Over six million years of human evolution, brain size has increased by 300%. Was meat consumption the cause?

Top image by Karen Carr Studios, courtesy of the Smithsonian Human Origins Program

Our huge, complex brains can store and process decades of information in fractions of a second, solve multifactorial problems, and create abstract ideas and images. It is an indisputable prodigy, which we owe to evolution, and which shelters the foundations of humanity. The relative size of the human brain, in relation to the rest of the body, is the largest of any species. What made you grow up so much?

Many scientists are betting that the rise of meat on the Paleo Diet, an evolving era, had a lot to do with the brain development of our ancestors. The contribution of calories that meat supposed, according to this hypothesis, allowed the brain and body of one of our first ancestors, Homo erect, will increase in size.

To claim that meat consumption has increased, they mainly rely on fossil remains found in ancient archaeological sites from two million years ago, because then marks begin to appear on animal bones that correspond to having been eaten by a human. But before they didn’t eat meat?

reasonable doubt

However, a new study published in PNAS argues that the evidence behind this hypothesis is statistically flawed. Even before the study, many experts suspected that the link between carnivores and larger brains and bodies in early humans was not entirely clear.

The new study, which takes W. Andrew Barr, a paleoanthropologist at George Washington University, reviews data on the occurrence of carnage marks at nine archaeological foci of early human activity in East Africa, from 2.6 million to 1.2 million years ago.

What he found is an interesting bias maintained over time, and is that, as seems obvious, more butcher-marked remains are found in the most studied, that is, more superficial and accessible places. This does not allow us to establish as a conclusion that meat consumption has increased, but it is necessary to study the previous deposits in more depth.

Each of these sites contains multiple layers of sediment; the deeper the layers, the older the treasures they contain.

Layers that are between 2.5 and 2 million years old are simply not as exposed and therefore not as easy to study.

Did our ancestors eat less meat before that date? Well, according to this study, it is not possible to give a conclusive answer.

According to the study, meat consumption remained essentially constant between 2.6 million and 1.2 million years ago.

couldn’t be the meat

Instead of an increase in meat consumption, there are other explanations for the humanization associated with brain size.

For example, the establishment of the kitchen, which makes food easier to digest, may have driven higher calorie intake and therefore bigger brains.

Humans were also able to get more calories as their groups became more socially complex. An extended hunting and gathering family for the group provides a greater amount of food for the entire family. This is known as “grandmother hypothesis.

So the “flesh made us human” hypothesis may be too simplistic.


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