The idea that the frequent consumption of meat would have allowed an unprecedented leap in the evolutionary trajectory of humanity may be the result of a simple methodological error, says a new study.
When analyzing the archaeological sites in Africa on which this hypothesis is based, American and South African researchers say that the apparent increase in animal protein in the diet of our ancestors from 1.9 million years ago is nothing more than an illusion created by the higher frequency of excavations in rock layers with this age.
“Considering that human ancestors clearly shredded animal carcasses at least 2.6 million years ago, it is certainly possible that eating meat had an impact on the evolution of our lineage,” he told leaf the coordinator of the new research, Andrew Barr, from George Washington University (USA).
“Our study shows, however, that any estimate of the importance of carnivorous habits over time needs to deal with the extremely low sampling of archaeological sites during the period between 2.6 million and 1.9 million years ago.” Without more data on this phase, it’s impossible to say whether, all of a sudden, hominins (members of the human lineage) became inveterate beef eaters, so to speak, or whether the process was much slower and more gradual—and therefore with less repercussions. dramatic.
The work by Barr and his colleagues, which has just appeared in the American journal PNAS, compares the periods before and after the “magic date” of 1.9 million years because it is at this time that the species Homo erectus, the first hominin with characteristics closer to current human beings.
Although hominins had become bipedal long ago, the H. erectus it was the first to have body proportions essentially identical to ours, with long legs that probably allowed it to get around relatively quickly and stably in open environments. Your brain has also undergone significant growth, reaching up to two-thirds of the brain volume of people today.
The more complex stone tools produced by the species are perhaps a reflection of this increase, as well as the fact that, in the 100,000 years that followed its African origin, the H. erectus has spread over much of the Old World, reaching the Caucasus (on the border between Europe and Asia) and even Indonesia.
For many paleoanthropologists, an obvious candidate for the “gasoline” of these different processes is meat, a food rich in the proteins and fats necessary to boost the development of larger brains (since brain tissue consumes proportionately much more energy than the rest of the organism).
Eating meat would not be a completely unreasonable innovation, as other primates occasionally consume it as well. Chimpanzees, for example, hunt and eat small monkeys, antelopes and swine when they have the opportunity to do so. With the development of simple stone tools, the H. erectus would have increased both its ability to capture small animals and, mainly, the use of carcasses abandoned by lions, hyenas and other large predators, starting to consume much more animal protein than the average of today’s chimpanzees.
In the new study, the researchers analyzed data from 59 archaeological sites across East Africa, from Ethiopia to Tanzania — the most important region for understanding this phase of the human evolutionary trajectory. Their statistical control showed, according to Barr, that there is simply no real increase in evidence of meat consumption (basically animal bones with cut marks on them) in the period from 2.6 million to 1.2 million people. years ago. What happens is that simply the sites with more recent ages have been explored more by scientists and therefore seem to bring in more data.
“Furthermore, I think the preservation [das camadas de rocha] plays an important role here. There are fewer paleontological sites in the range between 2.6 million and 1.9 million years ago, which suggests that the deposits [camadas] this age are not as exposed in the region”, he explains. This fact introduces another bias in traditional analyses, also weakening the hypothesis of meat consumption as a catalyst for changes in the H. erectus.
If this idea were to be discarded, what could explain the species’ “Great Leap Forward”, then? There are other cards on the table, such as the cooking hypothesis, according to which the use of fire would have increased the quality of nutrients in all types of food, including those of plant origin. The effect would be the same: more energy to turbocharge the brain enlargement. Barr, however, urges caution. “As we say in the article, the archaeological evidence supporting any of these hypotheses is limited.”
Source: Folha
