The human brain is not something that has been built from scratch, but has arisen from the brains that our ancestors had: the first mammals, which were mice that lived about 195 million years ago.
The brain of these mice was not made from scratch either, but inherited some traits and discarded others from the brain of their ancestors, who were no longer mammals. So really our brain has been building like a house with many remodels.
We have greatly enlarged the external part of the brain, the cerebral cortex, which is eighty percent of it. But even if we have this new zone, we also conserve basic structures of brain functioning; structures that were already present in the brains of our ancestors.
All these structures that are in our brain and that have been preserved for millennia in those of our animal ancestors are often called “the reptilian brain” . According to this concept, we would have a non-reptilian brain that would be all this huge cortex that we have and the rest, which was already in a very similar way in our ancestors, would be the reptilian brain.
What happens is that ” reptilian brain ” is not a very correct term. First of all, both reptiles and humans have a common ancestor brain which comes from the first land animals. And from these primal animals derive some brain structures that have been conserved in reptiles as well as in birds or mammals.
But it is also that calling our most ancestral parts a reptilian brain is confusing: it seems that we had the brain of a reptile directly inside our head and it is not like that. Both our brains and that of reptiles have evolved in parallel in different ways according to the needs of each species.
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About Neurocosas:
Directed and presented by Pablo Barrecheguren, Neurocosas is a scientific dissemination project carried out by Big Van, Scientists on Wheels and Very Interesting, financed with the help of the Spanish Foundation for Science and Technology (FECYT)
