If excess population growth expands then it drives the competition to struggle leading to starvation and diseases. When two species exsisted as one when there were originally two Darwin called this splitting- and- specializing phenomonon the "principle of divergence". This explained the overall diversity of life as well as the adaptation of indivisual species.
Dictionary.com defines theory as a coherent group of general propositions used as principles of explanation for a class of phenomena. There are many theories that are accepted as fact, but aren't facts at all, they are simply theories. For example, the existence and structure of atoms is called Atomic Theory. Evolutionary Theory is a very hotly debated topic.
Many people disregard Evolutionary Theory as nonsense because of their close followings of the Book of Genesis. According to Wikipedia The Book of Genesis is about the creation of the universe as well as the creation of man and how God is responsible for these happenings. Many people disagree with the beliefs of Evolutionary theory due to their beliefs in the fact of The Book of Genesis.
In a Gallup Poll (an opinion poll) forty-five percent of responding adults believed that God created life, and evolution was a non-factor in the creation of mankind. Some believe that a lack of education in biology classes can lead to beliefs like this.
According to this article, the supporting evidence for evolution is abundant, various, ever increasing, solidly interconnected, and easily available in books, museums, textbooks, and scientific studies.
Nearly half of Americans believe that Charles Darwin was wrong where it mattered most. Creationist proselytizers and political activists, work hard to interfere with the teaching of evolutionary biology in public schools.
Many people have never taken a biology course that dealt with evolution nor read a book in which the theory was explained in great detail. Most sources that of information from which most Americans have drawn their awareness it seems, are haphazard ones at best: cultural osmosis, nature documentaries, and hearsay.
"The theory of evolution is no longer just a theory; an overwhelming amount evidence has accumulated since Darwin. Darwin's theory has never been successfully refuted. Darwin discovered a law just as surely as Copernicus, Galileo and Newton discovered laws: natural laws." (Biographies - The Scientists: Charles Darwin.)
