For nearly two million years, early human ancestors — including Homo sapiens — rejected a plant-only diet and relied heavily on meat. That shift helped them climb to the top of the food chain.
Researchers from Tel Aviv University (Israel) and Minho University (Portugal) argue we’ve been wrong about our ancestors’ diets.
It’s not the balanced mix of berries, grains, and fire-cooked meat you might imagine when picturing Paleolithic populations.
After analyzing hundreds of previous studies, the team found that as recently as 12,000 years ago, humans were predominantly apex predators. Reconstructing the diets of hominins from 2.5 million years ago is difficult because plant remains don’t preserve as well as bones, teeth, or shells.
Meat-Eaters by Nature
Ben-Dor says Earth’s ecosystems have changed since then. He calls the Pleistocene a defining period in human history. During that time, we spread into the farthest corners of the globe and gradually outpaced other hominins on our branch of the evolutionary tree.
During the last major ice age, much of what is now Europe and North America was covered by thick glaciers. With so much water locked up in ice, ecosystems around the world were very different from those we see today.
Countless large animals roamed the landscapes, including mammoths, mastodons, and giant sloths. Homo sapiens used ingenuity and endurance to hunt those giants, but scientists still struggle to determine how often ancient humans hunted such megafauna.
Instead of relying only on fossils or comparisons with modern pre-agricultural cultures, the researchers looked to evidence embedded in our bodies and compared it with what is known about our ancestors.
“We used different methods to reconstruct Stone Age diets: we studied biological ‘memories’ preserved in our bodies—metabolism, genetics, and anatomy,” said Ben-Dor.
Through the Lens of Nutritional Evolution
Human behavior changes quickly, but our bodies retain traces of those changes. Compared with other primates, we require more energy per unit of body mass—especially to power our energy-hungry brains, Science Alert reported.
Modern humans have limited time to search for food, so we rely on ample fat reserves that we can quickly convert into ketones—molecules the liver produces from fat to serve as an alternate energy source. Unlike other omnivores, which have fewer large fat cells, humans have many small fat cells—more like those of predators.
Ben-Dor says our digestive systems also resemble those of top predators. Strong stomach acid helps break down proteins and kill harmful bacteria—useful if you’re eating a week-old mammoth steak.
Our genomes also point to a greater reliance on meat. The team’s case draws on tool use, micronutrient traces, nitrogen isotopes in Paleolithic remains, and dental wear.
Analysis suggests that around 2.5 million years ago, our ancestors were highly carnivorous, occupying the role of apex predators and remaining so until the Upper Paleolithic (about 11,700 years ago).
That doesn’t mean we should eat more meat. Evolutionary history isn’t a guide to modern health, and the world today is very different.
Still, knowing our ancestors’ role in the food chain helps explain many things—from our physiology and health to our environmental impact in ancient times.
The study was published in the American Journal of Physical Anthropology.
