When the earth appeared for the first time it was very different from its current conditions. The surface of the earth was represented by bare bedrock. At the time of its birth, the earth represented cold matter, close by its composition to meteorites. Material it was mad of, contained radioactive elements. In consequence of the heat excretion while radioactive decomposition of the core and gravitational compression. However, because of continuous loss of heat through he surface and lack of radiation heat complete melting of the earth did not happen. In result of earth’s melting, water and different gases were brought up to the surface. This water began formation of hydrosphere.
Location of continents and oceans were very different. According to Wegener’s hypothesize, which he later supported by evidence, earth’s continents used to be a single land, which was called Pangea. About two hundred million years ago Africa and South America slowly began their movement toward their current location. Wegener supported his hypothesize by geological and biological evidence. At the place where the continents were aligned, were found fossilized animals and plants dated more than two hundred million years old. Besides, if Africa and South America had always been separate continents as they are now, both of them would have had very different flora and fauna, which are not.
Starting at 1950 up to 1970 evidence begin exposing to the world that support hypothesis of continent’s slow movement. Sonar mapping of the ocean floor showed winding, continuous ridges system around the planet. The ridges appeared where molten matter was coming up from the earth’s inside.
Not only topography of the earth has changed, but composition atmosphere has changed as well. Current atmosphere contains a lot of oxygen, which is result of existence of life. During photosynthesis, green plants consume water and dioxide and release oxygen in atmosphere. This is considered to be a secondary claim because even if the earth would not developed as it considered, it would have no impact on evolutionary theory.
Origin of human being was an interest of human more than origin of plant and animals. Attempt to understand and explain origin of humans is expressed in religions, legends of all kind of trails and folks. For a long period of time science knowledge were abrupt and incomplete in order to solve a problem of human origin. Only in 1857 Darwin expressed hypothesis, and in 1871 in his book “The Origin of man and relation to sex,” convincelly proved that humans originate from pre-existing humanlike, but were not created by intelligent designer. Role of social factors, which was pointed out by Darwin, was detailly described by Fredrik Engels in his book “Role of labor in the process of turning ape into humans.” (1896)
Human and vertebrates commonness is strongly supported by similar arrangement of internal organs: skeleton, nerve system, blood system, respiration, and digestion.
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Rudiments and atavisms are very important evidences of human relatedness to animals. There are about 90 rudiments in human body: coccyx bone (remaining of the reduced tail); folds in the corner of the eyes (remaining of the blinking tympanum; thin body hair (remaining of the hair). All these rudiments are inherited from an animal ancestor. An external tail, which sometimes people are born with, is related to atavisms. Another atavism is abandon hair on the face and body.
Common details of the body arrangement are evidence of close relativeness of human and anthropoids: wrist with flat nails, shape of eyes and years, the same number of canine and molar teeth, complete change of baby teeth, and so forth. Physiological commonness is very important: the same blood groups, diseases (tuberculosis, fly, smallpox, cholera, AIDS, pneumonia) and parasites (louse). Besides numerous common features, there is a number of explicit differences evidencing that its current stage, human is considered to be different species. Only human has ability of upright walking and related to that peculiarity of structure of the S-shaped backbone with explicit neck and lumber bend, low extended pelvis, and etc. Human skull is higher and more rounded without superciliary arch; brain part of skull is in most part dominated by facial; high forehead, weak jaws with small canine. Human brain is about two and half times bigger than one of humanlike apes, and 3-4 times heavier.
Human being evolved from other pre-existing species. Even in ancient times it has been noticed that humans have a lot of in common with a other animals just like other animals human had the same internal organs (heart, lungs, liver etc.). Ancient Greeks had a scale of living organisms known by their time. Human being was placed at the end of the scale. Below were higher animals like houses, sheep and so forth, but it is hard to believe that humans were next step in the biological evolution of living organisms right after higher animals. Only by the eighteenth century ape-like being became known to Europe. This discover shed light on a huge gap between higher animal and humans (Darwinism defended, Ruse, pp. 230). After that some scientists (for example Huxley) assumed that humans descended from apes. Later, having examined all differences between apes and humans, Huxley came to conclusion that humans and apes descended from a common ancestor. One would probably ask why our common ancestor did split into two branches, apes and Australopithecus afarensis (which is considered to be an ancestor of all hominids). There is a scientific explanation, which relates to climatic changes in Africa. Our ancestor was used to live in the area of heavy precipitation. With a passage of time climate started turning into dry one and forestlands began retreating, leaving behind Savannah’s. Some species stayed in dwindling forests. Others (our ancestors) started advancing toward opened spaces.
With a change of place of inhabitation, there were some changes in diet of our ancestor. Anthropologists suggested that tooth reduction took place because our ancestor started to use grass seeds and the like as a food source (Darwinism Defended).
