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Chapter II. Evolution of the Human Mind >> Summary of Chapter II

Summary of Chapter II

About ten million years ago, the earth's climate entered a cooler and drier phase. This led eventually to the growth of permanent ice sheets in Greenland and North America about three million years ago. The Earth is still technically in the ice age, with tropical sea surface temperatures some 5 °C to 20 °C cooler than at its peak about 75 million years ago (Veizer, 1999, 2000). One consequence of the cooling was that the North African tropical forest began to retreat, being replaced first by patches of forest separated by expanses of grassland, then by savannas, later by open grasslands, and eventually by desert (modern Sahara). Our tree-dwelling hominid ancestors were practically thrown off the trees on to the planes of savannas. The reduction of territory forced some tree-dwelling hominid ancestors to adapt to the new environment. In savannas, predators were plentiful [8]. Hominids were forced to venture away from the safety of treetop canopies and were exposed to stronger and faster predators. Hominids could not rely on their sense of smell or sound to detect predators from far away; they had to rely on their visual system. Unlike smell and sound, visual information decays very little, even after it has been transmitted over great distances. The hominids who were able to detect a predator earlier had a better chance to escape the encounter. Those who could not identify a predator from far away were swiftly eaten by the predators and removed from the gene pool. Thus, the hominid visual system was continuously selected to be able to detect predators using fewer and fewer visual cues: a shadow, a pattern of moving grass, a small body part, etc. The hominid with a more advanced visual system had a greater chance for survival. Accordingly, every aspect of the hominids’ visual system had to greatly improve. The major improvement was achieved by separating visual identification into two distinct systems: the holistic visual identification system that matches visual cues to complete objects in memory and the visual analysis system that matched visual cues to an object’s elements stored in memory.

The holistic identification system stores complete objects in memory. It works best when a complete object is available in the visual field. It can then quickly match the complete object in the visual field to the one stored in memory and decide on a course of action to be taken. Even when the image of an object is partially obstructed, the holistic identification system can recognize the object. It uses the process of amodal completion to fill in the missing information before matching the completed object to memory. Amodal completion is an evolutionarily old process. The existence of amodal completion has been demonstrated to some extent in both primates and birds. The holistic identification system, however, may be utterly inefficient when only a small visual detail (such as a tail) is visible.

The visual analysis system, on the other hand, automatically dissects objects into meaningful elements (an eye, an ear, a body, a tail) and stores these elements in memory. When, at a later time, any detail appears in the field of view, it is matched to memory directly in a fast and efficient process. The matching results in recognition of the object and the brain can then decide on the proper course of action. Hominids equipped with visual analysis were more successful in identifying partially obstructed predators than hominids who needed more visual cues to complete the hidden body before matching it to memory via visual amodal completion. In modern humans, both the holistic visual identification system and the visual analysis system are well developed and function in parallel. The holistic system is usually located in the right hemisphere of the brain, while the visual analysis system is usually located in the left hemisphere.

Around 2.4 million years ago, the visual analysis system acquired elements of voluntary visual analysis. Homo habilis was able to voluntarily analyze a cobble into a future chopper and flakes. That is, Homo habilis was able to voluntarily form a mental template of the chopper. The voluntary aspect of the visual system continued to develop in hominids and has culminated in modern humans with the acquisition of mental synthesis: a system for voluntary manipulation of any number of visual elements.

In summary, upright walking enabled australopithecines to see above the grass and allowed them to conduct trips into savannas from the safety of treetop canopies. Visual analysis allowed Homo habilis to voluntarily form a primitive mental template of a future chopper and thus manufacture Oldowan tools. Advanced visual analysis with a well-developed mental template allowed Homo erectus to manufacture Acheulean tools and to colonize Africa, Asia, and Europe. Mental synthesis allowed modern humans to create arts, religion, advanced tools, and to settle the entire planet.

The manufacturing of stone tools was not the primary driving force of evolution

The manufacturing of sharp-edged stone tools was not the primary driving force of evolution. Advancement in stone-tool manufacturing was a byproduct of the improved visual system. It is the visual system that allowed Homo erectus to avoid a leopard, a snake, and other predators and, in doing so, saved his life. Sharp-edged stones are only marginally more helpful in direct confrontation with a leopard than natural stones. How many times did Homo erectus come out a winner from that fight? Further, sharp-edged stone tools are also only marginally more helpful than natural stones in food preparation. Nuts can be broken with natural stones. Carcasses can be cut and flesh can be separated from bones with the use of teeth. Bones can be cracked open with any stone; the stone does not need to have sharp edges.

If sharp-edged stones were not vital, then why were they manufactured at all? They were manufactured because Homo erectus was able to manufacture them and because sharp-edged stones were a bit more convenient for the tasks mentioned above. Look at the market today. Why do we need things like an electric can opener, barbecue set, and lawn aerators? We manufacture them because we can, and because each of them makes our life a little bit easier. Nobody claims that a hand knife drove evolution. By the same token, sharp-edged stones did not drive evolution. These items are just a reflection of cortical development in general, and of progress within the visual system in particular. If one is still convinced that sharp-edged stones alone drove evolution, one needs to consider the fact that sharp-edged stones occur naturally. Rock weathering generates nearly unlimited number of sharp-edged stones. There are plenty of sharp stones in my backyard. If the use of sharp stones alone was so beneficial for survival, then the tribe that was better at collecting and carrying the sharp-edged stones would win the competition. Archeological evidence, on the contrary, invariably demonstrates that more advanced, bigger-brained hominids were associated with the manufacturing of superior stone tools. It appears that sharp-edged stone tools played only a marginal role in survival. Rather, the manufacturing of stone tools is a reflection of visual system development. Homo habilis won the competition over australopithecines not because it was able to manufacture sharp-edged choppers, but because a better visual system allowed Homo habilis to identify predators and prey from farther away. Homo erectus won the competition over Homo habilis not because it was better able to fight a leopard with a symmetrical handaxe, but because it was smart enough to recognize the leopard from farther away and therefore avoid an encounter more often than Homo habilis could.

Language development

Language was also not the primary driver of evolution. Try to use language to explain to an attacking leopard that it should not eat you… It is self-evident that language does not protect you when you encounter a leopard. Just as the case with stone tools, the development of the speech apparatus was a consequence of a better visual system. With the development of visual analysis, hominids were able to identify more objects (an eye, an ear, a tail) and therefore they needed more words to describe those objects.

Language reflects the capabilities of the visual system. No matter how many words Neanderthals had, language could not help them fight weaker Homo sapiens because Homo sapiens were able to plan an attack (using mental synthesis) and Neanderthals were not. Modern armies not capable of predicting the actions of their enemy lose battles no matter their culture and language complexity.

Language undeniably plays a great role in the life of modern humans because it allows us to accumulate knowledge over generations. However, cultural transmission was not as important for Homo erectus and Neanderthals. Archeological evidence does not show much cultural transmission (that could have revealed itself in stone tool improvement) over the two million years that the Homo erectus species existed and over the 600,000 years that the Neanderthal species existed. Therefore, for Homo erectus and Neanderthals, language was much less important than it is for modern humans.

Language, however, was important enough to drive the development of the vocal apparatus. Why? Even the non-synthesizing language of Homo erectus and Neanderthals was able to increase their chances for survival. With hundreds of words, the warning calls generated by Neanderthals could have been much more specific than those produced by monkeys. A developed speech apparatus enabled more warning calls and marginally improved the hominids’ chances for survival.

A non-synthesizing language could also marginally improve communication during hunting. Neanderthal hunters could not explain to each other the best way to attack, but they were able to command a simultaneous attack on a large mammal. The disproportionally large number of broken bones found in Neanderthal remains is a witness of this attack technique. Neanderthals likely threw themselves onto a large mammal as one group in an attempt to simultaneously stab the animal with as many spears as possible.

Arrival of modern humans

The situation changed dramatically sometime between 200,000 and 50,000 years ago when hominids acquired mental synthesis. The tribe that acquired mental synthesis was able to mentally plan an escape from a predator and, therefore, had a better chance of survival than hominids who relied on instincts when escaping from a predator. This tribe was also better at hunting since it was now, for example, able to plan a trap for a large animal. At some point after acquisition of mental synthesis, the tribe also acquired a synthesizing language. We can safely assume that by the time Homo sapiens left Africa 50,000 years ago, humans had already acquired a synthesizing language. Was it a dramatic event? Probably not. Homo sapiens had all the elements for developing a synthesizing language. Archeological evidence of Homo erectus and Neanderthals show that these hominids were already in possession of an improved speech apparatus, which indicates that they may have been using hundreds of words (otherwise they would have no need for an improved speech apparatus - chimpanzees are able to exchange tens of words with their primitive speech apparatus). It is likely that the cortical language areas were also well developed. With the addition of mental synthesis, the language could naturally transform itself into a synthesizing language. It is possible that minor adjustments had to be made in order to enable a greater vocabulary, but probably no major changes in the brain were necessary.

There is, of course, a cultural aspect to language. Language is transmitted from generation to generation. Children learn language by being engaged into conversations. Accordingly, people have a tendency to look for the “first” language. The Greek historian Herodotus conveyed a story about an experiment conducted by the King of Egypt, Psamtik I. The king gave two newborn babies to a shepherd with the instructions that no one should speak to them, but that the shepherd should feed and care for them. The king was interested in finding out whether or not two children left alone and deprived of any external communication would develop their own language. In addition, Psamtik I sought to discover the origin of language. The shepherd was asked to listen to the children and to write down their first words. The story goes that the children did in fact develop their own language and that the first word was "bekos", which sounded like the Phrygian word for "bread." Thus, Psamtik I concluded that the Phrygians were an older people than the Egyptians, and that Phrygian was the original language of men.

In fact, there is some evidence that a synthesizing language arises spontaneously in any group of modern humans, even when the group is isolated from the outside world. For example, deaf children in Nicaragua were able to spontaneously develop an original sign language. In 1980, following the Sandinista revolution, the Nicaraguan government opened several vocational schools for deaf children. By 1983 there were over 400 students in the two schools. The school program emphasized spoken Spanish and lip reading, and discouraged the use of signs by teachers. The program failed and students did not learn the Spanish language. However, the school provided fertile ground for deaf students to communicate with each other. In this process, children spontaneously generated a new sign language, complete with syntax. Schoolteachers were unaware of the development of the sign language and considered the children's gesturing as mime. A failure to acquire the Spanish language triggered teachers to call for help. By 1987, Dr. Judy Kegl, a linguist from MIT, arrived in Nicaragua and began to analyze the new sign language. Judy realized that the children developed a language of great complexity, with verb agreement and other conventions of grammar.

It appears that we don’t need to look for the “first” language. A synthesizing language could have arisen spontaneously from a complex non-synthesizing language as soon as hominids acquired mental synthesis. This new invention of nature - the modern human complete with mental synthesis and armed with a synthesizing language - was a “killer product”. The modern human could plan an attack in its mind using mental synthesis and then use a synthesizing language to explain the plan to his companions (that is, to synthesize mental images in the minds of his companions of where to run and how to attack). Modern humans were much better hunters; they could deceive any animal by building a trap, making sophisticated weapons and using these weapons in a new way. They could now throw spears and stones at an animal from a distance and thus save themselves from being crushed by the large animal [9]. Early modern humans, as a group, were truly excellent hunters.

Modern humans could also use mental synthesis in combination with a synthesizing language to better protect themselves from predators by collectively building stronger villages. The tribe that acquired a synthesizing language was able to conquer other tribes and eventually to rule the world. This tribe spread from Africa about 50,000 years ago. By 35,000 years ago, modern humans conquered most of the planet: a pace of expansion unparalleled in history.

Was the arrival of Homo sapiens inevitable?

The answer is, most likely, yes. As soon as hominids chose to rely on their visual system rather than speed or strength as their primary mechanism of protection, the acquisition of visual analysis for faster predator-recognition was inevitable. Analytical abilities of the visual system put a lot of pressure on the vocal apparatus, which, in turn, improved communication between tribe members. Homo sapiens acquired the ability to integrate unrelated visual elements into a single imaginary percept (mental synthesis), quickly followed by acquisition of a synthesizing language. Mental synthesis, synthesizing language, and excellent hand dexterity created an ultimate hunting machine with unmatched abilities for planning and execution of attacks. The same skills (mental synthesis, synthesizing language, and excellent hand dexterity) enabled modern humans to develop culture and build cities. Therefore, foraging in savannas, while relying on the visual system rather than smell, sound, speed, or strength for protection, lead (in five million years) to the development of modern humans.