Over 1952, a physician and neuroscientist named Paul MacLean proposed that our skull holds not one brain, but three, each representing a distinct evolutionary stratum that has formed upon the older layer before it, like an archaeological site: The Triune Brain.

The reptilian brain, the limbic system and the neocortex, each of the three brains is connected by nerves to the other two, but each seems to operate as its own brain system with distinct capacities. Kaslev,M.A. et. al. (2003).The Triune Brain. [Online].29th October 2003.

Availble from:

[Accesed: 15th June 2016]

Reptile Brain, the most primitive of our brains, is the fundamental core of our nervous system. The survival is its main focus that is why the visceral stimulus response are part of his language like the aggression, the defense of territory, fight, flight, deception and also basic life support functions like breathing, blood pressure and heart rate.

As Clifford, R. (2009) refers the limbic system also named mammalian brain, links our reptile brain with the more advanced structures and gives us “the power of feeling, as opposed to simply reacting. Complex care of young, and other behaviors not so purely instinctual flow from the limbic system; so do primal urges and powerful emotions that ensure self-preservation, such as terror, rage, sexual desire, hunger…and even more complex emotions such as love, compassion, empathy, envy, indignation and hope”.

The last one is the neocortex or the human brain, which is in fact the thinking brain as the center of the “soul”. Voluntary movement begins here, and integration of all sensory inputs. We share the neocortex only with higher apes, ours being more advanced. By far the largest brain, completely encompassing the limbic system, the neocortex is our path to words and symbols, logic and time, abstract thought. Clifford, R. (2009). From Reptiles to Humans: A Three Brain Odyssey. [Online]. 1st September 2009.

Available from:

[Accesed: 15th June 2016]

Nowadays, this theory is taking a great importance in the neuroscience world. That is because the human being, as this perspective, has more than one brain that gives us a connecting link between.

As an interesting fact, the reptilian brain is the oldest of those three brains which appears around 500 million years ago…

Ruth Talavera Flores


Research Associate & IRIANS’s Representative for

the Iberian Peninsula and Mexico

IRIANS – The Neuroscience Institute


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