Scientists already knew that the human brain is larger than that of other primates, our closest living relatives – the chimpanzee, bonobo and gorilla – but the difference in size does not explain the characteristics and functions that make it unique.
An analysis of tissues from the brains of humans, chimpanzees and macaques, published in an article in the journal Science , has revealed that our thinking organ is not only a larger model than the brain of ancestral primates, but that throughout evolution has been acquiring many different characteristics. Thanks to all these peculiarities, the brain is the organ that configures the identity of our species.
According to the SINC agency Tomàs Marquès-Bonet, ICREA research professor at Pompeu Fabra University (UPF), director of the Institute of Evolutionary Biology (IBE) and one of the authors of the study, the fact that our brains are three times larger than those of chimpanzees is a very remarkable fact that has been achieved in just over a million years : “Human brains have many more cells than those of other primates, and also these cells are more interconnected ; therefore, they have more processing power. “
The research authors analyzed 247 tissue samples from 16 brain regions – the hippocampus, the amygdala, the striatum, the dorsomedial nucleus of the thalamus, the cerebellar cortex and eleven areas of the neocortex – involved in the behavior and cognitive process of high level . The samples came from six humans, five chimpanzees, and five macaques.
From these analyzes, led by Nenad Sestan, a professor at Yale University in the United States and a researcher at the Kavli Institute of Neurosciences, it was revealed that all primate species had striking similarities in terms of gene expression in all regions of the brain. studied, and even in the prefrontal cortex, the brain region that deals with higher-order learning that most differentiates humans from other species of apes.
In contrast, the area of the human brain that showed a more specific gene expression was the striatum , a region that is normally associated with movement and that could logically be linked to bipedalism.
Other co-authors of the study, such as André MM Sousa and Ying Zhu, researchers in Sestan’s laboratory, focused on the TH gene, whose primary function is the production of dopamine, a neurotransmitter that plays a decisive role in higher order function and do not have people affected by Parkinson’s disease.
Sousa and Zhu observed that, while this gene was abundantly expressed in a rare population of inhibitory neurons of the neocortex and striatum in humans, it did not appear in the neocortex of our thinking organ. According to Sousa, the expression of this gene in the neocortex was probably lost in a common ancestor, and reappeared in the human lineage .
Those responsible for the research also found high levels of expression of the MET gene in the human prefrontal cortex, linked to autism spectrum disorder, compared to the other primates studied.
