Moroccan study reveals plant-based diet

Around 11,000 years ago, humans made a major transition from hunting and gathering to farming. This change, known as the Neolithic Revolution, changed our diets dramatically.

For decades, scientists have thought that pre-agricultural human groups ate a lot of animal protein. But analysis has always been hampered by the scarcity of well-preserved human remains from Pleistocene sites. So, in reality, very little is known about the dietary practices of that time.

I am a PhD candidate studying this topic in Morocco, and I was part of a research team that revealed some new insights into the Stone Age diet.

Using new research techniques, we found evidence that our hunter-gatherer ancestors from the Late Stone Age in northern Africa, thousands of years before the advent of agriculture, had a largely plant-based diet.

Most studies of pre-agricultural populations have been conducted at Palaeolithic sites in Europe and Asia, so our understanding of the diet during this period is largely based on findings from those regions. Our knowledge is also limited due to the poor preservation of certain materials in arid regions such as northern Africa.

Our research changes this. It challenges the long-held belief that hunter-gatherers relied primarily on animal protein, and adds to what is known about pre-agricultural diets across different regions.

Chemical traces in bones and teeth

Imagine being able to tell what someone ate thousands of years ago just by examining their bones and teeth.

This is possible thanks to a wonderful technique called isotopic analysis. Isotopes of the food we eat are tiny chemical markers that are stored in our bones and teeth. They can be preserved for thousands of years. By studying them, we can learn firsthand about the diets of ancient people.

Since the 1970s, scientists have used stable isotope analysis to learn about the diets and lifestyles of ancient human groups by analyzing the collagen protein in their bones. Collagen is a protein found in connective tissue, skin, tendon, bone and cartilage. For example, carbon isotope analysis has been used to detect maize consumption by prehistoric people in North America. Researchers have also used this technique to compare the diets of Neanderthals and early modern humans (Homo sapiens) in Europe.

Together with an international team of scientists, I analyzed the teeth and bones of the people buried in Taforalt Cave in northeastern Morocco. The burials were deliberate. Researchers have referred to the site as a cemetery due to the organized nature of the burials and the long period in which they occurred. The cave is one of the best studied sites in northwest Africa for the Palaeolithic period. It is probably the oldest cemetery in northern Africa. It has some of the oldest ancient human DNA in Africa, which has allowed scientists to characterize human genetic ancestry in this region.

A cave opening on the side of a rocky mountain
Taforalt Cave, Morocco. Nicolas Perrault III., CC AG

The human burials associated with the Iberomaurusian culture have been radiocarbon dated to between 15,100 and 13,900 years ago. Zoologists have identified that the population hunted Barbary sheep and other animal species in their environment, such as gazelles, hartebeest, and blackbucks. The macrobotanical remains found at the site show that they also had access to a variety of plant species native to the Mediterranean region, including sweet acorns, pine nuts, oats, beans and pistachios.

We looked at isotopes of carbon, nitrogen, strontium, sulfur and zinc. Different foods leave unique isotopic “fingerprints”. For example, meat, plants and seafood have specific isotope ratios of carbon and nitrogen, which help us determine what types of food people were eating.

We also used pioneering zinc isotope techniques developed by one of my PhD supervisors, Klervia Jaouen, which we applied to tooth enamel. This method, combined with analyzes of amino acids, allowed us to further distinguish between plant and animal sources in the diet.

This innovative approach gave us a clearer and more detailed picture of what ancient diets looked like, revealing how these people adapted to their environment long before anyone started farming crops.

a surprising diet for hunter-gatherers

We analyzed seven tooth enamels and bones from the Taforalt cave and various isolated teeth. Our analysis revealed something unexpected: instead of a meat-heavy diet, the isotopic signatures showed a heavy reliance on wild plants. We also found minimal evidence of consumption of seafood or freshwater food, which was surprising given the proximity to water sources. Our research showed that although the Iberomaurusians did eat some meat, their diet depended heavily on wild plants that they may have stored to provide a year-round food supply.

One of the interesting discoveries we made was that a child started eating solid foods at an early age of six to 12 months. This child appears to have been fed plant-based foods, probably in the form of porridge or soup. This gives us a great insight into how hunters looked after their children in the past.

The findings also help explain why tooth cavities were common among the Taforalt people. They ate a lot of starchy foods, which could lead to cavities, especially since they didn’t have toothbrushes or good dental hygiene back then. The plant bits would get stuck in their teeth and cause decay, leading to dental problems.

People who were primarily hunters had to follow a nomadic lifestyle. At Taforalt, however, archaeologists discovered that grinding stones were likely used for plant processing. The use of the cave as a burial site, as well as the heavy consumption of plants, suggests that this population may have already had a more settled lifestyle, taking advantage of food resources available from the surrounding area.

Read more: Chemical traces in ancient West African pots show plant-rich diet

Looking forward

These findings challenge the traditional view that heavy reliance on plant-based diets began with agriculture alone. The Iberomaurusians were eating many wild plants 8,000 years before farming began in Morocco. This suggests that early humans were more adaptable and resourceful in their dietary habits than previously thought. This helps us understand the complexity and flexibility of prehistoric human diets and the impact these dietary practices had on our evolution and health.

Our study also shows how novel isotopic techniques can give us detailed insights into the diets of our ancestors, helping us to understand the foundations of human nutrition.

This article is republished from The Conversation, a non-profit, independent news organization that brings you reliable facts and analysis to help you make sense of our complex world. It was written by: Zineb Moubtahij, University of Leiden

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Zineb Moubtahij received funding from the Max Planck Institute. She is affiliated with Leiden University.

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