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What is Evolution?

Evolution is the process by which all living things have developed from primitive organisms through changes occurring over billions of years, a progression that includes the most advanced animals and plants. Exactly how evolution occurs is still a matter of debate, but that it occurs is a scientific fact. Biologists agree that all living things arose through a long history of changes shaped by physical and chemical processes that are still taking place. It is plausible that all organisms can be traced back to the origin of LIFE from inanimate matter.

The most direct proof of evolution is furnished by the science of PALEONTOLOGY, or the study of life in the past through fossil remains or impressions, usually in rock. Additional evidence comes from comparative studies of living animals and plants, including their structure (COMPARATIVE ANATOMY), BIOCHEMISTRY, EMBRYOLOGY, and geographical distribution. Approximately 2 million different species of organisms are now living, but it is estimated that at least 99.9 percent of the species that have ever lived are now extinct and that some 2 billion species have evolved during the past 600 million years.

Changes occur in living organisms that serve to increase their adaptability, or potential for survival and reproduction, in the face of changing environments. Evolution apparently has no built-in direction or foreordained purpose. A given kind of organism may evolve only when it occurs in a variety of forms differing in hereditary characteristics, or traits, that are passed from parent to offspring. Purely by chance, some varieties prove to be ill adapted to their current environment and thus disappear, whereas others prove to be adaptive, and their numbers increase. The elimination of the unfit, or the "survival of the fittest," is known as NATURAL SELECTION because it is nature that discards or favors a particular variant. Basically, evolution takes place only when natural selection operates on a population of organisms containing diverse inheritable forms. Recently, natural selection was demonstrated for the first time outside of the laboratory when scientists observed guppies change their reproductive behavior over an 11-year period in direct response to being transferred to a new environment that had different predators.

What other evidence does evolution offer in it's favor? Is it the best explanation science has to offer? Let's explore this debate by proceeding to an essay I have written on the subject, an essay titled

Veracity of the Theory of Evolution

1997 Eduardo Diaz Diaz

Last updated: June 20th, 1997