Evolution of Consciousness

Abstract

The natural evolution of consciousness in different animal species mandates that conscious experiences are causally potent in order to confer any advantage in the struggle for survival. Any endeavor to construct a physical theory of consciousness based on emergence within the framework of classical physics, however, leads to causally impotent conscious experiences in direct contradiction to evolutionary theory since epiphenomenal consciousness cannot evolve through natural selection. Here, we review recent theoretical advances in describing sentience and free will as fundamental aspects of reality granted by quantum physical laws. Modern quantum information theory considers quantum states as a physical resource that endows quantum systems with the capacity to perform physical tasks that are classically impossible. Reductive identification of conscious experiences with the quantum information comprised in quantum brain states allows for causally potent consciousness that is capable of performing genuine choices for future courses of physical action. The consequent evolution of brain cortical networks contributes to increased computational power, memory capacity, and cognitive intelligence of the living organisms.

Keywords: brain cortex; causal potency; conscious experience; quantum physics; sentience.

Figure 5

Different levels of organization of physical processes inside neurons. At the microscale, the morphology of the rendered CA1 pyramidal neuron (NMO_00223) from rat hippocampus (http://neuromorpho.org) (accessed on 1 December 2023) reflects the functional specialization of dendrites and axon for the input and output of electric signals, respectively. At the nanoscale, the electric activity of neurons is generated by voltage-gated ion channels, which are inserted in the neuronal plasma membrane. The general structure of ion channels is illustrated with a single voltage-gated K⁺ channel composed of four protein α-subunits, each of which has six α-helices traversing the plasma membrane. The fourth α-helix is positively charged and acts as voltage sensor. At the picoscale, elementary electric charges within the voltage sensor could be modeled as qubits represented by Bloch spheres. For the diameter of each qubit is used the Compton wavelength of electron. Consecutive magnifications from micrometer (μm) to picometer (pm) scale are indicated by × symbol. Modified from Ref. [149].

Figure 1

Prehistoric cave paintings depicting different animals as consciously perceived by their prehistoric painters. Top left: Polychrome bison from the Cave of Altamira in Cantabria, Spain, dated to the Magdalenian culture circa 14,000 years ago. Top right: Painting of a horse from the Lascaux Cave in Montignac, France, dated to circa 19,000 years ago. Bottom left: Painting of rhinos from the Chauvet Cave in Vallon-Pont-d’Arc, France, dated to circa 32,000 years ago. Bottom right: Painting of a bull from Lubang Jeriji Saléh in Borneo, Indonesia, dated to circa 40,000 years ago. The images of prehistoric work of art are in the public domain.

Figure 2

Prehistoric hand stencils communicating the identity of their prehistoric painters. Top left: Handprints created by blowing ochre mixed with water over the hands from the Cave of Altamira in Cantabria, Spain, dated to circa 17,200 years ago. Top right: The tree of life hand prints from Gua Tewet in Borneo, Indonesia, dated to circa 9800 years ago. Bottom left: Hand stencils from Cueva de las Manos in Argentina, dated to circa 9300 years ago. Bottom right: Hand stencils with mutilated little finger at the Djulirri rock art site in the Wellington Range of Arnhem Land, Northern Territory, Australia, dated to circa 7000 years ago. The images of prehistoric work of art are in the public domain.

Figure 3

Brains of different modern mammals, viewed from the side. Humans do not have the largest brain size, as evident from the average brain mass of elephants, whales, and dolphins. Furthermore, the human brain cortex does not have as many cortical convolutions and surface area as dolphins and whales do. Although humans are intelligent and have achieved remarkable control over the surrounding world, they are not situated “higher” than other animals in the evolutionary tree of life. The brain size is fully appropriate to the particular habitat and lifestyle enjoyed by each animal.

Figure 4

The human brain cortex communicates continuously with its physical environment through electric signals. Left: the somatosensory pathway delivers sensory information from the human body to the somatosensory cortex, which is located in the postcentral gyrus. Right: the somatomotor pathway delivers motor information from the motor cortex, which is located in the precentral gyrus, to the body muscles. The spinal cord segments, medulla and pons are represented with their transversal sections, whereas thalamus and cortex are shown in frontal slice. Modified from Ref. [1].

Figure 6

Molecular structure of full-length shaker Kv1.2 voltage-gated K⁺ channel from rat (Rattus norvegicus) composed of four α-subunits and four β-subunits incorporated into dipalmitoylphosphatidylcholine (DPPC) phospholipid bilayer. Free energy released by adenosine triphosphate (ATP) is used by Na⁺/K⁺-ATPase pump to establish different resting millimolar (mM) concentrations of K⁺ and Na⁺ ions on the inner side or on the outer side of neuronal plasma membrane. The phospholipid bilayer is hydrophobic and thus impermeable to ions, which are hydrophilic. The concentration gradient of K⁺ ions across the phospholipid bilayer acts as an electric battery that provides the energy for the generation of hyperpolarizing K⁺ electric current through the open voltage-gated K⁺ channels. The selectivity filter of the voltage-gated K⁺ channel contains a string of trapped K⁺ ions, which are allowed to move through the open channel pore only when the transmembrane voltage is depolarized toward more positive values compared to the physiological resting membrane potential of −70 mV. The 3LUT model from the Protein Data Bank (https://www.rcsb.org/structure/3LUT) (accessed on 1 December 2023) was visualized using the software UCSF Chimera ver. 1.11.2 (https://www.cgl.ucsf.edu/chimera/) (accessed on 1 December 2023).