[The evolution of the brain in the genus Homo: the neurobiology that makes us different]. / La evolución del cerebro en el género Homo: la neurobiología que nos hace diferentes.

INTRODUCTION: For the most part, what makes us different from other animal species is comprised within our brain. However, there is no single factor, no singular reason accounting for the difference between our brain and others; rather, differences appear multiple. DEVELOPMENT AND CONCLUSIONS: Here we perform an up-to-date review of the main divergences between ours and other species' brains, which might be explaining the singularities of our behavior. When brain volume is on focus, it can be appreciated that our brain is certainly large both in relative and absolute terms, being also the case that some subdivisions of the prefrontal regions, as much as the parietal or temporal lobes appear notably increased in size relative to other brain areas. Also at variance with other species, our brain is consistently more asymmetric. But differences also involve the cellular level. In this regard, they have been reported different and peculiar proportions of neurons both within and between cortical columns, as much as certain types of neurons (like fusiform and mirror neurons) that, even if they are not exclusively human, they display in our species peculiar quantitative and functional features. Finally, neuronal receptor systems seem to exhibit exclusively human traits that might be crucial to understanding some of the singularities of the evolution of our brain.

La evolución del cerebro en el género Homo: la neurobiología que nos hace diferentes / The evolution of the brain int he genus homo: the neurobiology that makes us different

Introducción. Gran parte de lo que nos hace diferentes de otras especies animales está en el cerebro. Sin embargo, no hay un único factor, una única razón por la que nuestro cerebro sea distinto, sino que las diferencias son múltiples. Desarrollo y conclusiones. En este trabajo se revisan las principales disparidades que se conocen hoy en día entre nuestro cerebro y el de otras especies y que podrían explicar las singularidades de nuestro comportamiento. Cuando se revisa el volumen cerebral y el de sus distintas subdivisiones, se observa que es realmente grande en nuestra especie, tanto en términos relativos como absolutos, y algunas partes de nuestro cerebro, como ciertas regiones prefrontales, los lóbulos parietales o los temporales, parecen haber aumentado de tamaño notablemente más que otras. También se constata que, a diferencia de otras especies, nuestro cerebro es más sistemáticamente asimétrico. Pero las diferencias entre nuestro cerebro y el de otras especies se aprecian también a escala celular, donde podemos encontrar diferentes y peculiares proporciones de neuronas dentro y entre las columnas corticales, así como determinados tipos de neuronas (como las células en huso o las neuronas espejo) que, si bien no son exclusivas de nuestra especie, en ésta presentan ciertas particularidades en cuanto a número y función. Por último, los sistemas de receptores de las neuronas también parecen tener características propias de nuestra especie que podrían ser la clave para entender algunas de las singularidades de la evolución de nuestro cerebro (Au)

Introduction. For the most part, what makes us different from other animal species is comprised within our brain. However, there is no single factor, no singular reason accounting for the difference between our brain and others; rather, differences appear multiple. Development and conclusions. Here we perform an up-to-date review of the main divergences between ours and other species’ brains, which might be explaining the singularities of our behavior. When brain volume is on focus, it can be appreciated that our brain is certainly large both in relative and absolute terms, being also the case that some subdivisions of the prefrontal regions, as much as the parietal or temporal lobes appear notably increased in size relative to other brain areas. Also at variance with other species, our brain is consistently more asymmetric. But differences also involve the cellular level. In this regard, they have been reported different and peculiar proportions of neurons both within and between cortical columns, as much as certain types of neurons (like fusiform and mirror neurons) that, even if they are not exclusively human, they display in our species peculiar quantitative and functional features. Finally, neuronal receptor systems seem to exhibit exclusively human traits that might be crucial to understanding some of the singularities of the evolution of our brain (AU)