What Is Evolution?

In trying to explain the existence of the complicated body structures in living things around us, the theory of evolution has been developed. This theory is that all the plants and animals in the world today have developed a natural way from earlier forms that were simpler. According to this theory, men are too, developed from some simpler form, just as the modern one-hoofed horse is the descendant of a small five-toed ancestor.

In trying to prove that evolution did take place, scientists depend on three chief "signs". One of these is the study of fossil remains of animals and plants of past ages. Some of these fossils seem to trace the steps of evolution at work. Fossils of certain crablike animals go back nearly 500,000,000 years and those have shown that fish developed in the waters of the earth before amphibians, amphibians before reptiles, reptiles before birds and so on.

Another "sign" of evolution came from the study of embryology, the growth of a new living thing from an egg. In studying the development of the chick from the hen's egg, there was a time when this embryo was like a fish, later it was like an amphibian, then it passed through the reptile stage and finally into its bird form. The unborn young of all animals go through the same kind of process, repeating their history of development.

The third "sign" is the bodies of living animals. For example, the bone and muscle structure in the paddles of a turtle, the wings of a bird, the flippers of a whale, and the front legs of a horse and the arms of a man are similar in structure. These are some of the "signs" that led to a theory of evolution.

The term evolution is a noun which refers to a gradual process wherein something transforms into a different and typically more complex or probably better form. It could be thought of as development. Thus it could refer to the process of developing; or possibly gradual development.

The term evolution is commonly used in the field of Biology where it implies a transformation in the basic genetic composition of a given population over successive generations, resulting due to natural selection which acts on the genetic deviation among individuals, ultimately resulting in the advancement of new species. Here it could also refer to the historical development of an interrelated group of organisms; that is, phylogeny.

The term evolution is a noun which refers to a gradual process wherein something transforms of ordered movements.