How is Darwin's theory different to other theories

Jean B.Lamarck (1744-1829): Lamarck developed a theory of evolution based on the idea of an organism's movement toward increasing complexity. As these organisms attained perfection, they became better adapted to their environments. These organisms responded to their "felt needs". Organisms that used a certain part of their body to cope with the environment developed these organs, while the organs that were not used deteriorated. This is commonly known as the use and disuse idea. These newly acquired characteristics where then passes on to its offspring. These ideas were in error since acquired characteristics cannot be passed on to an organism's offspring.

Charles Darwin : The Voyage of the Beagle, beginning in December of 1831, opened a new chapter in the study of evolution. The voyage was to chart the coast of the poorly known South American coastline. This voyage enabled Darwin to observe the various adaptations of the animals and plants that inhabited the diverse environments of South America. On this voyage Darwin came up with the conclusion that the earth was ancient and not static as the theories of the time presented. By 1840, Darwin had formulated his theory of Natural Selection. In June of 1858, Darwin received a letter from Alfred Wallace who was working on collecting specimens in the East Indies. Accompanying the letter was a manuscript detailing Wallace's own work on natural selection. It was almost identical to Darwin's work. Darwin's was given credit since his work was much more extensive than Wallace's. His The Origin Of Species was published in 1859.

Descent with Modification: Darwin did not the term evolution in his book, but used the phrase descent with modification. He perceived that life developed from an unknown common ancestor that lived in the remote past. As these organisms moved into different environments, modifications accumulated over millions of years. Darwin's idea of life was that of a tree with one trunk and many branches. Darwin's book centered on the role of natural selection in adaptation. Natural selection is a differential success in reproduction, and its product is adaptation of organisms to their environment.