Impact of Evolution on Human Thought

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.

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).

Major Claims of Evolutionary Theory

Natural selection is the major moving factor of the evolution of the living organisms. Almost at the same time, several English naturalists arrived at the idea of existence of natural selection (P. Mathew (1831), A. Blight (1935), A. Wallace (1858), C. Darwin (1858)), but only Darwin succeeded in exposing of the meaning of this phenomenon as the major factor of evolution and created the theory of natural selection. On the contrary, to artificial selection held by humans, natural selection is conditioned by influence of surrounding environment upon the organisms. According to Darwin natural selection is survival of the most accommodated organisms, in consequence of which, on the basis of undefined inherited changeableness in the series of generations evolution occurs.

In process of natural selection species more accommodated to surrounding environment survive, those who do are not, go extinct. Explicit example of that is our ancestors that had advantage of standing upright to look out and look for possible object of prey. Natural selection does not specifically have to lead to perfection. It leads only to surviving of species that can survive. If entire kind of particular animals can not survive in changed environment, entire kind will dye out.

“Organisms in nature topically produce more offspring that can survive and reproduce given the constraints of food, space, and other resources in the environment. These offspring often differ from one another in ways that are heritable—that is, they can pass on the differences genetically to their own offspring. If competing offspring have traits that are advantageous in a given environment, they will survive and pass on those traits. As differences continue to accumulate over generations, populations of organisms diverge from their ancestors.”Process of natural selection consists of two steps: the first one is reproduction of genetically different species; the second step is surviving of the most adopted individuals in surrounding environment. An example can be nest of birds in which some nestlings have a little bit different coloring than others. If this coloring better matches the tree these birds in habit, this will give them advantage of better hiding from predators, which leads to increase in changes of reproduction. Below are example that Wallace, Alfred Russle uses in his book “Contributions to the theory of Natural Selection” to demonstrate natural selection.

“The Duke of Argyll, in his “Reigh of Law,” has pointed out the admirable adaptation of the colors of the woodcock to its protection. The various browns and yellows and pale ash-color that occur in fallen leaves are all reproduced in its plumage, so that when according to its habit it rests upon the ground under trees, it is almost impossible to detect it. In snipes the colors are modified so as to be equally in harmony with the prevalent forms and colors of marshy vegetation. Mr. J.M.Lester, in a paper read before the Rugby School Natural History Society, observes: --“The wood-dove, when perched amongst the branches of its favorite fir, is scarcely discernible; whereas, were it among some lighter foliage, the blue and purple tints in its plumage would far sooner betray it. The robin redbreast too, although it might be thought that on its breast made it much easier to be seen, is in reality not at all endangered by it, since it generally contributes to get among some russet or yellow fading leaves, where the red matches very well with the autumn tints, and the brown of the rest of the body with the bare branches.”