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 If you do not have a specific article of interest in mind, please refer to "Road Map" at the end of "Listing" for directions. 

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Evolutionary Process of                                                                                 (1)Hominids                                                                                                   

The Beginning

Evolution is a continuous process and progresses in a step-wise manner where physiology and cognition evolve in tandem. It is stimulated by external forces, such as environmental changes or internal force like adaptation to a niche. Human’s niche is the brain, which enlarged during every step of our evolutionary process through stimuli of adaptation to this niche. Bipedal walking, power/precision grips of our hands and telescopic vision provided the initial impetus for us to evolve down the path of our ever-enlarging brain.

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Knowledge of the hominid evolutionary process helps us to better understand the human mind and behavior in the context of man’s biological origin. Hominid evolutionary process also provides us a framework to study the development of human cognition. Development of bipedalism, for example, illustrates its impact upon the physical changes of early man which in turn influences the development of human cognition.

The evolutionary history of hominids covers over seven million years, if one accepts TM266 ( Sahelantropus) as an ancestor of hominids leading to Ardipithecus/ Australopithecus, Homo habilis/Homo erectus to Homo sapiens sapiens. Our brain volume, over this time, range from 300ml, approximate the same size as apes of today, to 1600 ml where more than half of the encephalization occurred during the last million years of the evolutionary history of hominids. Such significant increase in the brain volume of hominids during its evolutionary history is the main thesis of the following articles.

The evolutionary process of hominids is best illustrated by the physiological progression of primates. It began with primates developing eyes forward or so-called "orbital convergence" providing telescopic vision to give depth perception with 3D pictures. Also with lemur, the forelimbs evolved as hands for grasping. This was followed by the rotation of the shoulder. Instead of forelimbs pointing downward for walking on four legs, the shoulder blades rotated about ninety degrees away from a nearly parallel to each other positon to facilitate the hanging motion of the body with the forelimbs. Combination of the grasping hands and rotated shoulder allowed monkeys to swing from tree branch to tree branch in search of food. Next, apes discovered knuckle walk, further improving the mobility of primates. The final step is the special bipedal walk by human in an upright position so that the hands were free to perform tasks while the legs provide desired mobility at the same time. This is a significant evolutionary advance, which equips us to be what we are today.

Human hands are more dexterous than apes. Brachiation helps to develop power grasp but contributes only some to the development of fine grasp. Human hands and fingers are more flexible than apes. We can touch all of our fingers with the thumb and also bend each finger independently. The movements of our hands entail complex mechanism involving bones, muscles, nerves and neurons in our brain. It must be a slow evolutionary process to attain these capabilities. The developments of such hands were in tandem with the development of the specific bipedal movements, during the days of early hominids.

Adam Chou                                                                                                                     (1)            

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Evolutionary Process of Hominids                                                                               (2)

Bipedal Development -I

Bipedal walking of modern man is a very complicated process requiring a delicate balancing act. It is not a shuffling gait like an ape but a flexible striding action of the legs. We do not know when early hominids descended from the trees and evolved gradually to this bipedal walk. Such manner of walking is the most effective and efficient means of traversing various types of terrain for a long distance. The consequence of this event is not only human walked on two legs but also evolved with articulated leg joints, allowing kneeling, squatting and crouching. In addition, the joints of the lower body can bend and rotate in running, jumping, pivoting, and walking backwards or on toes. The effect of this evolutionary process allowed hominids to move in a smooth motion into positions facilitating precise placement of the hands in conducting their tasks. Such flexibility of the legs and body is necessary as a moving base for performing conveniently many tasks humans encounter daily. Furthermore, it freed the hands to carry objects and to do other tasks. Knuckle walk of the apes is an inefficient bipedal movement in term of energy consumption and does not allow carrying objects for any significant range of distance.

To understand the development of bipedal walking, we need to appreciate the complex skills related to walking on two legs. While taking a step forward, one shifts weight to the leg and foot on the ground with the big toe providing the needed balance of the body. While moving the other leg forward, the body weight is temporarily balanced on one foot till the body leans forward for the next step. At this moment, man is essentially unbalanced and falling forward till the forward-moving leg touches the ground to restore balance. This type of bipedal motion is energy conservative because we only spend energy at the push-off and landing during a stride, but the forward-movement of the suspended leg swings like a pendulum, falling by gravity without the expenditure of energy. Further more, the articulate joints at the ankles, knees and hip gives flexibility to cushion the impact of landing the swing foot and the eyes help to select suitable spots for placing the foot while touching the ground. As result we are able to negotiate difficult and uneven terrain with easy and efficiency. We know that such bipedalism could not have developed quickly. There must have been a lot of trial and error till the bipedal technique of walking was perfected during the time of Australopithecus or later.

Adam Chou                                                                                                                             (2)

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Evolutionary Process of Hominids                                                                                      (3)   

Bipedal Development II

More thoughts on walking.

In view of the teetering position during walking on two legs, the nerve systems at the bottom of the feet play an important role in sensing the ground for gentle landing to minimize the impact to our legs and hip joints. Telescopic vision also further provides feed-forward messages to our brain about the contour of the path in front of us. We all experienced this while walking, when we misjudged a bump in front of us and stumbled. All of these imply a large amount of neurons involved in the development of bipedal walking.

Humans have a more flexible torso than apes. We can bend at the waist and rotate our upper body without moving the hips. This could be the effect of differences in shape of the upper bodies between apes and humans. Apes have bell shape rib cages while human rib cages are barrel shape. Such difference in configurations could lead to the narrowing of human waists allowing the flexibility of our upper torsos to perform tasks beyond apes.

The physical requirements for upright bipedal movement are numerous. To support the body weight, the spine formed in a “S” shaped curve in order to distribute the load. Though this is not an ideal solution, as evident by the back problems suffered by today’s humans, it is still the best compromise for supporting body weight in an upright position. In addition, the alignment of legs and hipbones were modified to accommodate the striding movement needed for bipedal beings. These physical changes impacted upon the diameter and limited the opening shape of the pelvic girdle of the birth canal with the resulting restriction upon the size of babies’ head at birth. As result human babies are born prematurely as compared to other primates.

Our bipedal movement is very complex involving many aspects of our physiology and it is not certain what were the stages evolved in the development of our walking strides. A recent discovery of a female child fossil about 3.3 million years old in Ethiopia might shed some light upon this matter. Based on the shape of the thighs and shins, she walked upright, but several apelike lower-body traits implied that her arms were used to climb in trees like apes to make nests or to escape from predators, as did Lucy, a previously discovered 3.2 million years old partial skeleton of an adult female. This topic, though still in hot debate, might be an indication that the free-striding style of walking by human might still be in the early developmental stage over 3 million years ago.

Adam Chou                                                                                                                    (3)

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Evolutionary Process of Hominids                                                                              (4)    

Bipedal Development III

The development of hominid brainpower can be traced to bipedalism. Humans inherited telescopic vision and thumbs opposite to the other fingers from the monkeys/apes. Combining this physical attribute with bipedalism, we have the very powerful assets of bipedal movement and hand handiness. Bipedalism not only means walking on two legs to any desired location, the legs are also flexible for up/down and right/left adjustments to provides a platform for our hands to do precise tasks. This is a unique feature possessed only by man. From this combination, our hands developed precision and power grips to perform tasks unknown to other species. We learned to make tools, hunt, gather, and other activities. These activities challenged us in engaging our brainpower and acted as the driving forces leading to a significant brain enlargement of humans through the evolutionary process of selection. It is also a self-feeding cyclic process where new activities led to encephalization, which in turn led to more new activities.

It is evident that there was an increase in the size of brain resulting from evolving to bipedal walking and use of hands. Maintenance of brain is very expensive in terms of nutrition. Our brain is only a few percent of our body weight, but requires 20% of the energy derived from our food intake. Australopithecus brains are larger than apes. Feeding on leaves and fruits was not sufficient to sustain the additional brain functions for walking and hand movements acquired by the early hominids. More nutritious food such as meat, nuts and root bulbs containing high protein was needed. Intense seeking of food became required daily activity in order to support the nutrition demanding enlarging brain.

One source of high protein food is meat. Early man scavenged meat from the carcass of animals killed by predators. They probably discovered that they could disjoint the bones of the carcass with the sharp edge of stone fragments and consumed the previously hidden meat. They also found that they could crack the animal bone with stones to extract the rich mallows. From scavenging, they later developed hunting skills and making sophisticated stone tools

Supply of meat from scavenging, even hunting, was sparse. It did not guarantee frequent success and was not reliable for daily supply of highly nutritious food. For pregnant women, nursing mothers or small children, a steady supply of food was crucial. Gathering nuts, tuber roots and other plants was more reliable for daily supply of nutrients than hunting alone. Picking and cracking nuts, digging for roots required dexterity of hands. To perform these tasks, one needs to be close to the ground by kneeling, squatting or crouching, frequently done as a group. These activities are the basis for the  Social Development.

Adam Chou                                                                                                                    (4)

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Evolutionary Process of Hominids                                                                               (5)   

Social Development I

The evolution of flexible legs, dexterous hands and enlarging brain is a cyclic process of adaptation. The impetus of this evolutionary process is to acquire food to maintain the ever enlarging brain. To perform all of these tasks, dexterous hands evolved. In parallel, bipedal walking played a large role in the evolutionary process of hominid by providing flexible legs as mobile platform for the hands to perform needed tasks. This tandem development of bipedal movement of the legs and advancement of dexterous hands led to the enlargement of the brain. In order to maintain the large brain, hominids developed skill for hunting and gathering food, which further fed back to the development of hands, legs and brain.

Social Development is a large “Bang” in the evolutionary process of hominids with the appearance of cognitive functions unique to human. Tool making is the keystone for abstract thoughts leading to the earliest technological and cognitive breakthrough beyond apes. Apes use tools such as sticks for fishing termites, rocks for cracking nuts. It is a behavior of perceptual reaction understanding the cause and effect of using the tool during the performance of the tasks but not the principles behind it. Though others repeat such tasks, but each has to rediscover the technique anew. In contrast, tool making by humans is based on conceptual thinking, which involves goals, abstract thoughts, planning, etc. Stone tool technology was passed on from individual to individual and generation to generation. Furthermore there is ratchet effect of improving technique with time by the toolmakers. We know the invention of stone tools was during the time of Homo habilis. Such cognitive activity did not appear previously which required higher intellectual functions with additional neurons to be provided by evolution. 

We learned to make tools, hunt, gather, and other activities. These activities challenged us in engaging our brainpower and acted as the driving forces netting a significant brain enlargement of humans through the evolutionary process of selection. It is also a self-feeding cyclic process where new activities led to encephalization, which in turn led to further activities. Such enlargement of brain is evident from the fossil skulls of Homo erectus where the brain volume more than doubles during the time from Australopithecus to Homo erectus. The consequence of these events is an important factor to human's development of large brain.

Adam Chou                                                                                                                    (5)

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Evolutionary Process of Hominids                                                                             (6)   

Social Development II

The awareness of oneself and ones role in a group is an important advancement in the development of cognition of hominids. Such traits must have involved when early man became migratory nomads. Homo erectus fossils were found all over Africa and spread out into Europe and Asia into what we now know as Georgia, China and Java. It is evident that these hominids, like the later nomads searching of pasture land for their herds, were migrating from place to place as they exhausted the fauna and flora of a location about one to two millions years ago. Their migratory movement, instead circular as present day nomads, seems to follow waterways such as rivers, streams, etc. This implies mutually supporting social structures searching for improved livelihood by moving into unknown territories. (Contrarily, the annual migration of other species over the same route is based on instincts.) Such migration of hominids could be caused by climatic changes at the time and the migration paths of the early hominids being along existing or ancient waterways based on fossils and artifacts found. These migrations were conducted by groups of several dozen individuals traveling over thousands of miles under various weather conditions. At the same time, they were hunting and gathering food along the way for survival. Such undertakings require social interaction and teamwork in addition to the newly acquired tool making abilities and adaptation to changing environment. These achievements are clear indications the possession of self-consciousness, self-awareness and social intelligence of early man more than a million years ago.

The physical development of bipedalism also influenced the psychological development of human. There is a clear interrelation between the physical and psychological development of hominid. The change in female sexuality from conspicuous to hidden leading to the awaking of self-consciousness about estrous as a part of oneself is clearly influenced by bipedal development. Though some primates are capable of self-recognition, however, self-consciousness requires deliberate thought process and is uniquely human. The use of skins and furs as covers for the bodies to shield from the cold climate further reduced person-to-person contacts. Adapting oneself to these new situations resulted psychological changes of hominids. Such developmental activities led to the awareness of ones-self. All of these factors induced self-consciousness and self-awareness.

Social intelligence is a natural product of interactions between people. The enlargement of human brain through evolution resulted in the birth of immature infants in order for their passage through the mother’s birth canal. The first few months after birth were crucial for the infant to be nursed with plenty of mother’s milk in order to gain weight and survive. In turn, the mother needed to be well fed to produce the needed milk. Modified K mode of childbearing (Pregnancy could occur immediately after child birth while still nursing the newborn.) caused the necessity for caring for several offspring at one time. Before the understanding and practice of birth control, a single female could give birth to a dozen or so babies in her lifetime, though not all of them would survive. Since a single mother alone would not be able to care for all of these remaining ones, couples and group cooperation sharing these duties appeared. Hunting and gathering for food required teamwork. These changes effected an increase in the people-to-people interactions and greatly expanded social intelligence of the early man

Adam Chou                                                                                                                       (6)

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Evolutionary Process of Hominids                                                                                  (7)   

Communication Development I

Communication development could have an even larger impact upon the encephalization of humans than Social Development. During the Social Developmental stage, social interactions were required from diverse activities such as hunting, gathering, and child care leading to cooperative efforts as a group. Gesturing with limited guttural sounds was insufficient for communication and efforts were made to generate more different sounds, which led to the reshaping of the vocal tract. The vocal tract of early man was modified for emitting wider range of sounds through evolution, such as lowering of the vocal box, doming of the mouth roof, additional nerve system for tongue, lips, diaphragm, etc. At the same time, fine tuning of hearing to receive different range of sounds was also evolved. To support these developments, enamors numbers of neurons were required. In addition to support the mechanics of vocal tract and fine-tuned hearing, addition neurons were needed for communicating complex thoughts by speech, hearing, interpret thought and storage of knowledge. By this mean, knowledge was accumulated, complex thoughts were passed on to others, and the succeeding generations were trained to learn complicated tasks.

Now we have arrived at a milestone in our effort to pinpoint the evolutionary process of human. The ability to communicate in the form of speaking and listening of complicated thoughts may be the crucial driving force to push the development of our brain and elevate us from Homo erectus to Homo sapiens. The ability to communicate to others and passing on knowledge to others is a very unique ability of humans separating us from the other animals. We all have observed that young children are taught by their parents in clear instructions  about their behavior for their daily life. This is a very important learning process. Only humans are able to pass on the wealth of knowledge in details from generation to generation by means of vocal communication. Speaking and listening played a much larger role in influencing our evolutionary process to become modern man than our ability to manipulating our fingers. These abilities were absent or very primitive with Homo erectus.

Adam Chou                                                                                                                           (7)

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Evolutionary Process of Hominids                                                                                      (8)

Communication Development II

It is well known that modern man has the unique skill to think symbolically in addition to thinking in pictures as when one tries to visualize a scene or maps of roads. We also know that animal thinks in term of pictures, therefore we can assume that early man also thinks in pictures. When did the early man adding to the picture type of thought process with the symbolic ones would be interesting to know.

Autism could provide an insight to our thought process and could even help us to hypothesize the development of our cognitive ability in verbal communication. Temple Grandin, an autistic person and author, gives us the understanding of the autistic world where people thinks in pictures. She sees connections between animal behavior with certain autistic instincts, which help her to work on systems to improve treatment of livestock such as designing slaughterhouse for meat plants. One important element in her belief is that animals think in pictures.

In Oliver Sacks’ book, “The Man Mistook His Wife for a Hat”, he describes his encounter with Jose, who is autistic. He asked him to draw a picture representing various objects. He found Jose, before drawing, observed the objects with absolute stillness and complete concentration. He, then, closed his eyes for a moment and then drew. When he drew, he was bold, without hesitation, drew swiftly with clear lines without erasures. The products, though distorted in some aspects, contained extreme details with subtle self-expression. Such results one often seen with people who associate their thinking in pictures.

Human verbal communication, as we practice today, developed late in our evolutionary process. If we assume that humans first thought in picture, later development communication skill with gestures and grunts, which is an inefficient way of communication but it works. I remember that when I first arrived in this country from China, my thought process was in Chinese, and then I translated my thoughts from Chinese into English followed by vocalizing them. Such steps must have been taken by the Australopithecus when they communicated with thoughts in picture and then translated into gestures and grunts. The development of verbal communication in abstract thought followed the thinking in pictures. The cave paintings in France have always struck me as being drawn by master artists as pictures in simple lines of charcoal or ochre representing animals in motions. Now I am not sure; could they be painted by ones thinking in pictures? Are they different in their thought process from Australian aborigines and American Indians, whose paintings are stylized in abstract symbols?

The three stages of evolutionary process of hominids provide us with some understanding the continuous and stepwise progress of evolutionary mechanism. It also shows that physiology and cognition evolves in tandem. Can this knowledge be used as a guideline to search the role neurons played in cognition?

Adam Chou                                                                                                                                (8)

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Evolutionary Process of Hominids                                                                                         (9)

Appendix

Peking Man I

Much might be learned from the habitats of early man; unfortunately such sites are limited, either obliterated by weather, human or others and Peking Man’s cave was no exception. This cave was a limestone quarry, from hearsay evidence as old as Song Dynasty (960 –1279). It was also a source for “dragon bone”, marketed to be used for medicinal purpose. In 1921, Dr. J. G. Andersson, Director of the Geological Survey of Sweden as a mining advisor to the Chinese Government, also an archaeologist, discovered the cave based on a clue provided by a local kiln worker. By 1927, a team led by Professor C. C. Young, a paleontologist, began the excavation of the site. After it had been discovered as a cave where hominids used it as shelter for several hundred thousand years, some publications still called into question whether the habitation was the cause of early man. Here are some examples.

Following the publication of an article in Science (1998), several newspapers in the world declared that Peking man did not used fire. Though the article did not support the use of fire by Peking man, it raised other questions for further investigation. The investigators found some siliceous aggregates but without any inorganic matter, such as Si, Fe, K or Al. This lack of inorganic elements with the aggregates is not surprising since these chemicals could exist originally in the organic matrix associated with the siliceous aggregates produced by fire. After soaking in water for thousands of years, these materials would decompose, disperse or dissolve leaving no trace of the associated inorganic matter.

There are some other interesting results published in the article. “Only 2.5% of the microfaunal bones were burnt as compared to 12% of the macrofaunal bones. These values are roughly similar to those obtained in much younger caves where fire was undoubtedly used by humans.” Also, “ The few burned bones we did observe above the base of Layer 4 and in the lower part of Layer 10 were turquoise colored, and we assume that they are fossil bones that were somehow burned by natural processes.” The first statement, regarding the percentages of burnt bone in the cave comparing agreeably to what was found in a younger cave, supports the use of fire by men. With the second statement, the author found a different cause of burning matters. However, their experiment showed that turquoise colored bone could be derived from black fossil bone (from layer 10) when heated for two hours at 400 to 800 degree C with optimal temperature of 600 degrees. This fact strongly supports that fire was built above these fossil bones. When heated to the required temperature these fossil bones turned color from gray to turquoise. Other evidence indicates that the fire was not caused by natural process such as burning of guano. From these results, the study, rather than disputing the use of fire by Peking man, may actually support it.

Adam Chou                                                                                                                                 (9)

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Evolutionary Process of Hominids                                                                                         (10) 

Appendix

Peking Man II

Peking man cave (or known as Zoukoudian or in other spellings representing Chinese pronunciations) is located thirty miles southwest from Beijing or Peking in a hill named Lungkushan ( translated as Dragon Bone Hill). In this vicinity there are twenty-six locations including several caves containing signs of early man activities: stone tools, ashes or fossil bone of hominids. Peking man cave is the largest and best known with the greatest amount of artifacts and human fossils.

Peking man cave consists mainly of limestone deposit and was first excavated in 1930. The excavated part is about 40 m high, 175 m long and 50 m wide; the volume of this cavity is larger than several three-story houses with three-bedrooms and baths. Parts of the cave are un-excavated to be saved for the future explorations, which have happened since the early excavation in 1930s. Eighteen layers of sediments in this partially excavated cave were resulted from flooding and collapsing of the roof numbers of times in the past, during a large part of Middle Pleistocene. Stalagmites were found in Layer 5. Active hyena presence was observed for this layer too. Many writers treated all excavated layers in the cave as one identity, which, to me, is unscientific. Some consider the total history of the layers, 1st to 10th, as 300,000 to 500,000 years, then, a minimum average time span of each layer must be over 30,000 years with some being longer and others shorter in the time span for its accumulation of debris. Much could happen during theses thousands of years and one would be in great error assuming that each layer was formed under a single circumstance. Let Layer 4 to be an example.

Layer 4 is general considered an ash layer due to its dark color. Hominid fossils were found in this layer and also hundreds bundles of fine bones appeared to be pellets ejected by raptors, which might not coexist in the cave with early man. It is reasonable to assume hominids lived in the cave during part of the time when the cave was dry; at the other times, birds and hyena might take refuge there. Other scenarios would be that hominids stayed in the cave during darkness since they had fire, or in the winter only. Therefore the intermingling of these remains do not preclude the existence of others. Layer 4 is the thickest of all layers at four meters, which might indicate an even longer time of accumulation than 30,000 years given as average value for each layer. If Peking man resided in the cave for tens or hundreds of years at a time, it is only a fraction of the time comparring to the age of Layer 4. Still, it is more than transient occupancy of the cave by the early man, as some believe.

Adam Chou                                                                                                                           (10)

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Evolutionary Process of Hominids                                                                                     (11)

Appendix

Peking man III

Binford’s article* was published over the protest of numerous Chinese scientists, the contents of the article “suggested’ or “implied” by stating that the cave was not inhabited by hominids. Incurring at this conclusion, Binford committed a mathematical error by overstating his case with too many examples to show alternative explanations for the existing evidences being from natural causes instead of man-made, where these evidences were previously presented by others as from hominid activities in the cave. He stated that human fossils were washed down from the hillside into the cave, so, also, happened to the thousands of stone artifacts, the charcoal fragments were the result of nature fire, the ash layer was discolored from manganese oxide, the location was hyena den, etc. Statistically he could be right some time with one example pointing to natural causes, the odds reduced largely with two examples to be both agreeing with him, and each additional example would reduce further his chance for all of his examples to be correct. In this case with numerous examples, as stated by him to be coincidentlaly caused by nature, would be most unlikely that all of his examples would favor his position. One single exception would be sufficient to refute his negative conclusions and to reinstate the commonly accepted belief that Zoukoudian cave was used by hominids. Furthermore, more than two layers in the cave show signs of human activities, and also Peking Man Cave is not the only site with hominid activities. On this hill, there are up to twenty-six locations, including other caves, contain artifacts, human remains or signs of human activities, some of these locations are older than Peking Man Cave.

Binford’s discussion about the tools found in the cave also raises interesting interpretations. Among the artifacts, there was a pastern bone of a horse, which seems to be used as an anvil. Also, he listed in a table the lithic materials from the 1966 excavation at Location I (also used to designate Peking man cave) which represented 60% as “untouched “ including cores, flakes and debris. The remaining included 27% as hammers and 14% as scrapers, points, burins and points. Such composition of lithic artifacts for this location is not surprising because the cave was used by early man, intermittently, over tens of thousands of years. When they left for some yet unidentified reasons, they would carry the finished tools and leave the detritus. Furthermore, the predominance of hammer stones can be easily explained. This cave is high above the river, the hammers stone were river pebbles which were carried from the riverbed into the cave and they were heavy, having no value to them when early man left this residence since they were easily replenished from the riverbed. According to a count made in 1955, stone tools, flakes, and unused stones removed from the cave are no less than 100,000 pieces.

We should all keep in mind the story of six blind men and the elephant while quoting publications.

* Binford, L R. and C. K. Ho (1985) Taphonomy at a Distance: Zhoukooudian, “The Cave Home of Beijing Man”? Current Anthropology vol. 26, no. 4, p. 413 - 442

Adam Chou                                                                                                                      (11)

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Evolutionary Perspective of Cognition                                                                          (12) 

Background I

Evolution is a continuous process in a step-wise manner and at the same time it is conservative in its changes, as we see the developmental progression of single cell to multi-cell, further to marine animals, amphibians, birds and land animals. During each stage of the evolution, some features of the previous stage are retained. For us, the most noticeable ones are vertebrates, we notice the same vertebral configuration for mammals with backbone and four limbs, birds with leg and wing and even fishes have backbone and fins. The discovery of Tiktaalik, a new found fossil, could be the link to fill the gap between fishes and vertebrates where the fins of this scale-covered fossil fish evolved into protolimbs included bones analogous to human wrists and fingers, enablig it to wade in marshland. Is there such conservation in the evolution of cognition?

Let us review the relationships between the developments of physical body and nervous system. The single cell animal like ameba appears to be sensitive to its surroundings, it moves away from light. Other animals with multiple-arms, such as hydra, jellyfish or anemone, possess a “nerve net” with neurons interconnected like a cylindrical fish net. Starfish has a central nerve ring with radial nerves into each arm. Chordate, an early form of vertebrates, has a small brain connected to a hollow nerve cord without the protection of the hard vertebral bones. Such primitive configurations of the nervous system evolved to the nervous system of humans with a large brain continuously increasing in size. From early form of a brain stem, it grew into cerebrum with four lobes, cerebellum, midbrain, thalamus, hypothalamus, limbic system, and basal ganglia, each with its own function and some overlapping. Recent discoveries by the Howard Hughes Medical Institute and the University of California, Santa Crus, show some genetic evidence for the evolutionary progression of the brain. Areas of some human DNA, HARI, changed partly after separation from chimpanzees, while the other part of the DNA had remained almost unchanged for millions of years, i.e. 18 out of 118 nucleotides had changed since the separation of chimpanzees and humans but only two had changed during 310 millions years, by extrapolation, between the separation of chimpanzees and chickens. (HARI, a regulatory gene produces RNA, is evolved with the migrations of neurons to the cortex of the brain during the formative period of human brain from 7 to 19 weeks of gestation.)  Unfortunately, such conservation of the vertebral system led to the back problems occurring commonly with upright walking man where a single column of bones is not able to provide proper leverage without straining this column of bones and nerves while exerting our body in performing daily tasks. Nevertheless, it is obvious that physiological evolution carries on with the evolution of the nervous system.

Another good example of evolutionary conservatism is the size of human skull which is limited by its proportion to the body carrying it and the tolerance of the birth canal for passing through the head of an infant without endangering the mother. To accommodate the ever expanding needs of extra neurons on the surface of the brain as cortex, the human brain, instead of growing larger and larger to provide the needed surface for the neurons, began to wrinkle with hills and valleys (gyrus and sulcus ) ending with a surface area about four typing sheets of paper which is many time of what would be if it has been smooth as the surface of a sphere. In this way, human has a very large cortex area in order squeeze in billions of neurons.

Adam Chou                                                                                                                              (12)          

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Evolutionary Perspective of Cognition                                                                     (13) 

Background II                   

It is obvious that when we speak about physiological evolution, we must include the evolution of the nervous system, which further extends to the control center of all - the brain. Does this trend apply to the evolution of cognition? The dictionary defines “cognition” as “act, facility, process and capacity of knowing” Cognition is the result derived from the activities of neurons in the brain. How do neurons perform such duties, which appear as Thoughts? In addition, neurons are linked to form certain configurations for carrying messages to different parts of the body. Do these neural configurations evolved from simple to complex and are they always conservative as evolution progresses from one species to another?

We frequently think in terms of body and mind, as distinct parts of the whole, which makes us human. We know, see and feel our body, but not the mind, it represents literal and abstract thoughts, logical thinking, emotion, and feeling, where we feel its metaphorical power. We know the mind is derived from activities produced by the neurons in the brain. We do not know exactly the mechanical functions of the neurons, which produce the phenomena of thinking we encounter every day. What are the configurations of the neurons (which will be referred to in the future as neural system)? Furthermore, what is the role of mirror neuron associated with action and perception? Is infant growth guided by genetics? Autism has its roots in wayward development of amygdala? How does damage to neurons in our brain alters our behavior? What is the relationship between malfunction of neurons and mental disease? What is the effect of hormones on neuron activities?

These are topics worth the joint efforts of scientists from different fields. I hope this website can provide the means for such cross-fertilization. Psychologists work in the metaphoric world of mind, neuroscientists explore the mechanical functions of neurons, studies about animal behavior, infant growth pattern, physiology of body provide us with field data. Aggregation of these data from different sources would greatly enhance our efforts to decode the mechanics of the neural system.

Adam Chou                                                                                                              (13)

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Genetic Data Bias I                                                                                                    (14)

Sampling

DNA Codes give us a most powerful tool to trace the ancestry of hominids. As any tools, there are deficiencies where one should be careful not to accept misleading conclusions. Sampling and molecular clock are two stumbling blocks for accurately tracing human history. We shall first deal with “sampling”.

Genome projects aimed at decipher of human evolutionary history with genetic data are widely funded nowadays, but their value greatly depends upon statistical sampling of the population to acquire a true representative distribution of the traits to be studied. Blood or saliva is taken as the genetic sample of modern men to back trace its history with mathematical technique. Incomplete sampling will lead to erroneous conclusions. Here are two examples.

Chinese Population – The population in present day China is over one billion, the majority being Hans with well-known minorities of Mongolians and Tibetans. In reality there are fifty-six identified ethnic groups derived from Homo erectus migrating into this part of the world over one million years ago. Most of the genome projects have been sampling Hans, with some of the two larger minority groups, without input from the rest of the fifty-three minority groups. In this manner, one can not attain a complete evolutionary history of these populations.

In the past, I published a paper about two genetic traits in East Asia, which hypothesized two migration routes into East Asia by Homo erectus over a million years ago. One was the commonly accepted southern route via Southeast Asia. The other was up through the Silk Route, an ancient trade route from Middle East into the northern part of East Asia. The northern group was overcame by the southern group, probably equipped with bamboo weapons, and scattered the northern group into west and north regions of East Asia as Tibet, Mongolia and parts of Siberia. There might also be possible link of the northern group to the Polynesia, Korean and Japanese as Ainu in term of genetics.

Neanderthal – There are several genome projects studying the genetic codes of Neanderthal and their relationship to modern man. Unfortunately all of these projects share one shortcoming. By filtering the sample to eliminate the DNA which might represent contamination of the samples from being handled by the laboratory technicians. In other word, any DNA representing modern man is removed from the data. From such bias sampling, one should be careful in drawing conclusions since any DNA shared by or with modern man are no longer there or any similarity in genes between Neanderthal and modern man no longer present. The remaining data would naturally point to the conclusion that Neanderthal did not share any DNA with modern man. Also, the sampling of DNA from one or two Neanderthals to study either the possible reproduction of Neanderthal with Homo sapiens sapiens or speciation of the two species would be unproductive since the variations of DNA within Neanderthal group were not evaluated, which could account for a large part of the dozens DNA difference found between Neanderthal and Homo sapiens sapiens.

Adam Chou                                                                                                              (14)

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Genetic Data Bias II                                                                                                   (15)

Molecular Clock

Molecular clock is a method to date the genetic history of hominids or age of species based on the accumulation of genetic mutations. However, the genetic codes change haphazardly and unpredictably resulting random intervals of DNA mutation. Several assumptions were made to apply this method for this purpose. In the case of either mitochondrial-DNA (mt-DNA) or Y-chromosome studies, we need DNA from representative groups of individuals out of the world population. For each group, there should be numbers of individuals. Let us assume that we have obtained such DNA sampling.

The first step to do is to eliminate the gene variations occurring within the groups from the overall gene pool. This is the reason we need several individuals from each group. The remaining gene variations would be shared commonly in different degrees by the different groups of the population selected. For example, some genes would appear in all groups of the population. This fact suggests these genes are the oldest in terms of evolution and would be placed at the main trunk of the tree. Others are possessed by a single population, naturally, they represent the youngest racial group and should be placed as the outer twigs, or as a single twig representing isolated group like Sami or Ainu. The computer program is designed to analyze this information in generating a tree representing the lineage of hominids.

In principle, this computer program algorithm is similar to the least-square–fit method for selecting mathematical function representation of a set of data. For this application, it is called principles of maximum parsimony. To initialize the computer program, some main branches of the tree are hypothesized as inputs to the computer program. Naturally, African gene would be used as the trunk or the first few closest branches. This is where some people dispute the results because a bias is introduced here. However, this issue is not in serious dispute since it is generally accepted that man’s origin was in Africa and numerous migrations out of Africa into the rest of the world occurred in the past. The computer program also provides statistical values to show “goodness of fit”. Changing the branching of the tree can be made to improve the fit.

Molecular clock is used to estimate the diverging time at which the populations evolved, as limbs, twigs, branches from the trunk, in the form of mutation of the genes. The constant used for the molecular clock method is a value calculated from average rates of mutation based on millions of years of evolutionary process, hence, it  introduces errors, especially serious ones for short spans of divergence time. Mutation as a part of evolution is a random process and the rate of change in terms of genes is erratic, not constant. However over a long period of time, as tens of million years, an average value of these rates can be calculated for estimating divergence time of species with tolerable error. Mathematically, molecular clock value is derived from linear approximation of a group of scattering data based on our known knowledge of evolutionary transfromation for species over tens of million years spans. The slope value of this straight line can be used for large time span as millions of years to approximate divergence time between the species or events with some uncertainty. On the other hand, a hundred thousand years time span is near the origin of the time coordinate where the error is the greatest, as in the case of African Eve application. For this application, the obtained result would be in significant error and could render it seriously flawed.

Adam Chou                                                                                                                    (15)

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                                 Gap Between Cognition and Neurons                                       (16)

Brain is the site as governor for numerous body functions such as cognition, emotion, memory, motor, and homeostatic functions. However, most of us usually make a distinction between “mind” and “brain”; the former is recognized as site for mental attributes such as cognition, emotion, beliefs while latter represents the site for electrochemical neural processor governing body functions. Neuroscientists, pursuing “brain”, study neurons and neural systems, and psychologists, pursuing “mind”, study cognitive functions such as emotion or feelings, mental diseases, and other psychological events. In between these two fields, there is somewhat a no-mans land where the knowledge linking the functions of neurons and cognition is limited.

We know that neurons are connected, like mirror neurons, through axons and dendrites across the gaps of synapses, but we have no or little knowledge about the configurations of the neural nets, or how they convert the chemical or electric codes via neural transmitters from neuron to neuron to perform different functions we do daily. We know one of the early body functions of animals is advance or retreat, which even simple ameba knows to avoid light. The understanding of eat/ be-eaten or fight/flight or distinguish between friends and foes requires more complex neural linkage than what ameba have. But it is easy to visualize that the neural network of ameba gradually evolved in succession into other species with additional neurons to form a network to perform the more demanding functions like distinguish friends from foes. If evolution is conservative, would this principle also apply to neural network, so it evolves from a simple configuration to a large network with thousands or million of neuron to perform some specific task?

We also know that infants grow in pre-specified progression, holding up head, rolling over, sitting up, standing on two legs and finally walking. Psychologists have found all infants progressing in this sequence within certain time frame as a rule. What directs these developments? Is it genetically coded to progress with this formidable schedule?

Adam Chou                                                                                                                (16)

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                                                 Thought Process I                                                    (17)    

                                                      Introduction

Evolution is a continuous process and progresses in a step-wise manner where some features from the previous stage of evolution would be conservatively retained for the next stage. Further more, physiology and cognition evolve in tandem, where they are stimulated by external forces, such as environmental changes or internal forces like adaptation to a niche. Human’s niche is our brain; as discussed in The Evolutionary Process of Hominids, our brain enlarged during every step of the evolutionary process through stimuli of adaptation to this niche. Early man inherited from the primates telescopic vision, forelimbs evolved as hands with opposite thumb for grasping, and also the rotation of the shoulder, instead of forelimbs pointing downwards for walking on four legs, the shoulder blades rotated to permit the forelimbs as arms to be used for swinging from tree branch to tree branch in search of food. Changes of climate, according to some scholars, in the region where the early man lived caused the trees to disappear resulting in savanna or grassland. As hominids came down from the trees, rather than adopting the knuckle walk of the apes, they began to develop walking upright with swing arms. Evolved into such bipedal locomotion represented a big break with the past and it must take a long time to reach this walking style. However, it greatly improved the ability of hominids to cross various terrain efficiently. From the achievement of upright walking and freeing of the hands, early men were able to extend their skills in acquisition of food to include anything eatable. The discovery of using stone tools greatly improved their ability to acquire high protein food like meat from scavenging carcass, cracking bones for mallow, even hunting small animals to provide additional nutrients for the maintenance of the brain. These started the cycle of more nutrient food fueling the brain, and larger brain leading to more mental agility in improving their life style through greater dependence upon the brainpower. Early men evolved from Bipedal Development, through Social Development ending with Communication Development. Would such an evolutionary process apply to the evolution of cognition?

To explore further the elements of thought process, we examine other scenarios, as given in the following articles, which seem to contain basic traits shared by many animals. Could they be based on the same basic configuration of neurons evolved into greater complexity?

Adam Chou                                                                                           (17)          

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                                   Thought Process II                                             (18)       

                                      Mirror Neurons I

Mirror neurons are the most interesting and important recent discovery showing the relationship of cognition with specific neurons as linkage between perception and motor action. These neurons react while one observes a scenario where a subject either performs an action or when the subject observes the same action performed by others. Mirror neurons were first found while observing activities in the left middle temporal gyrus and the inferior frontal gyrus of monkey brains, and the existence of these neurons in human brain was confirmed indirectly with neurophysiological and brain-imaging experiments. Besides humans and primates, mirror neurons have also  been observed in birds.

Mirror neurons were discovered by G. Rizzolatti, L Fogassi and V. Gallese during an experiment in which electrodes were placed in the inferior frontal cortex of a macaque monkey to study the control of hand movements by specific neurons. They found that these neurons not only reacted when the monkey reached for food such as fruits in a bowl, but also when the experimenter stood near the bowl containing the fruits. Further experiments confirmed that these neurons responded both while the subject performed the action or observed the same action done by others. However, when the food item was held by a tool, such as a pair of pliers, no response was observed. This is very significant since the monkey, not familiar with this tool, did not associate the food being held by the pliers as meaningful to his experience of being held by hand, hence no response. This is further evidence of mirror neurons’ association with conception related to previously learned experience.  

The test involved 532 neurons, while only 92 reacted to the stimulation of the experimenter. They were identified as in F5 and appear to be related to linkage between hand and mouth. Further tests showed that some neurons responded to the sight of a hand approaching and grasping object, where different manners of grasping were conducted such as precision grip, finger prehension or whole hand prehension. For these tests, less than dozen neurons appeared to be involved at a time. It is very exciting to think such a small group of well-defined neurons will give us new insights into neural configuration and the mechanism of cognition.

Adam Chou                                                                                                                       (18)

Gallese, V., L. Fadiga, L. Fogassi and G. Rizzolatti, (1996) Action Recognition in the Premotor Cortex. Brain, 119, 593-609 (Also available from Goggle Scholar)

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                                              Thought Process II                                                              (19)

                                                 Mirror Neurons II

Recent studies by the University of College of London with ballet dancers showed that the brain acted differently for an individual skilled in a certain dance routine than one who was not. Individuals from groups of expert dancers and non-dancers were asked to lie perfectly still in a MRI scanner watching a video of brief dance movements. It was found that the brain area known as “mirror neurons” lighted up more strongly when the subject, an expert dancer, observed movements he had been trained to do than the dance movements in which he had not been trained. At the same time, the non-dancers’ brain responses were appreciably less compared to the expert dancer. These results demonstrate another aspect of the mirror neuron functions in relationship to conceptual realms where hand and mouth are not involved and also the importance of the existence of prior knowledge.

So far, we have learned that mirror neurons describe a linkage between perception and action, each group involving only a limited numbers of neuron, which are located at frontal lobe, for thinking and parietal lobe, for action. We also know primates and at least some birds have them. Do other animals have them? Is ameba’s flight from light triggered by an early form of mirror neurons? I know that when I learned to play tennis, it was a constant drill to learn the skill and I soon lost what I had learned if I did not practice. How about great athletes, do they learn their sports easier; Tiger Woods, for example, do his mirror neurons perform more effectively than lesser players?  Do we have a set of mirror neurons for every action or every combination of sensor and motivator as in this case of hand and mouth? How many are there? For extreme sports, do  athletes develop new sets of mirror neurons while learning their skills? These are the questions facing us along the road of further research into cognition.

Mirror neurons, as originally discovered with monkeys, reside in F5 area of the premotor cortex. They show congruence between the visual actions they respond to and the motor responses they are coded. According to the degree of congruence, they are grouped as “strictly” and “broadly” congruent. Strictly congruence, representing one third of the F5 neurons, is defined as that the observed and executed actions both strictly correspond to the goal  (grasping) and means for reaching the goal (precision grip). The remaining two third of the F5 neurons, defined as broadly congruent, are less strictly congruent between the goal and the means for reaching the goal. This classification of the mirror neurons might provide insight to the above sports related questions, where strictly congruent neurons are trained such as my learning to play tennis. With Tiger Woods and other outstanding athletes, their broadly congruent neurons are easily trained to become strictly congruent neurons? 

Adam Chou                                                                                                                      (19)