Early humans were not the single-minded meat hunters often imagined in popular “Paleo” narratives. A new study published in the Journal of Archaeological Research argues that our ancestors were skilled at gathering, processing, and eating a wide range of plants long before the first farms appeared. Researchers from the Australian National University and the University of Toronto Mississauga reviewed archaeological evidence from sites across the world and concluded that humans evolved as “broad-spectrum” eaters, relying on diverse food sources rather than primarily on animal protein.
Early humans ate processed plant foods long before farming, new study shows. Credit: Gary Todd
This research challenges the long-standing view that plant foods became important only late in prehistory during the Epipaleolithic, when hunter-gatherers supposedly began using seeds, grasses, and other previously overlooked resources. Instead, researchers demonstrate that early humans were grinding wild seeds, cooking starchy roots, and processing nuts thousands of years earlier. Plant remains and stone tools with grinding residues at sites like Ohalo II in Israel and Madjedbebe in Australia illustrate the long tradition of complex food processing.
This broad diet was not only a preference but also a physiological necessity. Humans can’t subsist on lean meat alone. Our bodies have what’s called a “protein ceiling,” where too much protein without sufficient fat or carbohydrates leads to illness, and this is sometimes referred to as “rabbit starvation.” In most environments, early people balanced meat with plant foods, rich in carbohydrates and energy. Studies of different hunter-gatherer societies show plants supplying 35–55% of calories, and sometimes even more in arid landscapes.
The authors make the case that long-standing assumptions about a “Broad Spectrum Revolution,” a supposed late expansion of diet before farming, are outdated. Instead of a sudden shift, plant use appears to be a long-term adaptation that shaped human evolution. Processing technologies — such as grinding stones, pounding tools, and cooking — allowed people to unlock nutrients from otherwise tough, bitter, or low-calorie plant resources. This flexibility helped humans occupy deserts, savannas, highlands, and temperate regions.
Map of all archaeological sites with direct evidence for early plant food use, dating from ≥35 kya, as well as, Ohalo II; listed in chronological order. Credit: Florin, S.A., Ramsey, M.N., Journal of Archaeological Research (2025)
The authors propose a new term: the “Broad Spectrum Species.” Their analysis reveals that humans and other hominins succeeded because they were able to turn a wide range of natural materials into food. Today, about 80% of the global diet is composed of plant foods, a legacy of this ancient adaptability. Even though modern agriculture relies on a few highly productive crops, this study asserts that diverse plant use has always been central to human survival.
The study reframes early people not as strictly hunters, but as inventive, tool-using foragers who mixed animal fat, starches, seeds, and roots to meet their needs. Far from being a step toward farming, the broad plant use was itself one of the key strategies that allowed our species to spread around the world.
More information: Florin, S.A., Ramsey, M.N. (2025). The Broad Spectrum Species: Plant Use and Processing as Deep Time Adaptations. J Archaeol Res. doi:10.1007/s10814-025-09214-z