NATURAL SELECTION

Natural selection played a very important role in evolution. Natural selection is the process by which species adapt to their environment. Natural selection leads to evolutionary change when individuals with certain characteristics have a greater survival or reproductive rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring.The reason that natural selection is important is that it's the central idea, stemming from Charles Darwin and Alfred Russel Wallace, that explains design in nature. It is the one process that is responsible for the evolution of adaptations of organisms to their environment.Darwin's book On the Origin of Species by Means of Natural Selection caused quite a stir when it appeared in 1859. Evidence to support evolution and natural selection, of course, has accumulated over time, and now science accepts that evolution is a fact and that natural selection explains very well how adaptive evolution takes place.

The idea that life evolves may have been first proposed by Lucretius, a Roman philosopher who lived about 2,000 years ago before he modern theory of evolutions was proposed. Then, in 1859, the English naturalists Charles Darwin published convincing evidence that species evolve, and he proposed a reasonable mechanism explaining how evolution occurs.

Like all scientific theories, the theory of evolution has developed through decades of scientific observation and experimentation. The modern theory of evolution began to take shape as a result of Darwin's work. Today almost all scientists accept that evolution is the basis for the diversity of life on Earth.

Darwin realized that Thomas Malthus's hypothesis about human population apply to all species. Every organism has the potentials to produce many offspring during its lifetime. In most cases, however, only a limited number of those offspring survive to reproduce. Considering Malthus view and his own observations and experience in breeding domestic animals. Darwin made a key association, "individuals that have physical or behavioral traits that better suit their environments are more likely to to survive and reproduce more successfully than those that do not have such traits. Darwin called this differential rate of reproduction by natural selection. In time, the number of individuals that carry favorable characteristics that are also inherited will increase in a population. And thus the nature of the population will change-a process called evolution.

Darwin further suggested that organisms differ from place to place because their habitats present different challenges to, and opportunities for, survival and reproduction. Each species has evolved and has accumulated adaptations in response to its particular environments. An adaptation is an inherited trait that has become common in a population because the trait provides selective language.

In 1844, Darwin finally wrote down his ideas about evolution and natural selection in any early outline that he showed to only a few scientists he knew and trusted. At about this time, both a newly published book that claimed that evolution occurred, and Lamarck's hypothesis about evolution were harshly criticized. Shrinking from such controversy, Darwin put aside his manuscript.

Darwin decided to publish after he received a letter and essay in June 1858 from the young English naturalists Alfred Russel Wallace(1823-1913), who was in Malaysia at the time. Wallace's essay described a hypothesis of evolution by natural selection! In his letter, he asked if Darwin would help him get the essay published. Darwin's friend arranged for a summary of Derwin's manuscript to be presented with Wallace paper at a public scientific meeting.

Natural selection is only the process of adaptation within species, and we see many examples of that. Under some circumstances natural selection does play a role in the origin of new species, by which I mean a splitting of one species lineage into two different lineages that do not interbreed with one another - for example, the splitting of one ancestral primate lineage into one that became today's chimpanzee and the other that became the hominid line resulting in our own species. The process of splitting and becoming reproductively isolated, that is, incapable of breeding with one another, can often involve natural selection but perhaps not always.

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