Why is it said that we have three brains in one?

The complexity of the human mind has meant that, when trying to explain and understand its functioning, hypotheses and theories originating from many different, sometimes even opposing, perspectives have emerged Yes. This is nothing unusual; in fact, it is part of the essence of the generation of scientific knowledge.

After all, science is not the absolute and universal truth, but rather a very humble way of validating and making tests explanations about how the world works, substituting others closer to reality when they remain out of phase

Now, this diversity of theories and hypotheses is especially rich in the case of Psychology and Neurosciences, because what they are responsible for investigating is subject to the influence of many variables. Thus, the mind can be approached from the study of behavior, which is neither palpable nor locatable in a specific area, or from the study of the organism and, more specifically, of the brain. In the case of this last class of research, there is a hypothesis that has become very famous: that of the triune brain. According to this, where it seems that the human being simply has a brain,

there are actually three brains interacting with each other. Let's see what it is and what's true about it.

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What is the triune brain hypothesis?

The idea that we have three brains It was developed primarily by the American neuroscientist Paul MacLean in the 1960s.. From his point of view, what appears to be the human brain is actually the superposition of three different brains, showing three qualitatively distinct stages in the evolution of our lineage.

In the deepest part of the brain the reptilian brain, the most primitive of the three, whose characteristics are an adaptation to the way of life of reptiles, which emerged at a time when mammals did not yet exist. MacLean identified it with what is known as the basal ganglia and their adjacent areas, a series of nuclei of neurons located in the deepest area of ​​the brain, and proposed that this brain was responsible for triggering behaviors linked to instincts: the confrontation against competitors or attackers, the tendency to defend one's own territory, the rituals of mating etc

Above the reptilian brain, the passage of time would have given rise to the paleomammalian brain, emerged with the mammalian reptiles or the first mammals. This would include what is known as limbic system, and is responsible for the appearance of emotions linked to the motivation to feed, mate and associate with other individuals, as well as parenting. These are behaviors that are less based on pure impulse and do not lead to actions as predictable as those of the reptilian brain.

Finally, above the previous one would be the neomammalian brain, which can be seen in the most evolved forms of mammals, and especially in primates. This would have given the possibility of re-processing information already processed by other parts of the nervous system, giving rise to more abstract thoughts and, ultimately, our ability to imagine complex experiences and predict situations future.

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Do we really have three brains?

At present, it is considered that the idea of ​​the three brains is, in any case, a simplification that must be understood as a metaphor, and not as a scientifically valid explanation or capable of writing in detail the reality of the functioning of our nervous system.

While it is true that the human brain is far from being a totally homogeneous anatomical structure (in fact, it is more of a set of organs), reaching the extreme of considering that there are three physically separable brains and working in parallel results excessive. The nature of the brain means that there are different groups of nerve cells in charge of specialized tasks, but at the same time, these are constantly coordinating with each other in a constant way.

What happens in the human brain can be compared to what happens in an orchestra: different musicians specialize in instruments but the ultimate goal is to offer a unitary experience: music, which cannot be understood by analyzing only its parts by separated. Therefore, today we know that a human being without neurological problems has only one brain.

On the other hand, it can be said that it would not make sense for human beings to have a reptilian brain, another paleomammal and another neomammal. It is true that the evolution of species shows that in current forms of life there are "traces" or remnants of other forms of life. life that belonged to ancestral stages of their lineage (for example, the sacral bone of humans, which includes the remains of a line). However, what is preserved must be functional or, at least, not greatly hinder the possibility of survival.

This means that although sometimes vestigial organs remain that have lost their previous usefulness, or they are either so stunted that they no longer matter, or else they are modified so that they can perform a new function. In the case of the reptilian brain or the paleomammalian, it would not make sense to keep them as they are because it is not efficient to have several brains "competing" with each other to take control of the conduct; in any case, their anatomical characteristics would remain, but their functional characteristics would change and they would take on new tasks and give up others.

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The importance of ancestral brain structures

So the three-brain hypothesis doesn't teach us anything? Not exactly, as a metaphor there are aspects that it invites us to take into account. For example, the concepts of “limbic brain” and “neocortex” are useful because they help us to know in which parts of the brain the processes most related to emotions and to reasoning and decision-making are carried out. conscious decisions, respectively, although they do not dedicate themselves to these functions totally exclusively but rather cooperate with other structures of the system highly strung.

And it also gives us a glimpse that in our lineage, the tasks performed by the neocortex have not been as vital as those of deeper areas of the brain, since expanding “outward” to acquire new skills generates fewer risks than greatly modifying the rest of the brain structures that are already responsible for keeping us alive in the here and now.

The latter, in turn, reveals to what extent emotions go ahead of rationality. Practically, all our actions have a series of affective and motivational elements behind them, but only in some of them is there a conscious decision to achieve something, or a medium or long plan term.

While no animal can afford not to have a part of the brain dedicated to triggering impulses and giving rise to emotions, only a few have been able to become capable of developing abstract thought or even the ability to make physical tools (such as spears, arrows, or hunting traps) or non-physical tools (such as the language). And, in fact, most of the decisions we make are not due to reflection, but to what we do spontaneously depending on how we feel, without thinking much.

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