While many modern humans opt for a vegetarian either vegan diet, new research suggests our ancestors got most of their nutrition from meat, only diversifying their food intake to include more plants at the end of the Stone Age. Posted in the American Journal of Physical AnthropologyThe new study indicates that humans were top predators for around 2 million years, with numerous species within the Homo lineage that is dedicated to “hypercarnivory”.
Determining the trophic level, or position within the food web, of ancient humans is tricky, since we can’t directly observe the feeding behaviors of our earliest ancestors. Therefore, most attempts to do so have focused on present-day hunter-gatherer groups, assuming that the practices of such cultures mirror those of early humans.
However, the authors of this latest study explain that such comparisons are highly problematic, as changes in the ecological landscape will inevitably have forced humans to modify their hunting and gathering preferences over time. For example, the loss of megafauna such as mammoths and other large animals produced a major change in the human diet.
Therefore, the researchers sought to reconstruct the diet of ancient humans and determine the trophic level of our ancestors throughout the Pleistocene, which began 2.5 million years ago and ended at the time of the agricultural revolution, a long time ago. about 11,000 years. Taking a multidisciplinary approach, the team examined more than 400 scientific studies covering areas such as genetics, metabolism, morphology, archeology and paleontology to determine whether early humans were specialized carnivores or more general omnivores.
Their research turned up 25 sources of evidence that strongly suggest our predecessors were hypercarnivores. For example, heartburn is a hallmark of carnivorous animals, as this ensures that any pathogens lurking in the meat are killed. The fact that the stomachs of modern humans are more acidic than those of most carnivores points to the fact that our ancestors were well adapted to consuming the meat of the large animals they hunted, which would have fed a community for days or even weeks and therefore would have been full of bacteria.
This is supported by the fact that several archaic hominids were morphologically adapted to hunt megafauna. standing manfor example, it was equipped with shoulders that were ideal for throwing spears but unsuitable for climbing trees, suggesting that the species probably ate more meat than plants.
How the diet of ancient humans changed as our brains evolved. Image Credit: Dr. Miki Ben Dor
Furthermore, genes that facilitate digestion of plant acids and starch were not widely expressed in the human genome until the late Pleistocene. According to the study authors, this indicates a lack of evolutionary pressure to switch to a plant-based diet while hunting was good. However, as animal sources become more scarce, humans who consumed more vegetation enjoyed higher survival rates.
According to the researchers, this late shift to a more omnivorous diet provided the spark for the advent of agriculture, leading to a change in the types of stone tools used by ancient humans. Looking through the archaeological records, they found that the tools associated with processing plants only appeared around 40,000 years ago and increased in frequency around the time of the agricultural revolution. Prior to this, most tools were designed for hunting, with the same types of artifacts found in all human-inhabited areas.
“The archaeological evidence does not overlook the fact that stone-age humans also ate plants,” explained study author Miki Ben-Dor in a paper. declaration. “But based on the findings of this study, plants only became a significant component of the human diet towards the end of the era.”
A version of this article first appeared in April 2021.