For 2 million years, humans ate meat and little else — study
Tel Aviv University researchers says Stone Age humans were apex predators, only moved to more plant-based diet 85,000 years ago
Israeli researchers studying the nutrition of Stone Age humans say the species spent some 2 million years as hyper-carnivorous “apex predators” that ate mostly the meat of large animals.
The study at Tel Aviv University, in collaboration with Portugal’s University of Minho, challenges views that prehistoric humans were omnivores and that their eating habits can be compared to those of modern humans, TAU said in a statement.
“Our study addresses a very great current controversy – both scientific and non-scientific,” said Prof. Ran Barkai of TAU’s archeology department, one of the researchers. “We propose a picture that is unprecedented in its inclusiveness and breadth, which clearly shows that humans were initially apex predators, who specialized in hunting large animals.”
The results, which were published in the Yearbook of the American Physical Anthropology Association, have implications not only for how we see the past, but also for our modern diets, Barkai maintained. He cited the fad Paleolithic diet, which assumes prehistoric humans ate vegetables, fruits, nuts, roots, and meat — making those foods the most natural for consumption.
But the research suggests that only the last item on that list was on cave dwellers’ menu.
“For many people today, the Paleolithic diet is a critical issue, not only with regard to the past, but also concerning the present and future,” Barkai said. “It is hard to convince a devout vegetarian that his/her ancestors were not vegetarians, and people tend to confuse personal beliefs with scientific reality. Our study is both multidisciplinary and interdisciplinary.”
The researchers blended genetics, metabolism, physiology, morphology and archaeology of tool development to resolve the question of whether Stone Age humans were specialized carnivores or generalist omnivores.
“So far, attempts to reconstruct the diet of stone-age humans were mostly based on comparisons to 20th-century hunter-gatherer societies,” explained fellow TAU researcher Miki Ben-Dor. “This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals – while today’s hunter-gatherers do not have access to such bounty.”
The team examined the acidity of our stomachs, which is high even for predators, indicating a meat diet in which the acid would provide protection from harmful bacteria.
They also looked at fat’s structure in human cells: Similar to predators, human fat is stored in large numbers of small fat cells, whereas in omnivores it tends to be the other way around.
They further cited the human genome as evidence.
“For example, geneticists have concluded that ‘areas of the human genome were closed off to enable a fat-rich diet, while in chimpanzees, areas of the genome were opened to enable a sugar-rich diet,’” Ben-Dor said.
Further archaeological evidence supports their hypothesis, they argued, including the study of stable isotopes in the bones of prehistoric humans that point to consumption of meat with a high fat content, likely from large animals.
“Most probably, like in current-day predators, hunting itself was a focal human activity throughout most of human evolution,” Ben-Dor said. “Other archaeological evidence — like the fact that specialized tools for obtaining and processing vegetable foods only appeared in the later stages of human evolution — also supports the centrality of large animals in the human diet, throughout most of human history.”
The researchers believe humans only began moving toward a diet that is much more plant-based some 85,000 years ago, possibly as a result of a decline in larger animals as a food source.
“As Darwin discovered, the adaptation of species to obtaining and digesting their food is the main source of evolutionary changes, and thus the claim that humans were apex predators throughout most of their development may provide a broad basis for fundamental insights on the biological and cultural evolution of humans,” Barkai said.