The advent of agriculture roughly 11,500 years ago in the Middle East was a milestone for humankind - a revolution in diet and lifestyle that moved beyond the way hunter-gatherers had existed since Homo sapiens arose more than 300,000 years ago in Africa.

While the scarcity of well-preserved human remains from the period preceding this turning point has made the diet of pre-agricultural people a bit of a mystery, new research is now providing insight into this question. Scientists reconstructed the dietary practices of one such culture from North Africa, surprisingly documenting a heavily plant-based diet.

The researchers examined chemical signatures in bones and teeth from the remains of seven people, as well as various isolated teeth, from about 15,000 years ago found in a cave outside the village of Taforalt in northeastern Morocco. The people were part of what is called the Iberomaurusian culture.

Analysis of forms - or isotopes - of elements including carbon, nitrogen, zinc, sulfur and strontium in these remains indicated the type and amount of plants and meat they ate.

Found at the site were remains from different edible wild plants including sweet acorns, pine nuts, pistachio, oats and legumes called pulses. The main prey, based on bones discovered at the cave, was a species called Barbary sheep.

“The prevailing notion has been that hunter-gatherers’ diets were primarily composed of animal proteins. However, the evidence from Taforalt demonstrates that plants constituted a big part of the hunter-gatherers’ menu,” said Zineb Moubtahij, a doctoral student in archaeology at the Max Planck Institute for Evolutionary Anthropology in Germany and lead author of the study published on Monday in the journal Nature Ecology & Evolution.

“It is important as it suggests that possibly several populations in the world already started to include substantial amount of plants in their diet” in the period before agriculture was developed, added archeogeochemist and study co-author Klervia Jaouen of the French research agency CNRS.

The Iberomaurusians were hunter-gatherers who inhabited parts of Morocco and Libya from around 25,000 to 11,000 years ago. Evidence indicates the cave served as a living space and burial site.

These people used the cave for significant portions of each year, suggesting a lifestyle more sedentary than simply roaming the landscape searching for resources, the researchers said. They exploited wild plants that ripened at different seasons of the year, while their dental cavities illustrated a reliance on starchy botanical species.

Edible plants may have been stored by the hunter-gatherers year-round to guard against seasonal shortages of prey and ensure a regular food supply, the researchers said.

These people ate only wild plants, the researchers found. The Iberomaurusians never developed agriculture, which came relatively late to North Africa.

“Interestingly, our findings showed minimal evidence of seafood or freshwater food consumption among these ancient groups. Additionally, it seems that these humans may have introduced wild plants into the diets of their infants at an earlier stage than previously believed,” Moubtahij said.

“Specifically, we focused on the transition from breastfeeding to solid foods in infants. Breast milk has a unique isotopic signature, distinct from the isotopic composition of solid foods typically consumed by adults.”

Two infants were among the seven people whose remains were studied. By comparing the chemical composition of an infant’s tooth, formed during the breastfeeding period, with the composition of bone tissue, which reflects the diet shortly before death, the researchers discerned changes in the baby’s diet over time. The evidence indicated the introduction of solid foods at around the age of 12 months, with babies weaned earlier than expected for a pre-agricultural society.

North Africa is a key region for studying Homo sapiens evolution and dispersal out of Africa, opens new tab.

“Understanding why some hunter-gatherer groups transitioned to agriculture while others did not can provide valuable insights into the drivers of agricultural innovation and the factors that influenced human societies’ decisions to adopt new subsistence strategies,” Moubtahij said.