Saturday, May 21, 2011

Javier DeFelipe - The evolution of the brain, the human nature of cortical circuits, and intellectual creativity

Pillars at the temple of Göbekli Tepe

Frontiers in Neuroanatomy posted this article by Dr. Javier DeFelipe on "The evolution of the brain, the human nature of cortical circuits, and intellectual creativity." In this paper he looks at the evolutionary increase in (1) size and (2) complexity of the mammalian brain and how that change has been even more pronounced in primates/humans than in other mammal species.

Earlier this week, National Geographic posted an article on the origins of human civilization in religious temples, which combine art and devotion to gods/spirits - at the Göbekli Tepe.
Eleven millennia ago nobody had digital imaging equipment, of course. Yet things have changed less than one might think. Most of the world's great religious centers, past and present, have been destinations for pilgrimages—think of the Vatican, Mecca, Jerusalem, Bodh Gaya (where Buddha was enlightened), or Cahokia (the enormous Native American complex near St. Louis). They are monuments for spiritual travelers, who often came great distances, to gawk at and be stirred by. Göbekli Tepe may be the first of all of them, the beginning of a pattern. What it suggests, at least to the archaeologists working there, is that the human sense of the sacred—and the human love of a good spectacle—may have given rise to civilization itself.
It's interesting to keep this in mind as one reads the following article.

The evolution of the brain, the human nature of cortical circuits, and intellectual creativity

  • 1 Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
  • 2 Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain
  • 3 Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas, Madrid, Spain

The tremendous expansion and the differentiation of the neocortex constitute two major events in the evolution of the mammalian brain. The increase in size and complexity of our brains opened the way to a spectacular development of cognitive and mental skills. This expansion during evolution facilitated the addition of microcircuits with a similar basic structure, which increased the complexity of the human brain and contributed to its uniqueness. However, fundamental differences even exist between distinct mammalian species. Here, we shall discuss the issue of our humanity from a neurobiological and historical perspective.


DeFelipe, J. (2011). The evolution of the brain, the human nature of cortical circuits, and intellectual creativity. Frontiers in Neuroanatomy, 5:29. doi: 10.3389/fnana.2011.00029


The nervous system has evolved over millions of years, generating a wide variety of species-specific brains and behavioral capacities. For example, the production and appreciation of art seems to be a uniquely human attribute, a recently acquired cognitive capacity in the genus Homo. Almost everything that the human being creates has a touch of art, although we do not need beauty or an esthetic perception to survive but rather, it just simply produces intellectual pleasure. The same occurs with other mental activities, like reading a book or listening to music. It seems obvious that only anatomically modern humans (i.e., Homo sapiens) can be behaviorally modern, capable of creating symbolic objects. Maybe this is when we discovered the world of ideas and created the concept of the soul or spirit. From that moment, the relentless pursuit to define where such a trait is forged began, resulting in the so called “mind–body problem.” Of the numerous images available, we have chosen two here to illustrate in distinct ways the relationship between the mental and the physical worlds, both suggesting a separation between the two entities. Figure 1 shows the painting Fray Pedro de San Dionisio by Francisco de Zurbarán, 1598–1664, and a sculpture of Don Quixote present at the Museum of Modern Art in Mexico.


Figure 1. The mind–body problem. Left: Fray Pedro de San Dionisio, painted by Francisco de Zurbarán (1598–1664). © Fundació Institut d’Art Hispanic Amatller. Arxiu Mas. Right: Don Quixote, Museum of Arte Moderno in Mexico. These images are examples of the separation between the mental and the physical worlds. The saint levitates while praying, and his head is separated from his body; Don Quixote appears reflective, with an empty head.

Perhaps modern neuroscience has contributed most in this field by addressing the issue of mental processes from a biological standpoint. Nevertheless, it is striking how little influence this neuroscientific knowledge has had on society due to the failure in conciliating the relationship between the brain and our humanity. It is commonly thought that the increase in complexity as our brain has evolved is a product of the addition of microcircuits with a similar basic structure that incorporate only minor variations. Indeed, species-specific behaviors may arise from very small changes in neuronal circuits (Katz and Harris-Warrick, 1999). However, we will see that the human cerebral cortex has some distinctive circuits that are most likely related to our humanity. In addition, there are some erroneous popular beliefs regarding the relationship between brain size, evolution, and intellectual capabilities, and regarding the patterns of convolutions and the external morphology of the brain. Here, I shall deal with these topics with the aid of some historical notes.

The article is open source and can be downloaded as a PDF.

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