Research from Morocco reveals a plant-based diet

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

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

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

Using new research techniques, we have found evidence that our Late Stone Age hunter-gatherer ancestors in North Africa followed a highly plant-based diet thousands of years before the advent of agriculture.

Most studies of pre-agricultural populations have been conducted at European and Asian Paleolithic sites, so our understanding of diet during this period is largely based on findings from those regions. Our knowledge is also limited by the poor preservation of certain materials in arid areas such as North 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 in various 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 fascinating technique called isotope analysis. Isotopes are small chemical markers of the food we eat that are stored in our bones and teeth. They can be preserved for thousands of years. By studying them we can learn directly about the eating habits of ancient man.

Since the 1970s, scientists have used stable isotope analysis to learn about the diets and lifestyles of ancient human groups by analyzing collagen protein in their bones. Collagen is a protein found in connective tissue, skin, tendons, bones and cartilage. For example, carbon isotope analysis was used to detect corn 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 people buried in the Taforalt Cave in northeastern Morocco. The burials were purposeful. Researchers have called the site a cemetery because of the organized nature of the burials and the long period over which they took place. The cave is one of the best studied sites in Northwest Africa for the Paleolithic period. It is probably the oldest cemetery in North Africa. It boasts some of the oldest human DNA in Africa, allowing scientists to characterize human genetic ancestry in this region.

Cave opening in rocky mountainside
Taforalt Cave, Morocco. Nicolas Perrault III., CC BY

The human burials, associated with the Iberomaurusian culture, were radiocarbon dated to between 15,100 and 13,900 years ago. Zoologists have determined that the population hunted Barbary sheep and other animal species in their environment, such as gazelles, hartebeest and equines. 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 different carbon and nitrogen isotope ratios, which help us determine what types of food people ate.

We also used advanced zinc isotope techniques developed by one of my PhD students, Klervia Jaouen, and applied to tooth enamel. This method, combined with amino acid analyses, 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 were like, and shed light on how these people adapted to their environment long before anyone started growing crops.

Surprising diet for hunter-gatherers

We analyzed tooth enamel and bones from seven individuals from Taforalt cave and several isolated teeth. Our analysis revealed something unexpected: instead of a high-meat diet, the isotopic signatures showed a significant dependence on wild plants. We also found minimal evidence of seafood or freshwater food consumption, which was surprising given the proximity to water sources. Our research found that although Iberomaurus did eat some meat, their diet relied heavily on wild plants that they may have stockpiled to provide food year-round.

One of the interesting discoveries we made was that a baby started eating solid foods at an early age, about six to twelve months. This baby was apparently fed plant-based food, probably in the form of porridge or soup. This gives us a fascinating insight into how hunter-gatherers in the past cared for their children.

The findings also help explain why dental cavities are common among Taforalt residents. They ate a lot of starchy foods, which can lead to cavities, especially since they didn’t have toothbrushes or good oral hygiene at the time. The plant pieces would get stuck in their teeth and cause decay, leading to dental problems.

People who were mainly hunters would have to follow a nomadic lifestyle. However, at Taforalt, archaeologists found grinding stones that were probably used for processing plants. The use of the cave as a burial site, in addition to heavy plant consumption, suggests that this population may already have been living a more settled lifestyle and exploiting available food sources from the environment.

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

Look forward to something

These findings challenge the traditional view that a heavy reliance on plant-based diets only began in agriculture. The Iberomaurs consumed many wild plants 8,000 years before agriculture began in Morocco. This suggests that early humans were more flexible and resourceful in their dietary habits than previously thought. Understanding this allows us to appreciate the complexity and flexibility of human diets in prehistory and how these dietary practices influenced our evolution and health.

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

This article is republished from The Conversation, an independent nonprofit organization providing facts and trusted analysis to help you understand 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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