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Book Conclusions

In this book, we have put forth a simple model of the mind. In this model, conscious experiences are represented by synchronous activity of large groups of cortical neurons: neural ensembles. Enhanced connections between neurons in a neuronal ensemble enable the self-organization property of the ensemble and form the basis of memory. Re-activation of the neuronal ensemble in the memory recall process recreates a conscious experience of the object or event. In other words, substantially the same neurons are activated during a conscious experience of physical objects and a conscious experience of imaginary objects.

During their lifetime, both humans and non-human primates accumulate conscious experiences that can be recalled from memory. However, humans have the unique ability to construct new conscious experiences in the process of mental synthesis. On the neuronal level, mental synthesis involves synchronization of multiple neuronal ensembles with the attention rhythm. This process enables humans to synthesize new, never-before-seen mental images, to mentally plan their actions and test for possible outcomes, to engineer machinery and design cities. By using mental synthesis, humans create a conscious experience that they have never experienced before. As William James, the father of American psychology, said a century ago: consciousness is not a thing, but a process. Now we know what that process is. In humans, it is the process of mental synthesis: that of voluntary creation of new mental constructs by the synchronization of multiple ensembles of neurons coding for previous experiences.

A synthesizing language allows humans to share their conscious experiences with other humans by synthesizing new mental images in the mind of the listener. Animals are not able to voluntarily synchronize two neuronal ensembles in one conscious frame. Consequently, animal language in the wild is non-synthesizing. It is not intended for the synthesis of new images in the mind of listeners. Even animals that have been trained to use hundreds of words in a lab still do not learn mental synthesis. It is likely that animals lack the neuronal apparatus necessary for mental synthesis. Consequently, no degree of training could teach an animal to synthesize new mental images.

A lack of mental synthesis prevents animals from visually planning their actions in the mind. Animals rely on their memory and reflexes to solve complex problems. A chimp does not mentally plan the process of spear making. The chimp remembers to sharpen the stick by biting the stick several times. The chimp is conditioned to bite on the stick before hunting, just as a dog can be conditioned to sit still before receiving its food.

The uniqueness of the human mind has been described by scientists as the presence of thinking, judgment, cognitive fluidity, planning, common sense, adapting one's self to circumstances, creativity, wisdom, innate general cognitive ability, moral sense, predilection to story-telling, skills of problem solving, auto-critique, and propensity for active teaching. Note that at the core of all these truly human functions lies the process of mental synthesis. It is our ability to create an imaginary experience of a situation that allows us to ask the “if” question, to seek relational causality and demonstrate judgment: “What will happen if I leave the cup too close to the edge of the table? -- Somebody could accidentally knock the cup over.” “What will happen if I leave this ice-cream on the table? -- It will melt.” “What will happen if I disregard the red light? -- My car can be hit by another car coming sidewise.” We get the answer by imagining the result of our action in the process of mental synthesis.

Visual planning involves the mental synthesis of a plan: “We will make a trap by digging a large pit and covering it with tree branches. A mammoth will fall into the pit, no need to attack a mammoth head on” - humans are able to think through the plan by imagining a process of building a trap step-by-step and imagining a mammoth falling into the trap. The ultimate in planning is exemplified in the game of chess. I can visually imagine the position of figures five moves ahead (by mentally synthesizing figures in the new position) and decide if that position is advantageous. No animal, even if it were able to learn how to move the chess pieces, could imagine the figure position five moves ahead. Animals lack the neural circuitry necessary to imagine a figure in a new position; they cannot activate and synchronize multiple neuronal ensembles of figures in a new position in order to visually experience and evaluate that position.

All unique human cognitive abilities are based on the fundamental process of mental synthesis. Auto-critique involves self-reflection in the process of mental synthesis. Story-telling involves creating a story in the process of mental synthesis and then sharing it with others with the use of a synthesizing language (listeners, of course, must use mental synthesis to understand the story). Consider fairy tales or Sci-Fi literature. These genres, by definition, describe objects that the reader has never seen (three headed dragons or giant Cyclops). They rely on the reader’s mental synthesis to synthesize those objects in the mind.

Creativity involves the mental synthesis of new objects; we can invent a bicycle, because we can imagine a frame, wheels and pedals put together. We can visually understand the process of nuclear chain reaction and create a nuclear reactor. No human has ever seen a proton or a neutron. But ask a physicist to explain to you the nuclear chain reaction and he will paint a colorful picture of neutrons flying into nuclei and nuclei exploding. The physicist has never seen the reaction; he imagined the neutrons and the nuclei. He has mentally synthesized the events of the nuclear chain reaction. Nobody has ever seen a black hole. But we can use mental synthesis to imagine a super-dense mass pulling all kinds of energy and material towards its center. No one has ever seen the structure of DNA. Watson and Crick only saw the results of X-ray crystallography. They had to use mental synthesis to put Adenine, Thymine, Guanine, and Cytosine together into a beautiful double-stranded DNA structure. They mentally synthesized the four nucleotides into polymers and then imagined how those polymer configurations would project onto an X-ray film. To come up with the equivalence principle that would be the foundation of the General Relativity theory, Einstein imagined himself in an elevator falling freely towards the ground. It was a mental experiment. Science is a continuous exercise in mental synthesis.

It is the identification of the process of mental synthesis at the core of multiple human traits that allows this theory to bridge cognitive psychology and neuroscience and to describe the human uniqueness on the neuronal level.

How and when was mental synthesis acquired by humans? It was proposed in Chapter II of this book that the evolution of hominids from a chimpanzee-like ancestor to Homo sapiens was primarily driven by the development of the visual system. Pushed out of trees by deforestation, hominids, who were neither fast nor strong enough to protect themselves from predators in savannas, had to rely on early identification and avoidance of predators. Neither the sense of smell nor the sense of sound could have provided a warning from as far away as the sense of vision could. Far from the safety provided by treetop canopies, hominids had to rely on their visual system for an early warning of the presence of predators. Hominids that were not able to improve their visual identification of predators were eliminated by those predators.

Hominids first improved their visual analysis: the brain acquired the ability to automatically dissect a visual percept into elements and to match each element directly to memory. A single visual element such as an ear or a tail visible above the grass could have warned a hominid of a predator and allowed the hominid to avoid a deadly encounter.

Stone tools manufactured by Homo habilis indicate that as early as 2.4 million years ago, the hominid visual system was able to generate a mental template. The brain of Homo habilis was able to shift neurons representing the flakes out-of-phase with the attention rhythm (voluntary visual analysis) in order to reveal the chopper inside. This capability greatly improved in Homo erectus, who was so successful that it was able to move out of Africa and settle at multiple locations in Asia. The spread of Homo erectus out of Africa is a testament to its ability to avoid predators, supposedly with the help of visual analysis. A tripling of brain size in Homo erectus compared to Australopithecus afarensis reflects the development of cortical areas specialized for visual processing (visual cortex, temporal lobe, parietal lobe) and voluntary visual analysis (prefrontal cortex). Note that the brain size per se does not always correlate with how smart the species is: the brain of a sperm whale weighs 9 kg or seven times the weight of the human brain (which weighs 1.35 kg); an elephant brain weighs 4.2 kg or three times the weight of the human brain. The ratio of brain mass to body mass also does not necessarily correlate with intelligence: mice, squirrels, and shrews have a greater ratio of brain mass to body mass than humans do. Even within the Homo genus, modern humans do not have the largest brain: Neanderthals had bigger brains than modern humans. However, the speed of expansion of the hominid brain is quite dramatic. The brain quadrupled in size over just five million years; clearly the hominids had to rely on their brain for survival, more than on speed or muscle power.

Photographs of brains from eight species of mammals. Note that the dolphin brain is slightly bigger and more convoluted than the human brain; the elephant brain is nearly three times bigger than the human brain by weight.

The volume of the hominid brain increased rapidly over the course of evolution (for review, see Park, 2007).

There are multiple theories concerning the expansion of the hominid brain. The “clever foraging hypothesis” argues that a change in diet was instrumental for the development of a larger brain size. This theory draws support from observations that species which normally graze or feed opportunistically tend to have relatively smaller brains than species which hunt strategically, taking into account the habits of their prey (Parker, 1977; Striedter, 2005). The “social brain hypothesis” argues that the superior social organization of hominids influenced the development of a larger brain (Humphrey 1976; Byrne 1988). The “expensive tissue hypothesis” argues that a change from a predominantly plant-based diet to a predominantly meat-based diet provided a more easily digestible and nutrient-rich food, allowing for brain growth (Aiello, 1995; Milton, 1999). Some researchers take this theory further and argue that cooking had a significant impact on brain expansion in hominids (Wrangham, 1999, 2003). The “radiator hypothesis” examines the changes in blood circulation that allowed for better cooling of the human brain (Cabanac, 1995; Falk, 1990). The mental synthesis theory is not necessarily exclusive of these hypotheses. A combination of factors may be at play. Improved visual analysis and later acquisition of mental templates (voluntary visual analysis) in Homo habilis and Homo erectus proposed in this book must have also benefitted their social interactions, as well as advanced their hunting and food-preparation skills.

About two million years after Homo habilis first acquired the ability to form a mental template by voluntarily shifting some neurons out-of-phase with the attention rhythm, a new species, Homo sapiens, acquired the ability to shift neurons in-phase with the attention rhythm. Homo habilis and later Homo erectus were able to dissect visual images (i.e. a natural stone) into multiple neuronal ensembles (future chopper and future flakes) and then shift some ensembles (future flakes) out-of-phase with the attention rhythm to reveal the future chopper. The brain of the Homo sapiens is capable of shifting two or more neuronal ensembles in-phase with the attention rhythm (mental synthesis) thus forming new, never-before-experienced images. Homo sapiens spread out of Africa about 50,000 year ago. By that time, Homo sapiens clearly acquired mental synthesis as revealed by numerous symbolic objects, elaborated burials, objects of art, bone needles, exquisite sculptures, spectacular animal images on the walls of caves, and sophisticated musical instruments. The artifacts deposited by Homo sapiens clearly indicate that Homo sapiens were not limited in their conscious experience to the physical world but were inclined to synthesize new conscious experiences in the process of mental synthesis.

We observe evidence of a developing speech apparatus starting in Homo ergaster (two million years ago). It is likely that cortical areas specialized for speech analysis (Wernicke’s area) and speech synthesis (Broca’s area) developed in parallel with the speech apparatus. By the time Homo sapiens left Africa, they must have acquired a synthesizing language. Armed with mental synthesis and a synthesizing language, Homo sapiens were able to spread all over the world in just 15,000 years, develop agriculture in about 35,000 years, domesticate animals in about 40,000 years, build cities in 45,000 years and travel into space in only 50,000 years. All these accomplishments were achieved by humans because of the ability to mentally synthesize new conscious experiences in the process of mental synthesis and then use a synthesizing language to share our plans with fellow humans.