New findings offer fresh perspective on Stone Age individuals' actual diet.
But a new study on a Paleolithic people group known as the Iberomaurusians, who lived in present-day Morocco around 13,000 to 15,000 years ago, is disputing the idea that human ancestors heavily relied on meat. The discovery was published in Nature Ecology & Evolution on Monday.
Experts investigated the chemical signatures found in bones and teeth from at least seven Iberomaurusians and found that their main protein source was plants, not meat.
"Our analysis revealed that these hunter-gatherer communities consumed a significant amount of plant matter in their diets, which changes our understanding of the diet of pre-agricultural populations," said lead author Zineb Moubtahij, a doctoral student at Géosciences Environnement Toulouse and the Max Planck Institute for Evolutionary Anthropology.
The share of plant resources as a dietary protein source was comparable to what was seen in early farmers from the Levant (the Eastern Mediterranean).
The researchers also found evidence of more tooth decay among the people from Talforalt cave than was typical for hunter-gatherers of that era. This suggests the Iberomaurusians consumed "fermentable starchy plants" like wild cereals or acorns. The revelation raises questions about how agriculture spread through various regions and groups.
"Although not all individuals were primarily obtaining their proteins from plants at Taforalt, it's unusual to see such a high proportion of plant-based food in the diet of a pre-agricultural group," said co-author Klervia Jaouen, a researcher at Géosciences Environnement Toulouse, in an email.
"This might be the first time we've documented this significant plant-based component in a Paleolithic diet using isotope techniques," Jaouen added.
Cracking ancient dietary secrets
The researchers used stable isotope analysis to discern the dietary habits of the Iberomaurusians studied.
This method identifies the nitrogen and zinc isotopes in collagen and teeth enamel, revealing the proportion of meat in their diets, while focusing on carbon isotopes to determine whether the main protein was derived from meat or fish.
"When people consume these foods, the isotope information is recorded in tissues like bones and teeth, enabling us to distinguish whether someone ate more meat or plant-based ingredients," Moubtahij said.
The isotope analysis, however, does not provide specific details of the types of plants eaten. Fortunately, charred sweet acorns, pistachio, pine nuts, wild oats, and pulses were found at the site, along with grinding stones, indicating plants were consumed.
Yet, the Iberomaurusians weren't strict vegetarians. Remains of Barbary sheep, gazelles, and mammals similar to modern-day horses and cows with cut marks, suggesting they were butchered and processed, were discovered.
The increased reliance on plant food was likely influenced by several factors, including a wider variety of edible plants and a depletion of larger animal species, according to the study.
Revealing early weaning
The isotope analysis also detected signs of early weaning in one case, where an infant died between 6 and 12 months old while consuming starchy plant foods.
"This stands in contrast to hunter-gatherer societies, where extended breastfeeding is typically the norm due to the limited availability of weaning foods," the study said.
Studies investigating two burial sites in Peru dating back 9,000 to 6,500 years ago found that 80% of an ancient Andean diet was plant-based, while 20% was meat. A November 2022 study suggests Neanderthals and early Homo sapiens were skilled in combining plant-based ingredients such as wild nuts, peas, vetch, lentils, and wild mustard.
"I don't think there is one standard diet for everyone during this period; instead, it depends on the environment. Humans are adaptable and flexible in their diet habits," Moubtahij said.
The recent findings challenge the assumption that a Stone Age diet was primarily meat-heavy, a notion that has persisted due to contemporary dietary trends such as the Paleo diet. However, past research may have perpetuated this stereotype.
Another reason for the belief that meat played a major role in the diets of early humans is the idea that hunting, a crucial innovation during our evolutionary journey, was predominantly a male activity, stemming from studies of hunter-gatherer societies conducted mainly by men who primarily focused on hunting large game and overlooked, disregarded or underestimated the significant contribution of women who gathered smaller animals and plants.
Archaeological findings in the Levant region show that a plant-based diet similar to that of farmers was in practice among groups who engaged in hunting and gather. This raises doubts about why the agricultural transition did not occur among the Iberomaurusian population simultaneously.
"This suggests that multiple populations towards the end of the Stone Age adopted diets with comparable levels of plant consumption compared to that of farmers," explained Jaouen.
The shift towards agricultural practices was a multifaceted process, taking place at varying times and progressing at varying speeds in various locations, using different means, and involving diverse crops in different parts of the world. In essence, it was a locally-driven phenomenon with various intermediary forms of subsistence rather than a sudden, global switchover.
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Source: edition.cnn.com
