Researchers think they have finally found out why humans have larger brains than our evolutionary ancestors (even though gorillas, our closest living relatives, grow to three times the size of humans). The answer? Meat.
Vegetarian, vegan and raw diets can be healthy — likely far healthier than the typical American diet. But to continue to call these diets “natural” for humans, in terms of evolution, is a bit of a stretch, according to two recent, independent studies.
Eating meat and cooking food made us human, the studies suggest, enabling the brains of our prehuman ancestors to grow dramatically over a few million years.
One study suggests that the high calories found in meat helped fuel the development of the human brain. The researchers believed it would’ve been impossible for early humans to gather enough calories from meat-free foods to feed their growing brains. If early humans had followed a raw diet (like gorillas), they would have had to eat for a total of nine hours every day in order to consume enough calories for proper brain development. On the flip side, if gorillas were to develop a humanlike brain, they would need to eat 700 additional calories per day — an extra two hours of eating all those greens.
“The bottom line is, it is certainly possible to survive on an exclusively raw diet in our modern day, but it was most likely impossible to survive on an exclusively raw diet when our species appeared,” Herculano-Houzel told LiveScience.
But how does a filet mignon or rib eye steak exactly translate to a bigger brain? Some believe that by spending less time getting enough adequate calories, the body had more time to focus on other important tasks, like building a brain. Others say meat provided early humans with the proper amount of vitamins, minerals, and energy necessary to power the brain’s expansion. In other words, the human brain has been able to grow thanks to a nutrient- and calorie-dense diet.
If cooking wasn’t routine before the dawn of modern humans, eating meat certainly was.
The second study, published in October the journal PLoS ONE, examined the remains of a prehuman toddler who died from malnutrition about 1.5 million years ago. Shards of a skull found in modern-day Tanzania reveal that the child had porotic hyperostosis, a type of spongy bone growth associated with low levels of dietary iron and vitamins B9 and B12, the result of a diet lacking animal products in a species that requires them.
The child was around the weaning age. So either the child’s mother’s breast milk lacked key nutrients or the child himself did not consume enough nutrients directly from meat or eggs.
Either way, the finding implies that meat must have been an integral, and not sporadic, element of the prehuman diet more than 1 million years ago, said the study’s lead author, Manuel Dominguez-Rodrigo, an archaeologist at Complutense University in Madrid.
This supports the theory that meat fueled human brain evolution because meat — from arachnids to zebras — was plentiful on the African savanna, where humans evolved, and is the best package of calories, proteins, fats and Vitamin B12 needed for brain growth and maintenance.
“Carnivore animals, whether terrestrial or aquatic, are bigger-brained than herbivores,” Dominguez-Rodrigo told LiveScience. He added that “there is no [traditional] society that live as vegans,” essentially because it wouldn’t be possible to get Vitamin B12, which is only available in animal products.
Both sets of researchers said their conclusion — that cooked food and meat were necessary for human brain development — is not a statement of how the human diet must have been but rather how it likely was in order to make humans “human.”
With supermarkets and refrigeration, humans today can and increasingly do eat a vegetarian or vegan diet year-round. And given the amount of heart-stopping saturated fats in factory-produced animal products, a plant-based diet can be more healthful.
Just because meat might be what made our brains what they are today doesn’t mean a meat-rich diet is always best for modern humans. Every diet has its pros and cons, and finding the correct balance of nutrients that works for your body is what’s most important. So if eating meat isn’t your thing, don’t fret — just be thankful you weren’t born a few million years ago.