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What makes the human brain so special?

What makes the human brain so special?

November 27, 2021

The human brain is exceptionally unique , has very complex characteristics in relation to the rest of the animal species, including our phylogenetic cousins, the primates.

The capabilities of human beings, is very specific to our species: we can think in very complex terms, be creative and create technological artifacts that facilitate our lives and we are also the only species with the ability to study other animals and their behavior .

Why are we so special? The human brain ...

For years the scientific literature postulated that the cognitive capacity was proportional to the size of the brains. This is not quite correct, since two mammals with brains of similar sizes, such as a cow and a chimpanzee, should have behaviors of equal complexity, which does not happen. And what is even worse: Our brain is not the largest that exists. Anyway, our brain, despite not being the largest, is the best in terms of cognitive ability .

Apparently, the special quality of our great cognitive capacity does not come from the size of the brain in terms of its mass, but in terms of number of neurons it contains . And this is where we find ourselves with a study carried out by Suzana Herculano-Houzel, a Brazilian neuroscientist, who was entrusted with the task of determining the number of neurons that the human brain possesses.

Before their research, the vast majority of neuroscientists argued that the human brain possessed 100 billion neurons. The truth is that this figure was never determined in any study and was a norm for years within the scientific literature.

So Suzana Herculano-Houzel, through a method designed by her, manages to determine the final number of neurons in the human brain: 86,000 million neurons in total, of which 16,000 million are in the cerebral cortex (cortex involved in complex cognitive processes). And by applying the same method in the brain of different mammals and comparing them, he discovered that the human brain, although not the largest in terms of mass, is quantitatively in the number of neurons it has, even with primates , with whom we share many of our genetic load (97%). And this would be the specific reason for our cognitive abilities.

Why did the human being evolve to this surprising complexity?

From this, other questions arise: How come we evolve to this amazing number of neurons? And particularly, if the primates are bigger than us, why do not they have a bigger brain with more neurons?

To understand the answer to these situations, one should compare the size of the body and the size of the primate brain. Thus, he discovered that since neurons are so expensive, the size of the body and the number of neurons compensate each other. So a primate who eats 8 hours per day can have a maximum of 53 billion neurons, but his body could not be greater than 25 kg, so to weigh much more than that, he should give up on the number of neurons.

From determining the amount of neurons available to the human brain, it is understood that it needs an enormous amount of energy to maintain it. The human brain consumes 25% of the energy even though it only represents 2% of the body mass . In order to maintain a brain with such a large number of neurons, with a weight of 70 kg on average, we should devote more than 9 hours a day, which becomes impossible.

Humans cook food

So if the human brain consumes so much energy and we can not spend every waking hour dedicating ourselves to our food, then the only alternative is to somehow get more energy from the same foods. So, this coincides with the incorporation of food cooking by our ancestors a million and half years ago .

Cooking is using fire to predigest food outside the body. Cooked foods are softer, so they are easier to chew and turn into porridge in the mouth, which means that it can be better digested in the stomach and allows to absorb greater amounts of energy in much less time. Thus, we get a lot of energy for the functioning of all our neurons in much less time , which allows us to dedicate ourselves to other things beyond feeding ourselves and stimulating in this way our cognitive capacity achieved with a brain of such magnitude.

So, what is the advantage we have as human beings? What do we have that no other animal has?

The answer is that we have the brain with the largest number of neurons in the cerebral cortex, which explains our complex and extraordinary cognitive abilities to all nature.

What do we do and what does no animal do, to allow us to reach such a large number of neurons in the cerebral cortex?

In two words: we cook. No other animal cooks its food to digest it, only humans do it. And this is what allows us to become human as we are.

From this conception, we must realize the importance of food, how food influences the maintenance of our cognitive skills and the scope we have in achieving behaviors of enormous complexities.

So you know: the next time your mother cooks something that you do not like or that you hear someone will study gastronomy, congratulate them, because with their contributions they continue to make our cognitive skills continue to be just as complex.

What is so special about the human brain? | Suzana Herculano-Houzel (November 2021).

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