Natural selection and evolutionary theory

Natural Selection

First described in full by Charles Darwin, natural selection refers to the process by which organisms evolve by adapting to their environments. Natural selection does not occur instantly in response to an environmental change, however. Rather, natural selection occurs over the course of several successive generations. Those organisms that successfully survive the environmental changes due to their inherited traits will pass on their genes to their offspring. Thus, only those organisms with hardy genes will survive; hence the phrase "survival of the fittest." While natural selection does occur unaided by human beings in the natural world, humans are beginning to alter the course of natural evolution through the creation and implementation of certain chemical products. Moreover, environmental pollution and other human factors impact the process of natural selection and evolution in the plant and animal kingdoms. Chemical products such as antibiotics, pesticides, and herbicides in particular threaten to create strains of unwanted or destructive species. In the search for weed-free fields and disease-free bodies, human beings may be unwittingly creating "super bugs," or viruses that are virtually indestructible. Therefore, a thorough understanding of the basics of natural selection is important in understanding the full environmental and human health ramifications of using antibiotics, pesticides, herbicides, and other chemical means of killing off unwanted organisms and bacteria.

By creating and using new chemicals, human beings are directly causing rapid natural selection in bacteria strains, insects, viruses, and weeds, mainly because these products do not eradicate all the target organisms. Those organisms with hardy genes, genes resistant to the chemicals, will survive and in turn pass on their hardy genes to their offspring. The offspring will therefore be resistant or entirely immune to the chemicals, rendering them ineffective. Moreover, because only the stronger organisms survive, subsequent generations of unwanted species will continue to reproduce, according to natural selection, with increased strength and resistance. For example, a bug spray will not kill all ants or roaches. Furthermore, only those ants and roaches that are immune to the spray will survive and reproduce. Their offspring will also possess the resistant genes. The bug spray provided but a short-term solution to an insect problem. In the long run, more effective sprays must be developed. However, the same problem will happen with each subsequent spray development. In fact, the situation worsens because the harsher the chemicals become, the more hardy the ant populations will become. Before long, human beings might not be able to create chemicals that can challenge insect populations, or those chemicals might end up being more harmful or destructive than the insects themselves.