evolution
...ion or 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. By chance, some varieties prove to be poorly 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. The science of paleontology or the study of life provides the most direct proof of evolution in the past through fossil remains or impressions, usually in rock. Other evidence comes from comparative studies of living animals and plants, including their structure and geographical locations. “Mollusks and vascular plants account for more than 80 percent” (Futuyma 87) of the world’s species, with about “1.4 to 1.8 million species” (Futuyma 87) in all. Changes occur in living organisms to help increase their adaptability, or potential for survival and reproduction, in the face of changing environments. Evolution apparently has no built-in direct...