Social Sciences

Theory of Evolution

The evolution, the process of change over time, is the thread that connects the enormous diversity of the living world. An immense amount of evidence indicates that Earth has had a long history and that all living organisms-including humans-arose in the course of that history, from earliest previous forms. This implies that all species descended from other species, in other words, that all living things share common ancestors in the distant past. A series of evidence led Darwin to conceive the ideas that constitute the pillars of the theory contemporary evolutionary.

The concept of gene proposed by Mendel, but unknown to Darwin, possible to understand how the changes could arise, preserved and transmitted from one generation to the next (Hoyle & Wickramasinghe, 25-36).

Evolution: Theory and Evidence

The theory of Darwinian evolution is considered, with justice, as the major unifying principle of biology. Darwin was not the first to propose a theory of evolution, but it was the first to describe a valid mechanism by which it could happen. His theory differed from theories in which he imagined prior to evolution as a dual process, which depended on: 1) the existence of heritable variation among organisms, and 2) the process of natural selection by which some organisms, under heritable variations, left more offspring than others.

There are many evidences that show the existence of the evolutionary process. Distinguishing the field they came from can recognize five sources of evidence: the observation directly, biogeography, the fossil record, the study of the homologies and the imperfection of adaptation.

Since Darwin's time, has accumulated a wealth of new evidence in all these categories, particularly at the cellular, subcellular and molecular level, highlighting the historical unity of all living organisms. A central weakness of Darwin's theory, which remained unresolved for many years, was the absence of a valid mechanism to explain the inheritance (Criswell, 125-133).

In the 1930s, the work of many scientists resulted in the synthetic theory of evolution, which combines the principles of genetics Mendelian to Darwinian Theory. The Synthetic Theory has provided-and continues to provide-the basis for the work of biologists in their attempts to unravel the details of the history of life.

Evolutionary Process

All species of organisms have their origin in a process of biological evolution. During this process new species arise because of a series of natural changes. In animals that reproduce sexually, including humans, the term species refers to a group whose members are mated adults regularly giving rise to fertile offspring, i.e. rods which, in turn, are capable of reproducing. Scientists classify each species using a single scientific name of two terms.

The mechanism of evolutionary change resides in genes, the basic units of heredity. The genes determine the development of body and behavior of an organism during its life. The information contained in genes can vary and this process is known as mutation. The way, in which certain genes are expressed, how they affect the body or the behavior of an organism may also vary. Over time, genetic change can change a ...