Teetaert says. “This could have been an important incentive for the adoption of pottery technology.”

Investigating the question of why hunter-gatherers started using pots was one of the reasons the team undertook this study, Craig says. People in this region began making pottery 6,000 or 7,000 years ago, and the practice spread from east to west, he says. This work examines some of the earliest pots, Craig says. During seasonal gluts of fish, pots could have been used to cook fish to make oils to be stored for later use. People may also have been able to make and store plant oils too. The researchers plan to extend their work to a larger geographic area and over a longer time period, and also to investigate whether environmental changes impacted how people cooked.

Even later, in the Neolithic period, when people started domesticating plants and animals, they continue to rely on many of these wild foods, González Carretero says. They didn’t suddenly substitute barley, wheat and farmed animals for their wild fare. Hunter-gatherers had food traditions that were more established than people might think, she says. Combining these methods reveals a more complete picture of what they ate. “Without plants, we don’t really know about the whole diets or foodways of these people,” she says.