Researchers at Tel Aviv University were able to reconstruct the nutrition of stone-age humans. In a paper published in the Yearbook of the American Association of Physical Anthropology, Dr. Miki Ben-Dor and Professor Ran Barkai of the Department of Archeology Jacob M. Alkov at Tel Aviv University, along with Raphael Sirtoli of Portugal, show that humans were an apex predator for about two million years. Only the extinction of larger animals (megafauna) in various parts of the world and the decline of animal food sources towards the end of the Stone Age led humans to gradually increase the plant element in their nutrition, until they finally had no choice but to domesticate plants and animals, and became farmers.
“Until now, attempts to reconstruct the diet of Stone Age humans were based primarily on comparisons with twentieth-century hunter-gatherer societies,” explains Dr. Ben-Dor. “This comparison is useless, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals, while today’s hunter-gatherers have no access to this reward. the ecosystem has changed and conditions cannot be compared .. We decided to use other methods to reconstruct the diet of stone age humans: examining the memory preserved in our own bodies, our metabolism, genetics and physical construction. Human behavior changes quickly, but evolution is slow. The body remembers it. “
In a process unprecedented in its extent, Dr. Ben-Dor and his colleagues collected about 25 lines of evidence from about 400 scientific articles from different scientific disciplines, which addressed the main issue: Stone Age humans were specialized carnivores or were generalist omnivores. ? ? Most of the evidence was found in research on current biology, namely genetics, metabolism, physiology, and morphology.
“A notable example is the acidity of the human stomach,” says Dr. Ben-Dor. “Stomach acidity is high compared to omnivores and even other predators. The production and maintenance of strong acidity require large amounts of energy and their existence is evidence of the consumption of animal products. Strong acidity provides protection against harmful bacteria found in meat, and prehistoric humans, who hunted large animals with sufficient meat for days or even weeks, often consumed old meat that contained large amounts of meat. bacteria and therefore needed to maintain a high level of acidity.Another indication of being predatory is the structure of fat cells In omnivorous bodies, fat is stored in a relatively small number of large fat cells, while in predators, including humans, it is the other way around: we have a much larger number of smaller fat cells.The evolution of humans as predators has also been found in our very genome. For example, geneticists have concluded that “areas of the human genome were closed by a t-rich diet, while in chimpanzees, areas of the genome were opened to allow a high-sugar diet.”
Evidence from human biology was complemented by archaeological evidence. For example, research on stable isotopes in the bones of prehistoric humans, as well as exclusive hunting practices of humans, show that humans specialized in hunting large and medium-sized animals with a high fat content. Comparing humans with today’s large social predators, all of which hunt large animals and obtain more than 70% of their energy from animal sources, reinforced the conclusion that humans specialized in hunting large animals. and, in fact, they were hypercarnivores.
“Hunting large animals is not a hobby in the afternoon,” says Dr. Ben-Dor. “It requires a great deal of knowledge and lions and hyenas acquire these skills after long years of learning. It is clear that the remains of large animals found in countless archaeological sites are the result of the great experience of humans as hunters. Many researchers studying the extinction of large animals agree that hunting by humans played an important role in this extinction, and there is no better evidence of the specialization of humans in animal hunting. Most likely, as in today’s predators, the hunt itself was Other archaeological evidence, such as the fact that specialized tools for obtaining and processing plant food only appeared in the later stages of human evolution, also support the centrality of animals. grains in the human diet. human history “.
The multidisciplinary reconstruction carried out by TAU researchers for almost a decade proposes a complete paradigm shift in the understanding of human evolution. Contrary to the widespread hypothesis that humans owe their evolution and survival to their dietary flexibility, which allowed them to combine animal hunting with plant food, the image shown here is that of humans evolving primarily as predators of humans. large animals.
“Archaeological evidence does not overlook the fact that Stone Age humans also consumed plants,” Dr. Ben-Dor adds. “But according to the results of this study, plants only became an important component of the human diet by the end of the era.”
Evidence of genetic changes and the emergence of unique stone tools for plant processing led researchers to conclude that for about 85,000 years in Africa and about 40,000 years ago in Europe and Asia, produced a gradual increase in the consumption of plant foods as well as dietary diversity, in accordance with different ecological conditions. This increase was accompanied by an increase in the local uniqueness of the culture of stone tools, which is similar to the diversity of material cultures of twentieth-century hunter-gatherer societies. In contrast, during the two million years in which, according to researchers, humans were apex predators, long periods of similarity and continuity were observed in stone tools, regardless of local ecological conditions.
“Our study addresses a major current controversy, both scientific and non-scientific,” says Professor Barkai. “For many people today, the Paleolithic diet is a critical issue, not only in terms of the past, but also in terms of the present and the future. It is difficult to convince a devout vegetarian that their ancestors were not vegetarians and that people tend to confuse personal beliefs with scientific reality.Our study is multidisciplinary and interdisciplinary.We propose an unprecedented image in its inclusion and breadth, which clearly shows that humans were initially apex predators, who specialized in The adaptation of species to the obtaining and digestion of their food is the main source of evolutionary change and, therefore, the assertion that humans were apex predators for most of their development can provide a broad basis for fundamental knowledge about the biological and cultural evolution of humans. ”
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