Human evolution, the biological and cultural development of the species Homo Sapiens, or human beings. A large number of fossil bones and teeth have been found at various places throughout Africa, Europe, and Asia. It gives idea of human evolution during past 4 million to 5 million years. From a genome view point, the difference between modern man and the modern apes is only about 2 percent. From a physical viewpoint the greatest difference is in locomotion. The human walks upright, it is generally thought that this came about when the ancient hominid adopted the edge of the forest and plain and adapted to a life under the trees as opposed to in them. Fossil evidence shows that is bipedal adaptation was completed quite early, perhaps as early as four million years ago, long before we do today. Facial feature changes toward the modern appearance came much later. The facial characteristics, of modern man are about 100,000 years old.
The faces of earlier hominid were much more apelike. Any mutation must be applied to a DNA coding that already exists. It can not be applied to coding that does not exist. is this a silly statement? No at all. It leads to the way that evolution changes an organism. Mutations a real ways applied to the existing DNA coding. Evolution makes something new out of something that already exists. If a bear becomes distressed in a given environment, it does not sprout wings and fly. Instead, such things as longer legs or claws will be tested. Also, evolution often does not fix the thing that causes a problem, it patches the problem by doing something unrelated. If an organism suffers a mutation that shortens its life so that it has difficulty rearing its children to childbearing age, that mutation will started being culled from the gene pool. Before that mutaion has been completely removed from the gene pool, another mutation may occur which shortens, the ge!
station period or child development period. If this shortens the child caring requirements enough so that the shortened life is no longer a problem, then both mutations would be acceptable as permanent residents in the gene pool.
One must remember that every cell in the human body can perform any function. Two copies of the entire genome are in every cell. A cell that is in the liver chooses to do that function. The cells in bone or in the brain choose to do those functions. When a mutation happens, it is either to the inner function of a cell, or to the size and shape of the overall cell stuchture.
The brain did not start with man, there were many examples of single cells that had simple versions billion of years before the first hominid appeared. Photosynthesis requires light. If a cell that depended on light drifted too low in the water or drifted under a land overhang that abscured the sun, it was in deep trouble. Some developed a light sensor and a method of swimming. For the system to work, they developed a central control system that would judge the amount of light and if it was insufficient would turn the cell toward the light source and swim in that direction. It would keep swimming until it was bathed with sufficient light. This was all done within a single cell organism. Early animals developed cells that connected their various muscles to the central control area, Commands from the brain drive muscles through these nerve cells.
Every cell in an organism carries all of the information in its DNA for the entire organism. Evolution constructed the verve cell from the standard cell. It also constructed nerve cells that connect the various sensors (ear, eyes, nose, skin) to the central control area. These nerve cell scarried sensor information tot eh brain. Further cell adaptations in the central control area provided function linkes. If the ears hear a loud bang then tell the leg muscles to jump the other way. If the stomach says it is hungry, go bite something. We refer to these permanent. It must allow some leeway. No animal is totally instinctive. All animals have some memore, some reasoning ability, and some decision making ability. We differ only in degree. The first hominid had all of the neural elements that we have today, as do the chimp and your pet poodle. The mutaions that built our brain from that first hominid were more about quantity, shape, and organization tha!
The thing we must remember is that africanus had a 450cc brain. We now have a 1350cc brain. That africanus brain is still in there. Evolution patches over. It does not do house cleaning. Another rthing to remember is that evolution has a zero IQ. It was not bein gintelligent when it formed the rest of our brain. It was much more interested in the sex life o f our DNA.
Even that is not eh whole story. Africanus was largely insticntionve, most of the add-ons to his brain have been intellectural. Those original instincts were strong and uniform. Evolution was to that. His world was brutally uniform and required full time participation. Any deviant inividual behavior would affect the birthrate. Evolution would not tolerate it. His instincts were well maintained.
Intelligence is always at odds with instinct. If the instinct provided proper survival action, there would be no need for intelligence. Indeed this is the case with all of the other animals. There are literally thousands of species that survive quite well with little intellectual ability. That is why we got it in the first place. By controllight our instincts we could provide action that enhanced our survivability. A little self-discipline provided great survival dividends, and it worked. Man has conquered the world. He is the fat cat. He is on top of the heap. Yet now, peak intellectual performance and self-discipline are no longer requirements of survival. Man has become self-indulgent and has reverted to satisfying his instincts.
That is way today we act like africanus though we have a 1350cc brain. Africanus would object loudly to that statement, because that statement is not quite true. We would not live a hour in his environment. We have reverted to his instincts, that is true, but those instincts are now perverted. Through discipline, man substituted intelligence for instinct over a long period. During that time the instincts suffered mutations. Since both the original instincts and their mutations were being overridden by intelligence, the instinct mutaions were not considered detrimental by evolution and so accumulated in the gene pool. We have now reverted to a set of perverted instincts and now cater to those perversions by calling them normal. We excuse behavior now that would horrify africanus.
Alliance formaion and maintenance requires an animal to analyze a significant amount of information, including the relations between individuals involved in the alliance as well as their relations to othe rindividuals. Alliances can also operate in different levels of associations, and an individual must be able to weight and compare the costs and benefits of actions that may differentially affect different levels of alliances. These nested alliances entail a certain amount of mental sophistication, potentially involving predictions of others actions before a situation exists. Primates in particular seem to groom their relationship with potential allies before an actual contingency arises. The motivations underlying alliance formation are undoubtedly difficult or even impossible to assess, but it is clear that animals do rely on some base of knowledge about social relationships to guide them.
During the last Ice Age, about 30,000 years ago, Homo Sapiens modern humans were physically the same as people living today. Although the physical characteristics of human being shave changed little since the Ice Age ended about 10,000 years ago, cultural evolution has dramatically transformend human society. In the time span encompassed by Ice Age Paleolithic societies on the one end and contemporary information based societies on the other, a succession of forms of social organization has unfolded.
Form the other direction, while the field of behavioural ecology has blossomed in the last thirty years, especially with regard to primates, cognitive ethology is still being defined. The tow are intimately connected, and to the extent that cognitive ethology examines the social behavior of animals, its groundwork has been laid within behavioral ecology. Certainly only an extreme adherent of either an ecological or social hypothesis would claim that an animal¡¯s foraging strategy depends solely upon the nature of the food resource or upon its maneuverings within social context. Which came first? Can we Know? Similarly, did foraging strategies and social structures coevolve, or did one drive the evolution of the other? And finally, how did social interactions develop of primate intelligence can be definitively shunted into one category or another. While ecology may have provided the initial conditions, cognitive evolution undoubtedly soon spiraled into a complex, interconnected web of adaptation, co-evolution, and cooption of cerebral traits to cope with changing ecological and social conditions.