Does brain size matter?

In this post we are going to answer the question ‘’Does brain size matter?’’ We will discover what is the reason for the size of the brain in the human and we will establish the relationship of the size of the brain with the cognitive abilities. Come and find out!

Does brain size matter?

What makes us human? What is it that allows me to express my ideas through the symbolic code that I am typing right now, and what allows you to decipher these letter combinations?

Today we know that we share more than 95% of our DNA with our closest relatives in the animal kingdom, but the great apes cannot solve mathematical equations, or write poetry, or make computers, or elaborate treatises on metaphysics.

As Stephen Hawking says, “We are just an advanced species of monkeys on a smaller planet than a very normal star, but we can understand the Universe and that makes us very special.” But how has this evolutionary leap been possible? Where is the fundamental difference that has allowed us to become talking and thinking monkeys, imaginative and innovative?

In 1868, the German doctor and biologist Theodor Ludwig Wilhelm von Bischoff published his work The Cerebral Convolutions of Man, in which he presented the results of his research on this organ.

Among them, the one that indicated that brain size is an indicator of a person’s intelligence was especially controversial, hence, according to her, men were more intelligent than women.

Legend has it that after his death he donated his brain to science and that, when it was weighed, it was discovered that its mass was less than that of the average woman. Without a doubt it would have been a magnificent ending for the story, although the reality is that he was a little above the male average.

But does that mean he was very smart? It may be, despite his macho claims. But the results of the latest studies indicate that their claims were far from true.

Does brain size determine intelligence?

The volume of the brain would not have a relevant link with the IQ. Instead, its structure and integrity appear to be more important as a biological basis for IQ, suggests a study published in Neuroscience and Biobehavioral Reviews.

An international team of researchers, led by Jakob Pietschnig, Michael Zeiler, and Martin Voracek, from the Faculty of Psychology at the University of Vienna, together with Lars Penke (University of Göttingen) and Jelte Wicherts (University of Tilburg), carried out a meta-analysis that examines the correlations between in-vivo brain volume and IQ.

Based on data from 148 samples comprising more than 8000 participants, they reported a strong but weak association between brain size and IQ. This association appears to be independent of the sex and age of the participant.

Jakob Pietschnig, from the Institute of Applied Psychology at the University of Vienna, explains that: “The observed association means that brain volume plays only a minor role in explaining the performance of humans on IQ tests.”

And he clarifies that although a certain association is observed, “the volume of the brain seems to be only of small practical relevance. Rather, brain structure and integrity appear to be more important as a biological basis for IQ, while brain size functions as one of many compensatory mechanisms for cognitive functions. “

Differences in brain structure appear to be largely responsible for species differences in cognitive performance. Among Homo sapiens, there are indications that give a larger association between IQ and brain volume equally questionable.

For example, the differences in brain size between men and women are well established, giving men larger brains by comparison than women.

However, there are no differences in overall performance on IQ tests between men and women. Another example is individuals with megalencephaly syndrome (increased brain volume) who typically perform below the average population on IQ tests.

“Therefore, structural aspects appear to be more important for cognitive performance among humans as well,” Pietschnig concludes.

Size obsession

The obsession with size and with highlighting the individual and the human species from others has also led us to popularly spread the idea that the size of the human brain is an indicator of intelligence. Neuroscientist Christof Koch recounts this idea and the scientific data that supports or refutes it.

Koch tells us that one study noted that the average size of the brain volume in adult men is 1,274cm³ and that of a woman is 1,131cm³. However, intelligence tests do not show a substantial difference between the intelligence of the sexes.

A striking case is that of the Russian novelist Ivan Turgénev, a literary giant with a 2,001gr brain; that of another great writer, the French Anatole France, weighed only 1,017g.

According to Koch, the total volume of the brain is correlated with a percentage of between 9 and 16% more intelligence.

There is, however, no clear data that proves whether intelligence is the result of a larger brain or whether the larger brain is made that way by intelligence or even some other unknown factor.

On the other hand, according to Koch, studies that take into account unique associations of certain regions of the brain of a person (something like a ‘neural fingerprint’) are able to more accurately determine fluid intelligence, that is, the ability to solve problems separately in novel circumstances, identify patterns, and reason.

The importance of brain size is also questioned when we compare our brain with that of other animals and some hominids. The case of the Neanderthal is striking: despite having a brain of more than 150cm³ on average than ours, his brain mass did little to prevent extinction.

A bee, for example, can perform a series of complicated tasks to publicize the place where a food is found, and it does this with a brain 1 million times smaller than that of a human being. Koch wonders, “Are we really 1 million times smarter than bees? Certainly not, if I look at how we govern ourselves.”

Since normally larger animals have larger brains, there is a rule that seeks to designate the animals that have greater brain mass in proportion to their total body mass. In the case of humans it is 2%.

While this makes us outperform dolphins, whales or elephants, it also makes some birds and even some mammals like the shrew beat us in this regard.

Another attempt to make man reign in the hierarchy of the intellect has suggested that what matters is having more nerve cells in places linked to higher functions of intelligence.

But in this we are also surpassed by the so-called “pilot whales” (actually dolphins), which have twice the number of cells in the neocortex, the region chosen to make this distinction.

Koch recalls that Darwin himself had noticed that in reality what makes us unique is a series of combinations that as a whole distinguish us and not something specific. However, this quality of being special in its unique multifactoriality can perhaps be associated with many other species.

Why does brain size matter?

When we were primates, the large volume of our brains allowed us to acquire skills that no other animal species has been able to match. But thousands of years later, it is still very large in proportion to our body.

We still have it very big. If 30,000 years ago the average volume of the brain was 1,500 cubic centimeters, in all this time it has barely lost 200, remaining at the 1,300 cc on average it has today.

Our primate ancestors could not walk upright and this size allowed them to learn to walk, speak, and many other complex skills. But today its volume is still considerable, considering that we have not evolved for thousands of years, and some wonder if the current size of the brain is not excessive.

A study at Cornell University in New York answers a question that, like that of the chicken and the egg, divided the neuroscientist community: what came first in the evolution of the most intelligent animals, the development of large brains or the formation of specialized areas in different cognitive abilities?

The results of the research, led by Jordan Moore and Timothy DeVoogd, tip the balance towards the first hypothesis.

They work consisted of measuring the total size of the brains and that of 30 areas associated with different behaviors of 58 songbirds, belonging to 20 families. In this way, they detected that the brain areas that controlled the emission of sounds were significantly larger in birds with more varied and complex songs.

And the same happened with another area, the one that controlled the movements of the mouth and face: its size was greater in birds with short and thick beaks that feed on seeds, since they need to perform sophisticated maneuvers to open them.

In contrast, the insectivores, with long and thin beaks, presented the areas specialized in these smaller actions.

Although the gray mass of vertebrates differ in size, composition and performance, the evolution of the total size explains most of the differences between them, explain the researchers in the journal Proceedings of the Royal Society B.

And once the species acquires a voluminous brain, then additional neural networks appear adapted to specific cognitive abilities, such as language in the case of humans.

Size is what matters most at first: larger brains also have a more developed cortex, which is the center of operations for memory, attention span, consciousness, and thought.

FAQS: Does brain size matter?

Are bigger brains better?

An individual with a bigger brain would appear to do better on cognition tests than one with a smaller brain, according to scientists.

Does a bigger head mean a bigger brain?

Yes, a bigger head means a bigger brain.

Is a bigger brain better than a smaller brain?

Not really. Great characters have excelled in different fields regardless of the size of their brains.

Is an elephant’s brain bigger than a human’s?

Although the elephant brain is the largest in land animals, it occupies just a small region at the back of the head, and the elephant brain is much smaller in relation to the body than that of humans.

Is a big head a sign of intelligence?

Not necessarily. Although they have related the size of the head of babies with intelligence.

In this post we answered the question ‘’Does brain size matter?’’ We discovered what is the reason for the size of the brain in the human and we have established the relationship of the size of the brain with the cognitive abilities.

If you have any questions or comments please let us know!

References

Larger brains do not lead to high IQs, new meta-analysis finds. (2015). Retrieved December 1, 2020, from ScienceDaily website: https://www.sciencedaily.com/releases/2015/10/151014121103.htm

Pietschnig, J., Penke, L., Wicherts, J. M., Zeiler, M., & Voracek, M. (2015). Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean? Neuroscience & Biobehavioral Reviews, 57, 411–432. https://doi.org/10.1016/j.neubiorev.2015.09.017

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