Carnivore, Herbivore, or Omnivore: The Prehistoric Menu and the Vegan Future of Homo Sapiens

So, are we carnivores, herbivores or omnivores? The question sounds simple, but the answer that paleoanthropology has been building over recent decades is more interesting than any label. Over seven million years, the human lineage included species that were almost entirely herbivorous, others that ate a little meat when they could and, only much later, populations that depended on hunting in environments where plants were scarce. For most of that story, the meat-eating "caveman" is more myth than fact.

How do scientists know what they ate?

Nobody wrote down the prehistoric menu, but fossils hold surprisingly precise clues. Each technique reveals part of the story, and it is the combination of them that allows scientists to reconstruct diets from millions of years ago.

One important detail: bones last millions of years, but leaves, fruits and roots are almost never preserved. That is why the archaeological record tends to overestimate meat consumption, and part of the image of the "prehistoric hunter" comes from this bias.

A journey through the timeline

1. Today · our living relatives

   Gorillas and chimpanzees: the starting point

   The great apes closest to us help us imagine what our common ancestor was like. Gorillas are essentially herbivores that eat leaves, stems and fruit, and they are peaceful animals, very different from their monster image in the movies. Chimpanzees eat mostly fruit, supplemented with leaves, seeds and insects, and sometimes hunt smaller monkeys, but meat remains a small part of their diet.

   Plants

   Meat
2. ~7 to 6 million years ago

   Sahelanthropus and Orrorin: the first of the lineage

   

   Sahelanthropus tchadensis, from Chad, and Orrorin tugenensis, from Kenya, are among the oldest candidates for human ancestors. Fossils are few, but the shape and thickness of their tooth enamel are consistent with a diet of fruit and other plant parts, typical of forest-dwelling primates. There is no sign of hunting.

   Plants

   Meat
3. ~4.4 million years ago

   Ardipithecus ramidus: a forest generalist

   Described in detail in 2009, the skeleton nicknamed "Ardi", from Ethiopia, revealed a hominin that walked on two legs on the ground but still climbed trees. Its teeth and isotopes point to a varied diet of fruit, leaves and other forest foods, with no specialization for hard foods and no evidence of significant meat consumption.

   Plants

   Meat
4. 3.7 to 3.3 million years ago

   Australopithecus africanus: chemical proof of a plant-based diet

   

   In January 2025, a team led by Tina Lüdecke, of the Max Planck Institute for Chemistry, published in Science an analysis of nitrogen isotopes in the tooth enamel of seven Australopithecus africanus individuals from the Sterkfontein caves in South Africa, part of the so-called "Cradle of Humankind". Nitrogen works like a food-chain ruler: the more meat an animal eats, the higher the value.

   The results showed values similar to those of herbivores from the same period and much lower than those of carnivores such as hyenas and big cats. The authors conclude that these australopiths did not consume significant amounts of mammal meat. Occasional eating of eggs, insects or small animals cannot be ruled out, as with today's chimpanzees and baboons, but the basis of the diet was plants.

   Plants

   Meat
   Why is this study so important?

   Until then, nitrogen analysis of fossils this old was impossible, because the collagen in bones breaks down within a few tens of thousands of years. Lüdecke's group uses the nitrogen preserved inside enamel, the most resistant tissue in the body, which makes it possible to test directly, rather than by inference, when meat became important in our ancestors' diet.

5. ~3.4 to 3.2 million years ago

   Lucy, the first tools and an open debate

   Australopithecus afarensis, Lucy's species, discovered in 1974 in Ethiopia, lived in varied environments and had a brain about one third the size of ours, long arms and curved fingers still adapted for climbing trees. Its diet centered on plant resources.

   In the same region, at Dikika, researchers found animal bones with possible cut marks dating back 3.4 million years, and in Kenya, at Lomekwi, the oldest known stone tools, 3.3 million years old. The Dikika marks remain controversial: some researchers believe they were made by animals trampling the bones. And tools were also used to crack nuts, cut roots and process plants.

   Plants

   Meat
6. ~2.7 to 1.2 million years ago

   Paranthropus: the great herbivore of the family

   

   While the lineage that would lead to the genus Homo diversified, a parallel branch went the opposite way from meat. Paranthropus had huge jaws, broad molars and a crest on top of the skull to anchor powerful chewing muscles. Carbon isotopes show that Paranthropus boisei, from East Africa, had a diet dominated by grasses and sedges, similar to that of grazing herbivores.

   These hominins lived alongside early Homo for more than a million years, proof that an essentially herbivorous strategy was successful for a long time in our evolutionary family.

   Plants

   Meat
7. ~2.6 to 1.5 million years ago

   Homo habilis and stone tools

   

   With the emergence of the genus Homo and the flaked stone tools of the Oldowan tradition, evidence of meat eating becomes clearer. Homo habilis used sharp flakes to cut meat and crack bones for marrow, often scavenging carcasses left by predators. At Nyayanga, in Kenya, tools around 2.9 million years old were used both to butcher hippopotamus meat and to pound plants, and Paranthropus teeth were found there too.

   Plants

   Meat
8. ~1.9 million years ago

   Homo erectus: did meat make us human?

   

   Homo erectus had a larger brain, a body similar to ours and a shorter gut. For decades, the preferred explanation was that greater meat consumption drove these changes. But in 2022, researchers from the Smithsonian's National Museum of Natural History and other universities analyzed 59 archaeological levels in East Africa between 2.6 and 1.2 million years ago. After correcting for the fact that more recent sites have simply been excavated more, they found no sustained increase in evidence of meat eating after the appearance of Homo erectus.

   Other explanations are gaining ground, such as eating starchy tubers and roots, cooking with fire, which makes these foods far more nutritious, and social cooperation. A 2015 review argues that carbohydrates from cooked plants were essential to fuel a growing brain, which uses large amounts of glucose.

   Plants

   Meat
   What is the "meat made us human" hypothesis?

   It is the idea that animal protein and fat allowed the evolution of a large brain and a smaller gut. Meat was certainly part of the diet, but the 2022 analysis shows that the apparent rise in evidence of carnivory tracks the rise in excavation effort, not a real change in behavior. This does not prove that meat was irrelevant, but it weakens the idea that it was the main driver of our evolution.

9. ~780,000 years ago

   Gesher Benot Ya'aqov: a plant feast cooked over fire

   On the shores of an ancient lake in northern Israel, archaeologists found the remains of at least 55 species of edible plants, including fruits, seeds, nuts, leaves and roots, associated with hominins of that time. The site also holds some of the oldest evidence of controlled use of fire, which made edible plant parts that would have been toxic or indigestible when raw.

   Plants

   Meat
10. ~400,000 to 40,000 years ago

    Neanderthals: diet according to place

    

    Neanderthals are the best example that the human diet has always followed the environment. In glacial Europe, where plants were scarce, some groups ate a great deal of meat: a Neanderthal from Gabasa, in Spain, showed zinc isotope values typical of large carnivores. But DNA preserved in the tartar of Neanderthals from El Sidrón, also in Spain, revealed a diet based on mushrooms, pine nuts and moss, with no sign of meat, while those from Spy, in Belgium, ate woolly rhinoceros and wild sheep. Starch grains found on their teeth show that Neanderthals also cooked plants.

    Plants

     

    Meat
11. ~300,000 years ago until agriculture

    Homo sapiens hunter-gatherers

    

    The first Homo sapiens appeared in Africa around 300,000 years ago and, as hunter-gatherers, ate whatever each environment offered. In the tropics, fruit, roots, seeds and honey played a large role. As our ancestors moved into cold and inhospitable territories, where vegetation was scarce, hunting became essential for survival. This more meat-centered diet was a response to environmental demands, not a rule of our species.

    Plants

     

    Meat
12. 15,000 to 13,900 years ago

    Taforalt: hunter-gatherers who lived on plants

    At Taforalt cave, in Morocco, researchers from the Max Planck Institute for Evolutionary Anthropology analyzed zinc, carbon, nitrogen, sulfur and strontium isotopes in the teeth and bones of people of the Iberomaurusian culture. The results, published in 2024 in Nature Ecology & Evolution, revealed a predominantly plant-based diet, with values closer to those of herbivores than of carnivores.

    The site contained remains of sweet acorns, pine nuts, pistachios, wild oats and legumes, as well as grinding stones. Barbary sheep and gazelles were eaten, but in a lower proportion than at other Upper Paleolithic sites, all of this thousands of years before agriculture reached the region.

    Plants

    Meat
13. ~12,000 years ago to today

    Agriculture and modern humans

    

    With agriculture, the diet came to revolve around a few cultivated grains. Studies of skeletons from many parts of the world show that the first farming societies experienced a decline in stature and worse dental health, due to less dietary variety and more infectious disease in villages. Today, Homo sapiens is an omnivore with teeth and a digestive system able to process both plants and meat, and with a choice that no ancestor ever had.

The future: Homo sapiens ethicus

Evolution does not necessarily mean transformation into something "better", but rather adaptation to the environment. With what we know today about nutrition and about the harm our choices cause to the planet and to other animals, the next step in our adaptation involves a transition to a vegan or plant-based diet.

This change could mark the rise of a human being fully evolved in the broadest sense of the word, Homo sapiens ethicus: someone who uses their cognitive abilities to adopt a way of life that reduces the impact on the environment and on other animals, taking the reins of a conscious evolution. And remember: evolving does not always mean improving. As the saying goes, sometimes we can "evolve ourselves into oblivion". Let us choose the evolution that leads to life, health and sustainability.

Quick questions

Conclusion

The evolution of the human diet is a story of flexibility. Our earliest ancestors were essentially herbivores, some branches of the family lived on grasses for more than a million years, and meat came in gradually and opportunistically, gaining importance only in certain environments and periods. The portrait of the meat-eating "caveman" is a simplification that says more about our prejudices than about the past.

Today, for the first time, we have enough knowledge to choose. Research indicates that a whole-foods vegan diet may be the healthiest and most sustainable option for humans, and one of those that most reduces the impact on the planet. It is an exciting prospect, inviting us to look to the future with optimism and to make conscious choices for our health, for other animals and for the planet.

Related reading: The Diet of Early Humans

Author: Alex Fernandes

Webmaster of IVU and Guia Vegano

Alex Fernandes has been vegan since 2004 and vegetarian since 1995. He has volunteered in many projects promoting vegetarianism and veganism, notably as webmaster and advisor of SVB (Brazilian Vegetarian Society) and as a member of the IVU (International Vegetarian Union) International Council. He has given talks at VegFests around the world, always focusing on the analysis of the behavior of the vegetarian and vegan community.