Humans likely became apex predators around two million years ago, during the early Pleistocene, and held that position until roughly 12,000 years ago when agriculture began reshaping our diet. That’s the central finding of a 2021 study from Tel Aviv University, which reconstructed the human trophic level (our position on the food chain) across the entire Pleistocene epoch. The climb to the top started with early tool-using ancestors and peaked with Homo erectus, then gradually reversed as large prey animals disappeared and humans shifted toward plants and smaller game.
Two Million Years at the Top
The trajectory looks something like this: the Homo lineage started at a relatively low position on the food chain, eating a mix of plants and whatever meat could be scavenged. Over hundreds of thousands of years, our ancestors moved steadily upward, consuming more and more animal fat and protein. By the time Homo erectus appeared roughly 1.8 million years ago, the trophic level had climbed into firmly carnivorous territory.
That high position held for an extraordinarily long time. The reversal only began during the Upper Paleolithic, roughly 50,000 to 40,000 years ago, when diets started to diversify again. The shift accelerated through the Mesolithic and Neolithic periods and reached its endpoint with the invention of farming. In other words, for most of our evolutionary history as a genus, humans were functionally top predators, not the omnivores we are today.
What the Bones Tell Us
One of the strongest lines of evidence comes from nitrogen isotope analysis of fossil remains. Nitrogen-15 accumulates as you move up the food chain: plants have the least, herbivores have more, and carnivores have the most. By measuring nitrogen-15 levels in ancient bone and tooth collagen, researchers can reconstruct what an individual was eating.
Neanderthals, our close evolutionary cousins, provide a striking example. A Neandertal specimen from Les Cottés in France showed nitrogen-15 levels about 7 parts per thousand higher than the herbivores at the same site, which is what you’d expect from a dedicated meat-eater. Researchers calculated this individual’s trophic position at 2.9, indicating a purely carnivorous diet. Even more remarkably, a Neandertal infant from Grotte du Renne in France registered nitrogen-15 values 3 to 5 parts per thousand above the carnivores at that site, placing it at a trophic position of 3.2, higher than wolves and hyenas living in the same ecosystem. These aren’t omnivores who occasionally hunted. These are animals sitting at or above the level of dedicated predators.
Stomach Acid as a Fossil Clue
Your stomach offers a surprisingly useful window into this history. Human stomach acid has a baseline pH of about 1.5, which is remarkably acidic. That’s comparable to vultures (pH 1.2) and other obligate scavengers, and far more acidic than what you’d find in typical omnivores (pH 2.9 on average) or herbivores (pH 4.1 to 6.1). Even specialist carnivores like cats have less acidic stomachs, averaging around pH 3.6.
Why would humans need such powerful stomach acid? The leading explanation is that our ancestors were heavily exposed to carcass meat, which carries dangerous bacterial loads. Highly acidic stomachs act as a chemical barrier against foodborne pathogens. This adaptation makes much more sense for a species that spent millions of years eating large amounts of animal tissue, often scavenged, than for a plant-focused omnivore. Our stomachs, in a sense, still carry the signature of our predatory past.
Weapons That Changed the Equation
Becoming an apex predator without claws, fangs, or exceptional speed required technology. Early hominins likely started as scavengers and opportunistic hunters using simple tools, but the archaeological record shows a clear escalation.
Stone-tipped projectile weapons appeared earlier than many researchers once assumed. Archaeological evidence from the Gademotta Formation in Ethiopia’s Main Rift shows that pointed obsidian artifacts were being used as hafted javelin tips more than 279,000 years ago. These weren’t thrusting spears that required close contact with dangerous prey. They were throwing weapons, designed to be launched from a distance, which dramatically reduced the risk of injury during hunts and expanded the range of animals that could be taken down. The ability to kill at a distance was a turning point: it allowed relatively small, slow primates to reliably hunt animals many times their size.
Before these projectile weapons, coordinated hunting with simpler tools was already underway. Evidence for stone-tipped thrusting spears dates to roughly 500,000 years ago. But the shift from close-range thrusting to distance throwing represented a leap in both safety and efficiency that helped cement humans as the dominant predator in nearly every ecosystem they entered.
The Fall From Apex Status
If humans were apex predators for roughly two million years, what changed? The answer is a combination of ecological collapse and cultural innovation. As the Pleistocene drew to a close, many of the large-bodied prey animals that humans depended on went extinct. Mammoths, giant ground sloths, woolly rhinoceroses, and dozens of other megafauna disappeared between about 50,000 and 10,000 years ago, likely driven by some combination of climate change and human hunting pressure itself.
With large prey becoming scarce, human diets broadened. People began relying more on smaller animals, fish, and especially plants. This dietary diversification accelerated through the Mesolithic period and reached a tipping point with the Neolithic Revolution, when humans in multiple regions independently invented agriculture. Growing grain and domesticating livestock meant that most calories now came from plants or from herbivorous animals raised on plants, not from hunting wild prey.
Where Humans Sit Today
Modern humans are no longer apex predators by any ecological measure. A 2013 study published in the Proceedings of the National Academy of Sciences calculated the global human trophic level at 2.21, which is roughly the same as anchovies and pigs. National averages range from 2.04 to 2.57, reflecting differences in how much meat various populations consume. For comparison, actual apex predators like polar bears and killer whales occupy trophic levels up to 5.5.
That number, 2.21, captures something important: despite the widespread cultural image of humans as top predators, our current diet places us squarely in the middle of the food web. We eat some meat, but the bulk of global calories comes from plants and from animals that eat plants. The two-million-year reign as an apex predator left deep marks on our biology, from our stomach chemistry to our ability to digest fat, but our actual ecological role shifted dramatically once we started farming.