Evolution by definition of Webster dictionary is a gradual development of simple matters into more complex. When most of the people hear “evolution” it associates with development or history of the earth. History of the earth compiles of gazillions of steps. The very first step in our history is a birth of the earth, which took place over 4 billion years ago.
“Powerful telescopes reveal new stars coalescing from galactic dust, just as our sun did more than 4.5 billion years ago. The earth itself formed shortly thereafter, when rock, dust, and gas circling the sun condensed into the planets of our solar system. Fossils of primitive microorganisms show that life had emerged on earth by about 3.8 billion years ago (Teaching about evolution and the Natural of Science, ch. 1).”
Many people throughout the centuries have been trying to find explanations to the questions like: Why are surrounding us things the way they are?; why some type of animals resemble another one? It was hard to answer these questions without proper tools, experience and background knowledge. Even nowadays, not all questions are answered. Darwin was the first human who succeeded in responding to these questions. He was the first one who put discovered facts and knowledge available by his time in one big picture. In attempts to explain the history Darwin created the most outstanding achievement of human beings that had enormous impact of our thinking—evolutionary thinking. Ernest Mayer, in his book “One Long Argument” says following about impact of Darwin’s work on human thinking.
“It is almost impossible for a modern person to project back to the early half of the nineteenth century and reconstruct the thinking of this pre-Darwinian period, so great has been the impact of Darwinism on our views (E. Mayr, pp. 1)
For our further discussion, one should explicitly distinguish between evolution and evolutionary theory. Evolution (history) is a serious of facts that occurred since the birth of the earth, while evolutionary theory is the best way available nowadays to explain why evolution happened the way it happened, but not otherwise. Both evolution and evolutionary theory make series of claims. Some of them are secondary and some are primary. Primary claims if proved wrong, would change entire theory.
Primary Claims of Evolution
The earth is over 4 billion years old. In the past when technology was not very developed it was hard to prove age of the earth. Scientists had been aging by measuring the rate of sedimentation. Another method of defining age, which was used in 1800s, is noticing what kinds of fossil rocks have. Currently it is done by chemical analysis of composition of fossil.
“Some elements such as uranium, undergo radioactive decay to produce to produce other elements. By measuring the quantities of radioactive elements and elements into which they decay in rocks, geologists can determine how much time has elapsed since the rock cooled from initially molten state (Teaching About Evolution and the Nature of Science).”
Life on the earth did not appear right after appearance of the earth. The first sings of life were dated about 550 million years ago according to the oldest fossils. This fact does not specifically mean that where was not life forms before that time. Life forms were very simple and lacked hard parts like bones or shells and could rarely preserve in the fossils.
“However, a few pre-Cambrian organisms left traces of their existence. Some ancient rocks contain stromatolities—the remnants of bacteria that grew in columns like stacked pancakes (Teaching About Evolution, ch. 3, pp. 2)
Extinction is a major feature of biological evolution. It is in a tight connection with natural selection. Natural selection works only by means of surviving of changes, in some sense useful, and therefore, striking root. In the consequence, fast increase of the numbers of all organic matters in geometrical progression, every natural habitat already filed to the limits by its habitants. From this it follows those more adapted forms will increase in numbers and less adapted, will decrease in numbers and become rare. Rarity of the form is a predecessor of the extinction. Every form represented by small numbers of individuals has big chances for a complete extinction in consequence of significant climatic swings within a year or in consequence of temporary increase of enemies. Species, most abundant of individuals, have the biggest chances for appearance at any particular time of favorable changes. Rare individuals will at any particular time change and perfect at a slower pace and in consequence of that will be defeated in a life struggle with changed and improved descendants of more common individuals. From this it follows that since with a passage of time natural selection “creates” new species, than other species become more rare, and finally extinct.