There are very elegant ways to insult. For example, in my La Mancha family when someone tells you “your brain has grown today” it means that it is not your best day and you are a little “thicker” than normal.
As time goes by, the meaning of words changes and, it seems, so does the volume of our brain.
It is not surprising, therefore, that in the future and according to the latest studies in neuroscience, any reference to the size of this organ will be considered a compliment.
But to speak accurately on the subject, it is important to clarify something first.
The central nervous system is made up of the brain (which includes the cerebrum, brainstem, and cerebellum) and the spinal cord. Although the cerebrum is the largest part of the brain, it is only one part of it. Therefore, it is more accurate to refer to the set with the second term.
However, in a recent study that we will discuss in detail later, researchers found changes primarily in brain volume. Therefore, on this occasion, and without serving as a precedent, both terms will be used interchangeably.
Our brain has not hit the ceiling
Evolution has provided humans with a large brain, with a volume of between 1,200 and 1,400 cm³. Although there are animals, such as the sperm whale, that can be very large in absolute terms (8,000 cm³), we must consider the proportion with respect to the rest of the body.
In this sense, humans are the living beings with the largest brain, without discussion, since it is five times larger in relation to body size. This fact has traditionally been associated with greater intelligence and better higher cognitive abilities.
And the evolutionary process continues. Does this mean that our brains continue to grow or have we already reached our ceiling?
Well, it seems to be the first: the aforementioned research has found that people born in recent years have significantly larger brains than those of previous generations.
To find out, scientists performed MRIs on 3,226 people, women (53%) and men (47%) between 45 and 74 years old. Comparing the images of volunteers born between the 1930s and 1970s, they found that, on average, the brains of participants from the 1970s had a volume 6.6% larger than those of subjects who came into the world forty years earlier. , without significant differences between men and women.
The growth would affect important areas such as the white matter – a network of myelinated axons that allow communication between the different areas inside and outside the nervous system –, the cortical gray matter – where most cognitive and emotional processes are carried out – and the hippocampus, a structure responsible for various cognitive functions such as memory or the ability to orient and move.
This thickening could be influenced by several environmental and developmental factors, such as better pre- and postnatal medical care, advances in nutrition, lifestyle changes, increased access to education, and greater cognitive stimulation.
For intelligence, size (almost) doesn’t matter
The next question that assails us is: does the increase in brain size make us more intelligent? Not quite. Although the study analyzes trends in brain volumes and their association with temporal and environmental factors, size is not necessarily a direct indicator of intelligence.
The encephalization theory suggests that “extra” brain tissue allows more neurons to be dedicated to cognitive tasks. And although it is true that there is a small but significant correlation between brain dimensions and cognitive performance, there is no direct and absolute relationship between both parameters.
Intelligence is a multifaceted construct determined by a wide range of factors, including genetics, environment, and health.
In addition, higher cognitive abilities are influenced by brain structure and connectivity, plasticity and individual experience, among other elements.
Brain size is definitely not the only factor that determines intelligence.
Encephalization, or relative increase in brain size in relation to body size, has been a key process in the evolution of the human brain, but not the only one.
A reorganization of brain tissues and circuits was also necessary. Therefore, the relationship between size and intelligence is not linear, and species with smaller brains may have higher cognitive abilities than species with larger organs.
A clear example is birds compared to primates. Their brains are smaller in relation to their body, but they have a high neuronal density concentrated in certain areas.
This allows them to enjoy high levels of cognition, with skills such as planning for the future or finding patterns. The same can happen between different human individuals.
Better prepared to face cognitive decline
What these types of studies do seem to indicate is that increasing brain size can influence cognitive development by providing a greater brain reserve, potentially reducing the risk of cognitive decline and neurodegenerative diseases.
In Spain alone, nearly a million people suffer from some type of dementia, characterized by a decrease in brain volume. Scientific research suggests that a larger brain volume may be associated with better brain health and greater resistance to conditions such as Alzheimer’s.
That is, with a larger brain it would take longer to lose volume as a consequence of the disease, which could translate into greater hope and quality of life for patients with dementia.
At the moment, this is just a hypothesis that needs much more research to be confirmed. In fact, brain growth would have to be accompanied by an improvement in brain plasticity influenced by our environment.
This would be key to processing more information, learning better and adapting more easily to different situations throughout life.
In short, while increasing brain volume over the decades does not directly translate into greater intelligence, it offers a fascinating insight into our neurological evolution.
This growth could represent a kind of “cognitive reserve”, a hidden advantage that could help us combat neurodegenerative diseases such as Alzheimer’s.
Personally, I am in favor of this twist of evolution: between being smarter and not forgetting, I prefer the second option.
*José A. Morales García is a scientific researcher in neurodegenerative diseases and professor at the Faculty of Medicine, Complutense University of Madrid. His article was published in The Conversation whose original version you can read here.
Keep reading:
* Neuroscientist tells you how to “deprogram” your brain to avoid situations that harm us
* The brain is “rewired” at age 40 (and how to keep it healthy from that age onwards)
*What traumatic experiences do to the brain and body
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