Mente – Evolução da Consciência – Caso em Estudo

Evolution of consciousness

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Proc. Natl. Acad. Sci. USA

Vol. 89, pp. 7320-7324, August 1992



Max-Planck-Institute for Brain Research, D-6000 Frankfurt/Main 71, Federal Republic of Germany

Contributed by John C. Eccles, May 8, 1992


The hypothesis of the origin of consciousness is built upon the unique properties of the mammalian neocortex. The apical dendrites of the pyramidal cells bundle together as they ascend to lamina I to form neural receptor units of – 100 apical dendrites plus branches receiving hundreds of thousands of excitatory synapses, the collective assemblage being called a dendron. It is proposed that the whole world of consciousness, the mental world, is microgranular, with mental units called psychons, and that in mind-brain interaction one psychon is linked to one dendron through quantum physics. The hypothesis is that in mammalian evolution dendrons evolved for more effective integration of the increased complexity of sensory inputs. These evolved dendrons had the capacity for interacting with psychons that came to exist, so forming the mental world and giving the mammal conscious experiences. In Darwinian evolution, consciousness would have occurred initially some 200 million years ago in relation to the primitive cerebral cortices of evolving mammals. It would give global experiences of a surrounding world for guiding behavior beyond what is given by the unconscious operation of sensory cortical areasper se. So concious experiences would give mammals evolutionary advantage ever the reptiles, which lack a neocortex giving conscousness. The Wulst of the avian brain needs further investigation to discover how it could give birds the consciousness that they seem to have.

In the past decade or so there has been a general recognition of the centrality of consciousness in human experiences (1-9). The mental word consciousness is now an “in” word, being used shamelessly even -by strong materialists! An introductory statement for the evolution of consciousness is that one cannot expect that consciousness came to higher animals as a sudden illumination. Rather, as with life originating in a prebiotic world, it would be anticipated that consciousness came secretly and surreptitiously into a hitherto mindless world. Moreover, as we attempt to discover evidence for consciousness from the study of animal brains and behavior, we can only assess probability. We search for manifestations of consciousness in mammals because we recognize it as central to the ongoing human experiences, the qualia, that fill our waking life like a rich tapestry replete with feelings, thoughts, memories, imaginings, and sufferings.

Our experience is uniquely ours, but we are rescued from solipsism by communication with other human beings by language and other subtle creations, such as music and gesture, and by sharing our immersion in a rich inherited culture.

Mammalian Cerebral Cortex

Mammals have a cerebral cortex qualitatively similar to ours,though, with rare exceptions, much smaller. Some exhibit intelligence and a learned behavior and are moved by feelings and moods, even with emotional attachment and understanding. So we must give them some feelings and qualia such as we human beings experience even though it cannot be rationally established in the way that is possible by inter human communication (10). I am presenting a biological basis for an evolutionary origin of consciousness. It derives from a hypothesis of mind-brain interaction that has already been published (10, 11) and that is based on the special anatomical and functional properties of the mammalian cerebral cortex. The microproperties of neural communication in the cerebral cortex (Fig. 1A) are in classical physics and are not of immediate concern in mindbrain interaction. Rather, our concern is in the ultramicroproperties (Fig. 2B), where quantum physics may be expected to play a key role (10, 11, 16-17) (F. Beck and J.C.E.,

unpublished data).

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